ENHANCED IN-SITU ANAEROBIC BIOREMEDIATION: BEST PRACTICES, COST PERFORMANCE, AND LESSONS LEARNED

Enhanced In-Situ Anaerobic Bioremediation continues to prove its effectiveness in the degradation of chlorinated solvents at sites with varying geologic and hydrologic conditions. The ease of implementation, minimal impact to site infrastructure, cost/performance ratio, and ability to stimulate complete mineralization of the constituents of concern make it a strong alternative to engineered remedial strategies and mass removal techniques (e.g., pump and treat). The challenges of effective substrate delivery and distribution, establishing and maintaining favorable aquifer geochemistry, and applications in difficult geologic conditions are discussed. Additionally, microbiological conditions at a site may warrant inoculation with non-native cultures of dechlorinating bacteria that have the potential to accelerate progress toward remedial objectives (bioaugmentation). Case study performance data are presented from sites with difficult geologic conditions (fractured bedrock, geologic heterogeneity, shallow groundwater, and low aquifer permeability), complex site infrastructure, unfavorable biogeochemical conditions, and a variety of electron donors (emulsified vegetable oil, bark mulch, sodium lactate, and whey).