A Review on the Bioremediation Process for the Removal of Heavy Metals

Globally, environmental pollution is increasing carelessly on account of an unabated increment in population, industrialization, urbanization, anthropogenic activities and natural sources. Among various pollutants, heavy metals are released into soils and water from industrial operations such as smelting, mining, metal forging, manufacturing of alkaline storage batteries and combustion of fossil fuel. Moreover, the agricultural activities like application of agrochemicals and sewage sludge in agricultural fields also add a considerable amount of metals in the soils. However, heavy metals like zinc, copper, cadmium, lead, mercury and nickel have been reported as the most toxic pollutants. The metal pollution is of great concerns, as these hazardous pollutants are accumulated in living organisms including microorganisms, plants, animals and human and are responsible for many metabolic and physiological disorders. Many techniques for remediation of contaminated soil have been developed, such as physical, chemical degradation, photodegradation. However, most of these methods have some drawbacks in completely remediating contaminated soil. Biological treatment offers the best environmental friendly method for remediating heavy metal contaminated soil because it utilizes the capability of the indigenous microorganisms in the soil environment to break down the heavy metals into innocuous substances.