Recent Advances in Decolorization and Degradation of Dyes in Textile Effluent by Biological Approaches

Ram Lakhan Singh, Pradeep Kumar Singh, Rajat Pratap Singh

• Publisher: CRC Press
• Year: 2019
• Print ISBN: 9780367199524
• eBook ISBN: 9780429534539
• Edition: 1
• Topic: Business
• Subtopic: Fashion & Textile Industry
• Index: Business

Recent Advances in Decolorization and Degradation of Dyes in Textile Effluent by Biological Approaches outlines various eco-friendly, cost effective methods for removal of toxic textile dyes. L arge amounts of dye are unbound and released into the environment due to inefficient dyeing processes. The release of wastewater containing dye into the environment has several adverse effects as it is toxic, mutagenic and has other undesirable effects on living organisms. Hence, it is necessary to remove these dyes from industrial effluents to have a sustainable environment. This book deals with conventional as well as advanced effective treatment methods for the removal of dyes in order to increase the domain knowledge of readers.

Salient features:

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• Describes physico-chemical characteristics of textile effluent, dye classes and toxicity of dyes commonly used in the textile industry

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• Assembles effective approaches which are used to remove dyes from textile effluent prior to their release into the environment

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• Presents several advanced approaches such as genetic engineering, nanotechnology, immobilized cells or enzymes, biofilms and microbial fuel cells, etc. for the removal of dyes.

Chapter 1

Introduction

The population explosion combined with the industrial revolution has led to various environmental concerns. The rapid growth of industries has prompted the production of heavy loads of liquid waste. Environmental pollution, as a result of urbanization and industrialization, has been identified as a noteworthy issue throughout the world which has a detrimental effect on human wellbeing and the biodiversity of the Earth. Food, clothing and shelter are the three fundamental needs of mankind. With the increased demand for textile products, the textile industry, and its effluents have been increasing, making them one of the principle sources of serious pollution around the world. Nature has an impressive ability of coping with small amounts of wastewater and pollution, however, it would be unsafe if the large amounts of effluent produced daily were not treated before discharging them back into the environment. The amounts and characteristics of released effluents vary from industry to industry depending on the water consumption and the average daily product. Textile industries consume large volumes of potable water in various processing stages and produce vast volumes of liquid effluents containing dye (Andleeb et al. 2010; Singh et al. 2019). About 40–65 liters of effluent is released per kilogram of fabric during the coloring process (Manu and Chaudhari 2002). Textile effluent has high biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), total solids (TS) and also contains degradable and non-biodegradable chemicals such as dyes, dispersants and detergent, surfactants, leveling agents, heavy metal ions, dissolved inorganics, acids and alkali that are discharged into water bodies. Major pollutants and potentially hazardous compounds are discharged from the wet processing stages of textile industries.

Color is the primary contaminant to be seen in textile effluent which is mainly because of the presence of azo dyes. Azo dyes are synthetic aromatics compounds substituted with azo groups (-N=N-). In addition to azo dyes, other classes of synthetic dyes such as anthraquinone, triphenylmethane, phthalocyanine dyes, etc. are also used in various industries. More than 100,000 dyestuffs are available commercially and annual production of the dyes is more than 7×10⁵ tons worldwide (Selvam et al. 2003; Singh et al. 2019). These dyes are widely used in textile, paper, leather, food, cosmetic and other industries (Singh et al. 2017a). Due to inefficiency in the dyeing and finishing processes, 10–15 percent of the total dyestuffs are discharged with the effluent into the environment (Khehra et al. 2006). These effluents can alter the physical, chemical and biological nature of the receiving water bodies such as rivers and lakes. This increase in the BOD, COD, TDS and total suspended solids (TSS), alters the pH and gives the intense colorations to water bodies. The colloidal matter present along with the colors increases the turbidity and gives the water a dirty appearance and foul smell. The release of colored textile effluent poses a serious threat to the environment. Discharge of these effluents into water streams not only creates an aesthetic problem but also these are toxic to aquatic life and eventually affect the health of both humans and animals. These colored effluents influence the transparency of water bodies and decrease the rate of photosynthesis by aquatic plants leading to damage of the aquatic environment. Moreover, some azo dyes and their degradation products are a serious threat to the environment due to their toxicity including mutagenicity and carcinogenicity (Wang et al. 2013). The stability and xenobiotic nature of azo dyes makes them recalcitrant. Hence it is necessary to treat the dyes present in textile effluent prior to their disposal. The treatment of polluting dyes is an important issue for small scale textile industries. These small scale industries dump their effluent into the main stream of water resources in light of the fact that their working conditions and economic status do not enable them to treat their wastewater before disposal. Without sufficient and proper treatment these dyes will remain in the environment for an extended period of time.

Various physico-chemical methods are utilized to treat the dye containing textile effluent. Physical methods involve the utilization of adsorbents, coagulants and filtration techniques whereas chemical methods include Fenton oxidation, ozonation, electrochemical oxidation and irradiation. Some of these methods are observed to be effective but they are costly and have other drawbacks (Singh et al. 2017a). These methods are economically unattractive and produce secondary pollution problems due to the generation of a large amount of sludge (Singh et al. 2019). Moreover, these methods are not suitable for degrading the wide variety of dyes. Biological methods are effective, economic, specific, less energy intensive and an eco-friendly alternative for the treatment of textile effluent. The biological treatment processes are based on the degradative abilities of different trophic groups of microorganisms. These microorganisms are capable of decolorizing and degrading the dyes present in the effluents. The biological methods include the use of unicellular microorganisms (bacteria, fungi, algae) and plants (phytoremediation) to remove the dyes from textile effluent (Kirby et al. 2000). The bioremediation of dyes by biological methods is attributed to either biosorption or the enzyme mediated degradation process. Various enzymes which are produced by microorganisms and plants are utilized as a molecular tool for bioremediation of textile dyes with great success. However, although these methods are cost effective and produce less sludge they have some disadvantages. Recently several advanced methods/approaches such as genetic engineering, nanotechnology, immobilized cells or enzymes, biofilms and MFCs, etc. have been utilized to de...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• List of Figures
• List of Tables
• Preface
• Chapter 1 Introduction
• Chapter 2 Methods of Decolorization and Degradation of Dyes in Textile Effluent
• Chapter 3 Advanced Methods of Degradation of Dyes in Textile Effluent
• References
• Index