Decolourization of dye wastewater by microbial methods- A review

Abstract

Waste water originating from textile processing and dyestuff manufacturing industries contain varying amounts of dyes, metals/metalloids, salts and organic pollutants out of which dyes are the visible toxic contaminants. Presence of dyes in water bodies causes several problems including decreased photosynthesis and higher BOD and COD load, apart from their displeasing appearance. Dyestuffs are organic molecules, which may be toxic or mutagenic. In the last few years, environmental legislation about the presence of colour in discharges, coupled with the increasing cost of water for the industrial sector, has made the treatment and reuse of dyeing wastewaters increasingly important to the industry. A variety of approaches are available for treatment, out of which the biological treatment is the genuinely ecofriendly and cost effective method. The decolourization efficiencies of different biological methods are discussed in this review along with the detailed discussion on bacterial treatment and their relative merits and drawbacks.