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In Situ Bioremediation of TPH with Petrox

Petrox reduced the concentration of TPH in soil at a former gas station from 9,500 mg/kg to 52 mg/kg. The impacted soil was at more than 20 feet deep.  Injection of calcium peroxide provided the oxygen needed for metabolism of the petroleum by Petrox microbes.  The post treatment sampling was 90 days after the bioaugmentation, so that even though the average remediation rate was 105 mg/kg/day, the peak remediation rate must have been much higher when the Petrox population was higher.

This is another example of fast, reliable bioremediation by Petrox organisms.

In-situ Bioremediation of BTEX, TPH and PAHs in Groundwater

Convenience Store in Florida

After three underground storage tanks were removed from the location of a convenience store, investigation showed that petroleum contamination was present in small area near the former dispenser island.  The vadose-zone contaminated soil was excavation and disposed off-site.  Ground water monitoring showed that the ground water impact was limited to a small area near the source of contamination. The decision was made to close the site by applying Petrox® bioremediation to the ground water.

Ground Water Contamination

The ground water contamination was in a shallow water table aquifer that had a medium permeability.  The contamination was a suite of BTEX, PAHs, methylnaphthalene isomers and TRPH.

Bioremediation

A pilot study was completed to determine feasibility of Petrox bioremediation combined with a peroxide oxygen supplement.  The pilot study reduced contaminant concentrations by up to 92%.  A full-scale application completed the site remediation.

Results

The pilot study and full-scale applications of Petrox and an oxygen supplement reduced BTEX compounds by >99%, naphthalene by 99%, TRPH by 96% and naphthalene isomers by 88% to achieve the remediation goals and site closure.  The microbial cost for the pilot study and full-scale treatment was less than $2,000.

To learn more, click here to download the case study.

Improving Long-Term Bioremediation Results with Nutrients

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.

 

 

 

 

 

BTEX and Naphthalene Bioremediation to BDL by Petrox Microbes

Case Study:
Orange County Fire and Rescue Station 81, Orlando, Florida

Oculus Number 8520434

Petrox was used to treat the residual petroleum contamination in ground water after the leaking tank was removed.  The petroleum contamination exceeded applicable standards for benzene, toluene, ethylbenzene, and xylene (BTEX) and naphthalene.  Petrox was injected into the ground water through 28 injection points covering a plume area of approximately 6,300 square feet.   Petrox injections were completed on June 18, September 11, and November 1, 2002.

Prior to bioaugmentation 100 pounds of ORC was added to provide supplemental oxygen for the bioremediation.  After verifying the dissolved oxygen concentration was more than 1.0 mg/l, the site was ready for bioaugmentation.

During the first injection 10 drums of Petrox were injected to cover the full plume.  As the area of contamination decreased, less Petrox was injected.  Five drums were injected in a focused application on September 11 and November 1, 2002.

Quarterly monitoring was completed during and after the inoculation to determine the bioremediation results.  The cleanup goals were achieved in the source area after the first inoculation.  The contamination persisted, however, in the down gradient wells.  The cleanup goals were achieved in the down gradient monitoring well after the third injection, but there was subsequent rebound.  After full distribution of Petrox was reached throughout the plume, the BTEX and naphthalene concentration were below detection limits (BDL), and cleanup goals were achieved and maintained. 

Please refer to the table below for the ground water monitoring results.

Monitoring Well Date Benzene Toluene Ethylbenzene Total Xylenes Naphthalene
MW-7 Source Area 6/12/2000 5.0 46.0 18.0 90.0 24.0
6/13/2001 39.0 272.0 167.0 526.0 26.0
3/14/2002 21.0 19.0 102.0 266.0 39.0
6/5/2002 ORC Added
6/18/02 10 Drums of Petrox Added
7/14/2002 <1.0 <1.0 <1.0 <2.0 <1.0
9/11/2002 <1.0 <1.0 <1.0 <2.0 <1.0
9/11/02 5 Drums of Petrox Added
10/7/2002 <1.0 <1.0 <1.0 <2.0 <1.0
11/1/02 5 Drums of Petrox Added
12/2/2002 <1.0 <1.0 <1.0 <2.0 <1.0
1/9/2003 <1.0 <1.0 <1.0 <3.0 <5.0
4/17/2003 <1.0 <1.0 <1.0 <2.0 <1.0
             
MW-8

Down Gradient

6/12/2000 2.0 72.0 21.0 109.0 39.0
6/13/2001 14.8 677.0 207.0 1292.0 113.0
3/14/2002 71.0 1198.0 357.0 2408.0 193.0
6/5/2002 ORC Added
6/18/02 10 Drums of Petrox Added
7/15/2002 19.0 515.0 170.0 690.0 39.0
9/11/2002 <1.0 3.7 3.8 16.4 <1.0
9/11/02 5 Drums of Petrox Added
10/7/2002 6.4 2.3 4.7 23.8 15.0
11/1/02 5 Drums of Petrox Added
12/2/2002 38.0 515.0 95.0 460.0 10.0
1/9/2003 <1.0 <1.0 <1.0 <3.0 <5.0
4/17/2003 <110.0 1060.0 285.0 1120.0 65.0
4/29/2004 <1.0 <1.0 <1.0 <1.0 <1.0
9/1/2004 <1.0 <1.0 <1.0 <1.0 <1.0
12/1/2004 <1.0 <1.0 <1.0 <1.0 <1.0
3/21/2004 <1.0 <1.0 <1.0 <1.0 <1.0

Fast Naphthalene Bioremediation Using Petrox

South Carolina Industrial Site

Petrox microbes were injected in a petroleum ground water plume to remove contamination at an industrial site.  With one application, the petroleum constituents were below detection limits in under six months.

  Sampling Date Benzene

(ug/L)

Toluene

(ug/L)

Ethylbenzene

(ug/L)

Xylene

(ug/L)

Naphthalene

(ug/L)

Pre-Injection 1/8/14 210 1,100 180 3,500 530
30 Days After 4/25/14 58 300 28 1,100 65
6 Months After 9/3/14 <0.2 <1.7 <1.7 <1.7 <1.7

Petrox is a blend of  Pseudomonas sp. formulated to degrade a wide range of petroleum hydrocarbons including BTEX and naphthalene contaminants.  The application of Petrox at the case study site overcame some of the recalcitrance of xylenes and naphthalene that can result in slow remediation.