PREVENTING CONTAMINANT DISCHARGE TO SURFACE WATERS: PLUME CONTROL WITH BIOAUGMENTATION

摘要

Widespread use of chlorinated solvents has resulted in contamination of groundwater requiring effective source and plume containment strategies to prevent contaminant migration and mitigate adverse environmental impacts. The Bachman Road Residential Wells Site is contaminated with predominantly tetrachloroethene (PCE) and the contaminant plume flows into Lake Huron. Due to natural dechlorination processes, some of the PCE has been transformed to cis-l,2-dichloroethene (cis-DCE), with lesser amounts of trichloroethene (TCE) and chloroethene (VC). Laboratory and field investigations demonstrated the presence of a PCE to cis-DCE dechlorinating Desulfuromonas species and the presence of a Dehalococcoides species, which completely dechlorinates chloroethenes to ethene. Both populations are known to use chloroethenes as metabolic electron acceptors. A bioaugmentation strategy using these microorganisms at the pilot scale has resulted in complete dechlorination of the groundwater in less than 50 days. Additionally, a 16S rDNA-based molecular approach was developed to track the PCE to cis-DCE and the chloroethene dechlorinating species. This methodology allows us to quantitatively track the populations of interest, monitor their migration and to develop cause and effect relationships with contaminant degradation. This field demonstration illustrates that bioaugmentation using halorespiring microorganisms is a viable alternative for preventing contaminant migration into associated surface water systems.