Suthan Suthersan

Enhanced Reductive Dechlorination - A Broader Perspective

Enhanced reductive dechlorination of chlorinated compounds has been applied via in situ engineered anaerobic systems in increasing numbers over the past decade. Knowledge gained from these field applications, combined with academic literature, allows us to have a broader understanding of the technology. Microbial communities can be engineered through manipulation of aquifer inputs, creating in-situ reactive zones. Over a short segment of the groundwater flow path, the microbial biomass is shifted to a succession of facultative degraders and fermenters, sulfate reducers, acetogens and methanogens. At low - to-moderate electron donor loading rates, the aquifer microbial continuum is dominated by species that produce C-1 compounds and acetate as the fermentation products. When electron donor loading increases to high levels a significant portion of the electron donor flows into pathways that generate fatty acids. The network of anaerobic metabolic processes is introduced as an electron donor cascade. Bacteria occupying several points in the electron donor metabolic cascade have been shown to reductively dechlorinate halogenated compounds. Biostimulation using late -cascade compounds such as lactate and met hanol bypass much of the productive dechlorinating communities. These observations were developed from the authors’ research and published reports of numerous other field applications and lab research.