Recycling Textile and Plastic Waste (Woodhead Publishing Series in Textiles)

Recycling Textile and Plastic Waste edited by A Richard Horrocks

••••• ••••• ••••• .....-r., •

• •~Q •

BTTG

The 1extile Institute

WOODHEAD PUBLISHING LIMITED

RECYCLING TEXTILE AND PLASTIC WASTE

edited by

A Richard Horrocks Bolton Institute

••••• ..... T, • ••••• •••••

••~O •

BTTG

TIle1extile Instinne

WOODHEAD PUBLISHING LIMITED

Cambridge England

Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB21 6AH, England www.woodheadpublishing.com First published 1996 © 1996, Bolton Institute/British Textile Technology Group Conditions of sale All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 978-1-85573-306-0 Printed by Victoire Press Ltd, Cambridge, England

CONTENTS Section 1:

INTRODUCTION

1

Recycling and Recovery Strategies A Richard Horrocks

3

Municipal Waste Jim Cunliffe

17

Section 2:

27

WASTE MINIMISATION

Turning Environmental Concern into Real Profit Clive Jeanes

29

Reclaimed Fibres, the Source and Usage Andrew Simpson

33

Industrial Waste Water Minimisation and Treatment Allan K Delves

43

The Fibre Industry and Waste Management Nello Pasquini

51

Recycling of Plastic Fibres and Packaging Waste J A(Tony) Horrocks

61

Key Lessons for Plastic Bottle Recycling Andrew Wood

77

Section 3:

87

SCIENCE AND TECHNOLOGY

Nonwovens from Recycled Waste AlfndWmu

89

Recycling Zeftron Carpets Ian Wolstenholme

101

Cotton Waste Reclamation Ferdinand Leifeld

107

Recycling in the Far East Nasim A Minhas

121

The Production of High Tenacity Tapes from Waste Polypropylene Subhas Ghosh & A Richard Horrocks

127

The Role of Process Stabilisers in Recycling Polyolefins H(Heinz) Herbst, K Hoffman, R Pfaendner and F Sitek

135

Recycling Carbon Fibre-PEEK Composites A(Alan) K Wood, R J Day and S F Pang

145

Section 4:

153

ENVIRONMENTAL ASPECTS

The Eco Movement Brian McCarthy

155

Waste - The Politics and Philosophies Barry G Hazel

161

Dyestuffs: The Myths Explored and Problems Aired Brian Burdett

165

Environmental Husbandry Simon Kent

173

PREFACE The current interest in the environment is a consequence of a number of individual factors which have not only become more understood and quantifiable but have been recognised as having synergistic effects upon the biosphere and its ability to sustain life. Ofparticular relevance are the relationships between the depletion of ozone in the upper atmosphere and the increased use of chlorine and fluorine-containing compounds (CFCs), the increased release of carbon dioxide into the atmosphere and its affect on climate, the rapidly increasing world population and its consequences on other species and their ability to survive and, of course, the impact of modem technology which is able to consume greater resources, to produce large quantities of waste and generate consumer products which may have very short useful lifetimes and be difficult to recover and recycle from waste streams. Each of these interactions has major consequences for the textile and related industries including the plastic producing sectors whether from the point of view of the ability to sustain production of natural raw materials (eg cotton, wool, wood pulp,etc.,), the need to have economically and environmentally efficient processing sectors or the requirement that products must be designed with recovery and recyclability in mind. During April 1995 at Bolton, UK the first major and recent conference on the environmental aspects of the textile and related industries was held to examine and discuss the current position of textile and related plastics wastes. The conference, entitled "Wealth from Waste in Textiles," was organised jointly by Bolton Institute and the British Textile Technology Group with support from the Textile Institute and the Department of Trade and Industry. The two day conference attracted over 130 delegates from across Europe in the main, with some delegates travelling from the USA and the Far East. Almost thirty papers were presented which covered the general problems of waste production and its minimisation to the more specialised problems facing particular processors of virgin and waste raw materials as well as textile finishers and the advances made in effluent reduction. This text presents nineteen edited papers which together give a picture of the challenges facing the textile and plastics industries.Both must increasingly be able to demonstrate environmentally acceptable practices while working within a framework of economic viability. Thus they must be able to make products which consumers will buy based on both price and ecological factors. The papers selected will initially overview the magnitude and consequences of excessive waste production, then proceed to discuss waste minimisation strategies and practices, focus on selected areas where recent scientific and technological advances have been made and finally set the problems within the context of current public perceptions, politics and regulations. It is hoped that, although the nineteen papers are not meant to provide a completely comprehensive treatment of all aspects of textile and plastics waste problems and challenges, they will present a series of snapshots which create an overall picture of the current status of waste minimisation, waste recovery and waste recycling across the respective sectors. A Richard Horrocks Bolton Institute, Bolton,

January 1996

v

ACKNOWLEDGEMENTS lbis edited text could not have been produced without the contributions from each of the respective authors to whom I am grateful for generating the basic manuscripts. However, the creation of the manuscripts required the Ecotextile conference in the first place which took place at Bolton in the Bolton Moat House on 11th and 12 th April 1995. The major organisation of the conference, "Wealth from Waste in Textiles," was undertaken by Christine Wilkinson and Dinah Wharton of the British Textile Technology Group, Leeds and their input in this respect and their contribution to the success of the event must be acknowledged. The preparation of the original conference texts and the redrafting of each paper into the current form has required considerable efforts from my colleagues in the Research Office at Bolton Institute. I would like to thank Lorna Hollingum for her work prior to the conference in liaising with authors and ensuring that manuscripts arrived in time for the conference and also acknowledge the work of Diana Page for her painstaking efforts in word processing the edited manuscripts to the standards necessary for their formal publication.

vi

LIST OF CONTRIBUTORS Mr Brian Burdett, BTTG, Shirley House, Wilmslow Road, Didsbury, Manchester Mr Jim Cunliffe, Bolton MBC, Milton House, Wellington Street, Bolton, Lancs Mr Allan Delves, Du Pont Nylon, Ermin Street, Brockworth, Gloucester, Glos Professor Subhas Ghosh, USA

Institute of Textile Technology, Charlottesville, VA 22902,

Mr Barry Hazel, Textile Finishers Association, Reedham House, 31 King Street West, Manchester Dr Heinz Herbst, Ciba Additives GmbH, Nibelungstrasse 440, D-64686, Lautertal, Germany Professor A Richard Horrocks, Bolton Institute, Deane Road, Bolton, Lancs Mr Tony Horrocks, Norplas, Norton House, Stowupland Road, Stowmarket, Suffolk Mr Clive Jeanes OBE, Milliken Industrials Ltd., Gidlow Lane, Wigan, Lancs Mr Simon Kent, Parkland Manufacturing CO.,Meltham Road, Huddersfield, W. Yorks Dipl Ing Ferdinand Leifeld, Triitzschler GmbH and Co. KG, Duenstrasse 82-92, DW4050 Munchen Gladbach 3 , Germany Mr Brian McCarthy, BTTG, Shirley House, Wilmslow Road, Didsbury, Manchester Mr Nasim Minhas, Haroon Nasim Textile Mills Ltd., Al Faisal Place, Shahrah-e-Quaide-Azam, Lahore, Pakistan Mr Nello Pasquini, Montell Polyolefins, Woluwedal 24, 1932 Zaventem, Belgium Mr Andrew Simpson, Colne, Lancs

Wellhouse Wire Products, Ravenscroft Way, Barnoldswick,

Mr Alfred Watzl, Fleissner GmbH, Wolfsgartenstr 6, 6 3329, Egelbach, Germany Mr Ian Wolstenholme, BASF pIc, Willow Court, 34 Thermaston Lane, Leicester, Leics Mr Andrew Wood, EVC Components Ltd, Chester Road, Helsby, Cheshire Dr Alan K Wood, Material Science Centre, UMIST & University of Manchester, Grosvenor Street, Manchester

VB

RECYCLING AND RECOVERY STRATEGIES A Richard Horrocks

Introduction

The concept and practice of recycling has been a well-established part of the textile industry since the first industrial revolution. Historically, the waste reprocessing industries of Lancashire and Yorkshire, for example, reflected their respective interests in cotton and wool textile manufacture. Elements of these interests remain today but the impact of man-made fibres has introduced variety and blends to the industry. While basic textile and clothing manufacturing industries generate associated waste reprocessing sectors, there has been and continues to be a recycling industry associated with used clothing and other textiles or "used rags" . In post-industrial EU, which has significantly reduced manufacturing sectors and hence associated "new rag" reprocessing industries, the growth in consumerism has assured that "old rag" recycling is or could be a large industry, often generated by charitable institutions and driven by exports to the less developed areas of the world. Table 1 lists and Figure 1 schematically shows the traditional and well-established recycling routes. The strategy behind these traditional reprocessing industries was and still is purely one of wealth creation from waste and, as an industry, the textile and clothing sectors have always been able to demonstrate a degree of environmental sustainability in terms of fibre re-usage. In recent years there has been a shift to SE Asia of these traditional textile and garmentmaking waste reprocessing industries as the main textile manufacturing base has shifted to that region. Of more recent importance to the European and US textile economies has been the emergence of new waste recycling technologies based on the values of waste synthetic fibres, high performance textiles and composite materials and recycled polymers as synthetic fibre precursors. The second half of Table 1 lists these. The often reversibility of synthetic fibre production sequences has enabled technologies based on depolymerisation and monomer regeneration to be developed; this has especial significance where sources of used textiles comprise large amounts of a single fibre type such as polyamide floorcoverings. Similarly, the usefulness of some synthetic fibre-forming polymers like polyester (PET) in other markets such as beverage bottles, has provided impetus for improved plastic recycling technologies in the packaging sectors because of their potential as raw materials for synthetic fibres. Finally the complexity and value of many technical and industrial textiles has created opportunities for their effective recovering and recycling. Some companies like Gore, for example, (1) offer customers the service of accepting and disposal of used Goretex garments. This trend will probably increasingly occur for sophisticated garments and textiles in the contract and domestic sectors.

3

RAW FIBRE

~

.....

SPINNING

",...

~~

FABRIC PRODUCTION

~

.....

......

DYED,FINISHED, FABRIC, GARMENT MANUFACTURE

.... II""'"

TEXTILE PRODUCT

,

HARDWASTE: YARN,FABRIC, GARMENT

~ RE- USE AS FIBRE (SECONDARY FIBRES)

,

....... ~

: ~

,

SOFT WASTE :

....... ~

CONDENSER \ ~-----. FIBRE WASTE

Figure 1: Traditional textile recycling pathways

SORT, RE-USE

Table 1: Textile recycling strategies

TRADITIONAL STRATEGIES

Soft and hard waste processing from spinning (condenser waste, noils, sliver, roving, yarn waste, etc.) Hard fabric waste from fabric production and garment manufacture New rags from unused textiles Old rags from used textiles

MORE RECENT STRATEGIES:

Synthetic fibre production waste (polymer, extruded and drawn fibre waste, etc. ,) Depolymerisation of process and consumer waste (polyester, nylon 6 and 6.6) Synthetic fibre production from non-fibre polymer sources (PET bottle waste, blending of polypropylene waste with virgin polymer) Performance garments returned to manufacturers Technical fibre (and composite) recycling

Recycling Strategies beyond 2000 During the coming 21st century, the desire and need to recycle must be driven by ecological as well as economic forces, although in the end both are related in a finite world. In a world which • • • •

took 10,000 generations to reach 2 billion population (1935) and the last 3 generations to reach 5.6 billion; is losing 12 million tonnes of topsoil, 12 thousand hectares forest and 20 species every 4 hours witnesses 80 % of materials and wealth being consumed by 20 % of its population; and needs to increase its environmental efficiency by a factor of 10 - 50 if it is to have sustainable human life

5

then recycling is only a part of an integrated waste management programme at local, regional, national and international levels.

The magnitude of the textile waste problem Within the European context, for example, the question of whether there is an ecological need to recycle textiles and whether it should be a part of an EU integrated waste management programme might be asked. Currently within the EU the main focus is on the management of plastic waste which finds its way into municipal solid waste (MSW) streams. Typically about 10 % by weight of MSW comprises plastics which, while being non-biodegradable, offer recycling opportunities as valuable raw materials, and sources of energy because of their high fuel content (3). While industrial figures indicate an input of plastics packaging of about 20 kg/person per year, collected MSW data in Germany suggest disposal levels range from 9 - 17 kg/person per year. The magnitude of this plastics waste problem should be set against the following background in Table 2 (4).

Table 2: Western Europe's Municipal solid waste - 1990

%

Waste type

Million tonnes

Textiles Plastics Metals Glass Misc (ash, etc.) Paper, board Organics

4.8 8.9 9.6 9.6 36 39.6

8 8 9.6 30 33

TOTAL EU

120

100

4 7.4

11.5

From these figures there is an indication that textiles, in terms of MSW are 50% the size of the plastics problem. These figures are consistent with textile fibre consumption figures in W. Europe of about 20 kg/person per year coupled with a reasonably high fraction being handled by the textile recovery sectors.

6

INPUTS

OUTPUTS

r--------------------------------------------------------:, :' :, :: ,

MATERIALS + ENERGY

•

r--------------~

I I I I I I I I I I I I I I I I I I I

, , , , ,

RAW MONOMER

.

,, ,, ,, , , ,

,,

~,

RECLAIMED FIBRE

....

RAW FIBRE

JIll'"

EFFLUENTS : SOLID

~r

....... ......

SOFT IHARD WASTE

: GAS

FIBRE I TEXTILE PROCESSING , ,, ,, ,,

~r

SECONDHAND TEXTILES

..

-----------

.

: LIQUID

.

ENERGY

WASTE

TEXTILE PRODUCT: DISTRIBUTION TRANSPORTATION

.,

,

USE/RE-USEI MAINTENANCE

~

i

RECYCLE

....

,

DISPOSAL

I

I

1 _____ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ,

Figure 2: Textile recycling pathways with identified inputs and outputs 7

RAW MATERIALS ( POLYMER I FIBRE)

~

,

FIBRE I TEXTILE PROCESSING

.,, PRODUCT: DISTRIBUTION TRANSPORTATION

.,, USE

.,

e,

,

•

DISPOSAL

E,

A

E3 B

C

D

I

I

RECYCUNG STRATEGIES

Figure 3: Energy input values for recovering/reclaiming (En) and reprocessing (eJ 8

The ED Packaging and Packaging Waste Directive was finally adopted at the end of 1994 with the following targets:• • •

minimum rate of recovery of 50 %, maximum rate of 65 %; minimum recycling rate of 25 %, maximum rate of 45 %; minimum recycling rate for each type of material of 15 %;

This suggests that textile recovery and recycling could receive closer attention foreseeable future.

In

the

However, there is a current view that the traditional textile recycling sectors are very efficient and there is no need to give special attention to textile waste. In fact the energies expended in realising the value from PET bottles by converting a significant proportion into textile fibre is seen as a means of ultimately introducing this polyester source into an efficient, already existing, quite effective recycling process. The majority of the 4 % textile waste figure in Table 2 comprises discarded carpets and household textiles - this is a problem, but one which is being partly addressed by synthetic fibre companies like BASF and DuPont which have developed pilot reclamation schemes involving fibre depolymerisation (eg for nylons 6 and 6.6) which regenerate monomers for reintroduction into the fibre production process. Recycling targets - energy versus economics The traditional textile reprocessing/recycling sectors have developed economically - efficient systems with their need to function as viable businesses. In both the developing textile recycling sector which includes synthetic fibre production from plastics waste and possible depolymerisation of carpet waste, for example and the composite materials recycling scenario, there could come a point where an increased level of recycling becomes energy inefficient. In terms of cheap energy, this would not necessarily show as an uneconomical factor energy costs and/or carbon taxation factors could force recycling levels to an optimum, equilibrium level. This would be acceptable on energy, economic and ecological grounds if textile recycling were part of a larger waste management programme. Both Table 1 lists the newer textile recycling strategies and Figure 2 expands the traditional textile waste flows in Figure 1 and includes the emerging fibre depolymerisation and plastic waste-to-fibre routes. The figure also attempts to produce a more ecologically-balanced view. In order to address the economy versus energy question, the elements of Figure 2 can be simplified to give the flow chart in Figure 3 which introduces the energy factor. If Eo is the energy content of raw materials, e 1 is the energy to process raw materials into a product and El is the total energy input and cost of recovering/reclaiming this same textile made from ~rgin raw materials, then E2 to Es reflect the energy inputs of recycling textiles back to points of reprocessing exemplified by:-

9

• • • •

ROUTE A:

Secondhand garment recycling (E2)

ROUTE B:

fibre reclamation from "old rags" (E3)

ROUTE C:

reclamation/depolymerisation (E4)

ROUTE D:

fibre reclamation from new "soft" and "hard" wastes; chemical reclamation from textile effluents.

The full "energy cost" of recycling will be the recycling energy route value (E2 , .... Es) plus a component of the original energy to process route, el , namely, en or e2 ••• eS • However, against these "full energy" costs may be set the unit mass energy, Eo, for raw materials that recycling a similar unit mass saves plus the energy required to convert raw fibre into the process stages "saved" by recycling ie e l - en. Thus the true unit mass energy costs of recycling should be:Route A:

Eo

+

el

-

(EI

+

el )

(i.e. Energy to convert raw materials to product energy to recycle = energy saved)

Route B: Route C: Route D: This gives rise to a general equation for any Route n of Net energy saved by Recycled system, ~ = Eo

+

e1

-

(En

+

en)

To be energy efficient, recycling must save energy and so (i.e. denoting a positive saving of energy)

Energy input to recycle

Energy used in raw material costs and processing

Routes A and D on this simple model will have the smallest energy inputs and so perhaps offer greater energy savings and hence ecological efficiencies as well as economic efficiencies. This simple model therefore suggests that for a given fibre or textile type there may be an optimum balance of recycling and disposal strategies which together create the highest level 10

of ecological efficiency. In the far less complex but more important case of plastics waste disposal, it is considered that for a given plastic there is a maximum recycling level to be achieved which is balanced by an appropriate thermal recovery fraction. This simple model may be defined for plastics as:

Plastic waste

Recycling

x

Thermal recovery

y

Other

z

may be expanded for textiles as:

Textile waste

Recycling: Route " " "

A B C D etc.

Thermal recovery

y

Other

z

Clearly this model is oversimplified but it does raise the question of the need to introduce an element of science into the whole area of waste recycling in textiles. It is possible that given the correct model and data, efficient levels of recycling which are determined by both energy and economic efficiency criteria may be defined for each textile type. This is certainly the thrust of strategic developments for managing other material wastes. A further complicating issue is that for each process in Figure 3 which has been analysed more fully above, absolute values of En and en per unit mass of reclaimed textiles may vary as the total percentage of textile recycling increases. For instance, doubling a given level of recycling of a given textile type may more than double collection/transportation energy inputs because material is not dispersed uniformly in consumer societies. In other words, current recycling levels of textiles are determined by ease of finding and collecting which determines costs (and energy) of these activities. Figure 4 presents the outcome of such a model (5). In this figure, there is an energy efficient level of waste recycling where the total energy of the system is minimised (ie. energy saved, EJ as a consequence of the recycling energy costs being less than the energy of using equivalent new raw material. However, for 100% waste recycling (using one or more routes) it is possible that the energy costs of collection, concentration and transportation will exceed the costs of producing and processing virgin product. At some level, a maximum economic fractional mass value of recycling, Wm, may be defined, with We being the most energetically and environmentally

11

acceptable value.

Net system energy

E

o -----------:=:--='=-----

o

100 Textile waste recycled, 0/0

Figure 4: Net energy of recycling as a function of percentage waste recycled. 12

Current State of and Opportunities in Textile Recycling Within the EU it is probable that in spite of the reduction in size of the traditional textile and clothing manufacturing sectors, there is still a sizable soft and hard waste reprocessing industry which is becoming more involved with recycling technical and industrial wastes. Because these and the remaining traditional industrial sectors are using in many instances, technical fibres of relatively high value, then the economic opportunities here will probably assure its efficient continuation. Coupled with this is a consumer-based population of about 300 million each consuming about 20-30 kg fibre/person per year equivalent to a total EU consumption of about 7 million tonnes (6). Unless the EU is accumulating textile products, it may be assumed that this figure is the same as the annual textile consumer waste quantity. However, Table 2 indicates an annual W. European MSW textile loading of 4.8 million tonnes. The difference between these figures suggests that textile waste recovery/recycling within the EU is about 2 million tonnes per annum (see Table 3). This quantity will enter the traditional reclamation routes for used textiles (see Figure 1) which are accepted by those in authority as being efficient, even if a large part of this "efficiency" is determined by the needs of third world countries for exported garments. This market will not decline. Neither will the demand for "old rag" recycling into fibre for re-entry into the textile chain decrease as virgin raw material costs increase (as they are at the present time).

Table 3: W. European Textile consumption and waste production

Annual EU consumption of textiles (= total waste for steady state condition), tonnes

7 million

MSW textile loading (4%, see Table 2), tonnes

4.8 million

Shortfall = textiles recovered/recycled, tonnes

2.2 million

However, while OECD includes recovered textiles on its green list of materials, some 40 or so countries and potential markets for these products have yet to accept this designation (7). Thus markets for exported secondhand textiles and textiles comprising reclaimed fibres could be obstructed. With regard to the latter the need to distinguish between "waste" and "products containing secondary raw materials" is essential if export markets are to be fully opened. The current value and potential value of the UK reclaimed textile market is shown in Table 4. Based on the above figures and assuming the UK consumption of textiles and waste production is about 1/6 of the EU figures above, then estimates of textile waste in municipal 13

waste and recovered textile waste may be made. This shows an estimated 400,000 tonnes textile waste for reclaiming. (Note: Total UK household waste for 1992 was 20 million tonnes (8) which if 4 % (Table 2) is assumed to be textiles, gives 800,000 tonnes-the same figure in Table 3). The first half yearly figures for 1994 (9) in Table 4 suggest that about 200,000 tonnes per annum is exported outside the EU, leaving 200,000 tonnes within the EUfrom UK consumers/producers.

Table 4: UK textile waste production and reclamation

Total Textile Waste: Table 3:

1/6 of 48 m tonnes (EU figures for 1990)

Ref. 8 :

4% UK household MSW

= 800,000 tonnes for UK

= 800,000 tonnes

6 months UK exports outside EC. Jan - J one 1994 (9) Secondary Fibres: tonnes Silk Cotton (linter, yarn, fabric, garnetted stock) Bast Gute, flax) seed (coir, loaf (sisal) Man-made fibres (staple and filament) Wool, animal hair

£k

22

140

2,127

3,315

165

316

49,136

64,989

19,105

43,771

70.555 (73%)

112,531 (87%)

25,753 96.308

16,385 128,916

Used textiles: Clothing, used textiles 112 year total

Annual Total (approx)

200,000

250,000

14

The estimated 800,000 tonnes of textiles "lost" in UK municipal waste might be considered as a lost resource, especially when landfill and incineration are the main disposal routes. If energy recovery was on the UK disposal or recovery agenda then the value of this would be partly realised. This "lost" quantity of textiles surely must offer a challenge and opportunity to UK reclaimers. Exploiting this opportunity and "lost resource" (having an estimated value of about £500 million at used clothes prices) requires consumer education, local authority cooperation and UK reclaimer partnerships bearing in mind, of course, the energy versus economy arguments or law of diminishing returns discussed in the previous sections (see Figure 4). References 1.

R Leckenwalter in proceedings of R'95 Recovery Recycling Re-integration International Congress, Geneva, 1-3 February 1995 (eds. A Barrage and X Edelmann), EMPA, Dubendorf, Switz, Vol III, 372.

2.

G A Persson in proceedings of R'95 Recovery Recycling Re-integration International Congress, Geneva, 1-3 February 1995, (eds A Barrage and Edelmann), EMPA, Dubendorf, Switzerland, Vol.l,p.17.

3.

F E Mark and R Martin. Energy Recovery; Technical Paper by Association of Plastics Manufactures in Europe, Feb. 1995.

4.

Anon, Plastics Packaging, Association of Plastics Manufactures in Europe, p.7.

5.

I Boustead, personal communication, R'95 International Congress, Geneva, 1-3 February 1995 and in Eco-balance; Technical Paper by Association of Plastics Manufacturers in Europe.

6.

Anon, Economist Intelligence Unit publication, Technical Textile Markets, January 1994, p.128.

7.

Anon, Materials Recycling Week, Nov. 25, 1994, 22-23.

8.

Anon, Information sheet, Tidy Britain Group, Wigan, UK, 1993.

9.

Anon, UK Trade Statistics, HM Government, 1994.

15

MUNICIPAL WASTE - TRASH OR TREASURE Jim Cunliffe

Municipal waste is produced by each and everyone of us just by the act of living. It's the material that ends up in our dustbin - mainly packaging and food waste, or down at the local household dump - as old furniture, carpets, washing machines, fridges and the like, or as litter on our streets. Nationally in the UK we produce each year some 20 million tonnes of domestic, municipal waste, which is approaching a tonne per household per annum. From the individual's point of view, once you have thrown your waste in the domestic bin it is a case of "out of sight out of mind" and this is where the problem starts. Each local authority has a duty to collect and arrange disposal of this waste, and about 85 % of it is dumped untreated into holes in the ground - landfill sites - as the cheapest way of disposal, typically £10-15 per tonne. However the availability of convenient holes is falling rapidly, especially in the south of the UK, so transport costs escalate and because holes are becoming scarce - just like any other commodity - price tends to rise: The net result is the rising cost of landfill disposal. Increasing environmental awareness has focused attention on some of the problems associated with land filling such as landfill gas contributing to global warming, water and ground pollution due to leachate escape, restoration of the landscape and long term aftercare to ensure the integrity of the site after closure. Improved site management again pushes up costs of landfilling.

An alternative to landfill There is an alternative - it can be burnt. Currently, there are about 30 municipal incinerators in the UK that do just that, accounting for some 8 % of municipal waste. The obvious advantage is that 90% of the material "disappears" and the remaining ash is only a third of the weight of that which went in - so making much less demand on final disposal to landfill. Unfortunately, incineration costs twice as much as landfill at about £30-35 per tonne. Furthermore, nothing really "disappears", it just changes into something else, and in this case, if one third of the weight remains as ash, two thirds has gone up the chimney as air pollution. Again, increasing environmental awareness has focused on emISSIons to air, and more stringent controls are being introduced that will increase significantly the costs of incineration or even force plants to close down, putting even more pressure on landfill.

17

Typical composition of UK household (dustbin) waste and components commonly targeted for recycling - waste collected in Greater Manchester districts.

Table 1:

Concentration Weight %

Category

Paper Card

and

21.6

54.1

33.2

Weight %

% Range

Sub Category

Related to GM Districts Waste

Recycled

teo

teo

} 19,111 }

Minimum

Maximum

11.40 4.81

7.7 2.8

18.7 7.9

Newspapers Magazines

73,600 31,000

9.53 0.64 3.79 3.10

6.4 0.1 2.8 1.8

14.3 0.9 5.7 6.6

Oilier Paper Liq. Containers Card Packaging Oilier Card

61,600 4,000 24,500 20,000

Plastic Film

3.4

8.1

5.3

1.16 4.18

0.2 3.2

2.0 6.1

Refuse Sacks Oilier PI. Film

7,500 27,000

Dense Plastic

2.7

10.1

5.9

0.63 1.12 0.12

0.2 0.5

-

1.2 2.4 0.2

CIr. Bev Bonles Oilier PI. Bonles Col. Bev Bottles

4,000 7,200 800

1.91 2.14

0.8 1.2

3.1 3.2

Food Packaging Oilier Dense PI.

12,300 13,800

} } 211 }

Textiles

1.1

3.4

2.1

2.13

1.1

3.4

Textiles

13,700

123

Miscellaneous Combustibles

1.4

13.6

8.1

4.21 3.90

0.5 0.9

7.3 6.3

Disp. Nappies Misc. Combustibles

27,200 25,200

166

Glass

2.7

16.9

9.3

1.31 2.39 5.37

0.3 1.2 1.1

2.8 6.4 7.3

Brown Glass Green Glass Clear Glass

8,500 15,500 34,700

} } }

6,345 I

0.20

0.1

0.4

Oilier Glass

1,300

Putrescribles

13.9

27.8

20.2

3.40 16.77

0.7 13.2

6.5 21.3

Garden Waste Oilier Putrescibles

22,000 108,000

Ferrous Metal

2.8

10.8

5.7

0.53 3.74

-

1.2 6.0

Fe Beverage Cans Food Cans

3,400 24,200

0.06 0.40 0.98

0.2

0.5 0.9 2.2

Baneries Oilier Cans OIber Ferrous

400 2,500 6,300

1,828

0.43

0.1

0.8

Non Fe .. Bev. Cans

2,800

177

0.47 0.71

0.1 0.1

0.6 2.5

Foil OIber Non-Ferrous

3,000 4,600

77

3.5

12.4

10 mm Fines

43,800

Non Ferrous Metal

0.3

3.9

1.6

Fines

3.5

12.4

6.8

6.77

TOTALS

-

-

100.0

100.0

2.6

646,500

} }

7,030

35,068

Table extracted from Warren Spring Report: "Cost assessment of source separation schemes applied to household waste in the UK (Nov. 1993)" Notes: The basis is the District Collections figure of 744,758 tonnes less commercial Waste (a) collected, 98,248 tonnes, which amounts to 646.510 tonnes

18

I

In the past, municipal waste has been considered as just a burden of worthless material to be disposed of. But that burden is sizeable in Bolton let alone throughout the country as a whole. This is approaching £7 million annually to collect and dispose of and so, in the face of increasing environmental awareness and rising costs, minds are becoming concentrated on how to contain those costs and be more environmentally friendly. There appear to be two ways of reducing the amount of waste to go to final disposal. a)

Reduce the amount of waste produced in the first place i.e. waste minimisation.

b)

Take anything from the waste that can be useful, including heat and energy, and pass it to someone else to use i.e. reclamation/recycling.

Consider the contents of a typical waste stream; Table 1 shows this, courtesy of Warren Spring Laboratory, for waste collected in the Greater Manchester districts within the UK. Table 2 shows the typical contents of UK dustbin waste in general.

Table 2: Typical composition for U.K. dustbin waste

Packaging

Paper and Card Plastic Glass Steel Cans Aluminium Cans & Foil

17.5 % } 8% } 9% } 4.5% } 1% }

40%

16% 20% 4% 2% 18%

Newspaper & Magazines Kitchen & Garden Waste Disposable Nappies Textiles Batteries, Scrap Metal and miscellaneous

Scope for Waste Minimisation Local authorities have little or no influence over the amount of waste available to go into the waste stream - they can't ask people to buy and read fewer newspapers and magazines, or eat less to produce less kitchen waste or have less grass and fewer plants in their garden. Almost everything we buy is packaged in a bottle or a can, in paper or cardboard, in foil or in plastic. Manufacturers, packers and retailers could have greater impact here by reducing packaging material - local authorities can only campaign in this direction. Modern living and the high priority of convenience has a lot to answer for in this respect as illustrated by the growth in use of disposable razors, ladies tights, plastic bottles and drinks 19

cans. For example 3,285 million disposable nappies are used annually, weighing 821,000 tonnes. They are made of multi-materials and use 10 times the raw materials used in a cotton nappy, 5 times the energy and produce 10 times the waste. A worthwhile saving in waste could be made by banning disposables - could we? should we? Questions for both consumers and package manufacturers to ask are various. Why do we use something only once and then throw it away? Why do we throw bottles away - why can't we return them to be refilled like a milk bottle? Why do supermarkets have milk in plastic bottles and cardboard cartons that cannot be refilled and just go into the dustbin? One simple solution is for local authorities to charge individual households for the amount of waste put in the bin - the more waste there is the more that has to be paid! This would certainly raise awareness of how much the disposal of packaging is costing, and consumers might then pressurise retailers to reduce it. Such a remedy could lead to "fly tipping" rather than putting waste in the bin and if this happened, then it would be counter productive. However, it might just encourage people to use facilities for recycling their waste bottles, cans, newspapers and so on.

