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 9^th 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).

CL-Out bioremediation 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 the 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.

Cometabolism is considered the indirect beneficial destruction of a contaminant compound by a microorganism that is growing on another substrate. While the benefit may be fortuitous, cometabolism can be directed and controlled to improve the environmental benefit.

CL Solutions has used cometabolism in three ways for bioremediation of different types of compounds.

• CL-Out® is a consortium of microbes that cometabolize chlorinated solvents under aerobic to anoxic conditions. The microbes metabolize dextrose as a primary substrate and constituatively produce dioxygenase enzymes that convert PCE, TCE and other chlorinated aliphatic compounds into organic acids that are metabolized.

• CL-Out® has been used to remove perchlorate from soil and ground water while growing on a substrate and using perchlorate for respiration. The substrate provides a carbon source and the perchlorate reduced by respiration. This approach can also be used for denitrification.

• In a novel approach, a simple sugar can be used as a substrate to support microbial growth when the concentrations of the target contaminant are too low to support an effective population density. This approach was used for pesticide bioremediation when the ground water concentrations were less than 0.1 µg/L and the remediation goal was 0.002 µg/L.