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Fast Bioremediation Eases Site Development in Boston

Underground storage tank (UST) leaks from a former gas station contaminated shallow ground water under a parking lot for a commercial building.  The UST contamination was found during trenching for utilities.  As the presence of contamination prevented further property development, fast remediation was important to the stakeholders.

The size of ground water plume that resulted from leaching soil contaminants was estimated to be 5,000 square feet.    The contamination was mainly diesel-range petroleum constituents, with the highest concentrations in the aliphatic range, but there were also scattered detections of xylene, toluene, and ethylbenzene.

Petrox bioremediation was implemented in the ground water.  Three units of Petrox (165 gallons) were injected into the contaminated ground water through vertical injection wells located up gradient of the monitoring wells.

After a single inoculation of Petrox, the contaminant concentrations were reduced across the property.  The following table shows the overall reduction in both the volatile and semi-volatile range hydrocarbons.

Presentation1

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

 

Bioremediation of BTEX at an Industrial Site in Florida

Background

Petrox® bioaugmentation was used to remediate ground water contaminated by benzene, toluene, ethylbenzene and xylene (BTEX) at an industrial facility in central Florida (Facility ID No. 8521705). The bioremediation was implemented in perimeter wells around the source area where air sparging and vapor extraction was implemented. This combined approach provided cost-effective, full-site remediation by using complementary technologies.

Remediation Approach and Results

Petrox® was introduced into the contaminated ground water in the perimeter of the source area plume by injection through temporary well points. Two applications of Petrox® were completed. The initial application was in December 2007 and a subsequent application was completed in April 2008. During each application 550 gallons of Petrox® microbial slurry were injected into the ground water through 19 injection points. The treatment covered an area of approximately 7,000 square feet.

The ground water treatment results were monitored by laboratory analysis of ground water samples for the contaminants of concern. The quarterly monitoring results after the applications showed an immediate and continuous decrease in the BTEX concentrations. The following chart shows the total BTEX concentrations in three quarterly sampling events after the implementation of Petrox® bioaugmentation.

industrial-site6

Conclusions

This project demonstrates two of the benefits of aerobic bioaugmentation. Petrox® organisms were able to metabolize the BTEX compounds, which were initially at part per million levels, to below detection limits. Bioaugmentation provides active control of the site with hydrocarbon-degrading organisms compatible with air sparging and vapor extraction in the source area, where the contaminant concentrations persisted longer than in the bioaugmentation area.

Petrox® Bioaugmentation in Bedrock

Case Study: Petroleum Remediation in Central New Jersey

Summary

Petrox® bioaugmentation was implemented at a petroleum remediation site in Morris County, New Jersey to destroy residual petroleum compounds in ground water. The impacted ground water was in bedrock fractures under and down gradient of a former UST location. The UST was removed and an oxygen release compound was added to the ground water to stimulate bioremediation. However, residual contamination persisted and Petrox® bioremediation was implemented to remove the residual low concentration found at the site.

Geology and Hydrogeology

The bedrock surface was fairly close to the ground surface and the first ground water encountered upon drilling at the site was within the bedrock. Impacted ground water was contained within the fractures near the bedrock surface in a zone estimated to be 40 feet thick.

Contamination

Low concentrations of benzene, xylene, ethylbenzene and toluene were present in ground water at and down gradient of the former UST cavity. The area of proposed treatment was 3,600 square feet.

Implementation

Petrox was applied in two monthly applications of 8 units each. One unit of Petrox® is a 55-gallon slurry with a microbial concentration of 109 cfu/ml. ORC socks were installed in treatment wells to provide an oxygen source for the petroleum metabolism.

The monthly Petrox® injections were on May 29, 2009 and June 26, 2009. Post -treatment samples were taken on June 10, 2009 and May 4, 2010. The following table shows the contaminant concentration treads in the treatment area.

case-study-6-table

Results

The treatment was successful in reducing the BTEX concentration at the site. However, the increase in concentrations after the first treatment showed that there were residual petroleum constituents in the source that was not reflected in the pre-treatment sampling. Petrox® microbes were detected in all of the bedrock sampling points as far as 30 feet down gradient of an injection point. Overall the treatment verified the effectiveness of Petrox® bioaugmentation in fractured bedrock.