The following chart is a compilation of CL-Out bioremediation results from eleven different sites where ground water was contaminated by trichloroethylene (TCE). The sites represent all kinds of geological conditions with the full range of TCE concentrations in ground water.
CL-Out bioremediation was used in a keyhole treatment to reduce the mass of contamination near the source and down gradient concentrations in the plume. At a former manufacturing facility in Ohio the concentration of PCE near the source was over 100,000 ug/L. Down gradient of the source the PCE concentrations were less than 10% of the source concentration. Aggressive treatment in the source area reduced the source concentration and in the down gradient plume.
After one treatment with CL-Out bioremediation, the concentrations decreased as follows:
PCE was reduced from 120,000 to 12 ug/L.
TCE was reduced from 2,000 to 12 ug/L
Cis 1,2-DCE was reduced from 9,500 to 8,100 ug/L.
Vinyl chloride, however, increased from 1,200 to 22,000 ug/L.
The vinyl chloride increased as the aggressive cometabolic treatment stimulated some incomplete reductive dechlorination.
Down gradient from the source, the concentrations decreased with slight to no increase in daughter products. The following results were measured in the down gradient plume:
PCE reduced from 5,000 to 1,600 ug/L.
TCE reduced from 43 ug/L to BDL.
Cis 1,2-DCE was reduced from 140 to 23 ug/L.
Vinyl chloride was not detected before or after treatment.
Keyhole treatment was a cost effective approach to reducing the mass of contamination in a ground water plume by focusing aggressive treatment on the source area. Concentrations in the rest of the plume decreased as the microbes and treated water dispersed through the plume.
A pilot study of the applicability of CL-Out aerobic cometabolism of PCE and other chlorinated solvents was completed at Vandenberg Air Force Base. The pilot study consisted of injection in a single well and groundwater sampling at four surrounding wells to monitor the progress of bioremediation. During the pilot study, samples were analyzed for the contaminants and breakdown products, microbial population, and dissolved oxygen.
After three months, sampling showed the following contaminant removal near the injection well:
PCE reduced from 44 to 2.6 ug/L.
TCE reduced from 330 to 57.3 ug/L.
Cis 1,2-DCE reduced from 30.7 to 6.2 ug/L.
Vinyl chloride was not detected before or after treatment.
The ground water stayed aerobic during the 90 day pilot study. The CL-Out population reached a maximum of 9 million cells per milliliters 14 days after injection. The CL-Out population was maintained above background populations for at least 60 days and reached as far as 50 feet down gradient.
For more information about the pilot study results, contact CL Solutions.
Case Study :
Industrial Manufacturing Site, Illinois
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|
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
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.
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.
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.
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)|
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.