Bioremediation of Chlorate and Chromium in Soil Columns Using Contaminated Site Native Culture

Abstract

Chlorate and hexavalent chromium (chromate) are both widely used in different industries, and the improper waste management in the past left many sites with elevated concentrations in groundwater that pose potential risk to human and/or ecological health. Bioremediation is a sustainable management solution that can reduce both of these contaminants to less toxic species. In our earlier microcosms experiments, we have demonstrated that native microorganisms collected from a site contaminated with chlorate and chromate can lower the concentration of these chemicals in groundwater to acceptable regulatory levels provided sufficient electron donor, nitrogen, and phosphorous are provided. In this study, continuous flow column experiments were performed using soil from the site impacted by both chlorate and chromate in the Province of Manitoba (Canada) and synthetic groundwater amended with acetate, nitrogen, and phosphorous. The objective was to evaluate at a bench scale possibility of in-situ groundwater treatment. Concentrations of chromate and chlorate measured in the columns' effluent water dropped by 86% and 96%, respectively. However, increased biomass and precipitation of trivalent chromium reduced the water flow rate in the columns, a concern for implementing this method as a long-term in-situ remediation solution.