BIODEGRADATION OF CHROMIUM FROM INDUSTRIAL WASTEWATER

Abstract

Chromium is released into the environment from the effluents of industries such as tanneries, dyes and pigments, film and photography, galvanometry and electric, metal cleaning, plating and electroplating and mining. Chromium especially Cr (VI) species are toxic heavy metal compounds for biological systems and known to be human carcinogen. The most common forms of chromium are Cr (II), Cr (III), and Cr (VI). However, Cr3+ is one hundredth of the toxicity than Cr6+ and far less soluble in water. Therefore reduction of Cr (VI) to less toxic Cr (III) economically has become the key point of remediation strategies of Cr (VI) contaminated waters. Though there are many processes available for the removal of chromium, due to the disadvantages and limitations of conventional techniques, particular attention is paid to the use of biological methods for heavy-metal removal from industrial wastewater. Several microbial species can effectively degrade the chromium into less toxic state. Biological treatment of chromium under aerobic and anaerobic conditions is possible.