Contents
Contributor contact details ix
Introduction xi
1 European legislation relating to textile dyeing 1
T. CATTOOR, Centexbel, Belgium
1.1 Introduction 1
1.2 Legislation relating to textile dyeing in Europe 2
1.3 Integrated pollution prevention and control (IPPC) 3
1.4 EU legislation on chemical substances 8
1.5 EU legislation on water quality 16
1.6 EU legislation on air pollution 23
1.7 Future trends 25
1.8 Sources of further information and advice 27
1.9 References 28
2 Environmental legislation USA 30
H. A. BOYTER, Institute of Textile Technology, USA
2.1 Introduction 30
2.2 Current regulations 31
2.3 Toxic Release Inventory and Right-To-Know 31
2.4 Waste 33
2.5 Wastewater and water 33
2.6 Air 34
2.7 The Toxic Substances Control Act 36
2.8 California 36
2.9 Future trends 37
2.10 Sources of further information and advice 41
2.11 References 42
3 Toxicology of textile dyes 44
P. GREGORY, Avecia, UK
3.1 Introduction 44
3.2 Historical aspects 45
3.3 Acute toxicity of textile dyes 46
3.4 Chronic toxicity of textile dyes 49
3.5 Future trends 69
3.6 Sources of further information and advice 70
3.7 References 71
4 Environmentally responsible dye application 74
M. BIDE, University of Rhode Island, USA
4.1 Introduction 74
4.2 Background and scope 76
4.3 The influence of environment on the dyer’s task 76
4.4 General comments 79
4.5 Preparation 82
4.6 Dyeing, fibre by fibre 83
4.7 Textile printing 87
4.8 Conclusions 88
4.9 References 89
5 Supercritical fluid textile dyeing technology 93
E. BACH and E. SCHOLLMEYER, Deutsches Textilforschungszentrum
Nord-West, Germany
5.1 Introduction 93
5.2 History of supercritical fluid dyeing 96
5.3 Current supercritical fluid dyeing technologies 98
5.4 Future trends in supercritical fluid dyeing technologies 108
5.5 Sources of further information and advice 110
5.6 Acknowledgements 110
5.7 References 111
6 Pollution abatement and waste minimisation in textile dyeing 116
S. R. SHUKLA, Mumbai University Institute of Chemical
Technology, India
6.1 Introduction 116
6.2 Reducing pollution in textile dyeing 118
6.3 Waste minimisation in textile dyeing 133
6.4 Future trends 138
6.5 Sources of further information and advice 140
6.6 References 144
7 Decolorisation of effluent with ozone and re-use of spent dyebath 149
M. M. HASSAN, AgResearch Ltd, New Zealand and
C. J. HAWKYARD, University of Manchester, UK
7.1 Introduction 149
7.2 Decolorisation mechanisms with ozone and ozone-based AOPs 166
7.3 Decolorisation by ozonation 172
7.4 Reuse of spent dyebath 176
7.5 Future trends 181
7.6 References 183
8 Chemical treatment of textile dye effluent 191
I. R. HARDIN, University of Georgia, USA
8.1 Introduction 191
8.2 Colour 191
8.3 Dyes 192
8.4 Classes of dye 192
8.5 Measurement of colour removal 195
8.6 Other measures of dye molecule fate 196
8.7 Chemical methods for colour removal 197
8.8 Conclusions 208
8.9 References 208
9 Biotechnological treatment of textile dye effluent 212
A. KANDELBAUER, University of Natural Resources and Applied Life
Sciences, Austria; A. CAVACO-PAULO, University of Minho, Portugal
and G. M. GÜBITZ, Graz University of Technology, Austria
9.1 Introduction 212
9.2 Biotechnology and dye effluent treatment 212
9.3 Future trends 224
9.4 References 225
Index 233
Introduction
In recent decades, society has become increasingly concerned with protection of the environment. Major issues which are under constant debate include the destruction of rainforests, global warming and the depletion of the ozone layer. The textile dyeing industry faces the need to address its responsibility towards a wide range of health, safety and environmental issues, some of which are generic to the industry and some specific to the processes operating in particular cases. Indeed, these issues increasingly present the industry with some of its most significant challenges. This book is therefore timely in that it presents a review of the most important environmental issues currently facing the textile dyeing industry, and of the ways in which these issues may be addressed. For this purpose, an impressive range of authors has been assembled who are from prestigious organisations throughout Europe, USA, Australasia and Asia and are acknowledged as international experts in their field. They have contributed the chapters which bring together the variety of topics addressed in the book, selected to give as broad coverage of the issues as possible. Nevertheless, the text cannot claim to be completely comprehensive because the range of individual issues is immense, for example due to the diversity of chemical types of dyes and auxiliary chemicals used and of the application processes, and to the complexities of the relevant legislation throughout the world.
