Reduction of bromate in groundwater with an ex situ suspended growth bioreactor

A potential remediation technique for groundwater contaminated by bromate has been investigated, utilising biological bromate reduction to bromide by augmentation of indigenous microbial populations. This technique, involving addition of a carbon source to contaminated groundwater, is being developed as an ex-situ methodology analogous to commercial denitrification systems, but may also havein-situ applications. Trials have focussed on a laboratory-scale anaerobic suspended growth chemostat system, investigating glucose addition to real groundwater supplies. Steady states for a range of glucose and bromate concentrations demonstrated bromate reduction up to 700μgl−1 (50% of 1400μgl−1 influent) with glucose excess (above 52mgl−1), but specific reduction rates (up to 2.83μmol Br.g dry wt−1hr−1 for 1400μgl−1 bromate influent) were low compared to denitrification (up to 305μmol Ng dry wt−1hr−1). More recent enrichment trials have demonstrated reduction of 32mgl−1 bromate within a 40 hour residence time with specific reduction rates of up to 160.48μmol Br.g dry wt−1hr−1, suggesting the presence of high rate bromate reducing bacterial strains.