Industrialization is considered to be the key for the development in economic terms. At the same time it is also recognized to be the root cause for environmental perspective. The understanding that environmental pollution is a worldwide threat to public health has given rise to new initiatives for environmental restoration for both economic and ecological reasons. Toxic and hazardous pollutants are found in the industrial effluents. One particular class of synthetic chemicals which is of major concern is synthetic dyes and dye intermediates.
Due to rapid changes in the customer's demands, the textile dyeing and furnishing industries use wide variety of dyestuffs. More than 100,000 commercially available dyes are known and the world annual production of the dyestuffs amounts to more than 7x105 tonnes. Azo dyes which are used as textile colorants designed to bond covalently with cellulosic fibers (i.e. cotton) are extensively used because of their wide variety of color shades, ease of application, high wet fastness profiles, minimum energy consumption and brilliant colors. It has been estimated that more than 10 - 15 % of the total dyestuff used in dye manufacturing and textile industry is released in to the environment during their synthesis and dyeing process. Approximately 2, 80,000 tonnes of textile dyes are discharged every year worldwide. Waste streams generated from textile industries are hazardous and difficult to biodegrade owing to the presence of recalcitrant dyes and pigments. The problem of environmental pollution from textile industry has a serious dimension as India is a major producer and exporter of textiles. (Sarayu and Sandhya, 2009)
Environmental problems of the textile industry are mainly caused by discharges of wastewater. The textile sector has a high water requirement. Its biggest impact on the environment is related to primary water consumption (80100 m3/ton of finished textile) and waste water discharge (115175 kg of COD/ton of finished textile, colour, a large range of organic chemicals, salinity, and low biodegradability). Hence, the reuse of the effluents represents an economical and ecological challenge for the overall sector. Depending on the nature of the raw material and product, textile processing employs a variety of chemicals. The effluents resulting from these processes differ greatly in composition, used fabrics and machinery, due to differences in processes. Main pollution in textile wastewater came from finishing and dyeing processes. They require the input of a wide range of chemicals and dyestuffs that are generally organic compounds of complex structure. The final product becomes a waste and causes disposal problem because all the mentioned chemicals are not contained in it.