Buffering soil-water acidity in chlorinated solvent bioremediation schemes

Chlorinated solvents form a significant part of groundwater contamination worldwide. They are difficult to remove via physical means, and anaerobic source-zone remediation based on provision of fermentable e-donor is an attractive clean-up dechlorination option. However, organic acids and HCl lower the groundwater pH and thereby stall the microbial consortia responsible for the biodegradation process. Often, the soil’s natural buffering capacity will be exceeded, in which case a strategy of adding buffer to the groundwater is a priori beneficial to maintain dechlorination. Geochemical modelling was used to investigate the feasibility of adding naturally occurring buffering minerals to the groundwater for pH control. The simulations revealed that anorthite has the potential to be used as a sustainable pH buffering mineral.