Research on Aerobic Cometabolism of PCE

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Aerobic cometabolism of PCE and other halogenated solvents by Pseudomonas sp.  has been well established for more than 20 years.  The following research articles were key in the development of this approach to bioremediation.  This academic research provided parallel support to CL Solutions’ successful application of aerobic cometabolism to bioremediation of hundreds of contaminated sites since 1999.

Vandenbergh, P. A., and Kunka, B. S., Metabolism of Volatile Chlorinated Aliphatic Hydrocarbons by Pseudomonas fluorescens, Applied and Environmental Microbiology, v. 54, no. 10, Oct. 1988. p. 2578 – 2579.

Deckard, L. A., Willis, J. C., and Rivers, D. B. , Evidence for the Aerobic Degradation of Tetrachloroethylene by a Bacterial Isolate, Biotechnology Letters, v16, no. 11, November, 1994. p 1221-1224.

Ryoo, D., Shim, H., Canada, K., Barbieri, P., and Wood, T.K., Aerobic Degradation of Tetrachloroethylene by Toluene-O-xylene Monooxygenase of Pseudomonas stutzeri OX1, Nature Biotechnology, vol 18, July, 2000. p 775 – 778.

Shim, H., Ryoo, D., Barbieri, P, and Wood, T.K., Aerobic Degradation of Mixtures of Tetrachloroethylene, Trichloroethylene, Dichloroethylenes, and Vinyl Chloride by Toluene-O-Xylene Monooxygenase of Pseudomonas stutzeri OX1, Applied Microbiol Biotechnol, v. 56, May 2001. p 265-269.

 

 

TCE Aerobic Cometabolism Using Cl-Out

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CL-Out bioaugmentation was used to reduce the TCE concentrations in ground water at an industrial site in Louisville, Kentucky.  CL-Out microbes were injected into the TCE-contaminated ground water.  Dextrose was added to provide the carbon source for the microbial growth.  An oxygen supplement was necessary to maintain aerobic conditions in the aquifer.

Ground water sampling downgradient of the injection points showed that the CL-Out microbial population achieved a target population of 1 million cfu/ml and maintained an effective population for at least 60 days.  During that timeframe the TCE concentrations were reduced by 90%.

CL-Out Population Increase and Contaminant Destruction Trends

CL-Out Population Increase and Contaminant Destruction Trends

 

Bioremediation of BTEX at an Industrial Site in Florida

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Background

Petrox® bioaugmentation was used to remediate ground water contaminated by benzene, toluene, ethylbenzene and xylene (BTEX) at an industrial facility in central Florida (Facility ID No. 8521705). The bioremediation was implemented in perimeter wells around the source area where air sparging and vapor extraction was implemented. This combined approach provided cost-effective, full-site remediation by using complementary technologies.

Remediation Approach and Results

Petrox® was introduced into the contaminated ground water in the perimeter of the source area plume by injection through temporary well points. Two applications of Petrox® were completed. The initial application was in December 2007 and a subsequent application was completed in April 2008. During each application 550 gallons of Petrox® microbial slurry were injected into the ground water through 19 injection points. The treatment covered an area of approximately 7,000 square feet.

The ground water treatment results were monitored by laboratory analysis of ground water samples for the contaminants of concern. The quarterly monitoring results after the applications showed an immediate and continuous decrease in the BTEX concentrations. The following chart shows the total BTEX concentrations in three quarterly sampling events after the implementation of Petrox® bioaugmentation.

industrial-site6

Conclusions

This project demonstrates two of the benefits of aerobic bioaugmentation. Petrox® organisms were able to metabolize the BTEX compounds, which were initially at part per million levels, to below detection limits. Bioaugmentation provides active control of the site with hydrocarbon-degrading organisms compatible with air sparging and vapor extraction in the source area, where the contaminant concentrations persisted longer than in the bioaugmentation area.

