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

 

Fast, Low-Cost Petroleum Spill Treatment

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After removal of USTs, ground water was treated over a one-half acre plume in Houston, Texas.  Petrox bioaugmentation was implemented by injection of 110 gallons of high concentration microbial solution in April 2006.  Post-treatment sampling shows the bioaugmentation significantly reduced the source area contaminant levels  at a cost of less than $2,000 for the Petrox®.

Sampling Date Benzene Toluene Ethylbenzene Total    Xylenes
Pre-  bioaugmentation 4/4/06 2,000 1,400 1,600 2,460
Post- bioaugmentation 8/9/06 350 240 470 69

All concentrations shown in µg/L.

Pesticide Bioremediation with Petrox®

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Site Summary
Petrox® bioremediation was used to remediate dieldrin and other pesticides at a site in Pensacola, Florida. The remediation progressed in stages including a bench-scale treatability study and field pilot study prior to full-scale remediation. The full-scale remediation is also staged to take full advantage of the benefits of each application of Petrox® bioremediation prior to the next application. The remediation is in progress, but this case study reports the significant progress made in reducing the size of the impacted ground water plume and the contaminant concentrations.

 

Geology and Hydrogeology

The site is located on coastal plain sediments. The sediments are fine to medium-grained quartz sand to approximately 40 feet deep, where a medium to coarse grained sand layer is encountered. The coarse-grained layer is approximately five feet thick. The coarse-grained layer overlies a fine to medium-grained sand layer with interbedded discontinuous clay lenses. The sediments form a thick, unconfined aquifer. The water table is at approximately 45 feet below grade.

Contamination

Chlorinated pesticides were used at the site from 1982 to 1984. The release is assumed to be from the accumulation of small spills during on site mixing operations. The impacted soil was located on the property and concentrated in a drainage swale. The pesticides leached from the soil into the ground water forming a plume that was approximately 2,000 feet long and 200 feet wide. Soil source removal was conducted in August 2005 when a total of 1,272 tons of soil were excavated and disposed off-site. Bioremediation was selected to remediate the residual impacted soil and ground water.

Remediation

Petrox bioremediation was applied to the on-property source area and a mid-plume down gradient area. The down gradient plume treatment area was at a set of three injection wells 425 feet from the source area and up gradient from a cluster of monitoring wells.

Three full-scale applications of bioaugmentation were completed. The initial application in November 2011 was 1,540 gallons of Petrox solution injected into soil and 7 seven injection wells in the source area, and 3 mid-plume injection wells near the CW-13 well cluster. The injection in February 2012 was 990 gallons of Petrox solutions in 6 source area wells and 3 down gradient wells near the CW-13 wells. The third injection was 330 gallons of Petrox solution in the same 3 down gradient wells.

 

Dieldrin Plume Before Bioremediation

Dieldrin Plume Before Bioremediation

Dieldrin Plume After Bioremediation

Dieldrin Plume After Bioremediation

Following Petrox® bioaugmentation the source area dieldrin concentrations were reduced from a maximum of 9.9 µg/L to 0.47 µg/L. The down gradient treatment reduced the dieldrin concentrations over an area of more than one acre by at least 90%. Overall the size of the plume was reduced by about one half and concentration by 90% in less than one year.

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.