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1,1,1-TCA Bioremediation at an Industrial Site in Dayton, Ohio

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Fast, Economical Site Cleanup

CL-Out bioremediation reduced the concentration of 1,1,1-TCA in ground water at a steel manufacturing facility in Dayton, Ohio. Following implementation of ozone treatment and high vacuum extraction for more than 2 years, the contaminant concentrations remained high.  Bioaugmentation followed up on these treatments and reduced the 1,1,1-TCA concentration very quickly.  Within 30 days of bioaugmentation, the source area contaminant concentration decreased by 80%.  After a second application, the concentration decreased from the pre-treatment concentration of 1,100 ug/L to 1.4 ug/L.  The bioaugmentation effect was observed as far as 250 feet downgradient where the concentrations decreased by more than 50%.  Click here for the full case study.

 

 

Improving Long-Term Bioremediation Results with Nutrients

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Adding Nutrients Increases Long-Term Population and Bioremediation Results

The goal of bioaugmentation is to improve the rate of contaminant removal by adding a high population of beneficial microbes to the contaminated media.  The additional microbes  should provide short-term benefit as the microbes begin metabolizing the contaminants immediately upon injection. But what benefit does bioaugmentation provide in the long term? And how much benefit does bioaugmentation provide over biostimulation by adding nutrients to the native organisms?

A client of CL Solutions completed a bench-scale study to answer these questions.  A bench-scale study was preferred to a field study because it removes the potential distribution and time-lag issues associated with the distances between injection and monitoring locations in the field.

Samples of petroleum-contaminated soils were obtained and separated into split samples for treatment with microbes and nutrients. Some were untreated for comparison.  Samples were tested for petroleum concentrations, including C-fraction concentrations after 30, 40 and 60 days.  Heterotrophic populations were measured at 40 and 60 days.

The tests showed the following results in the early stages:

  • All of the treated samples showed more than 80% total petroleum reduction in the first 30 days.
  • The sample treated with nutrients only had the same level of petroleum removal as the bioaugmented samples in the first 30 days.
  • The heterotrophic population of the biostimulated sample was as high as in the bioaugmented samples at 40 days.

After 30 days the situation changed.

  • The bioaugmented microbial population continued to increase  after 40 days and may have increased by a factor of 100 times.  Meanwhile, the biostimulated population appeared to stall.
  • The petroleum removal continued in the bioaugmented samples and reached as high as 93% removal.  In comparison the biostimulated sample stalled at 82% removal.
  • The difference appears to be that the bioaugmented samples removed the C-21 to C-35 concentrations at a much higher rate than the biostimulated sample.
  • Phenanthrene was target chemical for bioremediation. The biostimulated sample showed 39% removal while the bioaugmented samples showed complete removal to BDL.

Overall, the superior performance of the bioaugmented samples appears to be related to having a greater metabolic range that removed the heavier hydrocarbon fractions.  Microbes with the extended metabolic range could continue to multiply as they grew on the heavy hydrocarbon fraction.  The results are consistent with field results showing the recalcitrance of heavier hydrocarbon fractions and compounds like naphthalene and phenanthrene under natural attenuation.

Contact CL Solutions for more information and insights.

 

 

 

 

 

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.

Overcoming TCE Cometabolism Rate Limits

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Aerobic cometabolism of TCE may be limited by the potential microbial toxicity of by products or by product metabolic repression.  An independent comparison of induced cometabolism using soluble methane and CL-Out bioaugmentation showed that CL-Out bioaugmentation removed more TCE.  The TCE removal rate by CL-Out when supplemented with an oxygen source was a steady rate that continued past apparent limits of induced cometabolism.  The significant difference may be in that the population of beneficial microbes that can be added is much higher than the population level that may be achieved through biostimulation.  For a brief summary of the study follow this link Overcoming TCE Metabolic Limits.

Surface Spills to Deep Subsurface Success With Petrox Bioremediation

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Petrox bioremediation is used to remove petroleum contamination from soil and water under many different conditions.  From surface spills to deep soil and ground water contamination, Petrox has successfully removed the contamination and environmental risk.  This summary of case studies demonstrates the applicability of Petrox bioremediation to the full range and life cycle of petroleum spills. Click here to view the document.