Biological methods for textile dyes removal from wastewaters

Dyes are colored compounds that when applied to a material provides color with or without a change in its chemical structure. Substance bearing coloring capacity has widespread applications in textile, pharmaceutical, food, cosmetics, plastics, photographic, and paper industries, etc. The disposal of wastewater from dyes industries to nearby water bodies contaminates the water and foist harmful effects on human life as well as aquatic animals, thereby upsetting the environment. In particular, the textile wastewater can be regarded as the most polluting of all the industrial sectors as it consumes a large volume of water during the dyeing and finishing process in the industries. Based on the increased demand for textile products, textile effluents have a crucial role in causing severe pollution to environment. Besides this, the hazardous impact of untreated textiles is also of great concern. Owing to the growing awareness and environmental impact, the decolorization, and detoxification of the industrial dye effluents are essential before it is disposed to the nearby water bodies. Several methods have been introduced for the detoxification of textile dyes, namely, (1) physical; (2) chemical; and (3) biological. Among all the established process for the decolorization of the textile dyes, the biological approach has gained considerable attention because of its economic viability, eco-friendliness, and broad applicability to a variety of dyes. In this chapter, a brief description of the decolorization of textile dyes from wastewater treatment has been discussed. The chapter starts with a brief outline of dye pollution, classification of textile dyes, and their environmental impact, treatment option for dye effluents such as physio-chemical method, and biological method. The chapter primarily focuses on the decolorization of textile dyes by biological methods, which include (1) fungal; (2) bacterial; (3) aerobic and anaerobic; (4) algae; (5) enzymatic; and (6) biosorption. Detailed information regarding the decolorization of textile dyes by various biological methods is briefly disclosed.