Recovery from the Waste Stream Is there any treasure buried in this trash which has a value and can be useful elsewhere , thereby reducing the amount of rubbish for disposal and perhaps being helpful to the environment? Consider again the contents of a typical Bolton dustbin, and what it might be worth , based on a figure of 80,500 tonnes of waste collected from the bins (see Table 3). If we recover the most recyclable materials then there are 41,755 tonnes less for disposal

(that is about 50% of the collected waste) at say £15 per tonne gate fee, this is a saving of £626,325. Adding this to the value of the material at £1,592,090 makes a grand total of £2,218,415. On this basis things are looking up. Unfortunately, the situation is not that simple because of the four following major points.

Duty to collect waste: A town like Bolton has a duty as a waste collection authority to collect household waste and deliver it to the Greater Manchester Waste Disposal Authority for disposal. Bolton is charged for the service not on a per tonne basis but on a per capita basis - therefore any reduction of waste is not reflected in a cost saving. However, to help overcome this difficulty, provision was made in the Environment Protection Act 1990 for Recycling Credits to be paid for household waste that was collected for recycling. The credit is to be paid by a waste disposal authority to reflect the savings made by not having to dispose of that waste.

20

Table 3: Potential value in Bolton's bins

Material

%

tonnes

Price/tonne delivered(£)

Potential Value (£)

Paper & Card Plastic Film Plastic Bottles Glass Steel Cans Aluminium Cans/Foil Newspaper & Magazines Kitchen & Garden Waste Disposable Nappies Textiles Miscellaneous

17.5 6 2 9 4.5

14,088 4,935 1,505 7,245 3,622

10 NIL 90 18 25

140,880 NIL 135,450 130,410 90,5504

1

805

900

724,500

16

12,880

35

450,800

20 4 2 18

16,100 3,220 1,610 14,490

NIL NIL 230 NIL

NIL NIL 370,300 NIL

Totals

100

80,500

1,592,090

So if the 41,755 tonnes of material in the waste stream could be recovered for recycling and avoid disposal, then a Recycling Credit of approx. £11 per tonne would be paid by the Greater Manchester Waste Disposal Authority - which equals £459,305. The net result is that if all the available material was collected and sold for recycling then there would be an income to Bolton of £2,051,395 from the sale of materials and recycling credit. Mixed waste: Recyclable materials may be in the waste stream, but are mixed up together and are unsaleable until the different materials are separated out and presented to the market in an acceptable condition - invariably to a recycler of that particular material. Markets: It is pointless to collect and separate the material if it cannot be sold to anyone. A market is essential. Recycling efficiency: The fourth point is the question of how much of that material which is actually present is in fact practically recoverable, as a great deal of it - particularly paper, card and plastic film - is contaminated with other wastes in the bin e.g. contents spilled from cans and bottles, waste food contamination, fats and oils and so on.

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The UK Government has set a target to recover by the year 2000, 50% of the recyclable part of household waste, which is roughly 25 % of the total. Local Councils are achieving only about 5 % - why? The short answer is that it costs too much to collect and separate materials so they are saleable at an economic price. The prices paid for recyclable material do not relate to the cost of collecting that material, but are determined on international commodity markets - paper, aluminium, oil (plastics) steel, and take into account the costs of providing virgin materials to the markets. If it is cheaper to buy virgin material rather than recycled, then that is what happens. The prices paid for recycled household material by and large do not cover the costs of providing it. A recent example is the price of waste paper. In 1992/93 the prices paid were £15-20 per tonne, in 1993/94 the price fell to £5-7 per tonne and, at one stage, there was a charge to take it away. Now the price is up to £30 per tonne. How waste material is collected and sorted in Bolton

"Bring (or drop off)" schemes are those where the public is relied upon to deliver material for recycling to special containers at various locations in the community. The larger the containers, the lower the frequency of emptying and the lower the transport costs and the more cost effective the scheme is. But the number of large supermarket car parks is relatively small and so how to increase the rate of collection is a major problem - smaller banks, more of them, emptied more frequently is one answer but this increases costs. Bolton intends to increase its 60 recycling sites to 105 by 1996 (1 to 2500 head population). A special vehicle is required to service the site and keep the materials separate, and storage bays need to be constructed to consolidate loads for long haul to the recyclers. On top of all this, there are operating costs to keep the whole thing running. The result is a net cost of recycling bottles and cans of approximately £103 per tonne as compared to the current collection and disposal costs of household waste at about £75 per tonne. The Local Authority also collects plastic bottles, but for the last year there has been no market for mixed plastic bottles. As a result, a sorting plant has been set up with assistance from the company Recoup so that it now costs about £160 per tonne to recycle plastic bottles. Kerbside collection schemes using blue boxes or twin bins and associated sorting facilities are even more expensive to set up and operate, and "high tech" central processing of wastes requires investment way beyond the means of individual councils.

So why bother recycling at all?

22

It is obvious that local authorities like Bolton are not in it for the money - and as far as I know there are few, if any, local authority recycling schemes that actually financially break even without grant aid, subsidy or sponsorship. At the beginning of this paper the impression was given that local councils embarked upon recycling to perhaps reduce overall disposal costs - that is not really true. In 1979 Bolton installed glass banks in the town to support the glass industry's initiative not to reduce costs or make money, but because it was a sensible thing to do, and the scheme just about broke even. At about the same time, the Council began supporting charity organisations who were collecting newspapers and magazines for their own funds, in conjunction with a local paper merchant; again this was not to cut costs or generate income but because it was a good idea. In the late 1980's and early 1990's, there was a great increase of concern for the environment, and Bolton responded by trying to enhance its recycling facilities by increasing the number of glass banks, and introducing banks for cans, paper and textiles. But because of the costs involved (in banks alone), the Council worked in partnership with recyclers and other organisations to initiate and develop new schemes at minimum cost. The point is that local authorities are there to satisfy the needs and aspirations of their residents, and certainly one of those growing aspirations is towards care and concern for the environment, and recycling features prominently in this concern. It is for this reason initially that Bolton began to be more involved in recycling. This involvement became more focused when the Environment Protection Act 1990 required each local authority to produce a Recycling Plan to show how each might recycle 25 % of its household waste by the year 2000. Ever since there has been growing pressure to demonstrate that councils are environmentally friendly in everything they do, and they are now charged with producing a Local Agenda 21 which is an action plan put together by all sections of the community that will ensure that generations in the 21st century and beyond will inherit an environment capable of satisfying their needs.

Where does recycling fit into the well-being of the environment? Referring to household waste - the present system of work is that energy is expended in extracting natural resources. More energy is used in transporting and processing that material into something useful e.g. a bottle, can, newspaper, plastic container and so on. When that item is discarded, it goes into the bin and is dumped into a landfill site, never to be seen again. Thus the need for another bottle, can or whatever requires that we go through the whole process again. Thus recycling: Saves Raw Materials Saves Energy

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Saves Pollution Saves Disposal Raw Materials: If raw materials have already been extracted then it makes sense to use them again if possible. This means that reserves last longer into the future. It means there is less environmental impact due to mining, quarrying, oil and gas drilling, deforestation and the like. If there are fewer of these operations, less energy is used to carry them out. Energy: Most energy used is produced by burning fossil fuels - coal, oil and gas. It takes special geological conditions and millions of years to produce these fossil fuels. They are being used up much faster than they can be renewed and so eventually they will run out - not in our lifetime but someone in the future is likely to suffer. Recycling saves energy because there is less need to extract basic raw materials, and less to transport to processing plants. If we already have a bottle or can or a newspaper, much less energy is required to transform it into another bottle, can or newspaper than making one from raw material ingredients. In the case of an aluminium can the energy saving is 95 %, for a steel can 75 %, paper 40 % and glass 20 %. These are very worthwhile savings on any dwindling resource. Pollution: Pollution in relation to raw material extraction has already been mentioned quarries, spoil heaps, destruction of natural beauty, destruction of wildlife habitat, oil spills in transportation and extraction (e.g. N. Siberia where the tundra is saturated with oil from leaking pipes). In addition, there is pollution from processing and manufacturing plants chemical works, paper mills, oil refineries and so on. Recycling plants and processes using recycled products may possibly be cleaner than primary processing industries. Then there is pollution from energy production itself - burning fossil fuel produces greenhouse gas to add to global warming and sulphur dioxide to produce acid rain; vehicle fuel combusion produces pollutnats which generate photochemical smog. Recycling uses less energy so there is less pollution. Disposal: Quite simply if we are recycling our waste, then the need to dispose of it by burial disappears and landfill sites will have a longer life. Furthermore, the concern regarding burning it and causing pollution that way vanishes, although there is growing movement in some quarters which says that burning waste and recovering heat and energy is the answer to everything! However, Friends of the Earth say that burning the waste will only recover about 3 % of the energy it took to produce the waste in the first place. That does not seem to be a good trade off!

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A personal view is that the real treasure in municipal trash is the potential for environmental improvements by recycling as much of it as possible, thereby conserving natural resources for future generations, conserving energy supplies, and reducing pollution. These are all elements to which a price tag has never been added. If they were properly valued and fed into the economics of recycling, I suspect we should be aiming to recycle 70 % of our household waste and be achieving it!

What is being done to encourage recycling? Various measures already exist or are in the pipeline to encourage better waste management and recycling. Recycling Credits

- paid to collectors of material for recycling to reflect the savings made by avoiding the costs of disposal, thereby making recycling more attractive.

Supplementary Credit Approval - permission for local councils to borrow money beyond their current limit to fund capital expenditure on recycling schemes - but not to assist in operating costs. But councils still have to find the money! Landfill Tax (1996)

- to make the disposal of waste more costly and encourage waste reduction, recycling and incineration.

Producer Responsibility Group (PRG) and Valpak

- a compulsory levy on the packaging chain to be used to achieve a recovery rate (not recycling rate) of 58 % by the year 2000. This puts the emphasis on industrial and commercial packaging and incineration of household waste with energy recovery.

European Packaging Directive

- member states directed to recover 50-65 % of packaging waste (including incineration with energy recovery) and to recycle 20-45 % of packaging waste (including 15 % of each individual packaging materials by the year 2000).

National Waste Strategy

- reduce waste, support close-to-home recycling facilities, promote local authority composting schemes, and promote incineration.

It remains to be seen just how effective these measures will be in recycling more household waste as w~ll as industrial and commercial waste. It seems that greater recycling of household waste is only likely to be achieved by continued public demand and HM Government making available resources specifically for this purpose.

25

Conclusions

The 3 R' s of waste management are Reduce Reuse Recycle

- the amount of waste produced - as much as this waste as possible - the remainder if we can.

These all contribute to a more sustainable use of our natural resources. But there is a 4th R:Respect

- for the Environment

The Environment gives us food to eat, water to drink, air to breathe and all the other resources to enhance our quality of life, yet all we seem to do in return is to abuse it! One day, at this rate, the environment is going to give up on us and quit - then what? There is only one Environment - it must be treated with the respect it deserves, which brings us back to municipal waste. There is clearly treasure in municipal trash in terms of useful materials contained within it. There is even more treasure to be found in the environmental benefits to be gained from recovering those materials. What is missing is an all embracing evaluation of that treasure and the will to go and get it!

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TURNING ENVIRONMENTAL CONCERN INTO REAL PROFIT Clive Jeanes

Introduction For many business people these days, viewing the protection of the environment as a business consideration provides a starting point to the question of waste and its management. Sadly, there are still a few "unreconstructed backwoodsmen" who are unaware, uncaring and too busy running their business to think about these issues. They accept that textile products cannot be made without incurring waste, and try to go on working in their traditional ways for as long as they can get away with it, paying little attention to the concerns of environmentalists . Thankfully, more and more people have woken up to the need for careful management of all assets, including waste, and major changes of attitude are being brought about by government legislation which obliges all producers of waste to consider recycling instead of disposal in a landfill site or discharge into air or water. Although some businesses may complain, they will eventually be obliged to comply with new regulations and so join the growing band of environmentalists actively working to preserve our planet's rich assets. Milliken personnel were in this position for a couple of years, when charts were kept showing progress in reducing the percentage of our solid waste going to landfill. We became increasingly smug as this figure halved itself over that time, and we all had a rosy glow of self-satisfaction that we were doing our bit to preserve the planet for future generations by doing less harm to the environment. However, we very soon realised that there was more to be gained from waste control than just self-satisfaction. We started to ask ourselves whether we could take waste control measures a step further by generating less waste to begin with. If we did so, could we reduce our need for raw materials, and possibly increase our profits? We started to challenge each step of our production processes to see whether they could be carried out differently. Studies of all current operations produced some interesting results, leading to the possibility of eliminating between 30% and 70% of our traditional amount of waste.

Waste Minimisation A prime opportunity for reducing waste was identified in our carpet manufacturing operation in Wigan. One of the processes involved a roll of carpet just over 2m wide, cut into modules measuring 0.5m square to produce carpet tiles. Four tiles per width, and one row at a time were cut. This operation produced two lots of waste - about 1-2 cm of selvedge waste left down the outside of the roll, and another narrow strip the full width of the roll,

29

which was left after each cut to ensure that the next cut would start with a clean line. It did not take a genius to see that, if the cutting die was changed from a four-tile cut to an eight-tile cut, then the side-to-side waste strip would occur once every eight tiles rather than once every four tiles. A new cutting die was ordered, and tests carried out off-line to ensure that the practice would match the theory. It did, and eight tiles are now cut at one time, with a consequent 50 % waste reduction as a result of a very simple and apparently obvious change. We looked further at the carpet production plant and, in early 1994, no less than seventeen opportunities were identified to eliminate or reduce waste. If successful, the material cost saved would be worth just over three quarters of a million pounds each year, and the full cost of implementing the changes, including any necessary machine modifications or new parts such as the eight-tile cutter, would be just under half a million pounds. A short pay-back period of the investment of about eight months would be realised, and savings would continue year after year. Most of the identified improvements have been implemented, and the results have been as expected. The reduction in waste varies from process to process but, overall, by the end of 1995, a reduction of waste of 32 % will have been achieved compared to that experienced in early 1994. This figure not only produces a nice cosy glow in terms of protein in the environment, but has a direct impact on improving raw material yield, reducing costs and producing a higher profit figure. This gives an even warmer glow! Initiatives of this sort are taking place in all of Milliken's manufacturing operations, including reducing water consumption by 90 %, reducing end-of-run dye dumps by 95 %, and recycling and reclaiming 70 % of all process chemical waste. In addition, the company has a clear policy of total compliance with all legislative requirements, including no illegal discharges or other infractions. In other words, statutory obligations to reduce waste and to recycle, have become part of the company's environmental management process which, in turn, is now part of our total management system. Can there be an ultimate stage of total waste elimination?

The answer to this is yes, and a few companies have already started to enter it. It will be characterised by a new product development mentality which includes, as one of its priorities, a plan for the minimisation of waste in the production process. It will be characterised by plant and process layouts which focus on keeping waste to a minimum, and recycling whenever possible. It will be characterised by new machinery specifications which recognises the importance of keeping waste to an absolute minimum, and which provide closed-loop recycling processes wherever possible. In other words, waste is seen as a cost to be minimised and an economic opportunity to be taken right from the start of a process, and not just as a necessary post-installation 30

improvement. Waste and environmental management will become cost and quality driven. It will not be an activity only undertaken in order to meet legislative standards imposed locally, or from Whitehall, Westminster or Brussels, or to satisfy the focus of the environmental movement. Governmental requirements and green issues will certainly be satisfied en route, but the main motivation for businesses will be the hard-nosed fact that good waste practice, and good management of the environment, are good for reducing costs and, therefore, good for increasing profits!

31

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

RECLAIMED FIBRES, THE SOURCE AND USAGE Andrew Simpson

Raw Material - Its Source and the Reclamation Industry There are two main types of raw materials that are processed back to their fibres for reclamation. Synthetic Materials Wool/Synthetic Mixture Material Synthetic Materials Here there are two products available: i)

Acrylic and hosiery clip waste. Both sources come from the clothing industry and, although a new material, it is still regarded as waste.

ii)

The purchase of mixed-coloured acrylic jumpers, sweaters, cardigans etc., from the clothing recycling industry. These are discarded garments, that due to the mixture of colours in each garment, cannot be sorted and sold as self shades. There is a large market for the reprocessing of self-shade garments for the reclamation and re-use of their fibres.

There is a third quality, but one, it has lost its market place in recent years, this being the stretchy synthetic garment, which comprises predominantly cheap ladies clothing such as dresses, skirts, etc. Because of their inherent elasticity and poor recyclable characteristics, these garments in recent years have tended to be put more into the industrial wipers market. Wool/Synthetic Mixtures The majority of material re-processed back to original fibres is known as flock. Traditionally, the flock produced from this material was manufactured from a simple waste rag cloth. These rags coming again from the clothing re-cycling industry. However, major changes have been forced upon this product in recent years. During the late nineteen sixties and early seventies, there was a British Standard (now obsolete) for the flock produced from this course of material. It stated that the flock produced should have a minimum wool content of 50 %. This was dropped during the nineteen seventies to 40% and was later removed altogether because the ever-changing fashion industry was using fabrics comprising a greater content of man-made fibres. Furthermore, the relatively high cost of wool as a raw material has again precluded its use as a main fibre.

33

However, the question of "what is a rag?" should be addressed. This can be illustrated as follows by considering the common types of clothing: jackets waistcoats trousers skirts overcoats dresses The majority of the rags purchased will be a mixture of the above items. The products not required in the rags are shirts, blouses, gabardines, leather coats, blankets, quilts, anoraks, bedspreads, sheets, etc. The rag product that we buy today, however, has changed dramatically, even in recent years. Fashion has changed and this is the major influence. It must be borne in mind that the reclamation industry is always at least 2 - 3 years behind fashion trends and is receiving cast-off goods from clothing that was bought at least 2 - 3 years ago. Clothes that are purchased today are different from those of several years ago, not only in design but also the fibres that are used. However, the industry has to cope with everything that the fashion industry has generated in order to produce a product economically, and thus enable it to compete in its market place. There has also been a decline in the clothing recycling industry, particularly in Great Britain. In recent years, it has gone through a very tough period, with two of the largest companies in the industry going out of business. One of the main reasons for this decline can be found in the prices that it now obtains for its product. It is not many years ago that sorted white woollen knits were able to fetch prices of £2500 per tonne, and these are now down to nearer £1200 per tonne. At the bottom end of the scale, the flocking rag, which is the product that our industry purchases, is still at the same price as it was approximately ten years ago. This has led this industry to look very closely at the materials it sorts, to see if better prices for certain items can be achieved. This is leading to a greater depth of sorting in an effort to maintain business viability. Finally, recent flammability legislation for upholstered furnishings and protective clothing has influenced the performance of the clothing recycling industry by demanding a higher wool content. To meet the demand, specialist grades of woollen rag have been generated from, e.g. overcoats, jackets, etc., where a high wool content can be guaranteed. Thus, a market has been found for a new product commanding higher prices. An alternative to the rag material are tailors' clippings. Traditionally of high wool content, these have other advantages in that the fibrous quality is high and the product is trash-free. Trash is very much associated with the use of rag clothing and is typically made up of: Zips (metal & plastic) Belt buckles (metal & plastic) spanners/tools (metal) Coins (metal) 34

Other (world war medals, rings, watches, bullets etc. ,) However, there are major disadvantages in the use of tailors' clippings, one being the price which can be up to double the price of rags. Secondly, availability is limited due to the demise of the UK clothing industry, where there is only a limited number of firms and the supply of their waste is always going to be restricted. This company is the largest single user of rags in this country and possibly Europe. However, in recent years we have had to go to the continent for an increasing percentage of what we buy. Presently, the company purchases approximately 90% of all its rags from the continent and this amounts to approximately 9000 tonnes per year. The move abroad has been brought about for many reasons amongst which price, quality and quantity are foremost: Price: The UK re-cycling industry tried a few years ago to adopt a cartel approach in order to push up prices. Quantity: There appears to be a constant supply available from the continent, unlike the UK Quality: The quality from the continent is generally of a higher standard and tends to be consistent. European sorters want flocking rag quality clothing to be constantly moved out of their factories, to allow them to bring in more raw material. Essentially, it is the sorting of the 5 - 7.5 % of what they call their "cream percentage" where they make their money, and the more that they can sort, the more they will be able to find. The Reclamation Industry - its Organisation and Markets The traditional view of this industry perhaps to the layman, is the "rag and bone man" image, collecting old clothes door to door. However, this is now far from the truth. EU Continental collection: The European industry is very well organised, and is closely involved with the charity collection agencies. Continental sorters purchase the clothing from the charities at approximately £150 - £250 per tonne, depending upon source of collection. Used clothing is collected by charities, door-to-door, throughout Europe, where they leave at each house in an area, polythene bags printed with the charities' names. These polythene bags are then collected at a future date, and are sold onwards in an unopened condition to the clothing recycling industry. Because of the tonnages involved, both collected and sorted, the largest percentage of the collected clothing is delivered by rail, particularly to the larger sorting factories, where delivery is made directly into the heart of the factories. The majority of secondhand clothing is collected from Germany, where it is believed that 6 7 kgs is collected per head from approximately 60 % of the population and it amounts to 35

approximately 200,000 tonnes p.a.

Continental sorting: The main countries and respective outputs are: Holland 100,000 tonnes per annum Germany 75,000 tonnes per annum Belgium 60,000 tonnes per annum France 30,000 tonnes per annum The largest sorter is the Boer & Zoon Group (Holland) with about 50,000 tonnes per annum and the second largest is Evedam (Belgium) which process about 12,000 tonnes per annum (member of Boer & Zoon Group). The probable overall sorting output in EU countries is in the range 250,000 - 300,000 tonnes per annum. Currently, East European sorting levels are about 50,000 - 60,000 tonnes which compares with a probable UK sorting level of 50,000 tonnes/year. Sorted production may be broken down into the following groups: 5 % cream percentage 45 % secondhand clothing for the third world 25-30% fibre reclamation 10-15 % wipers 10% rubbish

Cream percentage: The single most important factor to the industry is the need to receive the collected plastic bags of clothing waste in an unopened condition. In this way, they can be certain of receiving what they call the "cream percentage". This percentage varies from company to company depending upon their expertise, sorting, layout, etc., but is generally between 5 - 7.5%. For this small percentage, they can receive upwards of £3,000 per tonne. Important markets for the industry are France (particularly Paris), Italy and then London. However, there is a demand for good secondhand clothing throughout Europe, and the general quality of nearly new secondhand clothing sold into Europe, commands upwards of £1 ,250 per tonne.

Secondhand clothing: The largest market of all, amounting to 45 % of all the clothing sorted, is the third world market which is dependent upon where in the world the market is, the category of clothing sold and, of course, its price. An example of one market is detailed below in Table 1, for Africa:An important factor in the selling of secondhand clothing, is the political and financial stability of the country purchasing the goods. A market which is very good can be totally finished in a matter of months should there be political changes inside the country. A major example of this is Rwanda, where recent events have had horrific television coverage in this country (UK).

36

Table 1: Yearly tonnage of common market second hand clothing exports to Africa Country

Tonnes

Ghana Togo Benin Rwanda Burundi Tanzania Senegal Gambia Burkino Fasa1 Egypt Tunisia Sierra Leone Zaire Gabon Kenya Uganda

3000 2400 1500 3000 1500 3000 3000 200 500 1200 5000 200 1500 400 4500 2000 33,900

There are literally hundreds of grades of clothing sorted and sold including ladies' long-sleeved and short sleeved dresses, gents' trousers, gents' shorts, children's trousers, children's shorts, both ladies' and gentlemen's jeans, American Jewish jeans ie. Levi Strauss, American nonJewish jeans, etc., etc.; bras are divided into large and small size. Large bras go into Africa, small bras go to the Far East, to the Philippines, etc. Net curtains are heavily in demand from areas with mosquito infestation. Items such as handbags, are again sorted into several categories, as well as trouser and fashion belts. Shoes had one particularly large market, that of Afghanistan, although no direct trade took place between· Afghanistan and the industry. Items were smuggled in from Russia, Pakistan and other nearby countries. This market has now switched to Africa, which cannot purchase enough shoes to satisfy demand. Hong Kong is a very large purchaser of secondhand clothing, taking 2 - 3, 40 - 60 tonne container-loads each month, large percentages of which head onwards to China. Nigeria does not allow secondhand clothing but large volumes are sold in all neighbouring countries from where smuggling into Nigeria is organised. In fact smuggling is a very important occurrence for the industry, and unusual business practices are a common feature. Payment, as would be expected, is in European currencies, which, as can be appreciated, is difficult and often delayed. Payment is made often in various currencies, being paid out of Switzerland, Europe and even the USA. Prices for the graded clothing for the third world vary considerably. Depending on who the customer is, the prices seem to be between £500 - £1,500 37

per tonne. For instance, cotton shirts will demand approximately £1 ,000 per tonne. Cotton shirts are packed in tens to a bundle, 33 bundles to a 50 kilo bale. At a price of £2,500 per tonne, a shirt therefore, represents £0.40 in value. In a sealed container there are on average 10-15,000 assorted garments being despatched at any particular time. The majority of secondhand clothing is packed in 50kg bales which are covered with a woven polypropylene scrim. This is a weight able to be carried by an individual to the local market place with the woven polypropylene scrim becoming the "groundsheet" on which the goods are displayed. One Belgian sorter has one customer in Africa who will only accept 20-30 kg bales. The customer uses camels to move the bales into the countryside, 2 bales each side of the camel. Two 50 kg bales would break the proverbial camel's back! Fibre Reclamation: The third most important market is that of the fibre reclaiming industry. Here the industry sells its woollen knits and single shade synthetics to be processed back to fibre for their reuse. Prices for these items can range from £100 per tonne for the heather shade synthetics, up to £300 - £500 per tonne for the single shade synthetic and finally, up to £1,000£1 ,500 per tonne for wool knits.

However, one example of the recent problems experienced by this industry is the stagnation and indeed, fall of its selling prices. For example, in this category are the wool knits, where just a few short years ago upwards of £2,000 per tonne could be received for this particular grade; present prices are now between £1,000 - £1,500 per tonne. A particularly large market in this section is the sale of self-shade woollen jackets/overcoats to India for processing back to fibre, which is used in the production of cheap blankets. There are several problems with this particular product and market place. These are: Price: Prices are low in India, and like other products, have seen a decline in recent years. This, coupled with the problems of obtaining payments, makes it a very difficult market. Processing: All the items sold to India have to be mutilated due to the Indian government's ban on the sale of secondhand clothing. This of course adds further cost to the operation. Because of the potential risk in obtaining payments, most companies insist on at least a sizeable deposit that covers both carriage out and, if necessary, return carriage costs.

The last two years has seen the Indian government desperately trying to stem the level of imports and thus the demand for foreign currency. One action by the Indian government has been to require up to 21h times the foreign currency value to be deposited with the government for up to 6 months interest free. For example, for an import value of £10,000 the importer has to deposit £25,000 with the Indian government in addition to finding the £10,000 payment to the supplier. Industrial Wipers: The fourth most important market for the industry is the industrial wipers market. Traditionally based around engineering industries for cleaning machinery, a major market is the automotive industry for new vehicle cleaning. Again prices can vary tremendously

38

and this is where the expertise of the sorting company is most important. For instance, the following grades and prices are typical: (i) (ii) (iii) (iv)

Lowest grade (flat synthetics); £120 per tonne. White cotton sheets/pillows; £600 per tonne plus. White cotton wipers; £500 - £1000 per tonne. Flannelette sheeting; £600 - £800 per tonne.

Flocking Rags: Finally, the industry is left with its poorest quality percentage - flocking rags which constitute 8-15 % of total European sorting and upwards of 25 % plus of UK sorting. The single largest market is our own flocking industry. The whole business of sorting old clothing however, is very differently organised between Europe and the UK. It has been explained above how the continent is geared around the charity agencies with an essential requirement to receive the plastic bags, directly from the charities, ensuring that the cream percentage is received. In the UK however, the industry is organised on a completely different basis. Firstly, there are very few house collections specifically aimed at the clothing recycling industry. Local charities do collect, but are more geared to the jumble sale or the local charity shop; e.g. Oxfam, Sue Ryder, Help the Aged, Cancer Research, etc. It is through these charity shops that, in the UK, the cream percentage is lost to the industry. Because of the standing of the above organisations, many people (particularly after bereavements) take their clothing to these shops and in so doing assume that they are directly helping the charity organisations. The charity organisations, however, have to empty their shops on a weekly basis and it is this tonnage that the UK industry relies upon. Oxfam of course is the largest organisation in the industry, with hundreds of local charity shops, and a national collection organisation clearing the shops as required, delivering the product to local warehouses. Large containers are filled and then delivered onwards to Oxfam's national sorting depot in Huddersfield. Using these carriers, upwards of 250 tonnes per week are delivered to Oxfam at Huddersfield from all over the country. The weekly 250 tonnes per week that Oxfam sorts are aimed at providing for that organisation a constant supply of secondhand clothing. The quantity of third world quality clothing sorted, is then purchased by Oxfam' s central organisation and shipped to the areas in the world where local Oxfam agencies are needing supplies. These supplies are given away free of charge to the needy. Oxfam only involves itself with this level of trade, not wishing to trade openly in secondhand clothing to the third world. Their view is that by openly selling secondhand clothing, they might well compete against and damage any local clothing industry. Since there is only one central charity-based, clothing resorting centre in the UK namely Oxfam, so other charities such as Help the Aged, Sue Ryder etc., must rely upon Oxfam and the rest of the industry, to clear their shops of unwanted clothing. Oxfam are the recipients of far greater volumes than 250 tonnes per week, but the extra tonnage they receive is sold on to the rest of the industry at approximately £150 per tonne. Oxfam 39

themselves are charged by the carrier for the collection service from small shops. The industry has also geared itself up in recent years to collect its own rags either from clothing banks or directly from shops such as Sue Ryder. This is in an endeavour to achieve a better quality of clothing at a lower price. Because the UK industry loses out on the cream percentage, and because the general quality of what is collected is lower than in Europe, the quantity of reusable products is therefore reduced, and so of course is potential revenue. The quantity of lower value items such as flocking rags, is greater in the UK as a percentage, and therefore leads to the UK industry charging proportionately higher charges for this product.

Finished Product - Reclaimed Fibre End Product Usage There are three main finished product groups that use regenerated fibres in the UK and Europe; Mattress/upholstery felts Automotive components Traditional carpet underlays There are, of course, many other products such as shoulder pads, roofing felt, cheap blankets etc., but the three category groups detailed above are by far the main users of regenerated fibres in the UK. To provide an understanding of the vast tonnages and thus the size of the industry involved, detailed below are the approximate yearly tonnage usages of regenerated fibres purely in the UK in each of the above categories.

