CL-Out Bioremediation of Groundwater in Clay Soils

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CL-Out bioremediation of groundwater in clay soils reduced concentrations of PCE and TCE at a former dry cleaners in Illinois.  In just over 2 weeks after injection, CL-Out microbes cut the contaminant concentrations in half.

  • PCE from 62.2 to 25.6 mg/L
  • TCE from 11.2 to 6.0 mg/L
  • Cis 1,2-DCE from 3.8 to 1.2 mg/L
  • Vinyl chloride less than 0.001 mg/L before and after treatment

The remediation continues as the microbes grow and cometabolize the residual contamination.  Even in tight clay soils the aerobic cometabolism remediates dry cleaning solvents without producing vinyl chloride or other dangerous by products.

Aerobic PCE Bioremediation

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CL-Out Aerobic PCE Bioremediation Pilot Study Results

A CL-Out bioremediation pilot study confirmed that aerobic PCE cometabolism removed dry cleaning solvent contamination from ground water.  The pilot study was located at a former dry cleaners.  At the site, the PCE in ground water was 27 parts per billion (ppb).  Bioaugmentation introduced CL-Out microbes and dextrose as the metabolic substrate by injected into the ground water up gradient from the sentinal monitoring well.  After 30 days the PCE concentration decreased to 20 ppb.  After 6 months the PCE concentration decreased to 16 ppb.

As the PCE was decreasing, the site conditions stayed aerobic.  The dissolved oxygen level in ground water decreased from 1.07 to 0.71 mg/l.  Meanwhile,  the ORP decreased from 99 to 45 mv.  These aerobic aquifer conditions support the conclusion that the PCE removal was through aerobic bioremediation.

CL-Out cometabolism uses a dioxygenase enzyme that is produced constituatively as the metabolic substrate is consumed.  The dioxygenase enzyme destabilizes the carbon bond in the PCE to convert the molecule to an organic acid that leads to complete mineralization. Click here to view the PCE and TCE cometabolic degradation pathways.

CL-Out is a consortium of naturally-occurring microbes.  The microbes have the benefits of metabolic diversity and environmental stability.  They are non-pathogenic and safe for human health and the environment. Click here to find out more about CL-Out bioremediation.

 

 

Bioremediation of a Dry Cleaners

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Cost-effective Bioremediation of a Dry Cleaners Quickly Removed Contamination

Historical operations at a Houston area dry cleaners resulted in a chlorinated solvent plume (perchloroethylene or PCE) in the shallow ground water. Permeable shallow soil at the site allowed rapid vertical migration at the source and lateral migration in the shallow ground water. This migration resulted in an off-site migration of the plume beneath an apartment complex causing concern for potential vapor intrusion hazards; as well as, a decrease in property value.

A ground-water extraction and treatment system was installed to address the
dissolved phase concentrations. The system reduced the total volatile organic compound
(VOC) concentration in the source area from 115,400 to 36,500 µg/l. However, over
time, operating maintenance and cost escalations were exceeding the on-going remedial
benefit. The system was shut down after nine years of operation.

A review of available remedial technologies that could be implemented within the physical constraints of the
site was conducted. In-situ enhanced aerobic bioremediation was selected to address the
remaining ground-water concentrations because of the permeability of the formation, the
relatively aerobic conditions, and the benefit of reducing the risk of VC accumulation.  Click here to view the aerobic cometabolic degradation pathway.

Click here for a link to the full report from the 2007 Battelle Conference on Bioremediation

 

Aerobic Bioremediation of PCE and TCE

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CL-Out aerobic bioremediation PCE and TCE is a sustainable process for soil and ground water remediation.  As these compounds are not directly metabolized under aerobic conditions, the competitive advantage goes to the CL-Out organisms that cometabolize them.  While utilizing a sugar substrate, the CL-Out organisms produce  mono- and dioxygenase  enzymes that bridge the carbon bond to destabilize the compound.   The solvent is converted to an organic acid that the organism can metabolize.  View the degradation pathway.  The benefit is that CL-Out bioremediation can be applied to soils both in situ and ex situ.  Click here for to download a case study.  For further explanation call CL Solutions at 513-284-5940.

Case Study of In-Situ Bioremediation of Recalcitrant Organics

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A history of spills and/or releases at two adjacent dry cleaning facilities near Houston, TX, resulted in significant soil and shallow groundwater contamination with PCE and daughter products. Soil was relatively permeable, with rapid groundwater flow beneath the site. A long, narrow, off-site plume extended beneath a residential neighborhood. Chemical oxidation was employed initially with only limited success in the areas of highest contamination. To take advantage of the soil permeability and other site conditions, the response action was amended to include enhanced aerobic bioremediation by cometabolism. Specialty microbes were introduced into the plume in several injections over a 15-month period. This approach achieved total contaminant level reductions in the source area from 1,600 to less than 40 µg/L, and at the front edge of the plume, levels decreased from 500 to 5 µg/L.

For the full case study click here:

Brusenhan, J.D., M.F. Marcon, and M.T. Saul, CL-Solutions, LLC. A&WMA’s 98th Annual Conference and Exhibition, 21-24 June 2005, Minneapolis, Minnesota, Paper 1069, 10 pp, 2005