Field‐Scale Evaluation of Bioaugmentation Dosage for Treating Chlorinated Ethenes

Abstract

A field demonstration was performed to evaluate the impacts of bioaugmentation dosage for treatment of chlorinated ethenes in a sandy‐to‐silty shallow aquifer. Specifically, bioaugmentation using a commercially available Dehalococcoides (DHC)‐containing culture was performed in three separate groundwater recirculation loops, with one loop bioaugmented with 3.9 × 1011 DHC, the second loop bioaugmented with 3.9 × 1012 DHC, and the third loop bioaugmented with 3.9 × 1013 DHC. Groundwater monitoring was performed to evaluate DHC growth and migration, dechlorination rates, and aquifer geochemistry. The loop inoculated with 3.9 × 1012 DHC showed slower dechlorination rates and DHC migration/growth compared with the other loops. This relatively poor performance was attributed to low pH conditions. Results for the loops inoculated with 3.9 × 1011 and 3.9 × 1013 DHC showed similar timeframes for dechlorination, as evaluated at a monitoring well approximately 10 feet downgradient of the DHC injection well. Application of a recently developed one‐dimensional bioaugmentation fate and transport screening model provided a reasonable prediction of the data in these two loops. Overall, these results suggest that increasing bioaugmentation dosage does not necessarily result in decreased dechlorination timeframes in the field. The ability to predict results suggests that modeling potentially can serve as an effective tool for determining bioaugmentation dosage and predicting overall remedial timeframes.

Abiotic dechlorination in rock matrices impacted by long-term exposure to TCE

“…Ethene can be an abiotic or biotic daughter product. It is also noted that ethane can be a biotic daughter product of ethene under anaerobic conditions, but this process is not common (de Bruin et al, 1992;Koene-Cottaar and Schraa, 1998;Schaefer et al, 2009Schaefer et al, , 2010. Furthermore, we have shown in our previous work using this rock type (Schaefer et al, 2013) that the rate of daughter product generation was not impacted by the presence of the microbial inhibitor mercuric chloride, which also is consistent with abiotic degradation processes.…”

Evaluation of microbial transport during aerobic bioaugmentation of an RDX-contaminated aquifer

“…Bioaugmentation is an accepted treatment option with commercially available inocula targeted to biodegrade halogenated hydrocarbons (Schaefer et al 2010;Stroo et al 2013), aromatic hydrocarbons (Da Silva and Alvarez 2004), gasoline oxygenates (Salanitro et al 2000), and 1,4-dioxane (Lippincott et al 2015) among others. Bioaugmentation has not been used to treat explosive-contaminated groundwater, despite an increase in knowledge of RDX biodegradation in the past fifteen years (Andeer et al 2009;Bernstein et al 2011;Crocker et al 2006;Fuller et al 2009Fuller et al , 2010Hatzinger and Lippincott 2012;Livermore et al 2013;Seth-Smith et al 2008).…”

Detection of <b><i>Dehalococcoides</i></b> spp. by Peptide Nucleic Acid Fluorescent in situ Hybridization

“…Mixed cultures SDC-9 and Hawaii-05 were chosen due to their application as commercial bioaugmentation cultures that have been used at a variety of sites because of their ability to utilize chloroethenes [Schaefer et al, 2009[Schaefer et al, , 2010aVainberg et al, 2009]. SDC-9 was enriched from a chlorinated solvent-contaminated site in southern California with PCE and sodium lactate .…”