Mattress/upholstery felts: This market consumes about 30,000 - 40,000 tonnes per annum which averages 500 - 800 tonnes per week depending upon the time of year (September through to late November being the peak period). Products manufactured for the bedding and upholstery industry are in both cut sizes and rollform with weights ranging from 750 gm-2 to 1800 gm-2 • There is a range of products from layered felt, heavy needled felt through to bonded felt, both unbacked and backed, with a range of different backing materials such as woven polypropylene or Typar (DuPont). Recent flammability legislation has also resulted in several felt products being developed specifically for use in the UK by both the bedding and upholstery trades, all using regenerated fibres.

Automotive components: This area consumes about 4,000 tonnes per annum. Finished products are, for example, underdash trim, rear parcel shelves, headliners, bonnet liners, boot liners and undercarpet and bulJr.head sound absorbent sheets. 40

Traditional carpet underlays: Approximately 5,000 tonnes per annum are used here, equivalent to 80 - 120 tonnes per week, again depending upon the time of year (Easter and September through to late December being the peak periods). It can therefore, be seen that between the above three main category groups, there is a yearly demand for up to 50,000 tonnes of reclaimable material, purely from UK manufacturing companies.

41

INDUSTRIAL WASTE WATER MINIMISATION AND TREATMENT Allan K Delves

Introduction This paper will cover the following topics:

•

Production of nylon 6.6 yarn

•

"End of pipe" solutions

•

Targets and water/waste management at source

•

Water surveys and mass balances

•

Waste water minimisation in the textile industry - infinity dyeing

•

Planning for continuous improvement

- uses of water - problems

Production of Nylon 6.6 Yarn The DuPont Gloucester site consumes annually 380,000m3 (84mm gallons) in the manufacture of 21 ,000 tonnes per annum (pa) of Grade 1 nylon 6.6 yarn (see Table 1). This equates to 18 litres of water per kilo of product at a total cost of £201,733 pa. The site is one of Severn Trent's largest consumers in the Cotswold area of the UK. With costs of water expected to rise by 15-20%pa, conservation is of paramount importance. The basic raw material for the manufacture of nylon 6.6 yarn is polymer chip manufactured on DuPont's Teeside Site from hexamethylene diamine and adipic acid. Several batches of different chemicals are blended together and transported by road haulage to the spinning plants. The polymer chip is transferred to series of hoppers from where it is gravity fed into a screw pressure melter. Here it is melted and kept in equilibrium under a blanket of steam. The molten polymer is pumped through a filtration pack to a number of spinnerets and extruded as molten filaments. After cooling the filaments are brought together to form a threadline and conditioned in steam. Steam accounts for 13 % water usage. The threadline is then treated with an oil-in-water emulsion to confer lubricating, antistatic and adhesive properties to the yarn as processing aids. After passing over a system of godets or rolls, the yarn is wound onto cylinders at speeds of 1000-1200 m min- 1 typical of conventional melt spinning. 43

Table 1: Water Statistics at DuPont's Gloucester Works Current Water Consumption, pa

380,600m3

Grade 1 yarn, pa

21 ,000 tonnes pa

Water per Product

18 IIkg- 1

Cost of Water, pa

£201,733 pa

Cost of Effluent (6 months)

£29,707

Effluent Volume (6 months)

55,990 m3

Annual Cost Water & Effluent

£261,147

Cost of Water for GD 1 Yarn, per tonne

£12A34

NB: ABOVE FIGURES EXCLUDE ENERGY REQUIRED TO MANAGE SYSTEM

Table 2: Annual Water Costings for Gloucester Works Cost Water Consumption

380, 600m3

£201,733

Cooling Water Losses

27,300m3

£14,469

Air Conditioning

172,61Om3

£91,483

Spin Finish Water Losses

1,299m3

£6,360

Effluent Water Recycle

111,980m3

£59,414

The yarn takes up 4.5 % moisture at 65 % RH - the spinning plant atmosphere is humidified to maintain this atmosphere. This humidification is undertaken by water curtain humidifiers which consume of the order of 172, OOOm3 pa of water (this constitutes 40 % of water usage). Compressed air is used to entangle the filaments of yarn to strengthen the yarn bundle for further processing. The cooling of the compressors accounts for between 7-10% water usage. 44

Additionally, the Research and Development Laboratories and the Textile Centre Dyehouse, where consumer support work is carried out, will consume between 10-20 % of the total water intake. Table 2 shows the annual water and effluent costs.

"End-of-pipe" Solutions The main burden on effluent from the nylon 6.6 production process is associated with the application of spin finish. This is a complex cocktail of hydrocarbon, vegetable oils, ethanolamines, ethylene oxide condensates, fatty acids and sulphated oils with small amounts of biocides. Volume and recycling costs are shown in Table 2. In the late 1980's it was realised that this effluent posed a problem. The Gloucester consent did not include an "oils, fats and waxes" clause; the Severn Trent River Authority proposed a 500mg/Iitre ceiling; pump blockages and gels in lines caused major effluent sources. Also, because of acid and caustic imbalance from water treatment plants, the works, at best, met the pH consent limit for only 70-80% of the time. So the Site spent £2,000,000 on an effluent treatment plant comprising the following process sequence: Chemical cracking - polyelectrolytes pH correction - hydrochloric acid/sodium hydroxide Flocculation Flotation - separation - compressed air Sludge transfer Monitoring The resulting sludge is sent to Wessex Waters Biodrier Systems who produce BIOGRAN, a clean dry odourless soil conditioner which is a valuable organic product. The strategy achieved the desired goal.

Targets and Water/Waste Management at Source In 1991 Sir Denys Henderson, then chairman of ICI and before DuPont bought their nylon 6.6 business, issued Group Environmental Objectives for all sites. These were that:(i)

Compliance with regulatory legislation and standards was to be the minimum basis of the Group's environmental objective reflecting ICI's commitment to meeting relevant regulatory standards throughout all of its businesses worldwide.

(ii)

ICI would reduce wastes by 50 per cent by 1995. It would pay special attention to those which are hazardous. In addition, ICI would try to eliminate all off-site disposal of environmentally-harmful wastes.

This second objective referred to all discharges to land, water and air. 45

It was then and only then that the Company started to tackle the problem at source, i.e. to stop substances (or minimise them) getting into the effluent and to reduce the volume in the first place.

DuPont's environmental goals dovetail with those of ICI and are presented in Table 3. In order to do this the following stages were undertaken: (i)

Preparations of a drain map.

(ii)

The integrity of the drainage system was determined.

(iii)

Every drain was marked.

(iv)

All effluent was metered and a mass balance prepared.

(v)

Measuring/instrumentation (steam, compressed air, surface water and effluent) was installed.

(vi)

Water usage/wastage was costed.

The chemical oxygen demand or COD loading per year has been progressively reduced from 1990, 213 tonnes pa to 1993, 129 tonnes pa and suspended solids from 40 tonnes pa to 13 tonnes pa in 1993. Costing steam at £9 per tonne, the tagging of leaking flanges, pumps, etc, and rectifying at shutdown gives a saving of £11,295 on 1,322 tonnes lost per annum.

Environmental Systems and Auditing One of DuPont's European corporate goals is to reduce water costs by a defined percentage per pound of finished product. Defined cost reductions would be dependent upon local site conditions and regulations. At Gloucester works, for instance, this figure has been quantified as a 5 % reduction over the next two years. Water management must therefore become part of the quality system involving management and employee commitment. Employees need to be involved not only in detecting problems but also in preventing them from happening. Co-operation occurs only when everyone is working towards a common goal. Documentation is crucial to any quality system. Water management must be part of the Environmental Procedures, which are daughter documents of the Site Quality Manual. It must be remembered that the Company is a supplier of waste water to customers including the National Rivers Authority (NRA) and the water companies who have specifications regarding effluent consents. Documentation should define purpose, principles,

46

responsibilities, procedures, recorded documents, training, references and must be subject to periodic review. Table 3: DuPont Environmental Goals for Europe 1.

Reduce hazardous waste generated from the manufacture of products by 35 % from 1990 to 2000.

2.

Reduce Violative Organic Compounds (CEFIC List 1) by 50% from 1990 to 1997 (corresponds to the 33/50 priority list of chemicals in the USA)

3.

Reduce toxic air emissions (hazardous compounds emitted to the atmosphere) by 30% from 1990 to 1995, including boiler gases (CO,S02' NOx).

4.

Reduce carcinogenic air emissions (DEFIC List 2) by 90% from 1990 to 2000.

5.

Eliminate toxic discharges to the ground by 2000, or verify that they have become non hazardous; for Europe this means elimination of landfilling of hazardous waste.

6.

Improve energy use continuously, as measured in BTU's per pound of finished product (or kJ per kg). This is expected to result in a 15% reduction by the year 2000, relative to 1991.

7.

Reduce water consumption per mass of finished product by X % from 1993 to 2000 (where X% is a locally defmed figure).

8.

Cease production of chlorofluorocarbons (CFC's) by the end of 1994.

9.

Eliminate emissions of Nitrous Oxide (N20), a greenhouse gas, by the end of 1996.

10.

Install double-walled storage tanks at CONOCO gasoline outlets.

11.

Manage wildlife habitat enhancement programmes at all manufacturing sites.

12.

Reduce packaging waste by 50% by the year 2000.

Having a procedure and targets allows performance to be measured, and this should be subject to Annual Management Review. However, that alone is not sufficient, we need also to tell people what has been achieved using newsletters, notice boards, annual reports, for example.

Waste Water Minimisation in the Textile Industry Three examples of water conservation and effluent quality improvement applicable to DuPont and the textile industry in general are :

(i)

Infinity Dyeing.

47

This is a DuPont-developed process which, by careful and continuous dye metering, enables dye liquors to be almost fully exhausted. In doing so, lower levels of auxiliary chemicals, water and energy are achieved, plus improved light fastness and dye uniformity. Figure 1 schematically compares a conventional with an infinity dyeing process and Figure 2 shows the application of the latter to the dyeing of cotton/polyamide blends.

Conventional Process Conventional Dyeing Complete

Conventional Aftertreating

100

Bath Temp ( °C ) 40 ...............HIIIII

t

Conventional Process Complete Including Aftertreating

o

20

40

60

80 100 120 140 160 180 200 220 240 260 280

Time ( Minutes)

Infinity Process Start Metering Dyes

Dye Metering Complete

100

Bath Temp (oC) 40 Infinity Aftertreating (Metered)

o

20

40

60

80 100 120 140 160 180 200 220 240 260 280

Time ( Minutes)

Figure 1:

Schematic comparison of conventional and infmity dyeing techniques

48

(ii)

Water scrubbing of effluent gases from waste polymer incineration. Water Scrubbing at one of our sister sites currently consumes 37,600m3 , £20,000 of water a year, of which 24% is lost to the atmosphere and 76% to trade effluent contributing extensively to COD, toxics and suspended solids. This adds on approx £3/m3 to effluent costs. Gloucester has replaced this system with an afterburner which satisfies BEO/BATNEEC and produces natural gases at 16m3 /hr, at a cost of £8,400 pa. Rationalisation of water treatment plants and boiler blow down.

(iii)

For example, one demineralisation plant for the whole site enables bulk regeneration and total system management. In addition, reductions in boiler blow down by 5-10 % to the statutory minimum gives a secondary saving and hence reduced effluent discharge.

we « a: C!)

~

zw

U

1-BATH 2-STAGE METHOD FOR 120

All CHEMICALS AND DYES

COTTON/POL YAM/DE BLENDS

o

110 X 30'

AT START

110 100

ADD SODA ASH

90

CJ)

w w

a:

C!)

w

70

w

60

:::>

50~--..I

e

a:

45'

30' 80

I

RINSE

I

+

~

« a: w

a.. ~

30

w

~

10

20

30

40

50

60

70

80

90

100 110

1 20

130 140 150

1 60

170

190

TIME (MINS)

Figure 2:

Intlnity dyeing process applied to cotton/polyamide blends.

Planning for Continuous Improvement The quality management system, incorporating measures to ensure progress towards set goals, must be made to work and be subject to frequent audits to maintain the status quo.

49

Areas to be examined at Gloucester are (expressed annually): 27,300m3 172,61m3 1,200m3 111,980m3

Cooling Water Losses Air Conditioning Spin Finish Effluent Recycling Steam Losses

£14,469 £91,483 £6,360 £59,414 £11,895

It is imperative that water supplies are metered at each function - surveys are conducted to

address leakages and instigate speedy remediation. Questions to be answered are: Can water be recirculated to areas not requiring potable supply? Is the effluent being treated effectively to address the best environmental practice? How does water management reflect on energy savings? These, and many other issues regarding, for instance the challenges to be addressed regarding packaging, require a continuous improvement programme which should include short term, medium term and long term goals, targets and action plans.

50

FIBRE INDUSTRY AND WASTE MANAGEMENT NeIlo Pasquini

Introduction The Fibre Market represents an important industry segment for polypropylene (PP), accounting for approximately one quarter of PP consumption; in fact after packaging it is the most important polypropylene application area. Although a relatively well-established market for polyolefins, recent material developments will revitalize the industry and ensure that a high pace of growth will be sustained in the market. Figure 1 shows the expected growth in PP applications.

Figure 1

LEGEND:

POLYPROPYLENE MARKETS (%) 1993

1998

TOTAL = 4550 Kt

Total = 6300 Kt

II

Packaging

II

IIil!I

Fibre

~ Appliance

•

Transport

0

•

Furniture

Consumer

Others

FIBRE 1100 Kt --> 1400 Kt

Source: HI MONT

51

It can be seen from Figure 1 that the PP market is growing in a dynamic way and that the fibre contribution will roughly maintain its percentage share, accounting for 1400 ktonnes in 1998.

Waste from the Fibre Industry The fibre market generates waste as products complete their useful life cycle. The portion of fibre based waste in the total plastics waste scenario is shown in Figure 2.

[ Figure 2

[

TOTAL PLASTICS WASTE BY SECTOR IN W. EUROPE 1992

5%

5%

TOTAL •

Municipal Solid Wastes

L.J

Construction, Demolition, Civil works

~

II

=

16 Mill. t

Agricultural sector

•

Fibres

Electrical and Electronics applications

•

Automotive

~ Distribution and large industry

Source: APME and EATP Studies by Sopres Conseil - May 1994

In common with all industrial applications, notably the packaging arena, which has been the focus of considerable attention in recent years, the textiles waste issue needs to be addressed.

Waste level: In 1992 some 750 thousand tons of waste were generated in the fibres sector of the 1.0 million tons of polypropylene consumed that year, see Figure 3.

52

I

Figure 3

I

POLYPROPYLENE TEXTILE CONSUMPTION AND WASTE ARISING IN DIFFERENT APPLICATIONS IN W. EUROPE 1992 Others: twines & ropes, medical, apparels & domestic, strapping, other textiles CONSUMPTION 1992

WASTE 1992

Source: EATP study by Sofres Conseil - May 1994 749.000 tons

1.011.000 tons

The apparent discrepancy in the figures is explained when the pattern of use of the fibre products and the actual growth in the market are considered. Table 1 shows the breakdown of uses for fibres and it can be seen that there are four categories of life span. Table 1 - Approximate life time of polyolefm textiles Life time (years) Medical Hygiene Sacks (*) FIBC's (**)

<2

• • •

Ropes & twines

•

Carpets

• •

Construction Geotextiles

5-25

• •

Agrotextiles

Apparel, domestic

2-5

• •

0

0

•

• • •

•

"') ct. WhICh )U% less than two weeks (**) Flexible Intermediate Bulk Container • denotes typical and 0 possible examples Source: EATP study by Sofres Conseil - May 1994

53

>25

Textile waste occurs in several industry areas and these are broken down in Figure 4. The situation regarding waste disposal methods, as it stood in 1992, is shown in Figure 5. I

Figure 4

OCCURENCE OF TEXTILE WASTES 1992

I

Source: EA TP study by Sofres Conseil - May 1994 Household

362 Kt Hospital 10 Kt

Automotive

56 Kt

Agriculture

63 Kt

Office

107 Kt

TOTAL 749 Kt Figure 5

I

POLYPROPYLENE TEXTILE DISPOSAL METHODS W.E.

1990 21 %

30 %

7 % 60

%~10

%

Total: 777 Kt

Household: 339 Kt

Industry: 143 Kt

Total: 749 Kt

Household: 362 Kt

Industry: 139 Kt

1992

ETI

Landfill

Source: EATP study by Sofres Conseil - May 1994

54

D

Incineration

•

Energy recovery

Figure 5 also indicates that the level of incineration with energy recovery is gradually increasing (from 20% in 1990 to 22 % in 1992). The breakdown of the total textile waste disposal systems closely mirrors the fate of household textile wastes, which is the largest area, representing half of the total textile waste generated. The other major contributor is industrial textile waste, which has an even higher percentage (33 %) of energy recovery. The disposal situation today does not suit the legislators as landfill still dominates, and most regulatory bodies consider mechanical recycle as the best option. It is worthwhile evaluating the status of the current legislation and taking as a model for discussion the example of the packaging industry; where some parallels may be drawn.

Legislation: Environmental regulations affecting textiles have already been introduced, and these are listed in Table 2. Actually, some application areas in textiles fall under the scope of other established regulations. For example packaging legislation affects textiles used in packaging, such as sacks, FIBC's, twines, ropes and strapping.

Packaging and the Environment : An Explanatory Case So far legislation in the packaging sector has been driven by political expediency and emotional reactions, more than by scientific and practical considerations. Legislation or draft proposals are in place in almost all the major European countries. A prime example is the Topfer scheme which calls for mechanical recycling levels far in excess of the existing facilities to deal with it. The result is that huge stockpiles of plastics waste have apparently been generated. A further barrier towards the implementation of suitable mechanical recycling schemes is the net cost of recycle which is of the order of DM 3.55 per kilogramme; far in excess of the value of prime materials. In the end the German scheme will need to be drastically reworked. The German legislators also sought to have their approach adopted by their European neighbours, through the imposition of strict specifications on imported packages. Eventually all the existing legislation will be harmonized under a new EEC Packaging Directive, (the levels of mechanical recycling promoted under this directive are given at the end of Table 2). However, this approach of attempting to retro-actively introduce an all-encompassing directive which keeps the majority of the diversely opinioned legislators content, is a considerable task. This difficulty should be avoided in the textile sector. For this reason the fibre industry is being pro-active in lobbying for a balanced, rational and attainable approach to waste management and this will be discussed shortly. We have seen from the packaging experience that wholly inappropriate actions have been followed and regulations imposed for political expediency. Furthermore some of the regulations already in force also have implications for textile waste, such as big bags. It is vital therefore that these punitive regulations and negative experiences are not repeated in other industry segments. 55

Table 2 - Environmental Regulations Affecting Polyolefin Textile Waste. Application

Type of Waste

Scope of Regulation

Transportation & Elimination of Toxic Waste

Medical Hospital

Mandatory incineration, most countries - in hospital or MSW incinerator. Transport control also.

Limitation of Cross-border trade

All wastes

Problems arising from German household & contaminated wastes, exported due to ill-fitting regulations, stress need for Community response.

Tax on Polyethylene Packaging (Italy).

FIBC PE Linings

Only becoming effective now.

Packaging Wastes Management

Bags,Sacks, FIBC's,Rope Twines, Strapping

Germany -Topfer ordinance targets 64 % material recycle, 36 % landfill\energy recovery by 1995. RGK group to manage collection of FIBC, using same type of scheme as failed DSD. France-Conseil d'Etat approved framework for sacks & FIBC - producers exceeding 1100 tonnes weekly to create schemes & pay Austria - 'Altstoff now effective - based on Germany approach. UK -self-regulation by industry PRIG set up to monitor progress Spain -Discussions but no regulations Portugal,Greece-No regulations or funding systems. E.C.Directive - Management of Packaging Waste; within 5 yrs 50-65 % (wt) packaging recycled with 2545 % of this mechanical with min. of 15 % any material stream.

A Better Approach in the Fibre Industry For this reason the Fibre Chain Forum initially under the leadership of EATP and now COMITEXTIL (Coordination Committee for Textiles Industries in the E. U. )and supported by APME has been created. Its role is: To create a platform for intelligent debate. To initiate and evaluate appropriate schemes aimed at determining the feasibility of recycling systems. To lobby for a cohesive and complete (all encompassing) approach to waste management options and to present a unified single voice to legislators and

56

consumers alike. The Fibre Chain Forum (FCF): The precise aims and mandate of the FCF are now laid down in a draft white paper. The fibre industry has been considering environmental issues for more than 4 years, and therefore several recycle initiatives have already been evaluated. In the area of mechanical recycling it has been shown that it is entirely feasible from a technical standpoint to recycle textile waste. Significant work was carried out in the area of post-user carpet collection and recycling, and in FIBC's, ropes and twines. However, unfortunately, most of these schemes have not been pursued because the economics of recovery and/or the environmental impact of establishing such recycle systems is greater than adopting alternative waste management options. The floor coverings area is a notable exception, as they currently use industrial scraps such as cutting edges to produce backing in needle-felt which replaces foam or secondary backing for tufted carpets. Another scheme still being continued sorts floor covering into PVC, linoleum, and textiles; however the appropriate fraction is then used as a fuel. Projects on life cycle analysis of textiles are in place and will provide the basis for objective debate regarding the environmental impact of articles such as carpets in future. Feasibility studies into the separation of carpets have also been carried out; and have shown that mixed polymers create a problem. This could be overcome by the introduction of a monomaterial polypropylene carpet, and Himont is actively supporting such initiatives by broadening the property profile of polypropylene to enable it to replace other textile materials. The mechanical collection of FIBC's was also investigated but shown to be unsuitable for two mam reasons: a) Sacks are too widely dispersed geographically b) Some may have been used to transport dangerous goods. So it has been shown that the target of the legislators for a high percentage of mechanical recycling of textile waste is impractical and uneconomic. The FCF will champion suitable schemes that aim to reduce the amount of textiles used at source, as this is a rational way of reducing waste. Furthermore the FCF continues to investigate mechanical recycling initiatives, but they believe that the targets need to be properly set to reflect the actual situation and the realistic disposal options. United under the umbrella of APME, the FCF seeks to promote one voice in representing the interests of the fibre industry (see Figure 6), and ultimately the consumer, through correct and suitable waste management options. Under the coordinating role of COMITEXTIL, the following textile european associations are currently part of the Forum : COMITEXTIL - EATP - GuTT -

57

CIRFS -EFIBCA - Others. The current legislative position and the desirable approach that we in the industry believe should be followed, are laid out below in Figure 7.

I

Figure 6

I

FIBRE CHAIN FORUM· SPEAKING WITH ONE VOICE

Textile Polyolefins

APME

Natural

Fibre

Fibres

Chain

One

.I

Voice

One Voice

E.C. Leg islators

- fibres

- All plastics

Other Synthetic Fibre

Figure 7

I

•

Benefit from APME access to legislators.

•

Increase the weight of APME voice.

•

Ensure consistency of information and approach within EU.

PLASTICS INDUSTRY GLOBAL TARGET FOR WASTE MANAGEMENT

Current legislative objectives

Industry target through dialogue _Limited

o CI S

-Long term ONE VOICE

t::

o

2

o a.

-

'C

o)(

u:

Short & medium term

f---Strategic reduction 1992

1996

2000

:!lOO

58

Energy Recovery It can be seen from Figure 7, that incineration with energy recovery is believed to be a justifiable and suitable option. This is due to the very high calorific value of plastic materials and polyolefins in particular (their "Locked-In Potential" or LIP). Figure 8 shows the LIP rating for a range of common materials. Figure 8

I

LOCKED-IN POTENTIAL (LIP) EXPRESSED AS CALORIFIC VALUE FOR A RANGE OF MATERIAL

Product

Energy

Polymer

LIP (MJ/kg)

Polypropylene

46

Polyethylene

46

Polystyrene

41

Polyurethane

24 - 31

Polyester

19 - 30

PVC

20

Conventional Fuels

Energy (MJ/kg)

Diesel Oil

46

Naphtha

42 -46

Carbon

21 - 33

Wood

16 - 21

Paper

16 -19

It can be seen from the above figure that the energy of 1 litre of diesel oil = LIP of 1 kgm of polyolefin. In fact studies have shown that the removal of the plastics component from the Municipal Solids Waste stream, renders the remaining matter (vegetable waste and paper etc.) incombustible, requiring the addition of diesel oil in order to fire the kilns. So the inclusion of plastics components in the form of textiles or packaging, after their primary life, means that a quantity of oil equivalent to the LIP of the plastics matter can be saved. This is in effect extending the useful life of the plastics by using them as a secondary resource or fuel.

59

So the combustion of polyolefins textiles waste produces a high amount of energy. It may also create a small amount of ash, but this can normally be dealt with easily. One specific initiative built around carpet waste is to utilize these awkward articles as a fuel in cement kilns. The typically long burning time and large in-feed of these kilns are ideal for accepting bulky carpet waste. Furthermore any residual mineral fillers which generate ash are automatically incorporated into the final cement product. The Way Forward - A Considered Approach to Waste Management. APME calls for "equal dignity options", for the generation of a cohesive and comprehensive waste management strategy, which makes sense for the long-term future and not only the shortterm objectives of politicians. Naturally, it is recognized that landfilling must be reduced and that appropriate mechanical recycling schemes should be considered where they may be economically and environmentally viable, as this is a way of extending still further the life time of petroleum based products. However, energy recovery through carefully designed incinerators is an excellent way of dealing with waste matter (particularly contaminated articles). In addition feedstock recovery schemes, whether as raw polymer or regenerated monomer, are being investigated as they may offer a solution in the longer term. The FCF and APME will continue to unite all levels of the industrial chain in their struggle to positively influence the legislators of Europe in the derivation of a holistic and sensible approach to the management of plastics waste. Acknowledgements: I would like to thank T. Mc Cormack (Manager Rigid Packaging & Projects - Himont Europe) and A. Cicuta (Environmental Specialist -Himont Europe) for their kind assistance in the preparation of this paper. References 1)

A Statistical Survey of Textile Polyolefins Consumption and Waste Management in Europe. EATP 1992

2)

Updating of Above Survey. EATP 1994

3)

Working on the "Fibre Chain Forum". N.Pasquini

4)

Draft White Paper on the "Fibre Chain Forum". EATP

5)

Maintaining the Eco-balance Profitably. Himont Brochure

60

RECYCLING OF PLASTIC FIBRE AND PACKAGING WASTE J A(Tony) Horrocks

Introduction It is practically impossible to avoid producing waste in the manufacturing and use of synthetic fibres, tapes or packaging films and it is essential that this waste is recycled both to improve the economics of the industry and save polluting the environment. For the purposes of this paper scrap can arise from three sources:-

1. In House:- A first priority is to reuse the scrap produced and convert back into the finished product. If this is not possible then every effort must be made to use it in another product which has a higher added value than disposing of the scrap.

The manufacturer can have his own scrap recovery process or he can send the scrap to a trade recycler to be reclaimed into pellet and returned or he can sell it to the trade recycler. Only in rare instances should it be necessary to dispose of it in landfill or incineration. 2. Post Industrial:- This waste is produced when the synthetic fibre, filament or film is used by a customer in another product. It is desirable to recycle as much of this scrap as possible by either returning it to the manufacturer for reuse or by selling to a trade recycler for reprocessing. Only if unusable should disposal to landfill or incineration occur. Sometimes the material from this source is contaminated with dirt, metal, paper, etc., in which case it will have to be washed first. If not too highly contaminated it can be used without washing to make products such as pallets, composters, garden products directly from scrap. 3. Post Consumer:- This is household waste, and the plastics as packaging are usually mixed and contaminated with other materials such as glass, metal, paper etc. Material should be manually or automatically pre-sorted and washed before reclaiming - this is being carried out with PET,HDPE,PVC bottles. These reclaimed materials can then be reused in the production of primary products such as fibres, moulded products, etc. Methods of Recycling The simplest method of recycling scrap is by granulating but this produces a product which in most cases is impossible to reuse directly into the primary manufacturing process of fibre or film. It is noisy and dirty with much dust; the scrap cannot be filtered to remove impurities. The standard method of extrusion is by melting, filtering and pelletising. Scrap cannot be fed directly into the extruder and needs to be put through a granulator first. This gives problems 61

because the often light fluffy material is difficult to feed, output is low, different materials sometimes require different screws and dies, material is degraded due to high shear and heat, Semi-or fully automatic the process is dusty and noisy and energy usage is high. aggregators, also termed disc mills, can be used but they have to be fed with granulated material and the final pellet is not uniform in size; it has a lower bulk density, contains fines and has not been filtered. Consequently, it is difficult to feed material back into prime production process.

The Erema Process & Concept In 1982, three Austrian engineers designed and patented a system which utilised the advantages of all the above and overcame the disadvantages to produce THE EREMA PROCESS which is an in-line extrusion process that is dust free, has a low noise level, occupies a small space, has low energy usage and generates low maintenance costs. It can produce clean, full bulk density, filtered pellets with little or no degradation directly from PP, PE, PET film, fibre or scrap bottles at a high output and low operating cost. This high performance, which is independent of the shape and bulk density of material to be processed, results from the EREMA concept of using a shredder drum attached to an extruder (see Figure 1). The shredder drum is continuously fed, with the rate being automatically controlled by the load on the shredder motor which drives high speed rotary knives that not only cut the material but also heat it to just below its melting point. This hot material is then fed into an extruder which melts the material and passes it through a filter to remove contaminants, and then into a water cooled die head to produce pellets which are dried, stored or bagged. Because the material is fed hot into a short extruder, the screw is designed with deep flights which produces little or no shear. This provides a minimum heat history which results in little or no change in the melt index. Hence quality of material is such it can be used in higher added- value products (see Figure 2). This compares extremely favourably with conventional extrusion where material is heated from cold, primarily by shear from the extrusion screw, which thus causes considerable degradation of polymer, and a high energy usage. See Figure 3 for details of temperatures used for various polymers.

Erema Vented Process For hygroscopic materials such as PET, polyamide (PA) and materials containing volatile products ( foams, fibres with spinning oils, printed material, scrap with more than 4 % moisture, etc), it is necessary to have a vented extruder, so that a gas-free pellet can be obtained. With a conventional vented extruder, the screenchanger is normally at the end of the extruder and this can give problems because contaminants such as paper, PVC, etc. can stay on the filter and degrade thus giving an expanded pellet. Erema have overcome this by putting the screenchanger in front of the vents (see Figure 4) which also has the following advantages:•

It decreases any screw wear and prevents material seeping out of the vent because of high back pressure. Thus material with wood or paper residues,

62

•

•

labels, stickers, etc., can be processed. A second screenchanger with very fine screens can be fitted to the end of the line if required Glass fibres can be added to PA and PET after the filter which protects the screw barrel and glass fibres from damage.

