Contents
Preface i
1. Textile industry: An overview 1
1.1 Introduction 1
1.2 Textile manufacturing processes 1
1.3 Preparation of fibre 2
1.4 Spinning – conversion of fibre into yarn 2
2. Textile industry and its impact on environment 11
2.1 Introduction 11
2.2 Components of textile industry 11
2.3 Pollution aspects of textile industry 12
2.4 Processes involved 17
2.5 Waste stream 17
2.6 Some facts regarding environmental issues 18
2.7 Wastes generated 18
2.8 Pollution from areas other than chemical processing 20
2.9 Pollutants involved in the wet processing 22
2.10 Solution to environmental problems 23
3. Bioprocessing of textiles 29
3.1 Introduction 29
3.2 Role of enzymes in textile processing 30
3.3 Classification of enzymes 31
3.4 Enzyme applications in textile preparatory process 33
3.5 Silent features of enzymes application in textile processing 39
4. Enzymatic treatment of wastewater containing dyestuffs 41
4.1 Introduction 41
4.2 Need for dye removal from effluents 41
4.3 Conventional processes for removal of dyes from effluent streams 42
4.4 Enzymes in wastewater treatment 43
4.5 Delivery systems for enzymes in effluent treatment 45
5. Degradation of toxic dyes 51
5.1 Introduction 51
5.2 Various types of dyes 52
5.3 Methods of decolouration of dyes 53
6. Biological methods of removal of dyes from textile effluents 65
6.1 Introduction 65
6.2 Methods for textile dye removal 66
7. Water conservation in textile industry 73
7.1 Introduction 73
7.2 Water usage 73
7.3 Modern technologies can save water in textile industry 82
8. Noise pollution and its control in textile industry 85
8.1 Introduction 85
8.2 Noise sources 85
8.3 Industrial noise sources 86
8.4 Control of noise pollution 89
8.5 Techniques for reducing textile machinery noise 91
8.6 Lead-loaded fabrics 98
8.7 Control of noise in pumps and valves 103
8.8 Management of noise pollution control 108
8.9 Case study: Noise control in textile industry 111
9. Recovery of dyes and chromium from textile industry 119
9.1 Introduction 119
9.2 PVA recovery 120
9.3 Caustic recovery 120
9.4 Indigo recovery 121
9.5 Efficient methods for the removal of chromium
from textile effluents 127
10. Zero liquid discharge in textile industry 133
10.1 Introduction 133
10.2 Highlights of ZLD in textile sector 133
10.3 Promoting zero liquid discharge to Indian textile industry 134
10.4 Benefits and challenges facing the ZLD mandate in indian textile sector 135
10.5 Factors to be considered in framing policies for ZLD 136
10.6 Indian policy experience for promoting ZLD in the textile sector 139
10.7 Zero liquid discharge in dyes and dye intermediates 142
10.8 Problems of textile processing units in installation of ZLD 144
10.9 Way ahead 146
11. Hazards, risks and safety in textile industry 149
11.1 Introduction 149
11.2 Typical processes in textile finishing 149
11.3 Chemical hazards 151
11.4 Chemical safety programme 154
11.5 Risk assessment 155
11.6 Safety measures 157
11.7 Emergency preparedness 163
12. Cellulosic fibres (viscose, acetate and cuprammonium rayon) 165
12.1 Introduction 165
12.2 Manufacture of viscose, acetate and cuprammonium rayon 166
12.3 Polyester fibre 170
12.4 Wool 171
12.5 Rayon wastes treatment in U.S. and Germany 173
12.6 Treatment and disposal of fibre wastes 175
12.7 Treatment and reuse of wastewater from polyester dyeing houses 180
12.8 Application of enzymes for textile fibres processing 181
13. Pollution prevention in jute industry 197
13.1 Introduction 197
13.2 Jute fibre 197
13.3 Manufacturing aspects of jute 198
13.4 Pollution aspects in jute mills 203
13.5 Jute retting 210
13.6 Minimal national standards (MINAS) 213
14. Textile effluent testing 215
14.1 Introduction 215
14.2 Analysis of samples 215
15. Carbon footprint in textile industry 223
15.1 Introduction 223
15.2 Reducing of carbon foot print 224
15.3 Machinery/equipment related 226
15.4 Sustainability of textiles 227
15.5 Creating new green paradigm 232
15.6 Creating a carbon free environment 234
15.7 LCA, carbon footprint and ecological footprint 237
16. Energy conservation in textile industry 239
16.1 Introduction 239
16.2 Energy consumption in textile industry 239
16.3 Waste heat recovery in textile industries 240
16.4 Cost effectiveness in textile processing 248
16.5 Good housekeeping 256
17. Wastes minimisation in textile industry 261
17.1 Introduction 261
17.2 Yarn realisation 261
17.3 Waste control in spinning mill 268
17.4 Waste investigation 269
17.5 Waste reduction and control 273
17.6 Fibre waste recycling and its future 275
17.7 Managing waste in the textiles manufacturing industry 283
17.8 Textile waste minimisation 286
17.9 Trends and future applications 293
18. Nanotechnology in textile industry 295
18.1 Introduction 295
18.2 Definitions of nanotechnology 295
18.3 Nanomaterials 296
18.4 Nanotechnology in the textile industry 296
18.5 Quality label for nanotechnology 298
18.6 Application of nanotechnology in textile industry 299
19. Nanotechnology for removal of dyes and effluents 305
19.1 Introduction 305
19.2 Removal of azo dyes by nanotechnology 307
19.3 Nano-silica-silver composite material for removal
of textile effluents and dyes 319
Reference 321
Index 323
Preface
The textile industry is a significant contributor to many national economies, encompassing both small and large-scale operations worldwide. In terms of its output or production and employment, the textile industry is one of the largest industries in the world.
