Remediation of Organic Textile Dyes and Effluent by Freshwater Filamentous Cyanobacteria: A Review

Abstract

Organic chemical coloring compounds called dyes form an important constituent of the textile industry. Among the diverse range of dyes, azo dyes are the oldest and major group of dyes. These textile industries utilize large volumes of water for their various operation processes and release waste-water as effluents. The textile effluent consists of several toxic inorganics and organic ingredients along with heavy metals present in ionic and complex forms. Liberation of untreated dye containing textile effluents affects the environment and human health. Elimination of colored compounds released from textile industries can be carried out by a number of conventional modes of physicochemical methods, which has a high cost, and produce a large amount of sludge and harmful products. A better substitute to conventional methods is the degradation of dyes by microbes which involves low cost, less sludge build-up, and breaks down toxic dyes into simple inorganic compounds which cause less damage to living organisms. This review deals with the classification of dyes, environmental hazards encountered, conventional modes versus biological methods of treatment of textile dyes and effluent and the role of filamentous Cyanobacteria (also known as 74blue-green algae) in the decolorization of textile dyes by the mechanism of biosorption and enzymatic approach involving reductive and oxidative enzymes under various conditions.