Characterization and Treatment of Textile Wastewater | Himanshu Patel and R.T. Vashi


Characterization and Treatment of Textile Wastewater
By Himanshu Patel and R.T. Vashi

Characterization and Treatment of Textile Wastewater

Acknowledgment vii
1. Introduction 1
List of Figure 2
List of Tables 2
1.1 Current Scenario of Environment 2
1.2 General Processes in Dyeing Industry 5
1.3 Sources of Wastewater 8
1.4 Characteristics of Wastewater 9
1.5 Treatment of Wastewater 10
1.6 Remedial Measures 16
1.7 Effect of Wastes 17
References 18
2. Characterization of Textile Wastewater 21
List of Tables 24
2.1 Methods 25
2.2 Collection and Preservation of Samples 25
2.3 Characterization 66
References 70
3. Feasibility of Naturally Prepared Adsorbent 73
List of Figures 74
List of Tables 74
3.1 Introduction 75
3.2 Materials and Methods 89
3.3 Results and Discussion 93
3.4 Conclusion 98
References 99
4. Batch Adsorption Treatment of Textile Wastewater 111
List of Figures 111
List of Tables 112
4.1 Introduction 112
4.2 Experiments 112
4.3 Results and Discussion 113
4.4 Conclusion 125
5. Fixed-Bed Column Studies of Dyeing Mill Wastewater
Treatment Using Naturally Prepared Adsorbents 127
List of Figures 127
List of Tables 128
5.1 Introduction 128
5.2 Experiments 131
5.3 Results and Discussion 132
5.4 Conclusion 143
6. Use of Naturally Prepared Coagulants for the Treatment
of Wastewater from Dyeing Mills 147
List of Figures 148
List of Tables 148
6.1 Introduction 148
6.2 Material and Methods 149
6.3 Results and Discussion 151
6.4 Conclusion 156
References 157
Index 159

The environment is the sum of all social, economical, biological, physical, and chemical factors, which constitutes the surrounding of humans. The relationship of humankind with the environment is symbiotic. The environment is complex and dynamic in which all life forms are interdependent.1–3 The environment performs three basic functions in relation to humankind. First, it provides living space and other amenities that make life qualitatively rich for humankind. Second, the environment is a source of agricultural, mineral, water, and other resources that are consumed directly or indirectly by humans. Third, the environment is a sink where all the waste produced by humans is assimilated. It is essential that the capacity of the environment to perform these functions is not impaired; thus, it explains our general concern for it. It is important, therefore, that due to stresses imposed on the environment, the rate of exploitation of resources does not exceed nature’s capacity to reproduce them.

Environmental chemistry is the chemistry that generally focuses on the chemical phenomena in the environment. It deals with chemical composition, structure, properties, reactions, transport, effects, and fate of different chemical spices in the environment—air, water, soil, and their effects on living organisms particularly human beings. Humans live in the natural world of beautiful plants, animals, fresh air, clean water, and fertile soil that fulfill all their basic needs such as food, water, and shelter. Human populations and their activities, for example, industrialization, urbanization, and deforestation, have grown at alarming rates that in turn accelerate the extraction and modification of our environment to such an extent that threatens both our continued existence and that of many organisms. Humans have been continuously disturbing the delicate balance of nature and are changing the basic characteristics of the environment by removing some of its essential components; as a result, almost every aspect of modern living possesses a potential health risk. The environment encompasses everything that is around us, that is, air, water, and land. Air, water, and land have been contaminated with chemical additives called “pollutants.”4–7

Pollution is the introduction of contaminants into an environment, of whatever predetermined or agreed upon proportions or frame of reference; these contaminants cause instability, disorder, harm, or discomfort to the physical systems or living organisms therein. Pollution of water may be defined as the addition of undesirable substances or unwanted foreign matter into the water bodies, thereby adversely altering natural quality of water. It is of vital concern to humankind, since it is directly linked with human welfare.8 Science and technology, as part of their contribution to economic and social development, must be applied to the identification, avoidance, and control of environmental risks and the solution of environmental problems and for the common good of humankind. Humans have the fundamental right to freedom, quality, and adequate conditions of life, in an environment of quality that permits a life of dignity and well-being, and they bear a solemn responsibility to protect and improve the environment for the present and future generations. In this respect, policies promoting or perpetuating apartheid, racial segregation, discrimination, colonial and other forms of oppression, and foreign domination stand condemned and must be eliminated.

Water is obviously an important topic in environmental science; it is a vitally important substance in all parts of the environment. Water covers about 70% of Earth’s surface. It occurs in all spheres of the environment—in the oceans as a vast reservoir of saltwater, on land as surface water in lakes and rivers, underground as groundwater, in the atmosphere as water vapor, and in the polar ice caps as solid ice. Water is an essential part of all living systems and is the medium from which life evolved and in which life exists.9 Continuous economic development and growth of the developed and developing countries around the world lead to a considerable increase of water demand. The worldwide demand for high-quality water resources will be difficult to meet in the foreseeable future because of dwindling supply. The imbalance in the demand and supply of water resources will become a major problem confronting every country in the incoming few decades.

Water quality characteristics of aquatic environments arise from the multitude of physical, chemical, and biological interactions. Water bodies like rivers, lakes, and estuaries are continuously subject to a dynamic state of change with respect to their geologic age and geochemical characteristics. This is demonstrated by continuous circulation, transformation, and accumulation of energy and matter through the medium of living things and their activity. This dynamic balance in the aquatic ecosystem is upset by human activity, resulting in pollution that is manifested dramatically as fish kill, offensive taste and odor, etc. Water quality characterization must take into account (i) the distribution dynamics of chemicals in the aqueous phase (soluble, colloidal or absorbed, or particulate matter), (ii) accumulation and release of chemicals by aquatic biota, (iii) accumulation and release by bottom deposits, and (iv) input from land and atmosphere, that is, airborne contamination and land runoffs.

According to the American Dye Manufacturers Institute (ADMI), the largest trade association for the industry, capital expenditure by domestic dyeing companies has increased in recent years reaching $2.9 billion in 1995.12 Dyeing effluents contain several types of pollutants, such as dispersants, leveling agents, salts, carriers, acids, alkali, and various dyes; wastewater quality is variable and depends on the kind of process that generates the effluent.Most environmental concern relates to the effluents of the dyeing and finishing processes that contain a variety of contaminations of higher concentration of chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids, organic nitrogen, and some heavy metals. Color is usually noticeable at dye concentrations above 1 mg/L and has been reported in effluent from textile manufacturing at exceeding concentrations mainly because 10-15% of the dye is lost into wastewater during the dyeing processes.

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