Bioremediation of Arsenic-Contaminated Groundwater

摘要

The aim of the project was to study the remediation of arsenic-contaminated groundwater. A laboratory scale investigation was undertaken to develop a cost-competitive, easy-to-operate, safe, and environmentally friendly bioremediation process. The goal was to reduce the concentration of arsenic to below the WHO (World Health Organization) established maximum contamination limits (MCLs) of 10 μg/1. The method chosen involved precipitating out arsenic as sulfide salts using sulfate-reducing bacteria (SRB) that convert sulfate to sulfide (Kirk et al., 2004), and by adsorption on the surfaces of the supporting matrix. SRB were isolated from anaerobic sediments from the Msunduzi River (Pietermaritzburg, South Africa) and enriched in Postgate nutrient medium-B. The bioreactors were inoculated with sulfate reducing bacteria, molasses serving as a carbon source and sulfate as electron acceptor. Results to date indicate more than 90% reduction of both arsenic (Ⅲ) and (Ⅴ) species in bioreactors using polystyrene as the support matrix. The pH did not change appreciably except in the reactor containing pine bark as the matrix where a decrease in pH occurred. This might be due to the leaching of organic compounds from the pine. In the sand-containing and matrix-free bioreactors the concentrations of both arsenic species remained virtually unchanged.