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Aerobic Cometabolism of TCE and 1,4-Dioxane – Field Demonstration

In a pilot study to compare aerobic cometabolism with anaerobic reductive dechlorination  to remediation TCE and 1,4-dioxane at a former industrial facility in New Jersey, aerobic cometabolism reduced the concentrations of both compounds while anaerobic reductive dechlorination was unsuccessful.  For aerobic cometabolism, CL-Out microbes were injected into the aquifer to a depth of 60 to 90 feet below ground.  The pilot treatment area was 500 square feet.  Monitoring wells were placed upgradient, sidegradient and downgradient of the injection point.  Ground water samples were taken on a monthly basis for 9 months.

The results showed that complete TCE mineralization, without the production of daughter products, was measured within the first month.  CL-Out bioremediation removed 80% of the TCE at 40 feet downgradient in less than three months.  CL-Out bioremediation reduced the 1,4-dioxane concentration to below detection limits at 20 and 40 feet downgradient in the first month.

Click here to view a summary case study.

 

 

CL-Out Bioaugmentation Following ISCO to Remediate TCE

CL-Out bioremediation was used to remediate ground water at an active manufacturing plant in eastern Massachusetts after ISCO treatment of TCE in groundwater reached a limit.  CL-Out was selected because the aquifer was naturally aerobic.  CL-Out cometabolizes TCE and other chlorinated solvents under aerobic conditions by producing an oxygenase enzyme that breaks the carbon to carbon bond.  Under aerobic conditions daughter products such as DCE and vinyl chloride are not formed.  30 days after one application of CL-Out the TCE concentration was reduced by 97% and the site remediation goals were achieved. Click here to download the case study.

TCE Bioremediation Rates

The following chart is a compilation of TCE bioremediation rates by CL-Out microbes.  This data is from eleven different sites where ground water was contaminated by trichloroethylene (TCE) and remediatedby CL-Out microbes.  The sites represent all kinds of geological conditions with the full range of TCE concentrations in ground water.

Overall, the results show an average removal rate of 97% .  However, the final TCE concentration reached below detection limits on two sites, and an additional three had greater than 99% removal.  

In Situ CL-Out Bioremediation of Industrial Solvents

Case Study :

Industrial Manufacturing Site, Illinois

Remediation Summary

Leaks from an aboveground solvent tank impacted soil and ground water quality at a manufacturing site in Illinois.  The impact was found under the adjoining building as well as the area near the tank.  The soil and ground water were treated in situ with CL-Out® bioremediation microbes.  Through cometabolism CL-Out® microbes reduced the contaminant concentrations to acceptable levels in less than one year.

Contaminants Soil Results (mg/Kg) Ground Water Results (mg/L)
Pre-Treatment Post- Treatment Pre-Treatment Post- Treatment
PCE 41.8 1.69 5.59 0.006
TCE 4,670 632 15.6 0.026
Cis 1,2-DCE 171 56.6 7.43 0.029
Vinyl Chloride BDL BDL 0.095 0.013

Implementation and Results

Soil Type:  Silty clay till

Treatment Area:  15,000 sq. ft.

Unsaturated soil thickness:  16 ft.

Saturated aquifer thickness:  5 ft.

Treatment: Two applications, initial treatment with 13 units of CL-Out® and follow up treatment with 5 units.

Product Cost: $30,000

Conclusions

CL-Out® bioremediation quickly and cost-effectively reduced the contaminant concentrations to acceptable levels.  Through cometabolism the parent and daughter products were removed simultaneously.  CL-Out® bioaugmentation accelerated the site remediation and reduced uncertainty by applying the right microbes where they were needed.

Aerobic Cometabolism of PCE at an Industrial Site in Tampa, Florida

Project Summary

Degreasing solvents were found in the ground water at an industrial manufacturing facility in Tampa, Florida.  The solvents include PCE and its associated breakdown products. The source of the ground water contaminants was found to be a former water treatment system drain field.  CL-Out® bioremediation was implemented to reduce the volume of contamination in the source area and down gradient. CL-Out® is a consortium of Pseudomonas sp. that produces constitutive enzymes to cometabolize PCE and other halogenated solvents.  Dextrose is added with CL-Out® to provide a substrate for microbial growth.  Application of CL-Out® bioremediation at this site reduced the total chlorinated solvent concentrations as much as 99% in less than 6 months.

Geology and Hydrogeology

The site is located in Tampa, Florida where the geology is characteristically interbedded silt and sand.  The background ground water redox conditions of the aquifer are not known.

Contamination

The PCE and elevated concentrations of daughter products were found in ground water down gradient of the former drain field.  The PCE concentrations were as high as 280 µg/L and DCE concentrations were as high as 4,400 µg/L, which indicates that there was significant contaminant degradation occurring, but the natural degradation stalled at DCE.   Petroleum hydrocarbons were also present in the ground water and may have served as an oxygen sink during the degradation of the petroleum products.

Remediation Design

CL-Out bioremediation was implemented in the ground water to accelerate the remediation of the source area.  A 55-gallon slurry of  CL-Out was injected on February 11, 2003.

Monitoring wells in the source area and surrounding area were sampled to assess the progress of the remediation.   The following table shows the pre-treatment and post-treatment CVOC concentrations in a source area monitoring well (MW-1) near the application of CL-Out.

 Source Area (MW-1)

Sampling Date CVOC Concentrations (µg/L)
  PCE TCE DCE VC
3/28/02 280 750 4,400 BDL
12/19/02 86 120 1,100 BDL
2/11/03 CL-Out Injection
2/24/03 350 280 1,600 BDL
7/7/03 4.6 6.0 63 BDL

RESULTS

After application CL-Out bioaugmentation the chlorinated solvent concentrations in MW-1 decreased by as much as 99%.  Overall the total mass of contamination was significantly diminished by the bioaugmentation in a short period of time to accelerate the natural degradation.