CL-Out Bioaugmentation Saves Time and Money

By switching from active extraction to in situ CL-Out® bioremediation, In Control Technologies, Inc. of Houston, Texas saved their client $100,000s in on-going operation and maintenance costs.  The Site was a shopping center where soil and ground water were contaminated by dry cleaning chemicals.  A dual phase extraction system was installed and operated for 9 years.  The dual phase system reduced the total CVOCs by 70%, but the contaminant removal rate  reached the limit of cost effectiveness.

By switching to bioremediation, the client avoided $75,000 on-going annual operation and maintenance cost with a $20,000 investment in bioremediation. CL-Out® bioremediation reduced the residual contamination by more than 98% in less than 90 days.  This case study was reported at the 9th In Situ and On-Site Bioremediation Symposium, 2007

Irwin Engineers, Inc., of Natick, Massachusetts has undertaken a similar approach to reduce on-going pump and treat remediation costs at a site of perchlorate contamination.  Irwin Engineering presented that case study at the AEHS Soils, Sediment, Water and Energy Conference (2013).

Research on Aerobic Cometabolism of PCE

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.



Fast Dry Cleaner Bioremediation

Fast dry cleaner bioremediation by CL-Out microbes reduced PCE concentrations in ground water by more than 99% in less than 90 days to achieve GCTL standards at a dry cleaners in Florida.   The naturally aerobic aquifer conditions supported this aerobic cometabolism of PCE.

It is observed at many sites that naturally aerobic conditions prevent the natural reduction of PCE and TCE.  This is obvious when the suite of contaminants include high concentrations of PCE or TCE without daughter products.  Instead of working against the natural conditions to drive the aquifer conditions anaerobic to facilitate reductive dechlorination, a more sustainable approach is to use CL-Out aerobic cometabolism to remove the parent compounds without producing daughter products.  This approach has been used at hundreds of sites such as this example in Florida.

Contact CL Solutions for more information about this approach.


Fast Dry Cleaner Bioremediation

Case Study: Dry Cleaners Site, Southern California

Site Summary

CL-Out® fast dry cleaner bioremediation cost-effectively removed solvents from soil and ground water at a site in Soutern California.  After one application of CL-Out® bioremediation, the total chlorinated solvents concentration in ground water decreased by 90%. At the same time, the contaminant concentrations in soil decreased by an average of 85%. The remediation provided immediate risk reduction including avoiding vapor intrusion by vinyl chloride

Project Design and Implementation

Investigation found dry cleaning solvents in soil and groundwater around a dry cleaning machine. The solvent entered the soil below the building and percolated through the soil to a perched ground water.  The soil and sediments are interbedded alluvial and marine sediments with a high permeability.   The impacted soil volume covered approximately 80 cubic yards. The area of ground water impact and treatment covered approximately 2,000 square feet.

Based on the volumes of impacted soil and ground water, the remediation plan included five drums of hydrated CL-Out®.  Two drums treated the soil and perched ground water beneath the dry cleaning machine. Three drums treated the deeper ground water in the diffused area of the plume. The total injection volume was less than .1% of the pore volume of the treated soil and ground water.

CL-Out® bioremediation destroys chlorinated solvents by aerobic cometabolism. Dextrose provided the carbon source to support microbial growth. EHC-O by Adventus maintained the aerobic conditions to support cometabolism and prevent potential production of vinyl chloride.

Fast Dry Cleaner Bioremediation Results

Post–treatment soil and ground water sampling was approximately 30 days after the injection. The post-treatment soil samples came from locations adjacent to pretreatment sampling locations. The shallow soil samples all showed a decrease in solvent concentrations and no generation of vinyl chloride. Post-treatment ground water samples came from existing monitoring wells. The perched ground water showed a decrease in PCE concentrations but a slight increase in TCE and DCE concentrations. The deeper ground water showed a decrease in all concentrations. Vinyl chloride was not detected in either the perched or deep ground water. The following table shows the fast dry cleaner bioremediation results.

dry_cleaner_chart 6_11

The 30-sampling results show that the site progressing toward fast closure. Additional ground water treatment is unlikely to be necessary to achieve site closure after sufficient post-treatment monitoring.

Click here to learn more about CL-Out bioremediation.

Remediation of an Industrial Dry Cleaning Site

Site Summary

A CL-Out bioaugmentation pilot study verified the applicability of CL-Out remediation of an industrial dry cleaning site. The pilot study also determined whether the availability of oxygen to support cometabolism would limit the bioremediations.

Geology and Hydrology

Although the impacted ground water was relatively shallow, the site geology was complicated and varied across even this small site. In general the glacial deposits at the site were mainly till with interbedded sandy and silty zones. The impacted ground water was contained within the granular deposits.


The main ground water contaminant was PCE with lower concentrations of TCE, cis -1,2 DCE and vinyl chloride. In the pilot study area, the PCE concentration was 44,200 μg/L and the total of the daughter products was 14,750 μg/L.

Pilot Study Design

A pilot study was completed in the source area in the fall of 2009. One unit of CL-Out was injected into the affected ground water in the source area. One unit of CL-Out is a 55-gallon slurry with a microbial concentration of 109 cfu/ml. The CL-Out microbes were injected with 50 pounds of dextrose to provide a carbon source to support the energy requirements of the population. Pre- and post -treatment samples were taken on February 19 and December 10, 2009. The post-treatment sample was taken after the monitoring well was purged of the injected volume. The following table shows the contaminant concentration trends in the treatment area.



The pilot study verified the applicability of CL-Out bioremediation to the site. The total concentration of CVOCs was reduced from 59,000 to 13,740 μg/L. The CL-Out bioremediation was most effective in the removal of PCE and TCE. There was an increase in vinyl chloride suggesting some incomplete reductive dechlorination, probably by native dehalogenating organisms. Full-scale treatment will be most effective with the addition of an oxygen supplement to limit the dehalogenation and promote the cometabolism of the daughter products. Overall the push-pull pilot study verified the effectiveness of CL-Out bioremediation and provided insights for making full-scale application more effective.