Normally the Erema Process uses a "Hot Die Face" pelletiser but because of their viscosity, it is necessary when processing PET and P A, to use a strand die followed by a water bath at the end of the process. This arrangerrient will also handle all other polymers. Screenchangers

Erema have developed and patented two unique types of Screenchangers which are fitted to the Erema process or they can be fitted to other extrusion lines such as fibre production; other scrap processes, etc. The partial backflush screenchanger is shown schematically in Figure 5. Material flows through four filter packs installed in two pistons which provides a very large filtration area. Automatic backflushing of each screen in turn is achieved utilising extrusion pressure, and advantages over conventional screenchangers are: -

lower screen costs since they last between 50 - 200 times longer lower labour cost. melt temperature and pressure is reduced thus reducing degradation materials with a relatively high contamination level can be processed

The screenchangers are constructed from hard precision steel with wide sealing surfaces thus giving many years of operation free maintenance. The laser filter in Figure 6 is so-called because the specially designed "self cleaning" holes in the hardened steel filter screen have been made by use of laser beams. This allows much smaller diameters than conventional drilling with the ability to have more holes and a finer filtration in a given surface area. It is a "continuous" process whereby the screen is a circular disc through which the contaminated polymer flows and the contaminants are cleaned from the surface by rotating knives to produce a "continuous sausage " of contaminant and plastic in an approximate ratio 1:2. These filters are designed for large quantities of contaminant ( 5-10% ) but this must be a soft material such as wood, paper, aluminium, copper, higher melting plastics. The optimum filter fineness at present is 150 p.m which is sufficient for some purposes; however, a conventional RTF filter could also be added to the line. This arrangement allows material to be recycled which was not possible before. Use of a Melt Pump: If the scrap is not too mixed and is reasonably uniform in melt flow, then it is possible to produce the finished product direct from the scrap without going through the pelletising process. This can be achieved by fitting a melt pump ( gear pump) to the end of the Erema extruder and connecting this to an existing or appropriate die. By this method can be produced fibres, films, sheet, tubes, etc. 63

Use of a Vacuum Shredder Drum (see Figure 7): Even though the Erema process is gentle on processed polymer, the water which is present in PET still reacts to a certain extent and causes a reduction in the viscosity. Whilst the resulting pellets can be used to produce second grade fibres, they cannot be used in high grade bottle or film manufacture. Erema have developed a special shredder drum with a vacuum which removes most water before it enters the extruder so that the IV is changed only a little (see Figure 8). High water contents up to 12 % can also be processed. This allows the recycled PET to be used in high quality products. Other Processes Edge Trim Recycling: A recent development which consists of a small two shaft shredder fitted to the extruder allows edge trim from films, sheet, etc., to be processed directly into pellets or returned in a closed loop back into the primary process. Output rates of 20 - 90 kgs/hr are possible. De-gassing: Polystyrene foam used in bulk packaging can be recycled but until now it has not been possible to re-use it in foam manufacture because a pellet containing gas could not be produced. After two years development, Erema have produced and sell an in-line extrusion process which can introduce a gas and thus provide a pellet containing gas which can be used to manufacture the block foam packaging. Prome extrusion have developed a special haul-off which can be fitted to an extrusion line to produce profiles from difficult melts ( mixed and contaminated scrap ) and profiles that cannot normally be calibrated. Costs Total operating costs range from £35 to £95 I tonne depending on the machine size which compares extremely favourably with other processes. This, together with the ability to be able to produce higher added value products, provides increased profits for the manufacturer, particularly as the recycled material can often be used instead of virgin polymer with a lighter price of £400 - 600 per tonne. Advantages The advantages offered by the EREMA process are: • low operating costs • small space requirements • low noise level and no dust emission • high quality, filtered, full bulk density pellet with minimum degradation Applications These advantages provide financial gains compared to other processes. The low degradation allows the scrap to be reused at high levels ( sometimes 100 % ) and the quality of the finished product is improved as is the efficiency of the process i.e. not as many filter 64

changes. The film or fibre does not break as often and finished product is improved. It also allows the scrap to be used in applications which were not possible previously. The Erema process is used in the following applications:FILM - all types of film production e.g. LDPE, HDPE, film . With PP film 300 mesh filters can be used which allows film of 12 JA.m to be produced with over 30 % scrap level and 35 JA.m film with 100 % scrap FIBRE - PET, HDPE and PP fibres. A special process was developed to produce PP fibres from polymer with an MFI 600 - 1000. SHEET - PS, PP sheet production CARPETS - edge trim and other scrap can be reprocessed. ROPE - scrap reprocessed and reused IN LINE - PE films; PP tape; PE tubes; PE sheet are all being produced direct from scrap. Production of fibres and filaments is also possible. SCREENCHANGERS - these have been fitted to existing film; PET and PP fibre and tape lines Erema have sold over 700 machines worldwide with 75 in the UK. Over 300 machines are for PP ( 15 in the UK) and 40 for PET ( 3 in the UK ) The Remaplan Process (see Figure 9) Normally it is only with the extrusion process that scrap can be reused because it is not economically or technically viable to put contaminated or mixed scrap through an injection moulding machine. However, moulded products can now be produced from mixed slightly contaminated scrap using the unique, patented, fully automatic, computer controlled REMAPLAN PROCESS which is basically an Injection / Compression moulding machine connected to an Erema extruder by a special accumulator adaptor. This process allows finished products to be made direct from scrap in a single operation with only one operator. Consequently operating costs are low; excellent quality products and low capital costs result compared to injection moulding (see Figure 10). Normally mixed, slightly contaminated scrap is used and there is no need to prewash or sort depending on the finished article. Remaplan have successfully developed the process to use 100% PET scrap from bottles, etc, to produce pallets and other articles which will have technical and economic advantages over other materials. Applications: Pallets, garden composters, reels and in fact any moulded article with a wall thickness of 4 - 7 mm depending on cleanliness of the scrap. Two machines are installed in the UK producing Pallets and Geo-block Ancillary Processes: Sometimes the condition of the scrap requires some pre-preparation

65

and the following processes are also offered by Norplas:Tecnofore-washing plants from Italy; several are already installed in the UK and they may be used for prewashing of film, bottles and consumer waste by local authorities. In addition they are used for washing used car carpets from scrap cars; the PP and PET fibres are recycled by extrusion back into reusable pellets. Pierret cutters - these are special high speed cutters used to precut very thin film, fibres, filaments from baled or loose material. Many are installed throughout the world and Pierret have been given awards for their achievements in the textile industry. Conclusions It is essential that scrap in all its forms is recycled wherever possible. By choosing the right technology and process it is possible to reduce costs and to add value to existing and new products. Thus the product quality is improved, profitability is considerably increased and the environment is helped.

66

cutter compactor scrap

drive extruder

drive cutting tool

Figure 1: The Erema recycling plant concept

melt filter

I

A

"

Cuttrng,

8

1~~,~l~rl~~1~~~~~~~i(lr~l1~lU~11i~l~f\.: ...•.i I·.1, ,,~~~, ,.If:J!,nr{lP!:. ~ .I.~ ~"II~rc, M,t.n'L' .c'J:_l!:di!'~"""l

drying,

;.f. __

•. :.

..

.;,:0;.1.

.,: ~·i!t· ;:~~~ ';Cliifti~I~-'--' 1.!."',~a;;lrl' ...,':"~'."IP'""'""I!#i~' •.".".'' .I'."h~:~:y,:W~".'·~
I

.

precompressrng:;lll1l~1!il,~j~hi1t''c'!1f1fl!:\'!ij~lt~\~l:t!?~ . . , ,~~t~3 ~"'~'~~cW';~~"~~~'~" d'\l7~lf~fH~~t~~/tt~{}~*~;~ '1~:!::'I!l'f'llifi:;"l!!':i~~'f~fffi~ :'ilN~..'~I. li.,":"! r.\I. ~ I{;!i\~ r!.!lf."'.'~ "l:,!:\li~~,\!l;~l .'f~.'f.~'.:( .'"'"I:'.!~.~ ' ' .: . . ! .I feeding :~~~~~ '~W~_~~~~j~~;~ft ::~1!~~r{~J4~i~11~~! ~~j~~ , melting 1!\),'i~''''i;~'''J.rJl~;t"<;l':('i,~,-,jll''i,;,JL,'1)/;o, .r "

,!1j;'I,·

.•

I

•

I

"

'01

C

pressure build-up, metering

D

filtering

E

homogenizing

F

venting

G

discharging

Figure 2: The Erema short extruder system

A

Material temperature e.g. LOPE

1I11111111111~lllf:i:: 32

392 0 F

i,

:',.!lr

1. 00

0

200 C

0

,~~:';

I ... '.,

212

G

kW h 1100 kg

Heat content ( Enthalpy)

kJ I kg

24

864

20

720

16

576

12

432

8

288

4

144

00

50

100

150

200

Temperature Figure 3: Specific heat capacities of different thermoplastics versus temperature

250

3000C 0

Cleaning of screen pack II in piston 1 piston 1 in backflush position 2

2

main melt flow

backflush melt flow

Figure 5: The partial surface backflush action of the screenchanger

1

melt inlet

~

... , rotation

contaminations

~ melt outlet Figure 6: The melt laser filter

- precutting - crystallize - predrying

double venting

1\ t t t automatical slider for material feeding Figure 7: The vacuum shredder drum

screw intake under vakuum

......

CD

........ o

0,8

...... CD .........

o

~ 0,6 1-

~

Material b e for e reclaiming RII Material aft e r reclaiming

CJ

(/)

"S;

CJ l-

0,4

en

c .... "....., .E 0,2

o'

!I'nn

one-step-system

two ..step-system

Figure 8: Intrinsic viscosity of PET bottle polymer before and after reclaiming

ZALO CHECK VALVE VANNE VALVULA

ROLLEN[INZUG ROLL fEEDER ALIMENTEUR DE ROULEAU AUMENT ADOR DE .ROLLOS

PRESSE PRESS PRESSE PRWSA

FORM MOULD MOUlE MOLDE

IHJEKTOR INJECTOR INJECTEUR

fORDERBAND CONVEYOR BANDE TRANSPORTEUSE CINTA TRANSPORT ADORA

ZERKL[INERER SHREDDER CONCASSEVR TRITlJRADOR

MA TERIALZUFUHR fEEDING MATERIAL AUMENT A TlON MA TlERE ALIMENT ACtON MA TERIAL

AlHiKEL

PLASTlF:\ZIEREINHm PLASTlZI$ING uniT VNITE DE .PLA$TlI'tCAliON UNlOAD PLASTIFICAOORA

PLASTIFlZ1ERUNG PASTIZISING PLASTIFICA nON PLA5TIFICAClON

ARTICLE ARTICLE ARTICULO

DOSIEREN-INJEKTION DOSAGE -INJECTION ,; DOS.AGE-INJECTlON ) : DOStFICACION-INYECCION : ,

I

Figure 9: The Remaplan Process - Horizontal injection-compression installation for recycling

PRESSEN-ENTNAHME COMPRESSION- TAKE OUT COMPRESSION-RETIRER COMPRE 55 ION- SA CA R

HYDRAUlIK-AGGREGAT HYDRAULICS AGREGAT HYDRAUUQUE UNlOAD HIDRAL1LlCA

Comparison of PET-recycling - all figures in OEM per ton Operation costs Position as per December 1994

conventional 11300 1.000

Refinishing work, washing, separating paper, drying Granulating Pressing Overall costs Turnover per ton Value added

----

-1.300 1.500 200

remaplan 300 250* ---600 1.150 1.950 800

# Coca-Cola-Daten * only drying

Figure 10: Comparison of PET-recycling costs (in DM) for conventional versus Remaplan Processes.

76

KEY LESSONS FOR PLASTIC BOTTLE RECYCLING Andrew Wood

Introduction It is useful to break the recycling system into its key components. By taking a total systems view of the problem we can identify the key roles and the barriers to recycling and these are listed in Table 1.

Table 1:

Roles and Issues for Bottle Recycling

STAGE

ROLE

KEY ISSUES

LEGISLATION

GOVERNMENT

COMMON STRATEGY AND PLAN

BOTTLE PRODUCTION

MANUFACTURER MARKETEER RETAILER

+ MARKET SHARE + RECYCLED CONTENT

DEPOSIT

CITIZEN

+ PEOPLE WILLING +COMMUNICATION

LOCAL AUTHORITY

+ MRF'S-INTEGRATED + TECHNOLOGY + SUBSIDY

GRAN.lCLEAN

REPROCESS OR

+ BOTTLE DESIGN + SPECIFICATIONS + VIRGIN PRICE + VOLUME

MARKET

INDUSTRY

+ PRICE + QUALITY + HIGHEST VALUE + FIT FOR PURPOSE

COLLECTING SORTING

} }

77

Legislation The need for a common strategy and plan: The EEC packaging directive is an attempt to create a common strategy for recycling. The time it has taken to achieve consensus illustrates the variations of approach in each country. Nevertheless, it is a key step forward and will allow national governments to align their recycling strategies. In the UK where each Local authority has been charged with recycling 25 % of its domestic waste and each has its own plan and where industry has been charged with producing a plan to recycle between 50-75 % of all packaging (domestic plus commercial), it is clear that there is, as yet, no common strategy and plan. Hopefully, impending UK legislation on the environment will provide the necessary legal framework to enable all parts of the recycling chain to develop a common objective. Without a shared view of the problem and an agreed objective we will struggle to make recycling work. The challenge is to harness the goodwill of the public and align it with the responsibilities that Local Authorities have to recycle; and obtain the funding to enable it to happen from a levy on packaging organised by industry. The Plastics Industry has a clear responsibility to make sure plastic bottles which are relatively easy to recycle into high value application are recycled.

Production of Bottles for Recycling Plastic bottles offer design flexibility and low cost: The success of plastic bottles has been phenomenal. The relatively low costs of production combined with infinite design flexibility have enabled plastics to take a major share of the market. The three main polymers are PVC, PET and HDPE. PVC (about 34 ktonnes per annum) offers gas impermeability, moulding flexibility and low cost, and is successful in carrying still mineral water, cordials, edible oils and cosmetics. PET (100 ktonnes plus per annum) offers mechanical strength and clarity, and has been particularly successful in taking a major share of the carbonated drinks market. HDPE (about 100 ktonnes per annum) which is widely used for household and dairy products offers good mechanical properties and design flexibility. For plastics to continue to be favoured, we must continue to offer competitive materials but we must also meet the environmental challenge. The public has experienced the reduction in the use of plastics in detergent bottles as brand managers encourage its members to regard alternative packaging as more environmentally "friendly". Lever and Proctor and Gamble have both marketed concentrates in carton form. Another example is plastic pouches marketed together with refillable tins. It is essential to design plastic bottles which are easy to identify and recycle, whilst not putting unnecessary constraints on bottle designers. To achieve this it must be clear what the design criteria are which significantly affect recycling viability. This factor must be consistent in the overall recycling message so that it is understood.

78

Plastic bottles offer recyclability: Significant progress has been made to demonstrate that plastic bottles are recyclable and the work of RECOUP in the UK has been significant. The cost of collection and reprocessing, which are high when volumes are low, has been a constraint to growth. The promise of a funding system in the future will help keep the momentum going. However, there is a need to increase recycling rates rapidly to ensure plastic bottles continue to be regarded as environmentally "friendly". This is the major challenge for the industry. The recycled content of bottles is a key issue for some major companies who wish to offer environmentally "friendly" products. Either by using co-extrusion or by incorporating recycled polymer in non-food contact bottles recycling of bottles into bottles may be achieved. This provides an opportunity to demonstrate to the consumer that plastics are environmentally "friendly". Plastics can be reformed into numerous useful applications. Plastic bottles can be easily identified and separated from the waste stream. Recyclability of plastic bottles is a major strength and it must be utilised to the full.

Deposit of Bottles for Recycling People are willing to deposit plastic bottles for recycling: When REPRISE began its project in 1988, it had no idea what the public response would be. Two hundred homes were targeted in Stockport, and the response was emphatic, with everyone targeted (and some not) sending in their bottles. People wanted to recycle their plastic bottles. This may seem fairly obvious today but it is a key lesson and without this desire, recycling would not be possible. 70 % of those targeted in Milton Keynes now consistently deposit their plastic bottles. Post-consumer recycling is a new industry. It is an industry with a bright future. The key issue is who pays? The challenge is to make recycling as economic as possible and one day it will be on a sufficiently large scale to be self-financing. Some would argue that plastic bottles should be incinerated with energy recovery in mind and of course it makes sense to recover energy from those bottles that cannot be recycled for whatever reason. However, this will not satisfy our need as consumers to be involved in a process - hands on - by which we can contribute to recycling. Most of us do care! Communication of what we want is vital e.g. CAPS OFF!!: The first step in recycling is generally in the household. It is vital that we only collect materials which can be recycled. For example up to 10% of bottle weight is in the cap. The caps add considerably to the waste and incur extra costs to remove them. People do not like change so there must be clear and precise instructions at the beginning. This should be reinforced by regular contact, newsheets etc. and also with posters at deposit sites. On kerbside schemes, we should be able to reject unrecyclable materials at the household level. People want to be helpful so let us make best use of this willingness and free labour and give clear instruction. The need to remove caps which is addressed below is an example of how clear communication to the householder can reduce recycling costs.

79

In this case, if all caps were removed before depositing, recycling efficiencies could be improved dramatically. The same principle applies at the Material Reclamation Facility (MRF). The reprocessor should give clear specifications for recyclable materials and reject non-recyclable elements.

Collection and Sorting Integrated Material Reclamation Facilities (MRF) are needed to make recycling work: Until December 1993 REPRISE reprocessed loose mixed bottles collected locally and delivered, with non-sorting, direct to the plant. Non-recyclable content was typically more than 25 %, which means total process losses were high with the consequent effect on economics. The loose bottles could swamp the factory giving no room for manoeuvre if a breakdown or other unplanned event occurred. There were also hygiene problems. In contrast, when dealing with pre-sorted bales as feedstock, quality can be monitored and communicated back up the chain. Furthermore, the Local Authority is used to providing a waste disposal system for its citizens, so it makes sense for the Local Authority to collect recyclable materials as part of a waste management strategy. The Local Authority can communicate directly with each household to enable best possible value to be derived from the waste. This approach has one additional key advantage namely, the ability to handle mixed recyclable waste in an integrated facility. Thus cans, glass, paper and textiles as well as plastics can be collected together and separated before onward shipment to dedicated reprocessors. Information from the USA suggests that plastic bottle collection can make a contribution to income for the Local Authority when combined with other recyclable materials. These Material Reclamation Facilities (MRF's) will need to be on a scale which is economic. They will also need to utilise reliable machines which can accurately separate recyclable elements. Business plans will need to be developed to optimise the potential of collectable raw materials in each major city and town in the UK. We do not know yet what can be achieved and whether value can be derived from the waste stream at no extra cost. Facilities such as that at Milton Keynes (£6m MRF) will be studied closely and will help point the direction. Waste levels as low as 3 % have been consistently achieved. The Milton Keynes Borough scheme yields 8 tonnes of plastic bottles per week from 53,000 out of 75,000 households targeted (70%). On average this is about 100 grammes (2 bottles) per household per week. In another town in the UK the MFR installed recently is collecting 4.5 tonnes of plastic bottles from 115,000 households. This is about 40 grammes (1 bottle) per household per week. Significantly this scheme is compulsory rather than voluntary and is experiencing waste levels of 70 %. In the USA schemes are achieving 300 grammes or 6 bottles per household per week and where overall 19% of all bottles are recovered. If we assume 250,000 tonnes of plastic each year is converted into bottles which find their way into the 80

home, then about 5 bottles per household per week (average 50 grammes) will be available for recycling. Funds need to be found for detailed statistical work to verify the amount of bottles available and how this varies across the country. When the UK achieves the USA recovery levels of 19%, we can expect to reprocess 48,000 tonnes of bottles. This is a totally different scale from the current level of 4000 tonnes or about 2 %. However, this is still a considerable achievement because 2 bottles in every hundred on the shelf are being recycled. It is clear that a total systems approach is required to achieve success. Simply building a

MRF and leaving bags or green bins will not work without effective communication and coordination together with a programme of continual improvement. It is clear also from the Milton Keynes experiment that integration of commercial and

industrial waste streams is the way forward, at least until volumes of domestic collection grow. 70% of the 9000 tonnes per annum (of mixed recyclable) is commercial rather than domestic waste. By combining industrial and commercial waste, Milton Keynes is able to set the objective of covering its running costs by April 1995. Ultimately there is a need for integrated material recycling facilities which are designed for multi-material wastes and with integrated domestic and commercial waste processing capabilities. A subsidy is needed to increase collection: Until large-scale, integrated MRF's are fully utilised it will cost Local Authorities money to collect and separate plastic bottles even allowing for income from material sales. Typically the deficit is between £100 and £200 per tonne depending on local circumstances. This means a subsidy system is required to encourage collection. The Local Authorities currently collecting plastic bottles are doing so because they want to preserve the environment and they have a vision of successful recycling where plastics have a key role. We must not allow these pioneering efforts to fail. The UK government has now accepted industry recommendations that legislation is required to ensure the whole packaging chain participates in a system of funding. It is important that any funding system encourages the collection and separation of recyclable material and not just large volumes of waste packaging. It should be possible to credit

Authorities for materials actually accepted by the reprocessor. This will prevent large quantities of unusable material being collected and thus avoid the adverse effects this would have on public opinion. We should also think about how we ensure that reprocessing capacity will be in place to cope with rapidly increasing volumes. Automation of sorting will improve efficiencies: The REPRISE project has been based on the premise that full automation of bottle sorting and flake production was the key to success. This led to the development of the Vinyl Cycle PVC separator and to encourage Milton Keynes to incorporate this device in their "state of the art" plant. REPRISE together with a partner has also developed a concept of a new type of optical sorting device for plastic

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flakes. However, it has not yet been able to raise sufficient funding to implement the system. Whilst today at REPRISE hand sorting is still needed at the beginning of the process, automation enables bottles to be sorted accurately at high volume. The health risk to workers is also reduced as they have less direct contact with the waste. We will always need people in our sorting plants but their primary function should be quality assurance rather than sorting bottles. Companies like REPRISE need to work with Local Authorities especially those in large centres of population to implement fully automatic plastic bottle sorting systems including PVC , PET and HDPE so that we can build on the achievements of REPRISE and Milton Keynes. Funding will need to be found for this important development work. Each country has a unique recycling position but the UK should review systems in use throughout the world to learn from the experience of others. Reprocessing Bottle design determines costs and therefore the viability of recycling: If all bottles were designed for ease of recycling, most of the problems faced would be removed. The technology required to reprocess then would be a fraction of the cost. This is clearly not going to happen overnight but many design decisions are made today, without regard to the costs of recycling. There are numerous examples, such as high temperature melt glues which cannot easily be washed away and inks printed directly on the bottles which cannot be washed out, or blue tinted PET bottles which are confused with PVC, or PET G which is used for cosmetics and contaminates PVC and PET streams. Perhaps the best known problem is the use of PVC seals in caps on PET bottles. The PVC seal will degrade when the PET is processed and contamination levels need to be below 50 parts per million and below 10 parts per million in some cases to have adverse effects. The specific gravity of PET and PVC being very close means density separation is not possible. The options therefore are to remove the cap before washing or remove the fragments of seal by some type of optical sorter. Both of which are expensive. One or possibly both of these devices will be installed at REPRISE. At REPRISE we compared the costs of recycling baled bottles with most (but not all) of the caps already removed with baled bottles with most of the caps still on. Labour costs were nearly 50 % higher, waste losses rose by 30 % which means profitability fell by about 50 % and the recyclate was of much poorer quality. PVC seals on PET bottles need to be phased out. Even without the PVC seals the caps are major contributor to costs. The cap material, at up to 10 % of the bottle weight, significantly adds to the waste costs. They are usually a different colour and/or polymer which means that unless they are removed, they will reduce the value of the recyclate. An example of this is coloured caps on white HDPE milk bottles. The problem of coloured PET bottles also requires mention. Much of the success of PET

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recycling has been built on clear PET bottles being recycled into white fibre. There are limited markets for green and tinted bottles but there seems to be general agreement that the choice of a coloured or tinted bottle by the designer will limit PET recycling. This is why we must communicate the message to the designers to stick to clear bottles. Any shape of bottle or label design may be used but choice of a coloured or tinted bottle should be determined by environmental reasons. Thoughtful bottle design will enable Local Authorities and Reprocessors to derive full benefit from automatic sorting systems and enable quality specifications to be met. Specifications are essential: It is apparent that without specifications enforced by the reprocessor and ultimately the end-user, the Local Authority and the public will not know what to collect. Without a target to hit, improvements cannot be made. The discipline of specifications means that each part of the chain understands what is required and what is not. The difference, as seen with the caps problem, can be significant in terms of costs and, in the long run, viability! Collecting waste costs money; but collecting useful raw material can add value. Where possible these specifications can be standardised across Europe but each reprocessor must contract with his/her supplier on the basis of an agreed specification. The best way to encourage meeting a specification is to place as high a value as possible on material which meets it and a financial penalty for material which does not. Any finding system to support recycling should take into account the need to enforce specifications. Virgin polymer supply and demand will directly affect the economics of recycling: The price obtained for recyclate is related to supply and demand. When prices are high, virgin together with sub-standard grades are in short supply and a higher price can be obtained for recyclate. There may be some effects from end-users preferring recycled materials but this has not been experienced yet in the PET or PVC markets. From our experience, realistic targets for PET appear to be 40-50 % of bottle grade polymer prices and similar targets can be set for PVC in relation to bottle compound prices. For PVC this means we can expect to obtain 70-75 % of virgin polymer prices. At current prices this means break-even is a possibility. However, the prevailing virgin price is critical. For example when considering a model of running PVC only and virgin PVC prices are £400 per tonne i.e. the recyclate price is £280 per tonne, REPRISE as it is set up now, could not break even at capacity. This means in addition to providing funding for collection there will need to be a system of support which enables the reprocessor to take domestic bottles in times when virgin prices fall below economic levels. The same principle applies when volumes are below economic levels and capacity needs to be maintained to cope with future growth. This is the current position at REPRISE.

83

Rapidly increasing volumes are needed for viability; this means integration with commercial waste streams: Integration with commercial and industrial streams is the way forward. There is now sufficient demand for recyclate but it cannot be met from the bottles from the UK collection systems. This means more effort being put into bottle collection although this depends on others to provide systems of funding to stimulate growth. It is imperative that a funding system is put into place rapidly, otherwise there is a danger of plastic bottle recycling declining. If a part of the infrastructure disappears it will be much more expensive to re-create it in the future and much public goodwill will have been lost forever. REPRISE has been successful in establishing a recycling route for PVC display trays used by retailers. About 12000 tonnes of PVC trays are used each year. For the past 3 years the company has been working with the Plastics Industry Films Association (PIF A) and Marks and Spencer to evaluate the feasibility of recycling PVC trays. Earlier this year we began recycling trays for 43 Marks and Spencer stores. The trays are delivered to REPRISE for washing and granulation on the PVC line (which is cleaned prior to operation) after which they are converted back into trays at Anson Packaging. This will produce about 50 tonnes per annum. Marks and Spencer plan to extend the scheme shortly to two other regions. We are also planning with Boots and other major UK retailers to recycle their PVC display trays. REPRISE has in addition, been active in using the scrap PVC and· PET bottles from the manufacturing process. The recyclate has been kept separate from the domestic stream to ensure that there is no interference with our approach to marketing recyclate from domestic waste. However, the integration of systems of recycling of domestic and commercial waste streams makes sense at least until volumes grow significantly.

Marketing Price is the main reason people buy recycled plastics: The demands for REPRISE PVC and PET are determined primarily by price. REPRISE is a source of cheap raw materials. The construction and fibre industries respectively which use these polymers have no motivation other than as a source of cheap raw material to promote packaging recycling. This may change in the future but the key to creating a demand for recycled PET and PVC is to have material of the right quality at the right price. Furthermore, some users of PVC would not wish to draw attention to the recycled content in their products. In the future, this may change as recycling takes a higher profile and major companies wish to be seen to be involved. In the early days of plastic bottle recycling, the price paid for recycled HDPE polymer was above virgin - this is known as "the green premium". The price was driven by a desire by the detergent manufacturers to beat the competition at a time when recycled bottle flake was in short supply, by having recycled bottles on the shelves. It was also hoped the consumer would continue to pay a premium for recycled packaging. This is no longer the situation. The evidence suggests that most of us do not wish to pay more for recycled products. The current marketing approach of the packaging specifiers is to use the recycled material if it is cheaper or at least no more expensive. However, the challenge in the UK is to find 84

markets for 60,000 tonnes of plastic bottles as agreed between industry and the government. Highest value and highest volume markets should be targeted: This may seem an obvious point to make. However, a few years ago, about the time the author joined REPRISE, mixed plastic applications such as wood substitute were being identified as target markets for bottles. This would have valued the recyclate at less than £50 per tonne into established markets. It is worth emphasising at this point, however, that 100 % recycling is a false goal. For instance, an application such as extruded pipe may only tolerate 10 % recycled content but the total volume potential may be several thousand tonnes per annum. There is also the question of whether it is a good idea for bottles to be recycled back into bottles. They will only be back again next week! Two aspects of the opportunity need to be examined. First, there is value in the public being able to buy recycled products and see for themselves that recycling is happening. For example, it is possible to recycle PVC bottles back into non-food contact bottles at 20-30%, and REPRISE intends to do this. There is also the wellestablished route for HDPE as the middle layer of co-extruded bottles, and in some parts of the world for recycled PET as the middle layer of 3 layer drinks bottles. Furthermore, it is possible to recycle plastic bottles into other packaging applications such as PET or PVC trays. These are all relatively high value applications with potential for significant volumes. The number of times a bottle can go through the recycling process will be determined by experience but it is believed that recycled content can be optimised to give viable recycling for a number of recycles. However each bottle has a relatively short life before it needs reprocessmg. Second, it is possible to recycle packaging into second-life applications with a much longer life. This may be for many years as in the case of PVC which is used in construction applications. Here it may be claimed that there is a direct saving of energy in the manufacture of the virgin plastic and also an easily quantifiable saving of the earth's finite resources. Both of these opportunities must be explored and both will have a role to play. In the early days of recycling, there was perhaps a tendency to regard recycled bottles as only being suitable for low price, non-critical application where the material would not be subjected to a high specification. This is not the best way to approach to problem. There are barriers to entry in some applications for reasons such as: surface finish, colour, odour and mechanical properties. However, by targeting applications which match the properties of the recyclate, the highest value can be obtained. The key to markets is understanding quality requirements: To achieve success we must understand the quality requirements of the target market and the specification of the recyclate. This requires looking for a match of characteristics. It is not always the lowest

85

price markets where this match can be achieved. A clear example of this is EVe targeting PVC bottle recyclate into foam core profiles having a virgin/polymer skin. The mechanical properties and colour are not affected and there may actually be some benefits for the customer from using the formulation based on recyclate such as faster throughout. The PET contamination of about 0.05 % is not critical in this application. However, it may be in other lower value applications such as extruded ducting where surface finish is critical and impact properties are affected. To be able to target particular markets there must be the ability to measure the key characteristics of the recyclate e.g. PET or PVC contamination levels. There must also be control of the quality of the output with variable quality inputs. Understanding quality and measuring quality are the ways to obtaining the highest value for recycled bottles. Fit for purpose is the criterion for market acceptability: We can find high-value markets

for recyclate providing that proliferation of standards does not create artificial barriers. By artificial, is meant the need to consider the implications of using recyclate. Many of the standards in the construction sector have a "standard" clause which precludes the use of recyclate other than from the manufacturing process itself. Another well known example is the general use of a "General Specification" for HDPE wheeled refuse bins which states no recycled content. A final example is the UN standard for plastic drums where again no recycled content is allowed. These barriers are there to prevent poor quality products. However, if the standards are focused on achieving fitness for purpose then the emphasis must be on having appropriate test methods and which exclude waste polymer use only on sensible performance grounds.

