Chromium Removal Using Various Biosorbents

Pollution of water due to presence of certain heavy metal ions is a severe socio-environmental problem caused by the discharge of industrial wastewater. In view of their toxicity, non-biodegradebility and persistent nature, their removal becomes an absolute necessary. Chromium is one of the major pollutants in the environment and is frequently present in wastewaters from various industrial units. Several conventional physical and chemical treatment techniques may be used for the removal of chromium. However, such processes are not only expensive and highly energy intensive, but also lead to production of harmful by-products and end-products, the ultimate disposal of which again causes secondary pollution. Hence, the potential application of microorganisms as biosorbent for the removal of chromium has been recognized as an alternative to the existing conventional physico-chemical methods. The aim of the present study is to review the removal of chromium from aqueous solution using various materials of agricultural and biological origin , which have been studied as potential chromium biosorbent (plant leaves, saw dust, sugar cane bagassa, sugar beet pulp, maize cob and rice hulls). Also reported cases on chromium removal from aqueous solution by using fungal, algal and bacterial biomass under the growing, resting and dead conditions in batch as well as in continuous bioreactors are reviewed.