CL-Out® bioaugmentation was used to remediate ground after ISCO was unsuccessful in remediation of chlorobenzene isomers, including chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and 1,2-dichlorobenzene. At the initiation of bioaugmentation, individual concentrations were as high as 50,000 µg/L. The CL-Out® treatment quickly reduced contaminant concentrations.
Remediation Approach and Results
CL-Out® was introduced into the contaminated ground water in November 2010 by injection through temporary well points surrounding the monitoring point. One drum of the CL-Out® was injected into the ground water.
The ground water treatment results were monitored by analysis of ground water samples for the contaminants of concern, microbial population, and known functional genes, including naphthalene dioxygenase, phenol hydroxylase, and toluene dioxygenase. The 30-day monitoring results show an immediate decrease in the contaminant concentrations. After 30 days, 62% to 82% of individual contaminants were destroyed. The sampling results 30 days after bioaugmentation are compared to the pre-treatment concentrations on the following chart.
The total biomass increased from 1.5 million to 12.8 million cells per milliliter following the bioaugmentation. The concentration of the naphthalene dioxygenase functional gene also increased by more than ten fold, as shown on the following table.
This project demonstrates several of the benefits of aerobic bioaugmentation. Bioaugmentation provides active control of the site as effective organisms compatible with the site conditions were injected where they were needed. Furthermore, the CL-Out® aerobic cometabolism was compatible with the residual conditions following ISCO treatment. Treatment will continue to reduce the contaminant concentrations to acceptable levels.