86

RECYCLING ZEFTRON CARPETS Ian Wolstenholme

Introduction Carpet Recycling Market: In 1993, 1.3 million tonnes of fibre for carpet manufacture were produced in North America. This fibre was used in about 2.5 million tonnes of carpet. Of this amount, approximately 70 percent replaced existing floor coverings, resulting in approximately 1.7 million tonnes of replaced carpet. The vast majority of this material ended in landfills. Several approaches for diverting this material from landfill are under investigation. These include converting carpet into secondary products such as plastic wood, extruded profiles, or extenders and reinforcing agents in other products, and incineration/cogeneration. These markets are, however, limited by competition with other recycled polymers and, in the case of incineration/cogeneration, public resistance to siting. Carpet Construction: Complicating the recycling issue for carpets is their multicomponent construction. A typical broadloom carpet with a face weight of 850 gm-2 consists of approximately 50 % by weight face fibre. Most of the face fibre produced in North America is nylon, both 6 and 66, with smaller amounts of polyester, polypropylene, wool, cotton and acrylic fibres also used (see Table 1). The typical broadloom carpet also consists of 12 % polypropylene primary and secondary backings, and 8 % styrene-butadiene latex adhesive. Additionally, the carpet consists of about 30% calcium carbonate filler (see Table 2).

Table 1: Carpet face fibres in USA

Nylon 66

40%

Nylon 6

30%

Polypropylene

20%

Polyester

10%

101

Table 2: Carpet construction Face Fibre:

50%

Backing:

12%

Latex:

8%

Latex Filler:

30%

Note: Based on Typical 850 gm-2 Carpets

Other backing materials in use include jute, polyester, and nylon 6. Polyvinyl chloride, ethylene vinyl acetate, and polyurethane backing substrates are also used. Finally, the carpet contains small amounts of dyes, pigments, antistatic fibres, and surface treatments.

Closed Loop Recycling Chemical recycling of nylon 6 is not a new concept. BASF has been recycling post-industrial nylon 6 at its Enka, North Carolina and Arnprior, Ontario locations for more than thirty years. However, the material recycled has had a high nylon 6 content. Only recently has BASF developed the technology for chemically recycling materials with lower nylon 6 contents. For carpets this is a six-stage process. First, carpets are collected and identified as to face fibre content. The face fibre is then mechanically separated from the backing, adhesive, and filler. The resulting nylon is depolymerized back to its monomer, caprolactam, and purified for use. New nylon is then formed from the recovered caprolactam. This nylon is then spun into fibre and finally, new carpets are produced (see Table 3).

Table 3: Carpet recycling process

Carpet Collection

Carpet Separation

Monomer Recovery

J Carpet Manufacture

Fibre Spinning

102

...

Polymer -ization

Chemical Recycling is really a very simple concept. It begins by converting old product back to its basic raw materials. Once this is accomplished, contaminants and impurities are removed from the crude raw material. Finally, the purified raw material is reconverted or reconstructed, back into new product. The major advantage of this type of recycling is that the new product is the same as the original product. There is no loss in product quality by the proper implementation of a chemical recycling approach, unlike methods which simply reprocess old product into another form. Decomposing Tree in Forest Example: Examples of chemical recycling are all around us. A decomposing tree in the forest is an example. At its most fundamental level, this tree is slowly being converted to carbon dioxide, water and other basic nutrients. In the presence of seed and sunlight, these same basic raw materials are recombined to produce a new tree. Although the tree is new, it consists entirely of used raw materials. A tree is a renewable resource, unlike plastics derived primarily from crude oil; therefore the chemical recycling of plastic materials will become even more important in the future as oil supplies deplete and assume a higher value. Polymer - Monomer - Polymer: Nylon 6 polymer can be chemically converted back to caprolactam, its monomer; in fact this technology has been practised by BASF for 30 years. Nylon 6, unlike nylon 6.6, has the advantage of consisting of only one monomer and this means that the contaminant removal process, for monomer purification, can be more economical and less complicated than if the converted polymer consisted of two monomers. Simple filtration and distillation processes are all that are required to purify the crude single monomer intermediate stream. Two monomer mixtures involve more complex separation technologies as would be the case for nylon 6.6 and polyester, for example. Once pure caprolactam is obtained, it can be converted to new nylon 6 polymer once again by conventional polymerisation and so the process can be repeated over and over. The BASF Carpet Recycling Process BASF's carpet recycling process consists of six steps. The first two, Collection and Separation, are part of the infrastructure that will have to be developed for the carpet industry in future. BASF is taking the lead by working with others to put the necessary infrastructure in place. As mentioned earlier, the third step - Monomer Recovery of Nylon 6 scrap - has been practised at BASF facilities for over 30 years. This technology only requires modification to handle the more highly contaminated nylon 6 material obtained from waste carpet. The final three steps - Polymerization, Spinning and Carpet Manufacturing - are already well developed and it is envisioned that no major changes need to be employed in the carpet 103

recycling concept. One problem in waste carpet recycling is the need to identify the face fibre. A simple test, which specifically identifies nylon 6 face yarn, can be done in about 1 minute by determining whether a carpet tuft dissolves in a dilute solution of hydrochloric acid. This test will only dissolve nylon 6 as nylon 66, polypropylene, polyester and wool remain undissolved in the 4.4 Molar Hel solution. Separation: The second step is Separation. Shred-Tech, in cooperation with BASF, is designing a carpet separation system. Shred-Tech has had over 15 years of experience in designing and fabricating material handling equipment for recycling everything from scrap metal appliances to polyester drinks bottles.

Table 4 schematically shows the separation process in which the first component is size reduction; at this time no special pretreatment is envisioned for the waste carpet. Initially a shredder reduces the carpet to strips and further size reduction is accomplished with a rotary cutter.

Table 4: Carpet separation process

Initial Size Reduction

~

Second Size Reduction

~

I

E-

Pelletizing

I

Separation

Using an air classifier, which works by pulling a slight vacuum through a rotating cage, the small, low density face yarn fibres are pulled through the cage and collected in a receiving cyclone. The larger, higher density latex backing particles are thrown outwards and drop by gravity into the collection vessel below the rotating cage. Typically, each constituent is of equivalent weight in the separated piles of face yarn and carpet backing fractions from a 950g m-2 carpet. The separation step thus generates the first side stream of the carpet recycling process. Enduses for the enriched carpet backing stream are currently under investigation. In order to economically transport the separated carpet face yarn, to a monomer recovery 104

plant, densification is essential. A Condux Plastcompacter is one type of sintering mill capable of performing the densification. Over 200 of these mills are in operation worldwide, densifying materials such as yarn and film scrap. This essentially, is a sintering mill which works when frictional force is converted to heat causing the fibrous material to densify into pellets or granulate; thermal degradation of the polymer is avoided. Sprout-Bauer also manufactures a pelletising mill that works by using the same principle. Sintering increases the bulk density of the separated face yarn to about 70% of that of polymer chip. Typical separation efficiences for a typical 50:50 face : backing 950m-2 are shown in Table 5.

Table 5: Relative carpet component separation efficiencies Feed

Face Yarn

Nylon 6

50%

80%

20%

Calcium Carbonate

30%

10%

50%

Polypropylene

12%

6%

18%

Latex

8%

4%

12%

Rate Ratios

1.0

0.5

Carpet Backing

0.5

Nylon 6 Separation Efficiency = 80%

In initial feasibility tests, roughly 80% of the carpet's face yarn was recovered with the separation process so far described. The separated face yarn stream contains about 80 % nylon 6 and 20% backing materials, while the carpet backing stream contains about 20% nylon 6 and 80 % backing materials.

Monomer Recovery: The third step, in BASF's carpet recycling process, is monomer recovery and this is the heart of the chemical recycling approach. Nylon 6 depolymerization and caprolactam purification, from nylon 6 process waste and scrap materials have been economically practised for many years. Adapting the technology to old nylon 6 carpet materials is a matter of building upon what BASF and in fact other nylon producers already do. Essentially the densified nylon 6 face yarn is simply highly contaminated N6 scrap material, which because of the chemistry and process technology involved, can be converted to purified raw material, that is caprolactam.

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The first part of the monomer recovery step is hydrolytic depolymerization of the densified nylon 6 carpet face yarn produced in the separation process followed by extraction and distillation to generate monomer of acceptable priority for re-use as mentioned previously. Summary

In summary, BASF is developing the collection and separation infrastructure required to put a closed loop recycling process in place by working with others in the recycling industry. This part of the process must become a business in itself, working with the existing carpet industry. Secondly, BASF is building on its technological base, extending the inherent recyclability of the nylon 6 polymer to more highly contaminated carpet materials. Here BASF has submitted patents for its work in the recycling of nylon 6 based carpets. Finally BASF is ensuring the quality of future recyclable nylon 6 carpet by utilizing a higher quality chemical recycling approach in order to solve the long term waste carpet problem.

106

COTTON WASTE RECLAMATION Ferdinand Leifeld

Introduction During the chain of processing steps for cotton it changes its physical form at each step until it finally fulfils its intended purpose for the consumer (Figure 1). It is cultivated, harvested, ginned and baled before being opened, cleaned, carded, spun,

woven, finished, made into textiles of all kinds by the processing specialists, used by consumers and later, in the form of waste, disposed of, or regenerated/recycled. Then it is returned to a certain stage in the production process for repeated use. If one follows the above-mentioned processing steps, it becomes clear that at every stage the cotton is refined and extra value is generated (Figure 2). Some of the refinement processes involve cleaning cotton to separate the undesired substances from the desired, pure cotton. Separation is never entirely successful. In the process, waste is separated that contains trash as well as fibres. The fibres represent a resource that can be reclaimed if they are again separated out of the waste. The major part of this paper will deal with this form of fibre recovery. The cleaned fibres are sent in the form of silver, roving or yarn from machine to machine. These processes also generate waste. This occurs as a result of sliver breakage or when starting and stopping machines and production lines. This material, known as reworkable waste, is fed more or less directly back into the process (see Figure 3). This will be explained with reference to an example. In the processes following spinning, e.g. weaving and garment-making, further wastes are generated. These can be regenerated like the used textiles mentioned above. This is usually effected with cutting and tearing machines which reduce the fabrics to fibres. Such fibres are used as wadding, added to blends of virgin raw material for spinning, or spun in their pure state for special fabric qualities suitable for this process. This paper concentrates on the subject of waste recycling in the spinning process. Questions Whenever there is mention of waste separation and recycling in this field, various questions reflecting the various points of view are asked. First of all there is the opinion that it is no longer worthwhile recycling wastes because modern cleaners today separate waste with low fibre proportions. On the other hand the view is expressed that high rates of cleaning efficiency should be achieved and it would therefore do no harm to separate more waste even if it contains a higher proportion of fibres. Efficient cleaning is not that crucial, it is claimed in justification, because recycling is carried out anyway.

107

I

I

Consumer

I Garments I I Finishing I . Weaving I Spinning I

I Waste

Gin

Figure 2: Reclamation of primary waste

Figure 1: Processing stages

Trash T £%] 5) -

t

4CE .. 100%

3-

V

eV

C

2-

V

W V~

1-

0-

0

A

F j

o

J 1

I

I

2

3

Figure 4: Cleanogramme

Figure 3: Reclamation of reworkable waste 108

I

4 Waste W [%]

I

..

5

Over the course of the last 10 years the trash content of the raw material has been steadily reduced. Today trash contents of 1.2 to 1.5 % in the bale are perfectly normal. From this fact alone one could logically conclude that it is no longer worth recycling wastes. But is this really the case? Figure 2 however, helps to understand that ginning, cleaning and carding all produce wastes which fortunately can be reprocessed with recycling machines. In the spinning practice little attention for example is devoted to gin motes, which according to our analyses, can contain 70 to 80% fibres. These wastes are generally reprocessed by companies specialising in this activity and regenerated for special purposes. Waste separation In modern cleaning and carding rooms high cleaning efficiency with low fibre loss has been achieved. The rates of cleaning efficiency are closely related to the separated quantities of waste. It is easy to generate high-quality waste if one is prepared to accept a low rate of cleaning. In our terminology high quality waste refers to a low content of fibres, i.e. 10% and less. It is not difficult either to achieve a high rate of cleaning efficiency if a high proportion of fibres in the waste is tolerated. The ultimate objective, however, is to achieve a high cleaning efficiency and a low content of fibres in the waste. This is precisely what we expect from good cleaners and cleaning lines and what distinguishes them from less good ones. Because of the divergence in the two main requirements an ideal solution is only possible in the form of an acceptable compromise. This must be technically measurable, reliable and reproducible. The quality of cleaning can only be judged by figures. For this reason when referring to an achieved rate of cleaning it is essential to maintain the quantity of separated waste and its composition. A full picture is obtained when the following values are quoted: 1.

The content of trash in the material being cleaned.

2.

The content of trash in the cleaned material, which is the most important figure for yarn manufacturers.

3.

The cleaning efficiency [in %], calculated from 1 and 2.

4.

The waste content [in % of the treated input quantity].

5.

The waste composition, i.e. content of fibres and trash [in%].

Usually these results are graphically presented for ease of comparison and to enable relationships to be identified. To obtain a comprehensive picture, four or five graphic representations have to be generated, which regrettably is not always done because of the excessive effort involved. For this reason only certain data are supplied, and so that necessary for a proper assessment is often missing. The picture remains incomplete, but it 109

is possible to present these relationships in a single diagram (Figure 4) which is called a "Cleanogramme". On the x-axis is the quantity of separated waste and on the y-axis the quantity of separated pure trash. With the same scale on both axes, the plotted 45° line represents the ideal separation line. The points on this line refer to a cleaning process in which the separated quantity of waste consists of pure trash. Real points can only be expected on the right-hand side beneath the 45° line. The distance of a real point A from the ideal line says something about the purity of the waste. The closer the point to the ideal line, the lower the fibre content in the separated waste. From the horizontal line C-A, the following can be identified on the xaxIS:

the absolute quantity of the separated trash C-B, the separated trash B-A and the separated quantity of total waste C-A. In this "Cleanogramme" the initial trash content of the material being treated can be entered as the horizontal. In this case it is 3 %. From the distance between points D and A one can read off the residual trash still present after the cleaning cycle in this case, 1 %. In this "Cleanogramme" the cleaning processes can be clearly displayed and give important information. It can also be used for clearly describing, comparing and assessing very good multistage cleaning processes with all the relevant details. In an example, let us compare the cleaning efficiency of the two processing lines shown in Figure 5. The upper diagram shows a conventional preparation line with three individual cleaners and beneath it a modern line with just a single CVT4 four-roll cleaner and a DK 760 card. The cleaning result of both systems are presented in the "Cleanogramme" in Figure 6. The axes here no longer have the same scales. The left, diagonal straight line passing though point 1.1 is again the ideal line and in this case it no longer runs at 45°. The horizontal line shows the raw material's initial trash content, in this case 1.4 %. This line is also important for the achieved cleaning efficiency. When this line is reached, 100% cleaning efficiency has been achieved. The individual points show the achieved cleaning efficiency of each process. The comparison of the two systems shows the progress achieved in the development of the most recent generation of cleaners and cards, CVT4 and DK760 compared with the former concept consistent of the individual cleaners AXI-FLO, RN and RSK respectively. The cleaning performance of the licker-in is assessed separately here. One can see that the coarser cleaning steps at the beginning come closer to the ideal line than the fine ones. A better cleaning performance with reduced fibre waste is achieved with the CVT4. It has always been known that the final cleaning points and particularly the card cylinder with its separating equipment separates waste with a higher fibre content than the preceding separation points. As can be seen, the characteristic curve for the cleaning efficiency flattens and the distance from the ideal line grows. 110

LVSAB

BDT01.

BDT

SC

AFC

UPMI

TV

as

IYSA

DX

LVSA BEB RSK

DX

MMI CVT4

TV

lIN

FBK DK

FBK DK710

KH

Figure 5: Conventional and modern cleaning line Trash T [%]

-

!

2

Ce'100"

1

Vcr ---

ce· 96 " ce· 95 " r -0,05"- I-r -0,065"

~ ~"DK..... ~"DK

M~

~er-in

~

RSK

RN

-

,,~

0I

o

I

I

I

I

I

1

2

3

4

5

I

6

I

7 WasteW [%]

I

8

-

Figure 6: Comparison of the cleaning efficiencies between conventional and modern cleaning lines

111

KH

Therefore it is evident that the new cleaning line separates a total of 4 % waste which contains almost 1.4 % trash. This means that the total waste consists of 35 % trash and 65 % fibres. The former cleaning line extracted 1.4 % trash in a total waste quantity of 5.5 % and this means that with the former system, the waste contained 25 % trash and 75 % fibres. The effort to lower the fibre content in the separated waste with more advanced machines has thus been successful, and in the above example with the new machinery up to 1.5 % less fibres are separated in the waste. This means 1.5 % less input of raw material, or in other words 1.5 % savings of raw material with the new line in comparison with the conventional technology. This was one of the reasons for the rapid success of the new generation of cleaners because they very soon paid for themselves solely as a result of the lower input of raw materials. However, it is generally accepted practice for primary waste to be collected and processed together even though the proportion of 75 % fibres in the total waste has been reduced to 65 %. This being so, then the question of the nature and proportion of these waste fibres should be addressed. The wastes from the cleaners generally have a fibre content of only 20 to 30%. Even these quantities are still worth recycling. In the treatment of this subject so far the influence of the material on the waste quantities has been ignored. A certain degree of fluctuation has to be expected as a result of the material's cleansibility. The cleaners have cleaning points with adjustable guide vanes and can be adapted to the properties of the particular material. As a result the waste quantities can be regulated at each separation point while the machine is running. A major factor is the trash content in the raw material. For the modern cleaning line there is a rule of thumb that the proportion of waste separated in the cleaner should be equal to the proportion of trash in the material. On this basis, the CVT4 has to separate approximately 1.4% waste from a raw material containing 1.4% trash. If a cleaning efficiency of 70% is to be achieved in the process, the fibre content in the waste would then be approximately 30 %. One could now start calculating to find out how much waste can be saved at this point and how much is to be recycled. However, the CVT4/DK 760 system is an integrated system. In certain respects the action of the CGT4 cleaner only takes full effect in the card. When employing the CVT4 it was discovered at the card that the licker-in waste and the upper card waste were drastically reduced and the cleaning efficiency was improved over that of the combination conventional cleaners and card. This can be clearly seen in the "Cleanogramme" in Figure 6. A modern cleaning point is situated in the card's licker-in and makes it possible to influence cleaning efficiency and waste composition by regulating the rate of separation. The "Cleanogramme" in Figure 7 shows this relationship and the results of a licker-in study. We recommend adjustment to the first mote knife in such a way that a cleaning efficiency of about 30 % is achieved. With an input of 1 % trash in the material this means a pure trash separation of 0.3 % and this is achieved with a waste quantity of 0.4 %. One can then see that about 3,4 of the waste consists of pure trash and ~ of fibres, i.e. that the waste has a fibre content of about 25 %. If the waste quantity were to be raised above this, the cleaning 112

efficiency would improve but the fibre content in the waste would also increase disproportionately. If the rate of separation is reduced, the proportion of fibres in the waste declines but the rate of cleaning efficiency drops dramatically. The most favourable, real separation point characterises the ideal setting. In the "Cleanogramme" this is the point where the initial straight line ends and the curve starts to move away from the ideal line. The relationship between cleaning efficiency and fibre content shows another trend derived from the licker-in "Cleanogramme" (Figure 8). It is clearly apparent that it cannot be the objective to aim for only 10% fibres in the waste at the licker-in, for instance, because the cleaning efficiency inevitably falls to a value of about 10% for this to occur. If on the other hand the rule of thumb for the cleaning line is applied and as much waste is separated as is trash content in the material - in this case 1 % - a cleaning efficiency of 50 % would then be achieved with 50 % fibres in the waste. This according to his own priorities and within certain limits, the user can exert influence on trash separation, fibre separation and cleaning efficiency. These diagrams have been dealt with in detail because the aspects covered strongly influence the rate of material utilisation. Reducing fibre separation with efficient cleaning represents the biggest contribution towards cutting the cost of materials since, as already mentioned, the expensive primary raw material is at stake and because this, without any additional treatment such as recycling, yields direct savings. The licker-in also has a pre-cleaning function. The card cylinder, revolving flats and webcleaner in working together attain an extraordinary cleaning efficiency. If we proceed from the trash content still present in the area between licker-in and cylinder (i.e. 0.1 %), we can determine that stripping roller and webcleaner separate about seven to ten times additional waste (i.e. 0.7 to 1 %) of the reference trash content. That means that the separated waste contains about 85 to 90% fibres. It should be borne in mind that this waste, in particular, contains a considerable proportion of short fibres and neps, however. Waste reclamation The above estimations of fibre content of 65 to 70 %, depending on the machine configuration, may be compared with values obtained in the last few years from a large number of customer tests of cotton recycling. The frequency distribution for fibre percentages in the waste in Figure 9 clearly shows that even in industrial practice the greatest frequency lies within the 60-80 % range of fibre content in the waste. Triitzschler installations are used by its customers to process cleaning and carding wastes as well as gin motes. In the past, two basic installations for recycling have evolved which differ principally in their production rate. Firstly there is the small installation which is mostly found in spinning mills with a production rate of up to 100 kg/h depending on the quality of the material processed of which open-end (OE) spinners are the main users. Larger installations have a production rate of up to 700 kg/h and are characterised by a central precleaning section and individual cleaners arranged in parallel or in series according to the required production rate. 113

Trash T [%1 0, 6-

t~

J

5-

~~

il l/V

0, 4-

• Cleaning efficiency [%]

~ 1000-

0, 2

~

0, 1-

VJ f

I

o

o I

I

50

If

oJ-

1,0

I

/V

0, 3-

.;. Trash [%]

100

I

I

I

I

I

I

I

I

I

o

0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8

Waste W [%]

0,5

..

I

I

50

100

Good fibres [%1

o

-

Figure 8: Correlation between cleaning efficiency and good fibre in waste

Figure 7: Cleanogramme

Frequency 1

t 5

I

I

I

I

OIL---

I

40 50 60 70 80

Good fibres [%]

-

Figure 9: Frequency of good fibre in waste 114

Figure 10: Wasteomat

The central element of these installations are the Wasteomat machines. These are a new development and supersede the successful Cotonia. The Wasteomats (Figure 10) are derived from the successful Cleanomats and are available in two versions, i.e. in a two-roll version for low production rates and in a four-roll version for high production rates. The Wasteomats differ from the Cleanomats in their feeding and choice of clothing. The Wasteomat feeding system has a tray intake, which is superior to the roll intake of the Cleanomats in its opening action and cleaning efficiency. In the Wasteomats all the rolls are saw-tooth rolls, even at the first position, unlike the Cleanomats which always have a fully spiked roll or a spiked lattice roll a the first position. This is to ensure gentler opening. Like the earlier Cotonia, the clothing of the rolls becomes progressively finer as the material proceeds towards outlet and they are generally finer and have a more powerful action than the Cleanomat clothing. The effective, continuous direct waste extraction has been adopted from the Cleanomat and represents an improvement in comparison with the Cotonia system. Furthermore, all modern monitoring and control devices have been taken from the Cleanomat. The small installation (Figure 11) can be assembled as follows:

o c:::::t

on ,

L'

ASTA

LVSA BOA

LVSA BEW WST2

BALING PRESS

Figure 11: Wasteomat - small installation

Storage and delivery point for the wastes, e.g. BOA, precleaner and BEW feed device, consists of condenser, top feed trunk, intermittent grid cleaning, bottom feed trunk, and a Wasteomat 2 (WSTI) with two cleaning rolls and condensers for collection of the cleaned fibre material. In the BEW stage a multiple cycle via the grids is effected by opening and closing a flap at the outlet. Ideally the waste output should go to a baling press. Returning the material in bales to the spinning process thus becomes flexible and a favourable blend is ensured. The large installation (Figure 12) also starts with a storage facility as the delivery point for the line. This is followed by a series of two AXI-FLO cleaners. These replace the Wilomat. The double passage through the AXI-FLO yields the same cleaning effect as with the Wilomat. It is worth mentioning at this point that grids are the ideal cleaning elements for material containing large quantities of heavy impurities which can easily fall out. Use of these is made both in the AXI-FLO and the BEW stages in the installations. When the bulk of the heavy waste has been separated, the clothed rolls with mote knives and carding elements are the most effective cleaning instruments. 115

o

LVSA BEW WST 4

o BO

AFC

LVSAB

AFC

BAUNG PRESS

ASTA

LVSA BEW WST 4

Figure 12: Wasteomat - Large installation

• Yield [56]

• Waste [56]

100

100

I

I

50

o

50

I

o

I

I

50

100

Good fibres [56]

Figure 13: Detlnition of waste separation

Figure 14: Yield 116

..

o

Use of these is also made in the Wasteomat WST4 which, because of the higher production rate, has four rolls. Owing to the progressive increase in the speed of each successive roll, the last roll can generate an extremely powerful centrifugal force. This yields extremely high separation forces and powerful separation action. This machine is also served by a condenser for waste extraction which collects the regenerated material and separates if from the air current. The process of separating trash from fibres is effective but not 100 % as explained in Figure 13. The primary waste containing trash and fibres is divided into two categories, the first containing a high fibre and low trash content, and the secondary waste with reverse proportions. For the sake of completeness the losses due to the extraction devices which trap dust and short fibres in the filters require mention. These are disregarded in Figure 13 but can account for between 1 and 10% of the material weight. Actual results are shown in Figure 14 where the diagonal again shows the ideal separation line. The real points give an indication of how good the actual yield is and a high yield reflects a high fibre content in the material. The bottom region of Figure 14 presents the achieved residual trash content after cleaning and this area varies essentially between 2 and 10% residual trash in the yield. The scatter of data points in the respective areas is largely attributable to the properties of the material being treated. The results of cleaning and yield are approximately the same for the small and large installations. The small installation is usually used in the spinning mill and the large installation generally be specialist waste processors.

AS DRAW FIWE

HS.oo

----

--

BOT

ASTA

TV

MMI CVT4

Figure 15: Distribution of waste 117

OX

FBK

DK

KH KHC

The waste flow in spinning preparation is shown in Figure 15 in which the upper part shows the direct feedback of reworkable waste such as card or draw-frame silver via the waste feeder. The feedback into the process should take place before the heavy trash separation and before metal separation. It is at this point that valuable reworkable waste is returned almost without loss to the process. The primary waste is indicated beneath the processing line. The feedback of this waste into a certain processing stage varies from company to company according to its final utilisation as shown in Figure 16 .

.....

Reclamation

;;",;;",'"

!WMY~

;," Primary ~;, Waste " ",,",',',' ......', ........ ',,'........... ":;

100 kg/h

-

rSale v

,

;," ,; "

rzzz;$

Small Installation

Ginmotes

......, ........' Large Installation

Sale

700 kg/h

Comber Noils

Sale

~Vzzzzzzzzzzzzzzzzzzzzzp Sale

:>

Figure 16: Utilisation of waste Two main alternatives exist, the first of which is where the wastes are reprocessed directly in the spinning mill and are then used for minor qualities or sold as purified waste. Alternatively the wastes are collected and sold unprocessed. These wastes usually end up at reprocessing companies. These mostly operate large reprocessing lines where wastes from all kind of sources are processed. These wastes include Pneumafil, comber noils and gin motes. Economic aspects In order to decide whether it is worthwhile recycling wastes from a modern processing line with reduced fibre separation, a rough calculation of costs may be undertaken. Consider again the example above in the "Cleanogramme" for the CVT4line with card where the trash content in the bales is low at 1.4% (see Figure 6). The total quantity of waste from the cleaner and card is 4% comprising about 1.4% trash and thus 2.6% fibres. The fibre content in the waste is therefore 65 %. Figure 17 shows this and the following calculations. 118

1_

1;;g$§;,~~4:0"*-S'Ri1r~"¥!

I

2.6%

II 0.4%

2.2%

Total Amount of Waste from Cleaner and Card - Trash in 8ale

Spinning Mill .......... . Production .............................. x Operating Hours ......... '" ........... ~

= Fibres in Waste - Loss on Waste (10% of the Total Amount of Waste)

Annual Amount of Production ...... .

30 Cards 50 kg/h 6,000 hlYear

------9,000,000 kglYear

=Fibre Reclamation

x 0.5 of Raw Material Price

1% of the Annual Amount 01 Productiuon Price of Raw Material .............. ..... x

= Yield

Saving ..................................

=

90.000 kglYear 4 DMlkg 360,000 DMIYear

1Fngulllre :n. 7: Economic ca.i.cuiations

In. attempting to recover the 2.6% fibres from the waste, losses may be expected which in the most unfavourable case can be as much as 10 % of the original secondary raw material. This means 10% of 4% which is a 0.4% loss to give a fibre recovery of 2.6-0.4 = 2.2%. The secondary raw material is not as valuable as the primary raw material. If it is assumed to be haif as valuable, this would yield a raw material recovery potential of 1.1 % relative to the primary raw materials which for simplicity may be assumed to be 1 %. If this result is applied to a spinning mill which operates 30 cards each with an output of 50kg/h and 6,000 hours of production per year, then the annual production rate is 30 x 50 x 6,000 = 9,OOO,000kg. 1 % of this is 90,000 kg. This is a considerable value-added volume. With a material price of 4 DM/kg, this is equal to DM 360,000 per year (£150,000 per year).

Following from this, with 6,000 hours of production per year, the hourly production rate of the recycling installation is 360,000 : 6,000 = 60 kg/h. The small installation, therefore, with an actual hourly production rate of 100 kg/h is suitable for the spinning mill in this example. The questions posed in the introduction about the value of recycling and, particularly in relation to the employment of modern cleaners, cannot be answered with a good deal of certainty and as is often the case, the truth lies somewhere in the middle. Within given technological restrictions, it is thus worthwhile reducing the rate of fibre separation at all separation points. It is also worthwhiie recovering the content of fibres left in the waste with recycling machines. lin conclusion, therefore, recycling of waste fibres is not only environmentally desirable but also economically attractive.

119

RECYCLING IN THE FAR EAST - A STUDY OF COTTON WASTE Nasim A Minhas

Introduction The subject of recycling is a vast one and its importance is gaining ground every day. This can be attributed to several main reasons: •

The world's population, which is increasing according to a geometrical progression and is producing an excessive amount of waste of all kinds.

•

The problems of environmental pollution which can arise in the disposal of such waste.

•

The growing shortage of raw materials and the consequent increase in the significance of so-called secondary raw materials (ie. recycled wastes).

•

A widespread concern (especially amongst the very young and the very old) for proper conservation of the Earth's resources and for a frugal approach to consumption.

•

Economic constraints which necessitate making savings in every process and every business.

Recycling and conservation is now a factor in every field of our lives. Such heightened awareness, along with the changing economic factors, is a dominant force in bringing about change in industry and commerce. The concept and practice of waste processing in textiles is very old, and has been in existence in most European countries (especially Italy, Britain and Belgium) for more than a century, but it was always done "behind the scenes". Products made from recycled material were considered to be inferior and the word 'shoddy' (open waste) was used as a term of abuse and to denote poor quality. It was almost taboo in developed societies to use cloth made from recycled materials. But since the late 1960's attitudes have changed and people are now proud to use recycled material, and indeed they are becoming quite fashionable. For example, the firm Esprit established in Britain a few years ago is making garments from 100% reprocessed waste and achieving premium prices for them. In Europe and North America the economics of collection and sorting of various wastes has been influenced by very high wage structures and by the huge reduction in size of the domestic textile industries (in many cases to as little as 20% of their original size). However, these factors do not apply in Asia and the potential for profitable textile recycling is high.

