Bioremediation of Chlorobenzene Following ISCO

Compatable Techology To Finish Remediation

CL-Out® micorbes bioremediation of chlorobenzene continued treatment after ISCO remediation stalled.  The target isomers included chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and 1,2-dichlorobenzene. Before bioaugmentation, individual concentrations exceeded 50,000 µg/L. The CL-Out® treatment quickly reduced contaminant concentrations by as much as 82% more.

Remediation Approach and Results

Injection through temporary well points introduced CL-Out® micorbes into the contaminated ground water in November 2010. Only one drum of the CL-Out® was injected into the ground water.

The ground water monitoring included 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, bioremediation reduced 62% to 82% of individual contaminants. The sampling results 30 days after bioaugmentation are compared to the pre-treatment concentrations on the following chart.

isco-1

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.

isco-2

Conclusions

This project demonstrates several of the benefits of bioremediation of chlorobenzene. 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.

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