14 - Microbial Bioremediation of Industrial Effluents

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Microbial bioremediation is an economic and eco-friendly process that uses naturally occurring microorganisms to degrade hazardous toxic chemical substances into less toxic or nontoxic substances. The toxicity of metals occurs in humans due to environmental pollution or occupational exposure. Some of these metals are useful to us in low concentrations but are toxic in higher concentrations, which cause serious morbidity and mortality. Among these heavy metals, chromium toxicity can cause serious mutagenic, carcinogenic, and teratogenic effects in humans and animals. Chromium compounds are widely used in leather tanning, steel production, and alloy formation, as metal corrosion inhibitors, and in paints and various other applications. During these processes, many contaminants such as organic, inorganic, and heavy metals are released into the effluents that need to be treated in a safe manner. Generally, chromium is present in two oxidative states: Cr+3 is essential for the human system, whereas Cr+6 has harmful effects. So one of the ways of reducing chromium toxicity in Cr-contaminated industrial effluent is to reduce soluble Cr+6 to insoluble Cr+3. This can be achieved in situ or ex situ and mediated by microorganisms. The objective of the case study is to conduct hexavalent chromium reduction by using bacteria isolated from the Sukinda mining area, Odisha, for the bioremediation of industrial effluent. The mining industrial effluent, water, and soil samples were collected and physicochemical parameters were analyzed using standard methods of American Public Health Association (APHA). Experiments revealed that, out of the four bacterial isolates, 89.39% Cr6+ reduction was observed by Acinetobacter calcoaceticus at 30°C/24h/pH 8 and in the presence of 1ppm copper in Lauria Bertani (LB) medium. Thus, it is concluded that A. calcoaceticus may be used in the bioremediation of hexavalent chromium toxicity.