Bioremediation of 1,1,1-Trichloroethane and 1,1-Dichloroethene at a Confidential Site

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Background

CL-Out® bioaugmentation was used to remediate ground water contaminated by 1,1,1-trichloroethane (1,1,1-TCA) and 1,1-dichloroethene (1,1-DCE). The 1,1-DCE was formed as a product of the natural abiotic degradation of 1,1,1-TCA. The bioremediation was implemented as a pilot study and a subsequent interim action for source removal.

Remediation Approach and Results

CL-Out® was introduced into the contaminated ground water in the suspected source area by injection through temporary well points up gradient of the monitoring point. The initial application was in March 2007 and a subsequent application was completed in September 2007.

The ground water treatment results were monitored by analysis of ground water samples for the contaminants of concern. The 30-day monitoring results after the first application showed an immediate decrease in the contaminant concentrations. After 30 days, the 1,1,1-TCA concentration decreased from 1,000 µg/L to 190 µg/L and the 1,1-DCE concentration decreased from 160 µg/L to 27 µg/L . Long-term monitoring after the second application showed that the concentrations of both compounds were reduced to 1.4 µg/L. The following chart shows the long-term contaminant concentrations.

chart_industrial_TCA_DCE

Conclusions

This project demonstrates several of the benefits of aerobic bioaugmentation. CL-Out® organisms were able to metabolize the parent chloroethane compound and the daughter product, which was a chloroethene compound. The metabolic diversity of the CL-Out® organisms facilitates enables the bioremediation of mingled plumes and multiple contaminants. Bioaugmentation provides active control of the site as effective organisms compatible with the site conditions were injected where they were needed for quick contaminant removal.

Pest Control Company Located in Florida

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Bioremediation of Pesticides Using Petrox®  to Meet Part per Trillion
Remediation Goals

Summary

Petrox  bioremediation successfully reduced pesticide contaminant concentrations in ground water at a pest control company in Florida. Dieldrin and heptachlor epoxide were found in ground water at concentrations exceeding state drinking water standards, which were measured in parts per trillion. After three applications of Petrox, the pesticide concentrations decreased more than 99% in three source area monitoring wells.

Geology and Hydrogeology

The site is set in the Florida Panhandle where thick coastal sediments characterize the shallow geology. The sediments underlying the site were fine-grained sand and silt more than 60 feet thick. The depth to the water table was approximately 45 feet.

Contamination

Pesticides were found in shallow soil and ground water at the property. Pesticides had also migrated off the source property in the ground water. The pesticide concentrations in the ground water were relatively low, but exceeded state regulatory standards by orders of magnitude. Prior to remediation, the maximum concentration of dieldrin in ground water was 9.8 µg/L, while the remediation goal was 0.002 µg/L. Heptachlor epoxide was present in the source area ground water at 0.68 µg/L, with a remediation goal of 0.200 µg/L. The remediation challenge was to reduce the contamination levels from the very low initial concentrations to meet even lower remediation goals.

Remediation Design

Petrox bioremediation was direct injected into the ground water in three applications approximately 30 feet apart. During each injection 275 gallons of hydrated Petrox were injected into the three locations over a 15 foot thick interval. Monitoring wells in the treatment area were sampled to assess the progress of the remediation. Three injections were completed on 60 day intervals. The following charts show the contaminant concentration trends in the monitoring wells. The vertical red line shows the initiation of bioremediation.

dieldrinconcentrationtrend heptachlorepoxideconcentrationtrend

Results

Despite the low initial concentration and dispersed contamination, Petrox bioremediation significantly reduced the contaminant concentrations over the full treatment area.  The heptachlor epoxide concentrations met the remediation goals in all monitoring wells in the treatment area. The maximum dieldrin concentration was reduced from 9.8 µg/L to 0.22 µg/L. After three treatments and less than 9 months, the dieldrin and heptachlor epoxide concentrations were reduced by more than 99%. The product cost for treatment was less than $15,000. Petrox provided an efficient, cost-effective remediation solution for the site.