The industry is challenged by the requirement to satisfy the demands of increasingly stringent legislation and controls introduced by governments and regulatory agencies to ensure compliance with environmental issues. A significant source of complexity is the fact that the requirements vary substantially, in detail and in severity, around the world. The first chapter of this book (Cattoor) deals with European Union legislation and policy in general, and in relation specifically to environmental aspects of textile processing, with particular regard to emissions to water and air. A further complexity when dealing with legislation is its constant evolution, so that it is inevitable that some information presented will eventually become out of date. At the time of publication, the European Union is about to implement the REACH proposal as outlined in Chapter 1. The introduction of REACH, which places greater responsibility on the industry chain to manage the risk from chemicals and to provide safety information, is likely to have a significant impact on the textile industry. Chapter 2 (Boyter) reviews the comparable relevant Federal and state legislative situation in the USA and also speculates on future trends, including the impact of the imminent changes in Europe.
The importance of being aware of the potential adverse effects of exposure to chemicals on our health is self-evident. The textile dyeing industry has a clear duty to address risks arising from the materials it uses and produces, in relation to its workforce, the general public and the broader effect on the environment. The level of risk from exposure to potentially dangerous chemicals is clearly of prime concern for those handling materials in large quantities in the workplace. Modern work practices have been adopted to minimise such exposure. The approach towards addressing exposure to chemicals, which has been adopted in most countries, involves a risk evaluation, involving assessment of the toxicological hazards and exposure levels, and from this the development of risk management strategies. Chapter 3 (Gregory) deals with the toxicology of textile dyes. The chapter provides an introduction to the historical development of our knowledge of toxicological issues associated with the dyes, their intermediates and metabolites, and leads into a review of current understanding of the relationships between dye structures and their toxicology, with reference to the appropriate chemical and biochemical mechanisms.
Concern about the potential adverse effects of industry on the environment is global, although it is an escapable fact that the response in some parts of the world has been much faster and more intense than in others. Chapters 4– 6 cover a series of issues of importance to the textile dyeing industry with regard to its responsibility towards the environment. Chapter 4 (Bide) is of central importance to this book in that it deals, in general terms, with the principles of the ways in which the application of dyes to textiles can be carried out with due regard to environmental responsibility. Chapter 5 (Bach and Schollmeyer) is of special current interest in that it reviews the state of the art on the development of textile dyeing processes using supercritical fluids, notably carbon dioxide. Although not as yet exploited on an industrial scale, this technology offers significant potential environmental advantages over traditional dyeing methods, as discussed in detail in the chapter. Textile dyes are, by definition, highly visible materials. Even minor releases of colour into the environment, for example into open waters, understandably attracts the critical attention of the public and local authorities. There is thus a requirement on industry to minimise environmental release of colour, even in cases where a small but visible release might be considered as rather innocuous. The most likely source of colour release results from incomplete dyebath exhaustion, and the need to reduce the amount of residual dye in effluent has become a major concern. While this applies in principle to all application classes of dyes, the particular case of reactive dyes is of special importance because of the problem of accompanying dye hydrolysis, the hydrolysed dye inevitably appearing in the effluent. Chapter 6 (Shukla) focuses on the sources of pollution from textile dyeing processes, not only from the dyes themselves but also from the wide range of auxiliary chemicals used. The principles of the methods used to minimise pollution and waste in dyeing are also discussed.
An alternative approach to addressing the problem of colour in textile dyeing effluent has involved the development of effluent treatment methods to remove colour and these are discussed in Chapters 7–9. These methods can be effective but inevitably add to the cost of the overall process. Chapter 7 (Hassan and Hawkyard) provides an overview of the range of methods for dye effluent decolorisation, categorised as either physical, chemical or biological, with special emphasis on the use of ozone which is emerging as one of the most effective chemical treatments. The chapter also deals with recycling issues in terms of the re-use of spent dyebath. Chapter 8 (Hardin) is complementary to the previous chapter in providing a broader overview of the range of chemical treatment methods for colour removal, including coagulation methods, electrochemical methods and oxidative degradation. Biotechnological approaches to effluent treatment make use of the ability of living organisms to bind or degrade colour and these are dealt with in Chapter 9 (Kandelbauer, Cavaco-Paulo and Gübitz). Biodegradation processes offer the particular attraction of the potential for the decoloration of effluent with complete mineralisation of the organic materials present to relatively innocuous materials – carbon dioxide, water and inorganic ions such as nitrate, sulphate and chloride.
Environmental arguments are highly emotive. There are many reasons why the public has become sensitive to environmental issues and, to an extent, suspicious of industry attitudes. However, the point of view is often expressed that the pendulum may have swung to the opposite extreme, and that arguments based on perception are over-emphasised in comparison with those based on real scientific evidence. We should not lose sight of the fact that the principal reason for the existence of the coloration industry is that it positively enhances our environment, by bringing attractive colours into our lives. Equally, it is vital that the industry sector involved in the application of dyes should continue to be sensitive to potential adverse effects on the environment in its widest sense, and respond accordingly.