Bioremediation of Dinitrotoluene

Dinitrotoluene (DNT) may occur in soil and ground water as the result of spills and historical use of the chemical as a solvent and industrial intermediary or as a residual of explosives at military facilities.  CL Solutions and SpecPro, Inc. conducted a treatability study to determine the effectiveness of CL-Out microbes in the removal of DNT from contaminated ground water at the Badger Army Ammunition Plant (BAAP) near Baraboo, Wisconsin.  The treatability study showed the removal of all six isomers of DNT, with a 53% to 91% removal in 21 days.  Intermediate by-products were detected only temporarily during the treatability study.  For more detailed information call CL Solutions.

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.



TCE Aerobic Cometabolism Using Cl-Out

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


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.



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.