121

The Start of a Business The concept of recycling has always been fascinating. During my early career, in the decade from 1953, I worked in woollen mills in Pakistan where waste material was being imported from Italy and Britain for use in blends for blankets and other fabrics. A great variety of different fabrics came to us in this way, for example pastel stockings for blazers, open serge cuttings from overcoatings, and so on. In those days the use of man-made fibres such as polyester and acrylics was not very common, even in Europe. So the blends were mostly of wool or some mixture of wool with viscose or nylon. The Pakistan industry was spending a lot of foreign exchange on imports of such material from abroad. One Sunday in 1964, while driving through Anarkili, one of the main shopping areas in central Lahore where many tailors were working, outside each of their little shops I saw heaps of fabric cuttings - off cuts - lying on the pavement awaiting the refuse collectors. As I saw the sweeper loading them on to a cart en route to the central dump, I told my children that if all this waste were collected, sorted and opened we could earn good money. They laughed and told me that it would be degrading to collect such waste, and what would everyone say when they heard of such a venture! But in my mind a ball had stared rolling, and it became an obsession with me to start such a business. So, a few months later in 1965, I gathered enough strength to put my idea into a practical project: Farooq Waste Trading Company was launched! I engaged a few workers which would collect these cuttings from the shops and bring them to my warehouse for sorting and opening. I imported a single cylinder opener (rag machine) from Japan and from then on I never looked back! Initially cuttings from tailors were the main source, but after a few years damaged secondhand clothing, especially woollen knitwear, was added to my inventory. The sweaters and pullovers were opened by hand to recover yarn, which was later used in making rugs, carpets and blankets directly. The other secondhand clothes such as coats and skirts were put through the rag opener and subsequently mixed with virgin fibres for making blankets and various other fabrics. Materials which were previously thrown away become a source of income for me and for hundreds more. Tailor cuttings from military ordinance depots and railway garment factories were added to our inventory. It was heartening to seehow many people found jobs in this new vocation and new industry, especially women, who at that time had few employment opportunities. Some of my work people even set up in business on their own account in later years. Precious foreign exchange was conserved by using local waste instead of imported waste. So far I have talked about my own business and naturally about the conditions that pertain in Pakistan. Having being asked to talk in a wider Asian context, however, I have taken some time to research the prospect in the other SARAC nations: that is Indian, Pakistan, Nepal, Maldives, Bhutan, and Sri Lanka. In each of these countries such ventures can be started on a national level under what I may call the CRCS principle, being short for 'Collect, Recycle, Conserve, and Save'.

122

Cotton Waste Recycling - A Case Study It is always envisaged that cotton will become scarcer and dearer due to population growth and occasional crop failures because of natural calamities; indeed for the last three years, the latter has happened. In Asian cotton-growing areas, particularly China, India and Pakistan, the crop was badly affected by virus attack. In the following year, because growers did not realise good returns on their cotton crop, cotton was planted in reduced land areas which resulted in acute shortage of cotton supplies. Taking Pakistan's example, the 1994 cotton crop was reduced to only seven million bales (in 1992 the size of the crop was 12.00 million bales). Cotton prices in 1993 averaged at Rs. 1600 per 40 kgs whereas in 1994 the prices jumped to Rs 2400 per 40 kgs. Similar conditions prevailed in India and China. Thus the available cotton supplies to manufacturing industries were drastically reduced. The actual shortfall was in fact 1.5 million bales. In this scenario recycling of cotton wastes has become very important.

Cotton Waste types: First of all, it would be useful to give details of various wastes available in cotton ginning and spinning units and these are as follows:(i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi) (xii) (xiii)

Fibre waste from Ginning Plants; Blow-room gutter waste; Blow-room droppings; Card dropping/lickerin waste; Card fly; A.C. gutter waste; A. C. filter waste; Ring sweepings; Lap and web waste from pickers/cards; Roving waste; Cotton comber waste/noils; pneumafil/suction waste; and Yarn waste No.1 quality/oily yarn waste.

Processing Machinery: Many machinery manufacturers from Europe notably Trutzscler and Laroche use modified versions of the step cleaner as the first machine which is comprised of a filling chute with feed table and condenser on top. The feed rate is preselected on a timing relay. The step cleaner has six beaters with strong strikers which open the waste by interaction with the grids. Depending on condition of the material the cleaning time is adjusted from 3 - 60 seconds as the condenser draws the material from the top beater and after dedusting throws it into the filling chute back into the step cleaner. After cleaning, the cleaned material is delivered to a bale press or chamber from which it is taken to a second cleaning operation. Temafa use the "clean star" system as their first cleaning machine but due to low production rates this system, although very effective, has not been very popular. Chinese and other Asian manufacturers use intermittent "Willey" or "Willow" machines as the first cleaning stage. These machines are manufactured and used in Pakistan at a fraction 123

of the cost of the step cleaner described above. The second cleaning machine consists of a cylinder with sawtooth metallic wire in fixed bearings and a spring loaded fluted cylinder in movable bearings. A fixed tray feeding system feeds the material to a sawtooth drum which extracts the impurities from waste in conjunction with a moving knife and grid. This machine comes in single and double cylinder versions depending on requirements. Cleaned material from this machine is ready for use in subsequent processes. In China, India and Pakistan local versions of this machine are made with single, double or three cylinders at very low price. The third machine in this series is the roving waste opener which is used for opening rovings. The cylinder of this machine has 36 wooden lags with round-pointed pins for opening action. As the lags are made of laminated wool these can be repinned many times. The fourth machine is for opening hardwastes and fabric wastes and is called a combined tearing machine depending on the nature of the material; 2 to 6 cylinders with corresponding pinning are used.

Machinery costs: The price factor of such machines is most important, especially when these machines are to be installed in developing Asian Countries. For example, in Pakistan large textile mills may be able to afford machines at European quoted prices but for individual entrepreneurs this is a prohibitive factor. Roughly the prices are as follows:(i)

A one step cleaner type opener with one cylinder waste opener along with filtration system would cost around £150,000. This is out of range of most of the waste dealers/processors. Hence effective cheap local machines have been developed, which although may not give as good results as the original machines, but still process material to 70-80 % of the quality at a fraction of the machinery cost. For instance, instead of using a step cleaner type machine a Willey machine may be used for precleaning.

(ii)

The first step may be followed by local small width 2-3 cylinders opening machines. These will cost delivered from works to a local buyer:Willey type opener 3 Cylinder Novacotoniatype waste opener

£5000

£15000

This represents a total investment of £20,000 against £150,000 for a new European manufactured plant. The Willey will process 1001150 kgs of waste per hour. For the imported single cylinder opener, 75/100 kgs of waste is processed per hour. Maintenance costs of imported machines are very high as metallic wire needs replacement frequently, whereas on local openers small width wooden cylinders are used with locally made metallic wire which is very cheap. 124

Similarly, a two cylinder tearing machine (eg. Laroche) would cost around £150,000. There is no good substitute for this machine being made locally. These machines again use wooden cylinder type openers with metallic wire and process the material over and over again (6-7 passages) depending on the condition of hard waste and cuttings being fed in. This results in excessive fibre damage to the material being processed. Experience shows that cotton waste recovered on local Willey and wasteopeners is good enough for subsequent processing as recommended in Table 1 giving 80 % of the quality when compared with imported machines. But local tearing machines do not give the required good results. However, recycled wastes are exported in high quantities abroad for various industrial uses. As illustrated by the above case study, waste processing offers great opportunities for textile processors in Asia often using locally made machinery. The recycled fibres may be used wholly or as blends with virgin fibre to produce a range of products. This paper has attempted to introduce potentially new entrants to elements of the practical side of the waste recycling industry. Currently the industry relies on practical experience and not scientific principles.

125

Table 1: Waste types, processing routes and possible end-uses Principle machine use for fibre recovery WASTE CATEGORY

Fibre waste from Ginning: Ginning Plant Blow room gutter Blowroom dropping Card dropping/lickerin Card fly A C Gutter A C Filter Ring sweepings Lap & Web wastes from pickers/cards Roving Waste Cotton comber waste/noil PneumafiVsuction waste Yarn waste and oily yarn waste Cloth cuttings

None

Willey

-

+ + + +

-

+ +

First

manual

-

+

-

+ +

-

-

-

Step cleaner type open

Novacotonia

Possible End-Uses

Roving opener

+ + + + + + +

+ + + + +

-

-

-

-

-

picking then

Willey and

stepc1eaner

-

Combined Tearing

Fibre yield, %

Ring yarns

Rotor yarns

Wadding

Upholstery yarns

-

25-50 10-15 30-40 20-40 50-80 40-60 50-80 50-80

-

+

-

-

+ + + + + +

+ + + + + + + +

+ + + + + + + +

+ + + + + + + +

+ + + +

+ + + +

+ + + +

+ + + +

+ + + +

-

+ +

(+) (+)

+ +

+ +

-

-

+

-

-

-

Maybe

-

-

-

-

-

+ +

-

-

100 98 95-99 98-100

(+) -

+

-

Nonwoven

-

Acknowledgments with thanks to Trutzschler.

-

THE PRODUCTION POLYPROPYLENE

OF

IDGH

TENACITY

TAPES

FROM

WASTE

Subhas Ghosh & A Richard Horrocks

Introduction The more common uses of recycled polymer waste are for products in which tensile, mechanical and physical properties are not critical and so the presence of degradation centres, damage to polymer chains and impurities are of little consequence. Thus many recycled polyolefins, for example, find use in garden products such as plant containers and timber substitutes. Only where the quality and purity of waste can be assured are secondary products capable of maintaining high levels of mechanical, physical and chemical performance. Of special significance to the textile industry is the re-use of poly (ethylene terephthatlate) pressurised drink containers as raw materials for melt extrusion into fibres. However, because of the presence of inherent colour within the original bottles, fibres produced may also be coloured and so of less than premium quality. The area of technical textiles, where aesthetics are of less consequence than in other textile sectors, offers the opportunity to create fibres and tapes having first grade properties if the physics and chemistry of recycled polymer and its conversion are understood. Of particular interest is the field of geotextiles (textiles used in civil engineering) where the annual world market for geotextiles is approaching 1000 million square meters equivalent to about 250,000 tonnes of raw materials of which over 70 % comprises polypropylene. During the extrusion of component fibres and tapes, up to 10 % by weight of process waste polymer is introduced without noticeable affects on quality. There is a desire by producers(l) to increase the amount of blended recycled polypropylene and even include polyethylene with virgin polymer during the extrusion process. In this way, they can fully re-use their own wastes, supplement them by including wastes from other sources and so replace virgin polypropylene by cheaper , recycled polymer. Sources of non-processor waste may include polypropylene granules from recycled automobile battery housing(2) and industrial film waste, for example. To date no academic study has been undertaken and reported which investigates the effects that added polyolefin waste has on the tensile, physical and chemical properties of orientated polypropylene tapes although La Mantia and co-workers(3,4) have undertaken research into the consequences of adding heterogeneous waste to polyethylene. This paper reports such a study and analyses the effects that adding large proportions of waste has on the properties of orientated polypropylene tapes. The full details have been published elsewhere(5,6).

Experimental Materials: Isplen PP040 manufactured by Repsol, Spain was used as virgin polypropylene. The virgin Isplen PP040 had a nominal melt flow index (MFI) of 3.0 (g/lO min at 230°C,

127

2. 16kg). The polypropylene pellets contained 0.10% of a hindered phenol antioxidant, Irganox 1010, as a heat stabilizer. To produce simulated process waste, Isplen PP040 was re-extruded and pelletized up to ten times. At the end of two, five and ten cycles a mass of the recycled polypropylene was collected for recycling with virgin polymer. Industrial polypropylene film wastes having MFI of 8.6 (g/lO min at 230°C, 2.16 kg) was obtained from Cabot Plastics Limited, UK. This waste contained compacted films from various sources and was granulated prior to extrusion. In the following discussions waste designations A, B, C and D will be given to industrial film and 2x, 5x and lOx re-extruded PP040 polypropylene wastes, respectively.

Stabilizing System: In order to reduce the effects of degradation products present in recycled polymers and thus enhance the durabilities of tapes, an additional additive package comprising process (heat) and U. V. light stabilizers was used in this introduction into each polymer. This masterbatch contained Ciba-Geigy Type B561 stabilizer which comprises Irgafos 168 and Irganox 1010 in the weight proportion of 4: 1. Irgafos 168 is a phosphite type processing stabilizer which in combination with the phenolic antioxidant Irganox 1010 provides both processing and long term thermal stability(7). In addition, Tinuvin 770 DF, a hindered amine light stabilizer (HALS), was also used in the masterbatch in equal proportion by weight with the heat stabilizer. Tape Production: All tapes were produced from waste-virgin polymer blends on a Mk-l Lanline Laboratory extruder from Plasticisers Engineering, Ltd., England, as discussed fully elsewhere(5,6) to give tensile properties similar to those for normal commercial tapes. Melt Flow Index (MFI), Tape Tensile Property and Physical Characterisation: MFI of the polymer pellets and oriented tapes were determined on a Martin Melt Flow Indexer at 2300C + 1°C under a load of 2.1kg using BS2782: Part 7: Method 720A: 1979. Five measurements were made on each sample (see Table 1). Tensile properties were determined by tensile tensiometry and indications of tape crystallinities were measured as intensity ratios of the 974 and 995 cm'! bands as described fully elsewhere(5,6).

Results and Discussion Effect of Recycling History on Polymer Melt Flow Index: Table 1 lists the MFI values of virgin and waste polymers before and after extrusion, with and without additional stabiliser. It is clear that values increase with a number of recycling and that the presence of stabiliser reduces the magnitude of MFI increase during extrusion. Furthermore, the MFI value of the lOx re-extruded Isplen PP040 is close to that of the industrial film waste and may be taken to be an acceptable model waste.

128

TABLE I. MELT FLOW INDICES OF POLYMER PELLETS AND EXTRUDATES MFI, gllO min, 130°C, 2.16kg Extruded Tapes Polymer Pellets

Without

With

Stabiliser

Stabiliser

Virgin Isplen PP040

3.24

4.18

4.19

Isplen After 2x Recycled (B)

3.55

4.95

4.68

Isplen After 5x Recycled (C)

5.01

8.45

6.64

Isplen After lOx Recycled (D)

7.05

10.53

8.20

Industrial Film Waste (A)

8.64

11.87

10.39

Effect of Waste Inclusion on Tensile Properties: A general trend of decreasing tape tenacity consequential upon the addition of recycled wastes both in absence and presence of stabilizer has been observed. The relationships between tape tenacity and recycled waste concentration for all four types of recycled materials A,B, C and 0 are illustrated in Figure 1 respectively. In all cases, tape strength decreases with increasing recycled material concentration, however, strength losses were greater after the initial 10% additions than after subsequent incremental additions of waste. Reductions in tenacity are relatively smaIl for additions above 50 %. A variance analysis of tenacity data indicated that the tape strength loss increased in the waste order B (two passes) < C (five passes) < A (film waste < 0 (ten passes) i.e. tenacity retention are in the order B> C> A> 0 as illustrated in Figure 1. These general decreases in strength with increasing waste concentrations and hence increased thermal history of recycled polymer can be attributed to the thermo-oxidative degradation of the recycled polymers demonstrated by their increased MFI values shown in Table I. The presence of additional stabilizers has significantly improved tape strength retention as seen in Figure 1. The effect of stabilizers in reducing tenacity loss was greatest for both the industrial film waste and ten times recycled Isplen PP040 waste 0 which is probably a consequence of these two waste materials containing higher levels of degradation products. These would tend to promote higher levels of subsequent oxidative degradation during polymer blend extrusion. The retarding effects of the antioxidants on the degradation of the polymers are evident in lower MFI values (Table I) of recycled materials presence of additional stabilizers relative to their unstabilized analogues.

129

Breaking strain values of all tape samples were highly variable and did not show a significant relationship with waste concentration, unlike tenacity values. At higher waste concentrations and particularly for waste C, breaking strains of tape samples generally decreased. The improved retention in tenacity for each stabilized waste-containing tape series relative to its unstabilized analogue noted in Figure 1 were matched by similar improvements in breaking strain retention. This is to be expected as a consequence of improved melt stability and hence extrusion uniformity which the presence of melt stabilisation additives confers.

Z

o

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1'0~--------------------------------~

100

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>

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Z

....

w

C

~---A

lI-

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60

NO STABILISER

o

~

A : ~ FILM WASTE B : ~ 2 x RECYCLED PP

z

o ~

w w a::

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10

x RECYCLED PP

105r---------------------------------~

100

I-

>

I-

~ zw

II-

90 85

z

w

~ w

80

ADDITIONAL STABILISER

~

PERCENT WASTE

Figure 1:

Effect of addition of various polypropylene wastes, without and with additional stabiliser 130

IR Crystallinity Index: Figures 2 and 3 show the changes in crystallinity index as functions of increasing waste A (industrial) and B (lOx re-extruded virgin) concentrations. These Vshaped curves are typical of many polymer property dependencies on concentration of an interactive mixture of two similar components. It is well knowd 8) that mixing two similar and miscible polymers produces such a degree of crystallinity versus concentration dependence as a consequence of the presence of a smaller concentration of either component reducing the ordering tendency and hence crystallinity of the major component. In Figure 2 and 3 it is interesting to note that pure polymer, which has the highest order, shows a rapid drop on addition of small « 25 %) amounts of waste, passage through a minimum and then a gradual rise to the lower degree of crystallinity of the respective 100% waste orientated tape. Thus the V-shaped curve could be explained in terms of the change from a more highly ordered polycrystalline state (the virgin polypropylene) to one having lower order (the 100% recycled polypropylene). Intermediate mixtures or blends of virgin and waste represent the effect that the minor component has on the major component present which necessitates passing through a minimum state of order. The causes of the change in polycrystalline order between each component is a consequence of differences in thermal oxidative histories which five rise to variation in molecular weight averages and distribution and the presence of oxidative centres within polymer chains. The effects of stabilisers on tape IR crystallinity were not found to be significant according to art analysis of variance. A more comprehensive study on the fine structure may provide a better understanding of the role that stabilizers have on tape morphology.

> I-

~

-J -J ~

0.82 0.8

I-

UJ

> ~

0.78

~

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l-

e:;

0.76

i=

CJ ~

I-

0.74

0

~

0.72

0

20

40

60

80

100

PERCENT WASTE

TAPES:

~

-+-

Figure 2:

NO ADDITIONAL STABILISER STABILISER

The relationship between crystallinity index and waste concentration when industrial fIlm waste, polymer A was added. 131

>!::

z

::3

0.82 0.8

...J

c:{

l(,/)

>a:

~

>-

l-

e:; t= () c:{

I-

0

~

0.68 0

20

60

40

80

100

PERCENT WASTE

TAPES:

---

-+-

Figure 3:

NO ADDITIONAL ST ABILISER STABILISER

The relationship between crystallinity index and waste concentration when lOx recycled Isplen PP040, polymer D was added.

The sudden drop in crystallinity at low waste concentrations correlated with the similar reductions in tenacity. As it passes through a minimum with increasing waste content, so tape tenacity loss reduces. The lower sensitivity of tenacity at waste concentrations of 50 % and above may be partly explained by subsequent increased ordering which offsets the counter effects of increased chain scission. Thus it is possible that the effects of adding waste-containing oxidative centres are to promote oxidative chain scission to the polymer mixture during extrusion which at low levels causes reduction in tape crystallinity and tensile properties i.e., tenacity. At higher waste levels, the increased chain scission enables the effect of the initial crystallinity reductions to be offset as reordering tendencies increase once waste levels exceed 50 % by weight. Summary

It has been shown that while the addition of recycled materials into virgin polymers has significant effects on oriented tape properties, useful tape having acceptable tensile properties (tenacity > 0.5 tex- I ) can be produced in absence of added stabilizer using up to 25 % w/w degraded recycled wastes from three out of four waste types investigated. Use of additional stabilizers shows a significant improvement in tensile property retention and MFI. A

132

stabilizing system consIstmg of a primary hindered phenol e.g., Irganox 1010, and a secondary organic phosphite antioxidant, e.g., Irgafos 168 at an appropriate concentration and mass ratio, is particulary effective in counteracting the otherwise oxidizing effects that added waste has on resulting tape properties. The HALS stabilizers such as Tinuvin 770, normally present to function as a UV stabilizer may also offer some thermal protection whereby the hindered amine is oxidized to form nitroxyl radicals which react with free radicals in the polymer(7). Waste-sensitized thermal degradation of polypropylene is significantly impeded by the presence of these stabilisers as indicated by reduced MFI values and losses in tenacity. Under these circumstances, upto 75 % by weight waste may be added to the virgin polymer and yield acceptable commercial tape tenacities. It is probable that certain types of sorted, clean consumer waste may also be usefully added to virgin polymer and find acceptability in geotextile products. The issue of durability(lO) has not, however, been addressed in this paper and is currently being investigated.

References 1.

Private communication with Exxon Chemical Geopolymers (UK) Ltd., and Amoco Fabrics and Fibres Co., USA, 1994

2.

Anon, Britannia Plastics, UK., Technical Data, 1994

3.

F P La Mantia, C Perrone and E Bellio in Plastics Materials Recycling, ed. F P La Manita., ChemTex, Toronto, 1993, 83-98

4.

F P La Manita, Polym, Deg. Stab., 42, 213-218 (1993)

5.

A R Horrocks, S Ghosh and A F Richards, Text. Res. J., 65, 601-606 (1995)

6.

S Ghosh, PhD. Thesis, University of Manchester, 1994

7.

F K Meyer, F Gugumus and E Pedrazzetti, Chemiefasern Textilindustrie, 35/87, E97100 (1985)

8.

F W Billmeyer, Textbook of Polymer Science, Wiley Interscience, New York, 1962

9.

A J Chirinos-Padr6n and N S Allen in Handbook of Polymer Degradation, eds. S H Hamid, M B Amin and A G Maadhah, Marcel Dekker, N.York, 1992, 261-304

10.

A R Horrocks and J A D'Souza in Handbook of Polymer Degradation, Eds. S H Hamid, M B Amin and A G Maadhah, Marcel Dekker, N.York, 1992, p. 433-506

133

THE ROLE OF PROCESS STABILISERS IN RECYCLING POLYOLEFINS H(Heinz) Herbst, K Hoffmann, R Pfaendner and F Sitek

Introduction For ecological, economical, and political reasons, material recycling is of eminent importance as an integral component in the efforts of plastic wastes in terms of:• • • • • •

reduction of raw materials reuse material recycling chemical recycling incineration with energy recovery landfill reduction

Value after regeneration via thermo-mechanical processes can be achieved with high value products. Coupling qualitatively high value products with old, used plastics is often perceived today as a contradiction. Plastics and thus also recyclates, are subjected to damage of the polymeric chains during every processing step and long term use by oxidative and/or photooxidative ageing. Damage to the plastics by shear forces, heat or radiation (light), and oxidation often proceed in a cascading or concerted manner. Traces of transition metals, heat, light and predamage (see Figure 1) [1 -3] have an accelerating effect. Oxidation products such as hydroperoxides, carbonyl groups and double bonds are chromophores which, among others, interact with light. They enhance photooxidation and consequently are starting points for progressive degradation (see Figure 2). The oxidation process and the oxidation products [4, 5] can be blocked effectively and efficiently by stabilizers (eg. antioxidants and processing stabilizers such as phosphates). These processes are usually polymer-specific and lead to molecular weight degradation by chain scission or crosslinking of the polymeric chains. In both instances the consequence is deterioration of mechanical properties up to total uselessness of the products. Ageing processes are, furthermore, the reason for macroscopic surface damage such as discoloration, bleaching, crack formation, etc., that may also contribute to the product's failure. Qualitatively high value products, particularly from used plastics, are only possible if the above-mentioned deleterious influences are opposed in good time. They have to be neutralized effectively during the product's life cycle or be eliminated or inhibited by means of "repair" mechanisms.

135

/ PH

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(Polymer)

Metal

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..

~ ~eil

p. - - - - - + POH

~o\~ PH

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(POlyrn - ~ er)

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Figure 1: Oxidation and stabilisation of plastics

virgin polymers

post-used material

1) manufacturing 2) aging 3) weathering

o =,

pOlymer'

0

• =, Polymer !-C-R

}

'POlymer t-CH=CH-R

• Chromophores • starting point for further

'POlymer ,-!'lOOH

oxidation

Figure 2: Photo-oxidation of plastics

136

L ~

Reasons for recyclates usage are based on eco-marketing considerations, sometimes environmental and legislative measures or simple price advantage. Another market segment for recyclates is the substitution of classic materials such as hardwood, concrete, etc. It is precisely their plastics-specific properties from which technological advantages can be derived which lead to low system costs as long as comparable life-times can be achieved in the products containing recyclates. The following selected examples demonstrate quality improvement and quality assurance achievable by means of additives whose contribution to high-value plastics articles is of eminent importance.

High Density Polyethylene A considerable fraction of plastic domestic refuse of interest for many applications comprises HDPE blow-moulded articles. Although relatively good segregation from the total waste flow is possible, impurities such as polypropylene (PP) closures and bottles from other materials (PVC, PP, PET) cannot be completed excluded. For example, long term thermal stability of a 95 : 5 polyolefin mixture (HDPE : PP) is affected by the PP content. Injectionmoulded test specimens after one and five extrusions, if stored in a circulating air oven at 120°C until brittleness shows, in the absence of stabilizers, failure of the bending test after 18 and 14 days respectively as Table 1 shows. Restablization with 0.2 % Irganox B 225, a typical stabilizer for virgin material, improves long term thermal stability to 37 and 25 days. Still better stability is obtained with Recyclostab 451 - a Ciba Geigy stabilizer developed especially for recyclates - 116 and 115 days respectively were achieved. Noteworthy also is that the difference between the first and fifth extrusions is diminished in terms of differences in enhanced embrittlement times.

Table 1:

Effect of additional stabilisers on thermal stability of PIPP mixtures.

Sample P/PP Stabiliser

95:5

Days to embrittlement, one extrusion

120°C five extrusions

None

18

14

0.2 % Irganox B225

37

25

0.2 % Recyclostab 451

116

115

90:10

"

94

84

90:20

"

74

57

80:20 (+ 0.20% PVC)

"

50

35

137

MFR

Phillips type

MFR

~ I

I

stabilized

I

I

I

unstabil ized stabilized

I

Extrusion Passes

- cross linking - reduced output - gel fonnation - embrittlement

Figure 4:

Ziegler type

~

unstabilized

Extrusion Passes

Figure 3:

)

- degradation - fluctuating production process - loss ~f physical properties - embrittlement

High density polyethylene processing behaviour

Irrigation pipe from LLDPE/LDPE recyclate oven-aged at 100°C; Key- (1) 100% virgin stabilised;(2) Recyclate, 2.S%CB/0.3% Tinuvin 622;(3) Recyclate without restabilisation;(4) Recyclate, 2.S%CB/0.3% Tinuvin 622/0.1% Irganox 1010;(S) Recyclate, 2.S%CB (CB = carbon black). 138

The effect of increasing polypropylene content or traces of polyvinyl chloride is demonstrated in Table 1. At the same restabilization with 0.2 % Recyclostab 451 and oven-ageing at 120DC, time to embrittlement of the test specimens is reduced dramatically with increasing polypropylene content. Moreover, the difference between first and fifth extrusions is again evident. These experiments indicate that, within certain limits, constant composition of the recyclate is an important quality criterion. The molecular weight-stabilising effect of a combination of phenolic antioxidants and phosphates has been demonstrated by mUltiple extrusions of various polyethylene recyclates as bottles [6, 7]. Thus for example, a thorough study with HDPE (blow moulded) has shown that the addition of a stabilizer (phenolic antioxidant and phosphite) leads to uniform wall thickness and consequently, permits increased proportion of recyclate in blends with virgin material [7]. The behaviour of polyethylene during processing and ageing depends on the catalyst type used for its production (see Figure 3). HDPE of the classical Ziegler type exhibits molecular weight degradation, while Phillips-catalysed HDPE leads to crosslinking up to gel formation and thus molecular weight increase [8]. In working with HDPE recyclates it should always be borne in mind that one may be dealing with a blend of various types of fluctuating composition. Therefore, restabilization systems have to cope with both degradation mechanisms and in this way ensure uniform processing. Multiple processing of Phillips - type HDPE leads to reduction of the melt flow, i.e. to crosslinking and in the worst case, to gel formation. Restabilization with the combination Irganox 1010 and Irgafos 168 in 1 : 1 ratio permits maintaining the melt flow rate or index value after five extrusions. To achieve this effect, at least 0.1 % of each component is necessary, although in the recyclate a stabilizer residue concentration of approximately 0.09% phenolic antioxidant and 0.03 % phosphite was still found. The same result was achieved with 0.2 % Recyclostab 411 developed specifically for recyclates. Results of multiple extrusions of a Ziegler-type HDPE which tends to molecular weight degradation for the same application shows that a combination of Irganox 1010 and Irgafos 168 (1 : 1) is inferior to Recyclostab 411 with regard to molecular weight conservation during multiple processing. Pipe applications: Carbon black-pigmented irrigation pipes for vineyards in Cap Province, South Africa manufactured with LLDPE/LDPE recyclate over the course of one year showed crack formation and breakage which did not occur with pipes made of virgin material. Artificial weathering experiments revealed quickly that pigmenting with 2.5 % carbon black alone does not impart sufficient protection against light. Maintenance of physical properties during 9000 hrs artificial weathering, corresponding to natural weathering in South Africa of 2 - 3 years (approx. 160 kLy/year), requires the use of additional HALS light stabilizers such as Tinuvin 622. In addition, the thermal stress on black pipes in such applications should not be underestimated. Elevated temperatures accelerate thermal ageing and sometimes carbon black can have a negative effect on thermo-oxidation of polyolefins [9, 10]. Adequate lifetime can, therefore, be achieved only if the restabilization formulation

139

contains along with light stabilizers also thermal stabilizers such as e.g. the phenolic antioxidant Irganox 1010 (see Figure 4). A second example presents results obtained in a project concerned with optimization of raw materials for LDPE/HDPE recyclate-containing pipes. Oven ageing of LDPE/HDPE recyclate at 110°C exhibits crack formation after only 52 days without restabilization. This effect is observed after 97 days if the material is restabilized with 0.033 % Irganox 1010, 0.067%Irgafos 168 and 0.1 % HALS, Chimassorb 944. Ageing resistance can be further enhanced by the use of Recyclostab 411 (0.1 %) and Recyclostab 421 (0.1 %) stabilizers developed specifically for recyclates, to 106 days, and 116 days respectively, or to 125 days with 0.2% Recyclostab 421 + 0.1 % Chimassorb 944. Complementary to these ageing studies, tests are being carried out at present involving storage in water at 80°C and natural weathering in South Africa. Repair concept

As already discussed stabilizers enable processing and permit long term applications of virgin materials by providing protection against oxidation and photo-chemical ageing processes. It follows that almost all virgin plastics contain tailor-made stabilization packages focused on the specific processing and the specific application [1, 2]. Although the fundamental importance of restabilization of recyclates has been stressed by various authors in many publications [6, 11 -21], this is frequently neglected. It is often forgotten that stabilizers are added for one-time processing and first use conditions only. Decisive considerations become necessary if recyclates from a short-term application (e.g. packaging) are to enter long-term applications. Such materials contain from their original use insufficient stabilizer residues (eg antioxidants) and little or no light protection for the second application. In addition to the usual effect of stabilizers against degradation in virgin plastics, the deleterious influence of previous damage and impurities (as initiating sites) in recyclates has to be compensated or eliminated. It is, therefore, not surprising that stabilizer combinations are already on the market aimed at the particular characteristics of recyclates [22,23]. For the future is the development of a broad range of special additives and additive blends for recyclates [11, 24]. Heavily damaged materials would require considerable improvement of their physical properties if they are to be used in high-value secondary applications. In this context, reactive additives will gain particular importance by offering the possibility of repair or elimination of damaged sites or the bonding of damaged polymeric chains. Such "repair"molecules are already mentioned in the literature [25 - 30] in connection with recyclates and virgin plastics. PPIEPDM Automobile bumpers as recyclates

Bumpers are important materials for recycling because they can be recovered easily when disassembling used cars [31]. This is old material whose surface has been damaged in a 140

relatively severe way because of outdoor use. Contaminants are frequently paint residues which, as is well known, have a deleterious effect on mechanical properties such as notched impact strength [32]. The influence of paint residue on molecular weight degradation is relatively small during processing, however, thermal ageing of painted bumper production waste leads to extremely high deterioration. This extreme loss of long term properties can no longer be compensated by stabilization alone. Possibly certain improvement can be achieved by the addition of a thiosymergist [13]. However, the values of new material after ageing cannot be reached any longer. Stabilization of a paint-containing recyclate has to compensate the negative effect of the paint which is very often polyurethane-based. Surprisingly, with a new stabilizer combination, containing a reactive additive, molecular weight deterioration can be compensated and long term thermal stability improved. By this extrusion process, not only processing and long term properties are raised, but also mechanical properties such as e.g. elongation and impact tensile strength, so that the resulting material becomes comparable to virgin product. Conclusions

Data in the literature and experiments outlined above already allow the conclusion that reuse of recyclates is possible in demanding applications, provided the correspondingly necessary stabilization has been applied. This is equally valid for single plastic recyclates, recyclate blends and also for mixed plastics. Furthermore, it should be noted that because of initiator-(faulty) sites, old material degrades faster and differently and, therefore, in many instances, specially designed stabilizer systems are required. Although there are at present no sufficient scientific investigations concerning the oxidative and photo-oxidative behaviour of recyclates, already a number of applications have been realized in a variety of industries (e.g. packaging, automotive, construction). Hence, in summary, the following can be stated regarding restabilization of recyclates: •

Restabilization is absolutely necessary for the use of recyclates in high value applications.

