Full Length Research Paper

Comparative assessment of heavy metal removal by immobilized and dead bacterial cells: A biosorption approach

M. Johncy Rani, B. Hemambika*, J. Hemapriya and V. Rajesh Kannan

Rhizosphere Biology Laboratory, Department of Microbiology, School of Life Sciences, Bharathidasan University, Tiruchirappalli – 620 024, Tamil Nadu, India.

*Corresponding author. E-mail: uvrajesh@gmail.com.  Tel: +91- 431-2407082.

Fax: +91- 431-2407045.

Accepted 22 December, 2009

Abstract

Microorganisms play a vital role in heavy metal contaminated soil and wastewater by the mechanisms of biosorption. In this study, heavy metal resistant bacteria were isolated from an electroplating industrial effluent samples that uses copper, cadmium and lead for plating. These isolates were characterized to evaluate their applicability for heavy metal removal from industrial wastewaters. The physico-chemical parameters of the samples were initially analyzed. The optimum conditions of pH, biomass concen-tration and heavy metal concentration were determined for the microbial growth on biosorbents and correlated with heavy metal removal. The observed optimum conditions were applied for the biosorption process carried out in immobilized and dead bacterial isolates. The biosorption of immobilized cells of Bacillus sp. was 69.34% of Cu, Pseudomonas sp. was 90.41% of Cd and Micrococcus sp. was 84.27% of Pb, whereas the dead cells of Bacillus sp. was 44.73% of Cu, Pseudomonas sp. was 86.66% of Cd and Micrococcus sp. was 79.22%. Experimental results reveal that all the immobilized isolates have potential application for the removal of Cu, Cd and Pb from industrial wastewater than the dead bacterial cells.  

Key words: Biosorption, bacteria, heavy metal, dead bacterial cells, immobilization.