Nitrate and Perchlorate Bioremediation in Ground Water

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In Situ Bioremediation Eliminated Pump and Treat and Ion-Exhange Treatment Cost 

Site closure reached in less than half the time and at less than half the cost

CL-Out® bioremediation was implemented at a confidential manufacturing site to remediate nitrate and perchlorate concentrations in soil and ground water.  A pump and treatment system was installed and operated for years in immediate response to the discovery of contamination. While perchlorate was considered the primary contaminant,  the ion-exchange resin became quickly saturated with nitrate, which was present at much higher concentrations than the perchlorate.  In situ bioremediation was implemented to reduce the on-going cost of ground water extraction and treatment.

One of the key factors in CL-Out® cometabolism of perchlorate at this site was that CL-Out® organisms were able to reduce sequentially the oxygen and nitrate prior to perchlorate. The initial nitrate concentrations were typically much higher than the perchlorate concentrations. The perchlorate concentration did not decrease until the nitrate concentration decreased to less than the perchlorate concentration. One of the benefits of the CL-Out® organisms was this ability to utilize these different electron acceptors.

In eight months, the perchlorate concentration in the unconsolidated aquifer was reduced from 128 mg/L to 3.4 mg/L immediately down gradient of the source area and from 220 mg/L to 39 mg/L farther down gradient.

Simultaneously, the CL-Out® microbes also removed the nitrate. Down gradient of the source area the nitrate concentration decreased from 105 mg/L to <1.0 mg/L.  Farther down gradient the nitrate concentration decreased from 200 mg/L to 5 mg/L.

The in situ bioremediation provided immediate risk reduction and mitigated potential off-site migration. The contaminant levels were reduced to the remediation target in 3 years, saving 5 years of projected treatment time and millions of dollars in OM & M costs.  The property sold without environmental impairment upon completion of bioremediation.

 

 

 

 

Bioremediation of Phthalates

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Phthalates are a  a family of common industrial chemicals used in plastics and other consume products.  Phthalates can damage the liver, kidneys, lungs and reproductive system.  Petrox microbes can remove these contaminants from water or soil to reduce potential exposure to these risks.

Petrox bioremediation of phthalates has been demonstrated in field and laboratory studies to remove phthalates from soil and ground water.  Field application of Petrox bioremediation reduced bis(2-ethylhexyl)phthalate (BEP) concentrations from 650 ppm to 397  ppm in soil and 300 to 39 ppb in ground water at a site in Rochester, New York.  At the same site di-n-octylphthalate (DOP) in soil was reduced from 7.5 to 1.9 ppm. Click here to view the case study.

Keyhole Treatment – Cost Effective Plume Treatment Through Source Removal

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CL-Out bioremediation was used in a keyhole treatment to reduce the mass of contamination near the source and down gradient concentrations in the plume.  At a former manufacturing facility in 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 was reduced from 120,000 to 12 ug/L.
  • TCE was reduced from 2,000 to 12 ug/L
  • Cis 1,2-DCE was reduced 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 some incomplete reductive dechlorination.

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

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

TCE and 1,1,1-TCA Bioremediation at Indiana Industrial Site

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Cl-Out bioremediation successfully remediated TCE and 1,1,1-TCA and other chlorinated solvents in ground water under a drum storage area at a central Indiana industrial site.  After  three  monthly applications  of CL-Out microbes, the in situ treatment reduced total maximum CVOC concentrations from 102 mg/L to 3 mg/L in less than 6 months. Click here to view the complete case study.

Compatible Technologies to Improve In-Situ Remediation of Chlorinated Solvents: A Case Study

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A chlorinated solvent plume (perchloroethylene or PCE) was discovered
in the shallow ground water as a result of historical operating practices surrounding a
Houston area dry cleaning facility. 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 ongoing 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 for a link to the full report from the 2007 Battelle Conference on Bioremediation