Posts

In Situ CL-Out Bioremediation of Industrial Solvents

Case Study :

Industrial Manufacturing Site, Illinois

Remediation Summary

Leaks from an aboveground solvent tank impacted soil and ground water quality at a manufacturing site in Illinois.  The impact was found under the adjoining building as well as the area near the tank.  The soil and ground water were treated in situ with CL-Out® bioremediation microbes.  Through cometabolism CL-Out® microbes reduced the contaminant concentrations to acceptable levels in less than one year.

Contaminants Soil Results (mg/Kg) Ground Water Results (mg/L)
Pre-Treatment Post- Treatment Pre-Treatment Post- Treatment
PCE 41.8 1.69 5.59 0.006
TCE 4,670 632 15.6 0.026
Cis 1,2-DCE 171 56.6 7.43 0.029
Vinyl Chloride BDL BDL 0.095 0.013

Implementation and Results

Soil Type:  Silty clay till

Treatment Area:  15,000 sq. ft.

Unsaturated soil thickness:  16 ft.

Saturated aquifer thickness:  5 ft.

Treatment: Two applications, initial treatment with 13 units of CL-Out® and follow up treatment with 5 units.

Product Cost: $30,000

Conclusions

CL-Out® bioremediation quickly and cost-effectively reduced the contaminant concentrations to acceptable levels.  Through cometabolism the parent and daughter products were removed simultaneously.  CL-Out® bioaugmentation accelerated the site remediation and reduced uncertainty by applying the right microbes where they were needed.

Aerobic Cometabolism of PCE at an Industrial Site in Tampa, Florida

Project Summary

Degreasing solvents were found in the ground water at an industrial manufacturing facility in Tampa, Florida.  The solvents include PCE and its associated breakdown products. The source of the ground water contaminants was found to be a former water treatment system drain field.  CL-Out® bioremediation was implemented to reduce the volume of contamination in the source area and down gradient. CL-Out® is a consortium of Pseudomonas sp. that produces constitutive enzymes to cometabolize PCE and other halogenated solvents.  Dextrose is added with CL-Out® to provide a substrate for microbial growth.  Application of CL-Out® bioremediation at this site reduced the total chlorinated solvent concentrations as much as 99% in less than 6 months.

Geology and Hydrogeology

The site is located in Tampa, Florida where the geology is characteristically interbedded silt and sand.  The background ground water redox conditions of the aquifer are not known.

Contamination

The PCE and elevated concentrations of daughter products were found in ground water down gradient of the former drain field.  The PCE concentrations were as high as 280 µg/L and DCE concentrations were as high as 4,400 µg/L, which indicates that there was significant contaminant degradation occurring, but the natural degradation stalled at DCE.   Petroleum hydrocarbons were also present in the ground water and may have served as an oxygen sink during the degradation of the petroleum products.

Remediation Design

CL-Out bioremediation was implemented in the ground water to accelerate the remediation of the source area.  A 55-gallon slurry of  CL-Out was injected on February 11, 2003.

Monitoring wells in the source area and surrounding area were sampled to assess the progress of the remediation.   The following table shows the pre-treatment and post-treatment CVOC concentrations in a source area monitoring well (MW-1) near the application of CL-Out.

 Source Area (MW-1)

Sampling Date CVOC Concentrations (µg/L)
  PCE TCE DCE VC
3/28/02 280 750 4,400 BDL
12/19/02 86 120 1,100 BDL
2/11/03 CL-Out Injection
2/24/03 350 280 1,600 BDL
7/7/03 4.6 6.0 63 BDL

RESULTS

After application CL-Out bioaugmentation the chlorinated solvent concentrations in MW-1 decreased by as much as 99%.  Overall the total mass of contamination was significantly diminished by the bioaugmentation in a short period of time to accelerate the natural degradation.

Cometabolism of 1,1,1-TCA in a Mixed Solvent Plume

One of the benefits of CL-Out cometabolism is that the enzymes produced by the Pseudomonas sp. organisms convert a wide range of organic chemicals into organic acids that can be metabolized.  The aggressive application of CL-Out organisms to soil and ground water at a chemical mixing company removed the source of ground water contamination by chloroethanes and chloroethenes,  including PCE and 1,1,1-TCA.  The aerobic cometabolism of these compounds achieved MCLs in less than 6 months.  Click here to view the case study Mixed Solvent Plume Cometabolism by CL-Out

Overcoming TCE Cometabolism Rate Limits

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.

Field Bioremediation Rates For Petroleum and Solvents

The success of bioaugmentation depends on effective distribution of the beneficial microbes.  If the target population is achieved, the remediation rate ranges from 50% to over 99% removal.  The rate appears to be independent of the contaminant starting concentrations.  This indepedence is the advantage of bioaugmentation.  Through bioaugmentation the density of beneficial organisms is sufficient for frequent reactions with high or low contaminant levels.  The following chart shows the results of a single application of bioaugmentation at 11 sites in different states, with different contaminants.

remediation rates with bioaugmentation

 

The chart also suggests that the results are not time dependent.  The apparent time independence may be because the reactions are completed early and because these were grid applications with the monitoring locations within the bioaugmented area instead of downgradient where the results would depend on dispersion rates.

The USEPA tested the degradation rate of oil using Munox SR for NCP listing.  The degradation rate exceeded most comparable products with 95% removal of alkanes and 89% removal of aromatics in 28 days.  The NCP test results are available at https://19january2017snapshot.epa.gov/sites/production/files/2013-08/documents/notebook.pdf