Reduction of Heavy Metal by Biosorption

Abstract

Microorganisms can be used for treatment of metal and metalloid containing water streams in way to sequester the targeted species. The pollutants of concern include lead, chromium, mercury, uranium, selenium, zinc, arsenic, cadmium, gold, silver, copper and nickel. These toxic materials may be derived from mining operations, refining ores, sludge disposal, the processing of radioactive materials, metal plating, or the manufacture of electrical equipment, paints, alloys, batteries, pesticides or preservatives. Reduction of metal ions by microbial species involves various active and passive processes of biomass and result in reduction of toxicity. Microbial cell may sequester metal ions by various processes such as complexation, chelation, coordination, ion exchange, precipitation and reduction. Collectively, these mechanisms are referred as Biosorption. The term biosorption is generally used to describe the passive interaction of microbial biomass with targeted species. Biological treatment processes include mainly the oxidation of organic material to less harmful compounds such as carbon dioxide and nitrogen.