Textile processing industry is characterised not only by the large volume of water required for various unit operations, but also by the variety of chemicals used for various processes. There is a long sequence of wet processing stages requiring input of water, chemical and energy and generating wastes at each stage. Textile processing generates many waste streams, including liquid, gaseous and solid wastes, some of which may be hazardous. The nature of the waste generated depends on the type of textile facility, the processes and technologies being operated, and the types of fibres and chemicals used.
The main environmental problems associated with textile industry are typically those associated with water body pollution caused by the discharge of untreated effluents. Other environmental issues of equal importance are air emission, notably volatile organic compounds (VOC)’s and excessive noise or odour as well as workspace safety.
This book on pollution control in textile industry summarises various aspects of pollution control and is divided into 19 chapters.
Chapter 1 concentrates on textile industry: an overview. Chapter 2 is devoted to textile industry and its impact on environment. The impact of textile production on the environmental aspects is related to air, water, land and poor unhygienic working conditions. Chapter 3 focuses on bioprocessing of textiles. Bioprocessing is the application of biological organisms, systems or processes to manufacturing industries. Chapter 4 deals with enzymatic treatment of wastewater containing dyestuffs. Enzymes play an important role in removal of dyes and other effluents from textile industry. Chapter 5 focuses on degradation of toxic dyes. Various methods of degradation of dyes by fungi, algae, yeast and bacteria are discussed. Chapter 6 deals with biological methods of removal of dyes from textile effluents. Various methods such as biological, physical and chemicals for removal of dyes from textile effluents are discussed.
Chapter 7 concentrates on water conservation in textile industry. Water conservation and reuse can have tremendous benefits through decreased costs of purchased water and reduces costs for treatment of wastewaters. Chapter 8 focuses on noise pollution and its control in textile industry. Noise may be defined as an ‘unwanted sound’ and noise pollution as unwanted sound dumped into the atmosphere without any regard to its adverse affects. Chapter 9 deals with recovery of dyes and chromium from textile industry. Various methods for recovery of chemicals, PVA, caustic soda, solvents and chromium are discussed. Chapter 10 is devoted to zero liquid discharge in textile industry. Zero liquid discharge is a process that is beneficial to industrial and municipal organisations as well as the environment because it saves money and no effluent, or discharge, is left over.
Chapter 11 concentrates on hazards, risks and safety in textile industry. The chapter provides safety aspects of employees engaged in various operations of textile processing. Chapter 12 focuses on cellulosic fibres (viscose, acetate and cuprammonium rayon). The chapter discusses manufacturing aspects of various rayons, effluents generated (liquid and gaseous) and their treatment and disposal. Chapter 13 deals with pollution prevention in jute industry. Chapter discusses various pollution aspects in jute mills and methods of treatment of wastes. Chapter 14 is devoted to textile effluent testing. Various methods of testing of effluents are discussed.
Chapter 15 concentrates on carbon footprint in textile industry. Carbon foot print can be described as the extent of damage caused to the environment due to some actions. It is the measure of severity of our activities on the environment, especially on the climate change.
Chapter 16 focuses on energy conservation in textile industry. In general, energy in the textile industry is mostly used in the forms of: electricity, as a common power source for machinery, cooling and temperature control systems, lighting, office equipment, etc. Chapter 17 is devoted to wastes minimisation in textile industry. Waste minimisation refers to the use of source reduction and/or environmentally sound recycling methods prior to energy recovery, treatment, or disposal of wastes.
Chapter 18 deals with nanotechnology in textile industry. Nanotechnology by conventional methods can impart certain properties to textile materials. There is no doubt that in the next few years, nanotechnology will penetrate into every area of textile industry. Chapter 19 concentrates on nanotechnology for removal of dyes and effluents. This chapter discusses the removal of azo dyes and others effluents by nanomicrobiology, surface engineered nanoparticles, and nanophotocatalyst.
Such wide coverage makes this book a treatise on the subject. Diagrams, figures, tables and index supplement the text. All topics have been covered in a cogent and lucid style to help the reader grasp the information quickly and easily.
This book could not have been completed without the help of Mr Aman Bhatia (my nephew) who worked hard in locating and organising the material and spent many hours checking the manuscript. Appreciations are also extended to Mr Harinder Singh, Senior DTP operator, who drew and labelled the flow diagrams and worked long hours to bring the book on time. I am also thankful to the editorial team of Woodhead Publishing India Pvt. for their wholehearted cooperation in bringing out the book in time.
It may not be wrong to hold that this book on Pollution control in textile industry is essential reading for professionals and Technocrats. Besides students, this book will prove useful to industrialists and consultants in the respective fields.
It has been prepared with meticulous care, aiming at making the book errorfree. Constructive suggestions are always welcome from users of this book.