Constructed wetland: A promising technology for the treatment of hazardous textile dyes and effluent

Textile industries are one of the largest income and employment generating industries essentially involved in the production and creation of yarn, cloth, and fabrics. Among the different processes of textile production, finishing process involve the use of synthetic dyes in large concentrations. Unfortunately, inadequacy of the dyeing processes results in the discharge of most of the dyes into natural environment. Due to the complex aromatic structure, these dyes do not degrade within time; persist in the environment and causes harmful effects like soil infertility, contamination of ground water and reduction of light penetration in the water bodies affecting the aquatic ecosystem. In humans, dyes are mutagenic and known to cause cancers, asthma, skin diseases, and neurotoxic effects through bioaccumulation. Therefore, treatment of dyes containing textile effluent is a very important step towards environment and health protection. Among the several treatment strategies, biological methods using plants either alone or in consortium with microorganisms has proven more efficient and cost effective. Phytoremediation of synthetic dyes and other toxic elements using constructed wetland system (CW) is being actively studied and implemented. With this background, present chapter discusses types of dyes, their toxicity, different categories of wetland systems and the current status of constructed wetlands for the management of hazardous textile wastewater.