Bioaugmentation for chlorinated solvent remediation

Despite several successful field demonstrations and growing use of bioaugmentation, the application and spread of these introduced cultures in groundwater, which may significantly influence the design, cost, and performance of bioaugmentation systems, is poorly understood. For bioaugmentation to be a feasible technology for broader application, effective distribution of the bioaugmented microorganisms mediating remediation activity in the subsurface is essential. In the present investigation, laboratory-scale studies were conducted to assess aerobic spores of Bacillus and microorganism-sized polystyrene microspheres as potential surrogates for the subsurface transport of bioaugmentation cultures. Three predominant microorganisms in a bioaugmentation culture were significantly removed within the test columns, although some significant differences in transport were observed between organisms. The rate of TCE dechlorination by organisms passing through the columns was indistinguishable from the rate of TCE dechlorination by the influent bioaugmentation suspension, suggesting that differential transport of these organisms did not adversely impact dechlorinating activity. The large removals (9099.9%) indicated that short-term transport of the bioaugmented microorganisms was an insignificant mechanism for distributing microorganisms in the subsurface; however, the subsequent growth of those few viable organisms able to migrate significant distances was likely to be critical factor determining the success of bioaugmentation in the field.