Removal of Cadmium from a Sea-food Effluent Contaminated Soil by Indigenous Biological Adsorbents Assessed with Soil Microbial Biomass

Low-cost indigenous biological materials such as Dried Biomass of Azolla (DBA), Composted Coir Pith (CCP) and Dried Rice Husk (DRH) were tried as adsorbents for the removal of cadmium (Cd) from a sea-food effluent contaminated soil of south India. Soil incubation with indigenous biological materials significantly decreased the Cd concentration in contaminated soil as compared with non- incubated control. However, the concentration was far low in soils incubated with DBA followed by CCP. Furthermore, the Cd concentration of soil decreased with incubation time. Comparison of the Cd removal from soil revealed that the removal of Cd in treatment incubated with DBA and CCP was more or less on par. The kinetics of Cd adsorption followed the first-order rate expression given by Lagergren. Highest $k_{ad}$ value was noticed in treatment incubated with DBA followed by CCP. The present study revealed a significant inverse relationship between soil Cd concentration and soil microbial biomass carbon (SMBC). The SMBC significantly increased in treatments incubated with DBA and CCP.