Abstract
The textile processing mills consume large volumes of water for various processes such as sizing, desizing, scouring, bleaching, mercerization, dyeing, printing, finishing, and washing. Due to various chemical processing of textiles, large volumes of wastewater with numerous pollutants are discharged. Among the processing industries, textile dyeing units produce large volumes of high-strength wastes.
The control of water pollution has become of increasing importance in recent years. The release of dyes into the environment constitutes only a small proportion of water pollution, but dyes are visible in small quantities due to their brilliance. Tightening government legislation is forcing textile industries to treat their waste effluent to an increasingly high standard. Currently, removal of dyes from effluents by some physical and chemical methods such as adsorption, membrane filtration, photocatalytic degradation, and ozonation are quite effective in decolorization of dyes. Such methods are often very costly, and although the dyes are removed, the accumulation of concentrated sludge creates a disposal problem. There is a need to find alternative treatments that are effective in removing dyes from large volumes of effluents and are low in cost, such as biological systems. This paper reviews the current available technologies and suggests several effective, cheaper alternatives for dye removal and decolorization applicable on a large scale.
Introduction
Economy and ecology have been the driving force in modern technology, and therefore attempts are made to produce textiles more efficiently, with less water and less pollution. Society is now becoming more conscious of the needs to ensure that the environment is least affected. Environmental considerations are now becoming vital factors during the selection of consumer goods, including textiles all over the world. However, due to increased awareness of the polluting nature of textiles effluents, social pressures are increasing on textile processing units.
In textile dyeing, as well as other industrial applications, large amounts of dyestuffs are used. As a characteristic of the textile processing industry, a wide range of structurally diverse dyes can be used in a single factory, and therefore effluents from the industry are extremely variable in composition, strength, and volume. This underlines the need for a largely unspecific process for treating textile wastewater. It is known that 90% of reactive dyes entering activated sludge sewage treatment plants will pass through unchanged and be discharged into rivers.
The author is a Research Scholar in the Department of Textiles and Clothing at Avinashilingam University for Women, Coimbatore.
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