•

Restabilization has to take into account previous damage, subsequent application and residual stabilizer content and has to be specific for a given polymer.

•

Sufficient amount of processing stabilizers is needed to reduce as much as possible damage to the recyclate during processing. To this end, combinations of phenolic antioxidants and phosphites are primarily recommended.

•

Light stabilization is highly recommended for outdoor applications. The products of choice are HALS compounds or combinations of HALS compounds with UV absorbers.

Furthermore, the repair concept by use of reactive additives has to be taken into consideration with heavily degraded polymers and detrimental impurities.

141

References 1.

Gachter R., Miiller, H. Taschenbuch der Kunststoff-Additive., Carl Hanser Verlag, 3rd edition, Miinchen 1989

2.

Pospisil, J. and Klemchuk, P.P., Oxidation Inhibition in Organic Materials (1990), p.61 - 172

3.

Scott, G., Oxidation and Stabilisation of Polymers during Processing in Scott, G. Atmospheric Oxidation and Antioxidants, (1993), p. 141 - 218

4.

Klemchuk, P.P. and Tompson, T. Stabilization of Recycled Plastics, in Andrews, G.K. and Subramanian, P.M. Emerging Technologies in Plastics Recycling, ACS Symposium Series No. 513 (1993), 73 - 87

5.

Pearson, L.T. Stabilization of Recycled HDPE., Plastics Compounding (1992) Marchi April, p. 60 - 62

6.

Sitek, F.A., Todesco, R.V., and Hoffmann, K., Restabilization of Post-use Plastics: Philosophy and Examples. Presentation, Davos Recycle '92, Dacos 1992, p. 11/4-1 1111-14

7.

Pecora, L. and DiRaddo" R.W., Effect of Stabilization on the Recycling of Polyolefins in Blow Moulding. CNRC-NRC (Conseil National de Recerches Canada -National Research Council Canada), Industrial Materials Institute, CNRC 35348, March (1993)

8.

Moss, S. and Zweifel, H., Degradation and Stabilization of High Density Polyethylene during Multiple Extrusions. Polymer Degradation and Stability, 25 (1989), p. 217 - 245

9.

Rotschova, J. and Pospisil, J., Influence of the Carbon Black Chezacarb EC on Polyolefin Thermooxidation: A Model Study with Cyclohexene Doped with Chainbreaking Antioxidant. Makromol. Chern. 194 (1992), p. 201 - 211

10.

Mwila, J., Miraftab, M. and Horrocks, A. R., Effect of Carbon Black on the Oxidation of Polyolefins - An Overview. Polymer Degradation and Stability, 44 (1994), p. 351-356

11.

Sitek, F., Herbst, H., Hoffmann, K. and Pfaendner, R., Upgrading of Used Plastics: Why and How? Presentation, Davos Recycle '94, Davos 1994, p. 4-1.1. - 4-1.10

12.

Pfaendner, R., Herbst, H., Hoffmann, K. and Sitek, F., Nachstabilsieren von Recyclaten. Presentation, Siidderutsches Kunststoff-Zentrum: Natiirliche Bewitterung von Kunststoffen, Wiirzburg 1993, p. 121 - 170

13.

Pfaendner, R., Herbst, H., Hoffmann, K., and Sitek, F., Recycling and 142

Restabilization of Polymers for High Quality Applications - An Overview. Presentation, Sixteenth Annual International Conference on Advances in the Stabilization and Degradation of Polymers, Luzern 1994, p. 217 - 251 14.

Scott, G., The Role of Stabilising Additives in Polymer Recycling. Presentation, Davos Recycle '93, Davos 1993, p. 8/1-1 - 8/1-19

15.

Poschet, G., Beurteilung und Priifung der Eigenschaften von Kunststoffprodukten aus Kunststoff-Restgut, in Dolfen, E., Breuer, H. (Edit): Kunststoff-Recycling-Handbuch 1992, Hiithig Verlag, Heidelberg 1992, p. 12-1 12-8

16.

Dietx, S., The Use and Market Economics of Phosphite Stabilizers in Post Consumer Recycle. Presentation, Recycle '90 conference, Davos 1990

17.

Sadrmohaghegh, C., Scott, G. and Setudeh, E., Recycling of Mixed Plastics. PolymPlast. Technol. Eng., 24 (1985) 2/3, p. 149 - 185

18.

Ogando, J., Additives for Recycling, Maintaining Value the Second Time Around. Plastics Technology, July (1993), p. 56 - 60

19.

Dansie, J., Stabilisers Extend Life for Recycled Plastics. Performance Chemicals, June/July (1993), p. 16-18

20.

Monks, R., Stabilizers Help Process Reclaim. Plastics Technology, January (1991), p. 26 - 27

21.

Allbee, N., Plastics Recycling: Becoming a Reality. May/June (1993), P. 32 - 37

22.

N.N., Eigenschaften von Rezyklaten verbessern. Kunststoffe 83 (1993) 4, p.264

23.

N.N., Two Masterbatches ... Modern Plastics International, July (1993) 0.47

24.

Murphy, J., Recycling Plastics - Guidelines for Designers. Techline Industrial Data Services Limited, London, March 1994

25.

DE 4224668 C1: Verfahern zur Erh - hong der Molmassen von Polyamiden (1993), Christ, H., Schnieder, W.,

26.

Cardi, N., Po, R., Giannotta, G., Occhiello, E., Garbassi, F, and Messina, G.: Chain Extension of Recycled Poly(ethylene terephthalate) with 2,3' -Bis(2-oxazoline). Journal of Applied Polymer Science, 50 (1993), p. 1501 - 1509

27.

EP 0 583 807 AI: A Process for Preparing High Molecular Weight Polethyleneterephthatlate from Recycled PET (1993), Po, R., Cardi, N., Fiocca, L., Gennaro, A., Giannotta, G., Occhiello, E.

143

Plastics Compounding,

28.

Gebauer, M. and Buhler, K., Ma/3genschneiderte Polyolefine. Kunststoffe 82 (1992) 1, p. 21-26

29.

Fritx, H.-G., Cai, Q. and B61z, U., Polypropylene-Modifikaiton durch reactive Kunststoffaufbereitung. Kunststoffe 83 (1993) 6, p. 439 - 444

30.

DE 42 25 627 A 1: Verfahren zur Modifizierung von Polymeren (1994), Birnbrich, P., Eicken, U., Fischer, H., Klamann, 1.-D., Schieferstein, L.

31.

Thomas, G., Rohstoff-Ruckgewinnung aus gebrauchten Polypropylene-Sto/3fangern. Chem-Ing.-Tech. 63, (1991) 3, p. 243 - 245

32.

Rapp, N., Wiederverwertung von lackierten PP-EPDM-Sto/3fangern. Plastverarbeiter 42 (1991), p. 48 - 52

144

RECYCLING CARBON FIBRE-PEEK COMPOSITES A(Alan) K Wood, R J Day and S F Pang

Introduction Modern polymer based composites date from the turn of this century, these being based on thermosetting polymers, such as phenolic reins, coupled with natural-fibre reinforcements such as paper. The early 1950's saw the introduction of glass reinforced plastics, this resulting from the concurrent development of thermosetting polymers, for example unsaturated polyester resins, and the technology for the successful production of suitable glass fibre. However, these materials are not easily recycled due to the, often, highly-crosslinked structure. Thermoplastic based composites were not introduced into the market until the 1960's, these principally being off the short-fibre variety, the reinforcement overcoming some of the mechanical limitations of the materials. However, whilst these materials have the benefits of recyclability, processing of short fibre composites can lead to products with anisotropic properties due to the orientation of the fibres generated by the- flow processes occurring during fabrication. This presentation concerns the recycling of carbon fibre-PEEK composites. PEEK1,2, poly(ether ether ketone), is a semi-crystalline thermoplastic engineering polymer. It exhibits a glass transition temperature around 143°C and the crystalline melting point is around 334°C, the degree of crystallinity typically being around 30%. The polymer exhibits good chemical and thermal resistance. Carbon fibre-PEEK composites are available in two forms, a short fibre reinforced material and a uniaxial continuous carbon fibre-PEEK pre-preg. The short fibre reinforced material can be processed by the routes usually used for thermoplastics such as injection moulding. The uniaxial continuous carbon fibre-PEEK pre-preg, marketed commercially under the name APC-2 (aromatic-polymer composite), is typically utilised by a hand lay-up process followed by compression moulding, sheets of pre-preg being cut to the shape required to fit the mould. The fibre orientation in the product is controlled by changing the relative axis of the successive layers of pre-preg. This type of process generates quantities of offcuts and this presentation considers the recycling of this waste into a short fibre composite, suitable for injection moulding. McGrath and co-workers3 ,4 and Belbin et a15 ,6 have also consider the recycling of APC-2, the route used by the latter being similar to that investigated in this work. Experimental The material used for this work was in the form of a roll of the composite rather than actual offcuts. The reprocessing route consisted of three stages: 145

(1)

Size reduction of the offcuts.

(2)

Compounding of the size-reduced offcuts with more PEEK.

(3)

Fabrication of components, in this case, suitable test pieces.

Size Reduction: The offcuts from the moulding of the APC-2 can vary in size but will typically contain fibres very much larger than those normally found in a composite that can be processed by injection moulding. Typical fibre lengths in a short fibre-reinforced composite are of the order of 3mm. The initial stage of size reduction involved feeding the strip of composite from the roll into an office paper shredder in order to generate composite flakes, typically 5mm square. In order to produce a successful injection-moulding compound the fibre content of the recycled material needed to be reduced from that found in APC-2, typically around 60%, to 20%-30%. This required the addition of further PEEK resin (LNP LClO06) , this resin being chosen on the basis of its suitability for the injection moulding process. As will be shown later, the molar mass of this resin was substantially lower than that found in the pre-preg material. Attempts to use the flake directly, along with a quantity of unfilled PEEK resin, to produce injection moulded components did not prove successful due to the poor dispersion of the fibre in the components although this method would represent the simplest recycling route. The difficulties experienced arose due to: (i)

The relatively low shearing forces present during the injection moulding process.

(ii)

The rheological differences in the original resin, found in the pre-preg, and that added to reduce the fibre content of the composite.

As a consequence methods were investigated whereby the size of the flakes could be further reduced in order that this recycling method could be utilised. However attempts to reduce the size of the flakes by simple mechanical means proved unsuccessful. The methods evaluated included cryogenic grinding, the use of an internal mixer (Midget Banbury) and ball milling. Compounding: As a result of the difficulties found with the direct injection moulding of the flake/PEEK mixture, the mixture was compounded using a Betol BT30S co-rotating twinscrew extruder, the ratio of flake to additional PEEK being such that the product contained approximately 25 % by weight fibre.

The extruder was equipped with 30mm diameter screws of length-to-diameter ratio of 22: 1. The processing conditions are given in Table 1. The extruder was thoroughly cleaned, using a fluidised bed, prior to the compounding operations as any polymeric residues from previous compounding operations were likely to degrade at the elevated temperatures used to process the PEEK, this resulting in contamination of the product.

146

Extruder Temperature Settings

I

Die

380°C

Front

370 °C

Centre

360°C

Rear

350 °C

Extruder Screw Speed

I

I

70 rpm

Table 1: Extrusion processing conditions.

I

I

Parameter

Commercial

I

Recycled

Temperature Settings / °C Nozzle

399

399

Front

399

399

Centre

390

390

Rear

370

370

Mould

157

157

Cycle Timing / s Injection time

1

1

Hold-on time

10

10

Cooling time

40

40

Melt Pressure / bar Injection pressure

990

690

Hold-on pressure

950

600

Back pressure

150

20

Table 2: Injection moulding conditions.

147

I

Moulding: Test pieces were produced from the compounded recycled material and a commercial short fibre reinforced carbon fibre-PEEK composite, based on LNP LClO06, containing 30% by weight of fibre. Test specimens were manufactured using a Negri-Bossi NB60 microprocessor-controlled injection moulding machine, the operating conditions being given in Table 2. As was the case with the twin-screw extruder, the injection moulding machine needed to be cleaned thoroughly before mOUlding.

E

PL o3

4Cn 3y

The tensile and flexural moduli of the moulded products were determined, the samples being conditioned at 23°C and 50% relative humidity prior to testing. The flexural modulus was calculated using the expression7 below: where P = applied force (N) 1.0 = Distance between supports = 50mm C = specimen width (mm) D = specimen thickness (mm) Y = specimen deflection (mm) under load P Fracture surfaces were viewed using a Philips 525 scanning electron microscope (SEM). The effect of processing on the molar mass distribution of the polymer and the fibre length distribution of the reinforcement was determined. Determination of the viscosity average molar mass was done by solution viscometry using an Ubbelohde viscometer, the PEEK being dissolved in concentrated sulphuric acid, any fibres present being filtered off. The fibres, thus collected, were weighed to allow the determination of the fibre content of the composite, and their lengths measured so that the fibre length distributions occurring in the composites could be determined. Fibre length measurements were carried out by photographing the fibres under a Vickers optical microscope. Viewed using a video camera, the image produced was analysed using a Magiscan image analysis system. Approximately 500 fibres were measured for each sample. The thermal characteristics of the recycled and commercial materials were determined using differential scanning calorimetry (DSC), on a DuPont 2000 analyst system. The melting temperature of the materials, Tm , was taken as the temperature at the peak of the melting endotherm. Degree of crystallisation was determined by measuring the heat of fusion of the sample and comparing this with the heat of fusion for totally crystalline PEEK 8 , this being taken as 130 J g-l.

148

Material

Condition

PEEK LN LC 1006

As-received

15200

APC-2

As-received

35 800

Recycled material

before injection moulding

23200

after injection moulding

22400

before injection moulding

25700

after injection moulding

24200

Commercial material

(Mv)s

Table 3: Viscosity-average molar masses, (Mv)s' of PEEK samples.

Tm / °C

Crystallinity / %

PEEK

345

37

APC-2

342

27

Recycled materiat

343

36

Commercial material*

338

26

Material

Table 4: Thermal characteristics of the PEEK materials. after moulding)

r-

Stage of Processing

Weight-average fibre length (J.tm)

Number-average fibre length (J.tm)

Recycled composite

before moulding

271

200

after moulding

212

155

Commercial composite

before moulding

186

145

after moulding

151

109

Material

Table 5: Fibre length distributions in the recycled and commercial composites

149

Results and Discussion The viscosity average molar masses of the PEEK components of the composites are shown in Table 3 this indicating, as would be expected9 ,lO, that little degradation occurred as a result of processing and shows the similarity between the molar masses of the recycled and commercial materials. Table 4 shows the thermal characteristics of the recycled and commercial materials, slight variations being observed in the Tm of the PEEK. However, large differences are observed in the degree of crystallisation in the various materials. The degree of crystallinity can have a significant effect on the mechanical performance of PEEK lO ,l1, and thus the recycled material would be expected to have superior performance to the commercial material. The results regarding the fibre length distributions are shown in Table 5. It can be seen that the average fibre length in the recycled material is longer than that found in the commercial material. In both cases, a significant amount of fibre breakdown occurs on injection moulding. The greater reduction in average fibre length found in the case of the commercial material probably results from the increased fibre loading, this leading to a greater likelihood of fibre-fibre interactions during processing12.

Material

Young's Modulus I GPa

Ultimate Tensile Stress I MPa

Flexural Modulus IGPa

Recycled material (wf=25%)

26

+2

240

+

13

16.9

+ 0.2

Commercial material (wf=30%)

20

+2

202

+6

16.9

+ 0.3

Table 6: Mechanical properties of the recycled and commercial composites The results from the mechanical tests carried out are given in Table 6. It can be seen that the tensile properties of the recycled composite are around 25 % better whereas the flexural properties are similar. The difference in tensile properties is perhaps a little surprising due to the higher fibre loadings in the commercial material, although the average fibre length in the recycled material is higher as is the degree of crystallinity. The results obtained for the commercial material were consistent with those supplied by the manufacture~,4. It is apparent from the SEM micrographs of fracture surfaces that failure in the commercial

material was accompanied by substantial fibre pull-out whereas in the case of the recycled material the majority of fibres failed at the crack face. This suggests that the matrix fibre bonding was stronger in the recycled materials, this serving to improve the mechanical properties. This may in part result from the manufacturing process for the pre-preg. Some bundles of fibre were evident at the failure surfaces in the recycled materials, indicating that the mixing of the APC-2 composite with the PEEK resin may not have been complete. 150

Economics of Recycling The cost of recycling APC-2 in the manner described above was determined, based on: (1)

The scrap APC-2 is supplied to the recycling scheme free of charge and is readily available.

(2)

Compounding is carried out using a twin-screw extruder, capital cost £150 000, running costs £20 h-1 which is run on a 40 h week.

(3)

Operator costs are £10 h-1.

(4)

The capital cost of the extruder is to be recovered over a two year period.

(5)

The cost of the PEEK resin used to reduce the fibre concentration in the composite is £46 000 11.

(6)

The output rate from the plant is 250 kg h-1, full production being assumed.

This yields a cost of under £23 000 11, which is very much less than the price of the equivalent commercial compound, this being of the order of £49000-5600011. The price of the recycled material is relatively insensitive to all factors excluding the price of the PEEK polymer used in the formulation. However, whilst the economics of the process seem advantageous, it should be remembered that the quantity of offcuts produced is limited and probably widely distributed. Hence there may be a problem obtaining sufficient material to set up a commercial scale reprocessing facility. It has also been assumed that the offcuts are supplied free of charge. The modelled recycling system would generate 500 T of composite annually which represents a substantial proportion of the estimated market for the material, and would require 250 T of scrap APC-2. It is not known whether the latter quantity is realistic. However, if smaller quantities were available, the costs would be such that recycling would still be beneficial. Conclusions The results indicate that APC-2 composite can be reprocessed to produce short fibre composite suitable for the use in the injection moulding process. The properties of the recycled material are shown to be superior to that of an equivalent commercial grade of material. The economics of the recycling process indicate that the route is commercially viable, the main problem being the collection of sufficient scrap APC-2 to make the recycling process worthwhile. References 1.

Barton, 1.M., Lloyd, R., Goodwin, A.A. and Hay, 1.N. BritishPolym. J., 1990,23, 101. 151

2.

Stober, E.l., Seferis, 1.e. and Keenan, 1.0. Polym. 1984, 25, 1845.

3.

McGrath, G., Clegg, D.W. and Collyer, A.A. Composites 1988, 19,211.

4.

McGrath, G., Clegg, D.W. and Morris, M. Composites Manufacturing 1990, 1, 85.

5.

Belbin, G.R., Brewster, I., Cogswell, F.N., Hezzel, 0.1. and Swerdlow, M.S. 2nd Int SAMPE Conf., Stressa, lune 1982.

6.

Belbin, G.R. Proc. Inst. Mech. Eng., Ser. B 1984, 198, 71.

7.

Heap, R.D. and Norman, R.H. 'Flexural Testing of Plastics', Plastics Institute, London, 1969.

8.

Blundell, 0.1. and Osborn, B.N. Polymer 1983, 24, 953.

9.

Price, W.A., Anderson, D.P., and Carlin, D.M. 35th Int. SAMPE Symp., 2-5 April 1990.

10.

Arzak, A., Nazabal, 1. and Eguiazabal, 1.1. Plast., Rubber Compos. Process. Applic. 1991, 15, 119.

11.

Cebe,P. J.Mater Sci. 1988, 23, 3721.

12.

Pak, G.K. MSc Dissertation, University of Manchester, 1992

152

THE ECO MOVEMENT Brian J McCarthy

Introduction

The global human population is now increasing at the rate of 0.9% per annum. As a result, more than 11 % of the world's terrestrial landscape has been converted to cropland. A further 25% is occupied by pastureland. Humans use 8% of the world's available fresh water each year. As a result of these factors, significant environmental damage has occurred across the world with global implications. Growing legislation and public concern about the impact of industry on the environment has firmly established this issue on most business agendas in the 1990's. For example, more than one third of UK FT-SE 100 companies produced separate environmental reports in 1994. Concern about environmental issues is no longer limited to extreme environmental activists. The Eco-movement may be said to have begun in the second half of the 19th century with public reactions to urban pollution and species depletion (e.g. the over-hunting in the USA of the North American bison). Similarly, the publication of Silent Spring by Rachel Carson in 1962 greatly stimulated public awareness of the impact of pesticides on the environment. Public awareness in turn has led to the formation of local, national and international pressure and lobbying groups. For example, the Friends of the Earth Limited was established in the UK in 1971 and now operates in some 35 countries. FoE campaigns on a wide variety of environmental issues. Related organisations include Greenpeace, World Wide Fund for Nature, Royal Society for Nature Conservation and The Pesticides Trust. Public awareness and concern relating specifically to textile materials and their environmental and human ecology impact, may be illustrated by the significant 1994 media coverage given in Germany to dioxin levels found on textiles in contact with the skin and the media coverage in the UK associating cot deaths to added flame retardants. Consumers in general are becoming more environmentally aware. The following sections are intended to give a general overview of an increasingly complex and highly topical field. Cotton and Pesticides

Cotton is the world's most important fibre crop and the major non-food crop. It is grown in over 60 countries on more than 80 million hectares, or 5 % of all cultivated land. Cotton production involves over 180 million people and has an annual value of some $20-24 billion. Cotton cultivation represents the largest single market for insecticidal products, accounting for almost 25 % of the $7.4 billion global market. The Bhopal factory in central India was 155

producing pesticides for cotton production prior to the tragedy. The most recent Pesticide Manual (10th Edition) profiles over 700 pesticide active ingredients used globally. According to UN sources, some 250 pesticides are banned or restricted by various governments. Pesticide usage may lead to some unwanted side-effects. The recent UK Drinking Water Inspectorate Fourth Annual Report states that having tested over one million samples involving 54 pesticide parameters - they found that 2.13 % were in contravention of EC guidelines. Similarly, the UK government's food residue surveillance programme for 1993 revealed that 1 % of samples were found to contain pesticides above the maximum residue levels indicative of poor pesticide application and excess usage. Cotton farmers may apply up to eight to ten different herbicides and/or pesticides to provide overall crop protection. Environmentalists therefore continue to associate cotton production and widespread pesticide use. These green issues are now creating niche market opportunities. The UK Designer Katharine Hamnett provided a series of Summer 1994 designs - jeans made from organic cotton. THE GAP ( manufacturers and retail stores), who operate in the US and Europe, now supply organic cotton underwear. Similarly ESPRIT, the US-based fashion designer, is selling organic clothing (including T-shirts, sweat shirts and jeans) under the new ECOLLECTION label. ESPRIT would like all their production to be organic cotton by 1996 - requiring 125,000 tonnes by 1996. Organic cotton production has significantly increased over the last four years. It currently represents 15,000 tonnes of the 18.2 billion tonnes of cotton produced world-wide every year. The INTERNATIONAL FEDERATION OF ORGANIC AGRICULTURE MOVEMENTS (IFOAM) requires that for a crop to be called organic, no chemicals whatever should come into contact with it. The ground on which the crop was grown should be free of chemicals for at least three years prior to planting. In the US in 1993 growers received $2.77 per kilogram for organic cotton and $1.32 per kilogram for conventional cotton. But, organic cotton can lead to crop yield losses of 30-40 %. Re-cycling may also feature. Burlington recently announced the addition of a new fabric Reused Denim - to its line of environmentally friendly denim products. The re-used denim is made from 50% reclaimed cotton denim scraps used in the fill. The warp is virgin cotton. Other Burlington denims include Ecospun denim (made from cotton and recycled polyester) and Tencel denim (cotton and tencel). As a major fibre, cotton is likely to be the focus for further initiatives with environmental consequences (e.g. genetic manipulation). Eco-Labelling

Recent years have seen the appearance in Europe and elsewhere of a variety of textile labels reflecting environmental concerns. Such schemes are normally non-statutory and self-financing. For example, a number of years ago, the Austrian Textile Research Institute in Vienna presented a test regulation for harmful substances, the OTN 100, which has since been applied to textiles, clothing and carpets. Similarly, since 1991, the ·Hohenstein Research 156

Institute in Germany has been carrymg out pollution analyses m accordance with the "Hohensteiner Oeko-Check". Their combined experience was utilised by bringing the Austrian Textile Research Institute and the Hohenstein Research Institute together as the "International Association for Research and Testing in the Field of Textile Ecology". BTTG is now the official U.K. laboratory of the International Association for Research and Testing in the field of Textile Ecology - the host organisation for the Oko-Tex scheme. From an initial partnership between the two European Institutes, the Association has rapidly expanded and now comprises twelve Textile Research Institutes distributed throughout the European Union. The "Oko-Tex Standard 100" specification is for testing textiles, clothing and carpets based on their human ecological characteristics. This standard contains detailed analytical procedures for specific substances which are ecologically hazardous for humans and also stipulates individual limit values based on scientific research. If a textile product complies with the conditions laid down in the Standard, the Supplier is awarded the right to label the goods as being "Confidence in Textiles - Passed for Harmful Substances according to Oko-Tex 100". Harmful substances within the context of this standard refer to substances which either exceed a specific amount in a textile product or in accessories or evolve in a specific amount during normal use and may have some kind of effect on people during normal use and may, according to current scientific knowledge, be injurious to human health. The International Association is committed to an on-going policy of researching and reviewing standards, test methods, guidelines and health implications. The mark is not a quality label and relates only to the as-produced-state of the textile. When all the conditions specified in the standard are fulfilled, and the tests show no deviations from the detail~ provided by the applicant, and that the test values do not exceed the limit values specified in the special standards, a certificate (copy attached) will be issued giving the applicant the right to mark his products with the Oko-Tex mark valid for the duration of one year. A related scheme has been introduced to cover the carpet sector. In 1991, the European Carpet producers formed their own organisation - Gemeinschaft umweltfreundlicher Teppichboden (GuT) - the Association of Environmentally Friendly Wall-to-Wall Carpeting. In 1992, for example, over 920 million square metres of textile floor coverings were sold in Europe. The ecological impact of carpet production and subsequent disposal could potentially be significant. The scheme is voluntary and is member-based. GuT members are obliged to manufacture their products applying ecologically harmless methods (e.g. no formaldehyde, pentachlorophenol, etc.). GuT member companies can be identified in the marketplace by the label which states "Carpet tested for pollutants". In contrast, the European Union remains keen to promote eco-Iabelling across industrial sectors. The stylised flower of the EU eco-Iabelling scheme is granted on the basis of a complete life cycle analysis (cradle to grave evaluation). Work is currently underway, with Denmark leading, on T-shirts and bed linen. A series of problems will need to be addressed before the EU label is introduced into the textiles sector. Moreover, the EU will not make 157

the label available to all manufacturers who attempt to limit environmental impacts. The label will be limited to a defined percentage of manufacturers who can demonstrate best practice. Again, this scheme will be voluntary and self-financing. Environmental Initiatives

Environmental issues will remain central to commercial operations. Textile manufacturers seeking to comply with existing and proposed environmental legislation and to adopt best practice generally require advice. The 1994 UK Environmental Business Club Directory identifies over 80 separate clubs and networks providing help and advice to business (some aimed specifically at the Textile Sector e.g. BTTG's Environment Club). Again in the Textile sector, both Comitextil and the British Apparel and Textile Confederation (BATC) have created dedicated Environmental Committees. In the U.K., 1996 will see the merging of Her Majesty's Inspectorate of Pollution, the National Rivers Authority and the regional waste regulation authorities to form the UK Environment Agency and the Scottish Environmental Protection Agency. This body will take an integrated approach to environmental protection. The Department of the Environment has also created the UK Round Table on Sustainable Development. Similarly, the EU has formed the European Environment Agency based in Denmark. All of these initiatives will maintain focus on environmental matters. Environmental management is gaining attention. Textile businesses will continue to become more aware of the implications of BS7750 and the EU Eco-management and Audit scheme (EMAS). Textile Initiatives

The textile sector has responded to environmental concerns in a variety of ways. Basic and applied research in academic and industrial laboratories have in recent years resulted in novel cost-effective products and processes designed to reduce ecological damage. Most aspects of manufacture have been addressed. It is interesting to note that U.K. legislation has driven environmental technology sales in 1994 by over 25 %. Examples include: Water re-use and recycling Size recovery/recycling Energy Efficiency Noise and dust reductions Dyestuff selection Biocide/Pesticide selection Volatile organic compounds Further initiatives will be required as legislative guidelines continue to be tightened.

158

Conclusions The textile sector will continue to experience increasing national, European and global pressures and costs associated with environmental issues. Greater attention will be paid in future to integrated managed schemes with supporting documentation (e.g. BS7750 and EMAS). Environmental concerns will continue to apply from fibre production (e.g. pesticide usage) to finished garment (including packaging). Eco-Iabelling will become increasingly visible as further manufacturers join the supply chain resulting in greater recognition in the consumer market place. Greater demands will be placed on technology solutions, requiring an on-going policy of research and development investment at company, national and international levels to devise economically-viable best practice. Environmental pressure groups and informed consumers will demand constant innovation.

