Abstract

In situ stabilization of heavy metals through adsorption onto indigenous bacterial biofilm developed on soil particles was investigated. Biofilms were developed in soil columns by supply of various carbon sources such as acetate, lactate and glucose. During development of biofilms, acetate, lactate, and glucose solutions were flew out from the soil columns with volume ratios of 98.5%, 97.3%, and 94.7%, respectively, when compared with soil column supplied with deionized water. Decrease in effluent amounts through the soil columns amended with carbon sources over time indicated the formation of biofilms resulting in decrease of soil porosity. Solutions of Cd, Cr(VI), Cu, Pb, and Zn were injected into the biofilms supported on soil particles in the columns, and the dissolved heavy metals in effluents were determined. Concentrations of dissolved Cd, Cr(VI), Cu, and Zn in the effluents through biofilm columns were lower than those of control column supplied with deionized water. The result was likely due to enhanced adsorption of the metals onto biofilms. Efficiency of metal removal by biofilms depended on the type of carbon sources supplied. The enhanced removal of dissolved heavy metals by bacterial biofilms in this study may be effectively applied to technical development of in situ stabilization of heavy metals in natural soil formation contaminated with heavy metals.

Keywords biofilm, biosorption, heavy metals, indigenous bacteria, in situ stabilization