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CL-Out Bioremediation of Ground Water in Clay Soils

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Successful In Situ Remediation in Low Permeability

CL-Out bioremediation of groundwater in clay soils reduced concentrations of PCE and TCE at a former dry cleaners in Moline, 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.

Contact us for a free assessment of your site for bioremediation.

How Aerobic PCE Bioremediation Works

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How CL-Out Aerobic PCE Bioremediation Works

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, where 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.

 

 

How Key-hole Bioremediation Reduces Source and Down-gradient Contamination

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CL-Out aerobic PCE bioremediation in a keyhole treatment reduced the mass of contamination near the source and down gradient concentrations in the plume.  At a former manufacturing facility in Cincinnati, 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.

Source area concentrations decreased as follows after one treatment with CL-Out bioremediation:

  • PCE decreased from 120,000 to 12 ug/L.
  • TCE decreased from 2,000 to 12 ug/L
  • Cis 1,2-DCE decreased 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  incomplete reductive dechlorination by other naturally occuring organisms.

Down gradient from the source, the concentrations decreased with slight to no increase in daughter products.  The  down gradient plume had the following results:

  • PCE decreased from 5,000 to 1,600 ug/L.
  • TCE decreased from 43 ug/L to BDL.
  • Cis 1,2-DCE decreased 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.

Aerobic PCE Bioremediation By Cometabolism

CL-Out is a consortium selected for aerobic PCE bioremediation.  CL-Out cometabolizes PCE by growing on a simple sugar and producing a metabolic enzyme to degrade PCE.  The microbes produce a dioxygenase enzyme that breaks the carbon bond in PCE.  This reaction eliminates the biproducts of reductive dechlorination.  Also, the synergistic effect of the CL-Out consortium cometabolizes the full suite of chloroethenes and chloroethanes.

Click here to learn more about CL-Out bioremediation.

PCE Bioremediation in Aerobic Groundwater

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PCE bioremediation in aerobic groundwater by CL-Out microbes reduced environmental risk at a printing company in Kentucky.  Testing found high concentrations of PCE in perched ground-water.  The ground water aquifer was in sn alluvial sand deposit with high permeability.  The high permeability facilitated injection for in situ treatment.  Also, the high permeability of the aquifer matrix also supported aerobic ground water conditions.  With one application of CL-Out the concentration of PCE decreased from 3,600 ug/L to 250 ug/L in less than 45 days.  With further applications the concentration was reduced to below detection limits in 10 months.

Aerobic PCE Bioremediation By Cometabolism

CL-Out is a consortium selected for aerobic PCE bioremediation.  CL-Out cometabolizes PCE by growing on a simple sugar and producing a metabolic enzyme to degrade PCE.  The microbes produce a dioxygenase enzyme that breaks the carbon bond in PCE.  This reaction eliminates the biproducts of reductive dechlorination.  Also, the synergistic effect of the CL-Out consortium cometabolizes the full suite of chloroethenes and chloroethanes. Read more…

Click here for more information about CL-Out bioremediation.

CL-Out Pilot Study Vandenberg AFB

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Successful Aerobic Cometablism

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.