159

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

WASTE - THE POLITICS AND PHILOSOPHIES Barry G Hazel

Introduction The Stone Age lasted for 50,000-100,000 years, the Bronze Age for 3,000-4,000 years, the Iron Age for 2,000-3,000 years and the Plastics Age has been underway for around 100 years. So, what age exists now? The current age is typified by two things: • •

synthetic chemicals and derived products throwaway products

Both economically and environmentally this age is not sustainable. Nature, without the influence of man, is the perfect, totally closed recycling system. Think of the many features designed into the natural cycle, deciduous trees in Europe produce their leaves in the Spring, take advantage of the Summer sunshine to produce food and in the Autumn lose their leaves because they would be at a disadvantage in strong winter winds and water supply is difficult from frozen ground. But the leaves are not lost, they fall to the ground, are converted into fertilisers by the action of worms, microbes, bacteria, and the chemical energy is then re-absorbed by the tree roots to give additional energy for the production of the leaves in combination with sunlight for the following Spring. All animals are dependent on that plant growth for their food and survival. Plants also take in carbon dioxide and by photosynthesis convert it into carbohydrate and give off oxygen; the oxygen is an essential requirement for all animals and plants for respiration. They take oxygen in and give out carbon dioxide, thus completing the cycle. In times of food abundance, many animal species expand in numbers and, equally, in times of food scarcity many starve. Nature is cruel, but only by being cruel can it maintain its eco-balance. In comparison with the natural cycle, the industrial system is a very wasteful system. Can it be improved without introducing the cruelties of nature? The answer to that is "yes" and "no". Yes, by introducing many of the techniques and technologies which are currently available and no because there are certain products and processes which are so polluting that to continue with them would be to put the total environment at risk. With regard to recycling, the textile industry has always had an enviable record. recycling of textiles may be divided into two parts: • •

recycling within the processing chain and recycling post-consumer waste

Recycling Within the Processing Chain

161

The

We have recently been carrying out a study for the Department of Environment on where waste goes, because it is recognised that one man's waste is another man's raw material. Some key facts from our study were: 1.

In spinning and weaving less than 1 % of the textile product is lost, most waste goes into the reclamation industry.

2.

More waste is generated from packaging than from any other source.

3.

The introduction of plastic containers has increased the waste disposal problem.

4.

Waste from textile finishing is mainly water and chemicals and studies on recovery and recycling are underway.

Recycling Post-consumer This is an area where society seems to have gone backwards in recent years; for instance, wool reclaiming was a more significant industry in the past than now. It has been reduced by the introduction of blends of wool and other fibres but legislation, for other environmental reasons, can reduce recycling, ego the recent proposed German legislation on the use of azodyestuffs will reduce recycling because the reclaimers do not know which dyestuffs were used for the original dyeing. The Italians are most concerned about this as, in the Prato region of Italy, re-cycling is a major part of the textile industry, and much of their raw material is wool rags which are imported from Germany and from which, a new product is exported back to Germany. This cannot be done and guarantee to meet the new legislation if azo-dyed wool is to be banned. The end-use of most cotton materials was as rags and, forty years ago, in any engineering works there were always rags available to wipe up with or to wipe hands clean. These have generally been replaced by paper and even if available polyester/cotton blends are not as good as pure cotton because of reduced absorbency. Simply to recycle waste should not be an end in itself, it must be both cost and environmentally efficient. It must be remembered, however, that recycling can be polluting in itself and, for some waste, efficient incineration and energy recovery may be the best method. Post-consumer textile waste raises a number of political questions. Official EU statistics indicate that 7 % of dustbin waste is of textile origin and begs the question of what the textile industry can do about it. In every country of the community the general public consumer pays taxes for municipal disposal of waste and so it may be said that it is not the textile industry's responsibility for consumer waste from textiles, although this may change. Currently, however, there is new initiative in Germany by the carpet industry, so that when a carpet is purchased an old carpet is returned for disposal through official routes. This may work with carpets, it would be difficult to operate from other consumer textiles. That does not mean that the textile industry has no responsibilities, it has an important responsibility 162

in designing for disposal so that the products it sells can be disposed of in the most environmentally friendly conditions possible.

Environmental Management and Auditing Schemes In recent years, there have been major changes in the method of thinking about waste and its minimisation. This includes minimisation of the polluting effects of the processing chains and this can be done by a variety of methods: • • •

reduction of input of raw material changes in processing to reduce waste consumption or air pollution elimination of polluting products or substitution of a polluting product by a nonpolluting product

Before anything can be controlled, it is necessary to be able to measure it, and this is an essential requirement in order to undertake the recently introduced Environmental Management and Auditing Schemes (EMAS). EM AS is an EC voluntary scheme, very similar to BS7750. EMAS is designed to encourage companies to adopt a proactive approach to environmental management, rather than to wait and respond passively to demands of legislation. EM AS compliments legislation by giving official recognition to companies who volunteer to go further, by setting their own objectives and targets and committing themselves to continuous improvement. Effective environmental management is an integral part of good company management, as it leads to better control in the use of raw materials and energy and enables companies to minimise waste and reduce their costs. It comprises a series of stages:

1.

The production of an environmental policy.

2.

The company must carry out a thorough environmental review of the site.

3.

In light of the review policy, the company introduces an environmental programme for the site.

4.

The company sets up an environmental management system to implement the policy and programme.

5.

The management system must be audited periodically.

6.

The company produces an environmental statement designed for the public, setting out information on the environmental performance of the site, including the success in meeting targets, as well as setting new targets for the future.

7.

The validation of the statement is undertaken by an independent accredited environmental verifier. 163

The environmental audits at the site must be conducted at least every three years. On the general political front there is environmental legislation, which may originate from either the EU in the form of directives which are translated into National law or from the National Governments. In spite of often being considered "the dirty man of Europe", the UK has probably the widest and most stringent legislation on the environment in Europe. It certainly has the most comprehensive monitoring system; some countries may have more legislation, but no body which consistently monitors that legislation. The UK continually fights for a level playing field or, as some have pointed out, "a level battleground" in this area, because there are considerable commercial advantages in not having to meet certain items of legislation on the environment. The concepts of the eco-movement and "Ecolabels" are now well-established. The industry generally supports the concept of a single Ecolabel, which deals with controlling pollution, but has strong doubts about some of the private labels which only refer to human health and not to the environment and are used primarily as marketing tools. The environmental campaigners' "single issue" approach to the environment is naIve. These campaigners take no note of the effect of what they want on upstream or downstream sectors with respect to a given product or process. An example of this in the textile clothing chain is the use of easy-care treatments in the finishing of garments and bedlinens. These reduce pollution by the consumer by up to 60 % because they improve ease of laundering (both in terms of reduced detergent and energy usage), but many green campaigners would wish to see them removed because they involve the use of formaldehyde. In conclusion, the protection of the environment is an issue for producer, consumer, legislator and regulator alike. It can only be effectively addressed if all participants understand all aspects of the problem and act in concert. Fortunately, there are forces in society which are driving environmental progress forwards within an acceptable economic framework and, hopefully, these will create abetter, more sustainable environment.

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DYESTUFFS, THE MYTHS EXPLODED, THE PROBLEMS AIRED Brian C Burdett

Introduction Colour sells merchandise, whether apparel, furnishings or household. To satisfy the public demand for this colour, an excess of some 700,000 tonnes of dyes are consumed annually [1]. Their application to textile materials is varied and, in may instances, not at all beneficial to the environment. Those of us who work in or are connected with, the colour using industries have a long way to go before we can say that we are satisfied with the environmental friendliness of our procedures. Of course, this is not to denigrate the changes that have already taken place through the excellent work of dye manufacturers, research organisations and universities. Reduction in liquor ratios and salt additions, the increasing use of pigments for printing, and the introduction of the ink jet TruColor system [2] are but a few examples of increasing changes to dye application technology. More changes are necessary and those changes must affect the whole of the life cycle of the product, from removing the cause of the pollution in the first place to enabling disposal to take place in a controlled environmental manner. What happens to all that tonnage of dye? Eventually the textile merchandise becomes the owner's waste. It is taken to landfill, or incinerated, or recycled or reclaimed. In all these instances, pressure is increasing for knowledge of the characteristics of the dyes used and their method of application, so that the disposal of the merchandise can be controlled to manage emissions to air or through ground leakage to sensitive areas such as groundwater or rivers. In fact landfill and dumping will not be tolerated in the future, not only from an ecological point of view, but also from an economical view. Disposal ecology, that is the disposal of textile products through recycling, re-use, non-hazardous decomposition, or safe burning without air pollution and with the recovery of energy, will become more and more significant issues in the life-cycle of any project. Safe Dyestuffs - Natural Dyes Unless there is a change in human behaviour, the demands for coloured textile merchandise will continue despite advertisements such as the example below, which was for duvet covers, bed sheets, pillowcases and bath robes: "Commitment to the environment comes in many forms. Processing cotton normally produces large amount of waste and pollution, By using 100% unbleached and undyed cotton in the manufacture, these environmentally damaging elements have been reduced. Consequently, chlorine, optical bleaching agents and formaldehyde are not present in the fabric making all these items ideal for use next to the skin" According to some evangelistic members of the public, including some in the textile and

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garment industries, synthetic dyes should be replaced by the classical, traditional natural dyes. "Natural" to these peoples equates with environmentally friendliness. Many, and in particular some environmental activists, have no conception of the problems involved in the commercial use of such dyes. There is no doubt that the use of natural dyes on a commercial scale is gradually increasing. There is no difficulty in accepting the challenge of a retailer selling merchandise dyed or printed with natural dyes. If the public wishes to purchase unlevel, lower fastness coloured textiles, that is their prerogative. What is of concern is the belief that the use of such dyes will solve all the environmental ills of the industry; the dyes are 'natural', so all is well. That kind of belief is due to ignorance, and those in the industry who disseminate information, or who describe themselves as scientists, must be held partly responsible. From personal experience, when explanations are given as to why there cannot be whole scale return to a previous technology, there are mixed reactions from incredulous disbelief to a genuine desire to be educated, and that is the key. Careful education is required by scientists and non-scientists alike. It is the responsibility of industry to maintain an awareness of the underlying chemistry of environmental issues and to promote such awareness. Of course, that is to assume that the audience has an appreciation of basic chemistry or at least basic general science. Again experience shows that this is not always true and the educational system must then examine its part.

Natural Dyes and the Environment Technologically, natural dyes may be classified as substantive or direct dyes, vat dyes or mordant dyes. Whereas some are obtained from animal sources, the majority are from vegetable sources. The extraction and application of many of these dyes is not only very time consuming, but also environmentally, not at all friendly. The production of Turkey Red dyeings and prints, based on the use of madder, probably represent the ultimate in length of procedure. Although the precise nature of the process has never been established beyond doubt, typically there were 5 or 6 separate stages, described as oiling, sumaching (tanning), mordanting, dyeing, and clearing [3], the whole process carried out after a lengthy extraction of the dye from the plant root. The plant tops were fed to cattle, which then produced milk of a reddish hue and butter that had a distinct bright yellow tinge; the roots produced red bones. Tyrian Purple is obtained from a family of carnivorous shell-fish, the most common of which is found in the Mediterranean, that is Murex Brandaris. Enormous numbers of shell-fish were necessary to yield a very small quantity of dye. According to one calculation, to obtain l.4g of the dye, about 12,000 shell-fish would have to be collected and crushed. If the dye was to be used for all present blue dyeings, let alone in mixtures with other natural dyes, it would result in some 200 square miles of land being deep in shells [1]. The extraction of the mucus from the appropriate gland and the application to textiles was not a clean job and ancient writers have described dyers' hands shining in brighter colours: nothing ever changes! The peculiarity of the dye, of spreading an unsavoury smell when exposed to the sun, and remains of countless shells, made the centres of trade places of unsavoury odour [4]. 166

Cochineal requires about 150,000 dried insects reared on cactus to produce about lkg of dye [3]. The female insects are collected in a cloth or bowl and immediately killed. This is carried out by means of a hot oven, steam, or hot water. Under these treatments the insect bursts and turns red and is then finally dried. Dyes from vegetable sources, including roots, do not offer any easier environmental alternatives. Glover and Pierce [1] have stated that in dyeing of wool, assuming an average depth of colour of 1.7%, some 43,000 tonnes of synthetic dyes are used. To replace the synthetic dyes with natural dyes, 15 million tonnes of fresh plants would be required. In the cotton sector, the analogous figures are even more dramatic. Taking the average depth of colour as 2 %, about 400,000 tonnes of synthetic dyes are used. The weight of fresh plants, from which it would be necessary to extract the natural product to replace the synthetic dyes, would be 176 million tonnes. To grow that amount of vegetable matter for subsequent dye extraction, at least 30 % of the world's agricultural land would be required. This is all in despite of anticipated R&D successes regarding extraction techniques of these natural products and concern to improve the environment with the wider use of natural dyes [5]. The sustained growth of some of the resources would present formidable challenges, such as the planting and management of Haematoxylon Campechanium which is the botanical name of the logwood tree, which reaches a height of over 15 meters. Furthermore, once grown, cut down, and treated to extract the colorant there would be a need to dispose of millions of tonnes of waste vegetable matter every year. Whilst the banning of natural dyes on a commercial basis is not being advocated, they should be considered only where they can be utilised for the benefit of the industry. For instance, despite comments above on the use of classical natural dyes, some very active work has been undertaken for a number of years at BTTG to develop, through fermentation procedures, microbially-derived anthraquinoid pigments in a high state of purity for commercial exploitation. The method of production removes the need to use environmentally polluting synthetic chemistry; modification of the pigments hy classical synthetic chemistry enables useful dyes to be produced, which can be applied by normal methods and which give fastness properties higher than the synthetically produced analogues and brighter colours on dyed materials. Modification of the parent pigment by biotransformation will be a future activity in this area.

Natural Dye Mordants - Metal Ions and Effluent The majority of natural dyes are mordant dyes; in other words they require to be applied in conjunction with a metal salt to assist in fixation and thereby achieve some degree of fastness. Even then the fastness obtained is generally not adequate for today's discerning public. Salts of tin, aluminium, iron, copper, zinc and chromium (VI) are necessary, not only for fastness requirements, but in many cases to achieve the correct colour of the final product. The majority of the application processes would not be allowed today because of their impact on the environment. Taking Glover and Pierce's data [1] a hypothetical dyeing process could give us a level of metal contamination in exhaust liquors, which would be over 1,000 times greater than that allowed by UK consent limits (see Table 1).

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Table 1:

Metal contents in exhaust liquors

Amount of metal present

Actual UK consent

Metal

(hypothetical) (mg/l)

(mg/l)

Al Cr(VI) Zn Cu Fe

340 100 200 260 480

2 0.5 10 2 10

1380

10

Total

The inclusion of heavy metals in the often lengthy application procedures is contrary to the current trend of reducing or even banning, the use of such metals. As we have come to expect in this complex area, different approaches are being taken to reduce the impact of heavy metals on the environment. With pollution, and waste and recycling in mind, the members of the carpet ecolabelling scheme, GuT, gemeinschaft unweltfreundlicher Teppichboden EV, have voluntarily banned the use of metal-complex dyes on certain nylon carpet products as from January 1996. As from January 1998, this ban will be extended to all nylon products and, it is thought, during the remaining part of this century, the extension of the ban may occur to include all nylon and wool carpets. To emphasise the significance of the ban, there are 85 carpet manufacturers who are members of GuT and who produce between them over 75 % of carpets manufactured in Western Europe. As a check on the toxicity of the final coloured article, the Oko-tex ecolabelling scheme carries out an assessment of the extractable heavy metals from dyed or printed apparel The American Textile Manufacturers Institute (ATMI) is carrying out a study of the toxicity of metals present in textile effluents and has asked the European textile industry to participate.

Toxicity of Dyestuffs

Are dyes toxic? The normal reaction is to assume that the dyes commercially available are not toxic. Whereas it is known that three dyes are carcinogenic by themselves (see Table 2), and some are described -as allergenic (see Table 3), all new dyes undergo a stringent programme of auxocyte tests before being released on to the market.

168

Table 2: Carcenogenic dyes Acid Red 26 Basic Red 9 Disperse Blue 1

Table 3: Allergenic dyes Disperse Disperse Disperse Disperse Disperse Disperse Disperse Disperse

Red 1 Red 17 Orange 3 Yellow 3 Blue 1 Blue 3 Blue 106 Blue 124

However, when dyes are digested and broken down by the metabolic system, the breakdown products may be harmful.

The Case of Azo Dyes A regulation of July 1994 emanating from Germany bans certain consumer goods containing azo dyes, which on cleavage of one or more azo groups, form any of twenty listed aromatic amines as shown in Table 4. These amines are currently classified by the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) as Group III Al or III A2 carcinogens, that is, substances that have been unequivocally proved to be carcinogenic according to the Commission. The regulation has had a substantial impact internationally on consumer industries, especially in textiles and leather goods, because the ban concerns goods that remain in direct body contact for an extended period of time and includes clothing, bed linen and shoes. The difficulties are compounded by the lack of a validated analytical method for the examination of finished merchandise. Experience by test laboratories indicated that the methods currently used can give spurious results. Although many dye manufacturers, particularly those who are members of ETAD, Ecological and Toxicological Association of Dyes and Organic Pigment Manufacturers, no longer manufacture or sell azo dyes affected by this Regulation, there are some exceptions.

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Table 4: Carcinogenic amines

MAK Group III Al 4-Aminodiphenyl Benzidine 2-Amino-5-chlorotoluene 2-Aminonaphthalene MAK Group III A2 2-aminoazotoluene

2-Methoxy-5-methylaniline

2-amino-4-nitrotoluene

3,3' -Dimethyl-4' 4-diamino-diphenylmethane

4-Chloroaniline

4,4' -Meth ylene-bis(2-chloroaniline)

2,4-Diaminoanisole

4,4' -Oxydianiline

4,4' -Diaminodiphenylmethane

4,4' -Thiodianiline

3,3' -Dichlorobenzidine

2-Aminotol uene

3,3' -Dimethoxybenzidine

2,4-Diaminotoluene

3,3' -Dimethylbenzidine

2,4,5-Trimethylaniline

Ecolabelling schemes, such as Oko-tex and GuT, have already adopted the same list of 20 amines, and dyes which give rise to the amines are not to be used on textile materials if application is made for one of the respective Certificated and Logos. However, despite the legal requirement of the German regulation, and the commercial enforcement of the ecolabelling schemes, there is no official list of dyes to be banned. To determine whether or not a particular dye will be affected by the ban, it is essential to make contact with the manufacturer.

The Need for Chemical Understanding When exhaust dye liquors are treated in the normal course of effluent control, are we obtaining toxic breakdown products or is the parent dye, although visually abhorrent, any less or more toxic? The emphasis is on removing the colour by means of chemical attack, rather than removing the parent coloured dye molecule. What of the reactive dyes that get through the system? As this is the main environmental challenge facing the UK textile dyeing and finishing industry [6], many organisations are developing means of decolourising these dyes.

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One particular research activity, a joint collaboration between BTTG and Leeds University, suggests that it is possible to attack such dye liquors with a soup of enzymes and, overnight in a batchwise situation, to obtain decolourised products. Again, what are the products? The bacterial soup may be natural, but that does not mean that the breakdown products are any safer. It is necessary to understand the underlying chemistry and to identify the products generated and to assess the environmental risks. In an endeavour to understand some underlying chemistry, structure/carcinogenic relationships of dyes and their intermediates are being studied at the North Carolina State University [7]. On a world-wide basis environmental practices differ, and there is no such thing as "a level playing field" for efficient environmental management. Exploitation of this state of affairs will continue where environmental costs are lower. How many importers and merchants know how their merchandise has been processed, or what dyes and chemicals are on the goods? Ecolabelling protocols are certainly awakening the minds of many in the textile chain to these questions, whether the goods have been coloured with synthetic or natural dyes. References 1.

B Glover and J H Pierce, JSDC, 109, 1993,5

2.

J R Easton and J R Provost, International Dyer, September 1993

3.

Ciba Review No.7, 1938

4.

Ciba Review No.4, 1937

5.

Syed Ishrat Ali, JSDC, 109, 1993, 13

6.

I Holme and A Thornton, International Dyer, January 1994

7.

H S Freeman et aI., Chemtech, July 1991, 439

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I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

ENVIRONMENTAL HUSBANDRY Simon Kent

Introduction With privatisation of the water authorities legislation in the UK, and EEC harmonisation, political issues such as the "Green Vote", pollution and the environment have become an increasingly important. In addition, retailing chains are demanding that their suppliers demonstrate that their practices are environmentally acceptable. Marketing will dominate the companies of the future and decisions on whether to manufacture or purchase will necessitate the drawing up of environmental specifications as well as physical specifications; hence companies should look to the creation of new processes which are environmentally friendly. Companies have to respond to the challenges of maintaining growth, improved flexibility and optimisation of cost and efficiency but should seek the solutions to environmental issues and their impact on a broad basis, ie. atmosphere, pollution, dust effluent and noise. An Environmental Strategy But where can a start be made? - what with "red lists, black lists, PCP'S, BOD, VOC, CFC'S to be phased out by 1997 and 1, 1, 1, trichloroethane by the year 2005," it all seems confusing and becomes a balancing act of meeting deadlines on an important order and keeping within budgeted costs. Environmental issues easily get pushed to the back of the queue. At Parkland Manufacturing, the impact on the business of addressing environmental issues was considered. All sectors of the business compete for a finite resource - capital. This factor helped focus our minds on the objectives we could achieve. The first step was to develop an environmental strategy which itemised the following actions:(i)

Find out what the law requires. A copy of the Environmental Act 1990 is a start.

(ii)

Find a partner - a problem shared is a problem halved. Someone who can help, for example The Confederation of British Wool Textile Manufacturers, The Department of Trade and Industry, Her Majesty's Inspectorate of Pollution, dyestuff companies, research organisations, local authorities, universities and water authorities with their new business account managers - they really are very approachable, and tend to be proactive rather than reactive in their attitude.

(iii)

Designate a person who is responsible for environmental matters and develop a policy. 173

(iv)

Carry out an audit of raw materials, processes and producers with regard to their impact on the environment.

(v)

Carry out an environmental survey covering such items as water effluent, noise, dust and atmospheric pollution.

(vi)

Make provision for emergency contingency plans.

(vii)

Consider staff training.

(viii)

Consider insurance implications.

(ix)

Consider grants.

(x)

Make provision for resources for manpower and capital.

(xi)

Ensure the medium and long term stability of the company whilst maintaining a competitive edge and an excellent public image.

(xii)

Review the situation every two years.

It soon became very clear that the Company had to apply the same cost justifications to the management of environmental issues as many other aspects of the business. Thus it was essential to define objectives necessary to maintain a competitive edge whilst reducing the environmental impact.

Examination must occur of the systems which provide management solutions such as ecoauditing and eco-design, quality and environmental standards such as BS5750 and BS7750 respectively, life cycle analysis and waste minimisation. It is only waste minimisation however, which will provide any pay-back. Waste arises at every link in the manufacturing chain. Therefore, the question of spending capital on monitoring is of importance when analysis of the overall scenario and focusing on waste minimisation is the key to the problem. The need for an integrated approach is required; tighter controls on the generating and disposal of waste are the springboard for reassessing and minimising waste. Thus the following ideas were considered:Elimination Source Reduction Recycling Treatment and disposal each of which is analysed in more detail below and when put into practice, have cost little to implement and all have showed significant savings.

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Elimination It became evident 2 years ago that solvent processing would become increasingly unable to meet developing legislation. At the same time, our solvent dry-cleaning machine was nearing the end of its safe useful working life and a solution had to be found. Thus the question of whether solvent processing was required was asked. All stages of manufacture were examined and those areas were identified which required changing if solvent cleaning had to be eliminated. Three main areas were identified as the main sources for the need to dry clean:(i)

Mineral oils used in lubrication of the looms

(ii)

Paraffin waxes used in weaving

(iii)

General housekeeping

The mineral oils were substituted by water-soluble oils. The paraffin waxes were substituted by stearate-based water soluble products, and the level of housekeeping elevated to a much higher plane. Biodegradable blends of soap and detergents were successfully developed for scouring the Company's products and within a year the old process was phased out with no added expense, and indeed substantial savings have been made of the order of £33,000 p.a.

Source Reduction It has been established by many water authorities that certain banned substances were appearing in the effluent much to the annoyance of companies that were not using these same substances. It was found that these chemical contaminants were being applied by suppliers of yarn and fal}ric from countries where legislation did not exist or was ignored.

The problem was tackled by asking all suppliers not to supply goods which contain any of these banned substances. A comprehensive and detailed list was drawn up and forwarded to all suppliers with a statement that should any of the banned compounds be found, the goods would be returned or the suppliers would be charged with the safe removal of such substances. This policy has been running for at least three and a half years with no breach infringements to date, and costs of such implementation were minimal. Thus, a simple letter to all suppliers has potentially saved thousands of pounds should the company have been found to be in contravention of environmental legislation. Another source reduction was considered when dyeing and finishing units were amalgamated onto the one site. In principle, the Company wanted to double the capacity but still remain within the effluent consent limits imposed by the local water authority. Scenarios like this certainly help concentrate the mind.

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New continuous aqueous scouring had already been established as one way forward but greater machine utilisation was the key, especially in piece (individual garment) dyeing, and blind (i.e. without undertaking a trial dyeing techniques were introduced over a period of time. As a result, over a period of three years, production was doubled with only a marginal increase in effluent costs. All this was in addition to energy savings derived from a consideration of water usage and its minimisation.

A Combination of Source Reduction Culminating in Eliminisation Heavy metals in the form of chromium, for example, present an ever increasing threat to all wool dyers. Each year, tighter and tighter discharge limits are imposed. Parkland Manufacturing has endeavoured to take a proactive approach by considering future legislation and plotting a particular course of action which will help meet that legislation before or on the due date. The first step was to audit the dyeing processes and identify all four chrome-dyeing processes. After this, a reduced chrome technique was initiated as outlined by The International Wool Secretariat (IWS). The second stage was to replace as many chrome-dyed recipes with 1: 1 and 1:2 metal complex dyes thus reducing further the amount of chromium present in liquors. By following this path, the legislation limits were just met whilst managing to maintain and keep within the budgeted costs. A third stage is to look at yet further reductions and hopefully the elimination of chromium. Early trials look promising. The dyes used are expensive but it is hoped that the reduced dyeing times and energy costs coupled with improved quality will make it a feasible proposition. Energy Efficiency

Energy efficiency is yet another element to be carefully considered in the quest for improved environmental husbandry. It is claimed that up to twenty percent of energy can be saved immediately by following an energy conservation programme. The Company, therefore considered the following: (i)

The undertaking of an energy audit

(ii)

The monitoring of energy consumption

(iii)

Maintenance and housekeeping to make sure all energy processes are fully maintained and operated correctly.

(iv)

Measurement and analysis of the material and energy flows.

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(v)

Implementations of best cost saving options.

(vi)

Monitoring improvements by monitoring fuel consumption.

Thus energy savings are there for the taking when applying blind-dyeing techniques, and the same is true of optimisation of processes in general. Some three years ago, work began on implementing a system which would have a major controlling influence on the reproducibility of the Company's bulk production from initial trials. The system involved objectively measuring the finished product with the system, FAST - fabric assurance by sample testing. This comprises a series of three test machines and one test method which objectively measures the tailoring characteristics of finished fabric. The system enabled the Company to optimise its processes by reducing unnecessary and wasteful manufacturing routines and thereby save energy. Over a period of twelve months a reduction from 27 options down to 3 on one machine alone and an overall reduction of routines by at least 50 % has been achieved. The value of objective measurement becomes a useful tool in the environmental arsenal thus enabling energy and unit costs to fall while helping to promote and maintain best environmental and cost efficient practices. Recycling

Considerations were given to recycling when the Company was involved in the mothproofing of particular top-dyed fabrics. The legislation and consent limits with regard to the discharge of mothproofing agents are particularly demanding and there is a wish not to contravene this legislation. Consultations began in earnest with the dyestuff and chemical industry along with IWS. A product was selected which was the least harmful to aquatic life but conventional means of application would result in a breach of this consent limit. A pad impregnator was chosen as the best means of application. However, there was no control over the discharge so it was decided to build a mixing tank with metered water and temperature control along with a closed loop system allowing the mothproofing liquor to be mixed and added to the pad bath. A simple ball-cock mechanism maintained the correct level and a series of pipes flowing back to the tank allowed for recycling of the liquors. If the pad was to be used for something else the liquors were drained off into containers and stored ready for re-use. Finally, when the mothproofing is completed or the liquors can no longer be used because of contamination, they are drained off into a container. Small quantities of diluted liquor are then added to wool dye batches and exhausted on to the fibre over a period of time. This will not totally remove all mothproofing agents but will vastly reduce and keep effluents within consent limits. The main point to be stressed is that by adopting a waste minimisation policy, namely recycling of the mothproofing liquor, it paid for the mixing tank and closed loop system within one month and went on subsequently to save 25 % of the cost of the mothproofing agent. 177

Treatment and Disposal For some time the Company had a slight pH problem with its effluent and, as consent limits were to be tightened, it was decided to tackle the problem. It is not surprising for a wool dyehouse that the pH was, on occasions, on the acid side of the consent limits. At the same time there was a need to improve the handle of all wool-based products and so rather than incorporate expensive dosing systems, it was decided to investigate the use of slightly alkaline scouring chemicals. Mixing the alkaline scouring liquors with the acidic dyehouse liquors thereby neutralised the acidity and addressed the pH problem. Products were experimented with and the mixing of the effluent implemented, resulting in complete success. Additional gains were that considerable savings were made by looking closely at scouring chemicals and reducing them from six down to two types. Economies of scale resulted in savings of £12,000 pa. The final bonus was that not only had an environmental problem been addressed with some reduction in cost, but a much improved product handle was gained.

Summary This paper has attempted to give some useful pointers on a most fascinating subject with the old adage "prevention is better than cure". It is true today as it has ever been that environmental issues are no longer a passing fancy and, if not acted upon, will become missed opportunities. The main points are: Control the inputs, Control the process, Control the outputs and solutions come in many guises. Development of an integrated approach will ensure a tangible impact on the company's performance. There is no doubt that environmental husbandry is here to stay and will become an everincreasing management discipline in the furtherance of profitable and environmentally friendly manufacturing.

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Recycling Textile and Plastic Waste This text contains nineteen edited papers originally presented at the first major conference on the environmental aspects of the textile and related plastics industries 'Wealth from Waste in Textiles'. Both industries must increasingly be able to demonstrate environmentally acceptable practices while working within a framework of economic viability. Thus they must be able to make products which consumers will buy based on both price and ecological factors. The selected papers initially overview the magnitude and consequences of excessive waste production, then proceed to discuss waste minimisation strategies and practices, focus on selected areas where recent scientific and technological advances have been made and finally set the problem within the context of current public perceptions, politics and regulations. The conference was organised jointly by Bolton Institute and the British Textile Technology Group with support from the Textile Institute and the Department of Trade and Industry.

Woodhead Publishing Ltd Abington Hall Abington Cambridge CB21 6AH ISBN-13: 978-1-85573-306-0 England ISBN-10: 1-85573-306-4 www.woodheadpublishing.com