What is MEOR?

MEOR is microbial enhanced oil recovery.  Some microbes produce biosurfactants that increase the water-solubility of oil.  The biosurfactants’ benefit microbes by making it easier for the microbes to metabolize oil.  Additionally, the biosurfactants can strip oil from rock and soil surfaces to improve environmental remediation by extraction, air stripping, or sparging.

The Pseudomonas sp. in Petrox are naturally occuring petroleum-degrading microbes with the broadest metabolic capabilities.  Their production of biosurfactants is one of their features that makes them so effective.  Pseudomonas sp. produce both glycolipid and lipopeptide surfactants.

An initial increase in concentrations may be observed after Petrox is used at a site due to the biosurfactants.  However, the concentrations decrease as the microbes metabolize the oil.  This feature has been used to remove oil safely from inaccessible or sensitive locations such as near utilities, tanks or building structures.

Micorbial Insights, Inc. (micorbe.com) has biosurfactant assays available t0 test for the presence of the genes in Pseudomonas sp. and other organisms that produce biosurfactants.  If tests show that they are abscent from a site, you can enhance the oil recovery with Petrox and the surfactants it produces.

In addition to the biosurfactants that Petrox produces, a non-ionic surfactant is added to Petrox to formulate Petrox EC.  This combination makes Petrox EC a strong cleaning agent to remove oil and grease from surfaces or contaminated subsurface soil or rock.

CL Solutions continues to expand the use of biological products such as Petrox and Petrox EC for bioremediation and microbial enhanced oil recovery.

Fast BTEX and Methylnaphthalene Bioremediation

Petrox and Methylnaphthalene Bioremediation Site Summary

Petrox microbes accelerated BTEX and methylnaphthalene bioremediation at a former fueling station in Florida.  After a leaking tank underground storage tank (UST) was removed,  the consultants injected Petrox micorbes into the groundwater. A temporary well showed high concentrations of BTEX, methylnaphthalene isomers, and total recoverable petroleum hydrocarbons (TRPH) in the former tank location.  A permanent monitoring point replaced the temporary well. Since the contaminants were not detected outside of the UST cavity, the treatment focused on the cavity and its proximity. The consultant injected Petrox  into the ground water through 12 direct-push injection points in and around the UST cavity. They used approximately 10 gallons of Petrox solution at each of the injection points in August 2001. After one injection of Petrox, petroleum hydrocarbons concentrations decreased below detection levels in the UST cavity.  Please refer to the table below for the ground water monitoring results.

Persistence in Soil and Low Ground Water Concentrations

Methylnaphthalene and naphthalene persist in soil after other volatile components of fuels are gone.  The persistence comes from to their relatively high affinity for adsorption to soil and relatively low water solubility.  These factors account for the common rebound of ground water concentrations. Despite high concentrations of naphthalene and methylnaphthalene in soil near the ground water table, often the dissolved  concentration in the ground water is very low.  The accumulation of these compounds at the water table causes a problem for remediation.  Frequently after ground water remediation, seasonal fluctuation of the water table through the contaminated vadose zone recharges the concentrations of these compounds.  This results in seasonal fluctuation in the ground water concentrations.

Methylnaphthalene Metabolism

The microbes in Petrox  accelerate the remediation because they product an extracellular biosurfactant that desorbs the methylnaphthalene to make it available for extraction or for in situ bioremediation.  At this site, the contaminated soil was removed to the water table, so concentrations did not rebound after the initial ground water remediation.  At other sites where Petrox bioremediation addressed methylnaphthalene or naphthalene, the consultant combined bioremediation with extraction.  The combined technologies removed the contamination flushed from the soil in addition to the bioremediation.  Click here to view case studies from other sites.

Methylnaphthalene Bioremediation


Ammonia Bioremediation in Poultry Waste

Specially selected microbes treat poultry processing wastewater to reduce nitrogen and organic waste levels

Ammonia bioremediation prevents waste problems at poultry p[roducers.  Petrox DN organisms reduced ammonia-nitrogen  and BOD levels in the same wastewater reactor.  The organisms in Petrox removed 40% of the ammonia-nitrogen in 48 hours.  This reduction stabilized the concentrations in wastewater effluent to an acceptable level eliminating permit exceedances.

Nitrate and Perchlorate Bioremediation in Ground Water

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

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

CL-Out® bioremediation was implemented at a confidential manufacturing site to remediate nitrate and perchlorate concentrations in soil and ground water.  The consultant installed a pump and treatment system that was operated for several years in immediate response to the discovery of contamination. While perchlorate was  the primary contaminant,  the ion-exchange resin became quickly saturated with nitrate, which was present at much higher concentrations than the perchlorate.  After review of various options and completion of a bench-scale test, the consultant implemented in situ CL-Out bioremediation 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  much higher than the perchlorate concentrations and pre-maturely saturated the ion-exchange resin. 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.

The initial application of CL-Out to the soil reduced the perchlorate source concentration.  After eight months of ground water bioremediation, the perchlorate concentration in the unconsolidated aquifer decreased 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 nitrate and perchlorate bioremediation provided immediate risk reduction and mitigated potential off-site migration. The bioremediation contaminant levels to the remediation target in 3 years.  Bioremediation saved 5 years of projected treatment time and millions of dollars in OM & M costs.  The owner sold the property without environmental impairment upon completion of bioremediation. View the full case study  or  a slide presentation.

Project Consultant Received Green Leadership Award

The Massachusetts Department of Environmental Protection awarded Irwin Engineering of Natick, Massachusetts the 2016 Greener Cleanup Leadership Award for the innovative in situ bioremediation of perchorate contamination of soil and ground water at the Concord Road Site in Billerica, Massachusetts. The award honors LSPs and their clients for promoting greener cleanup principles and practices to reduce the overall net environmental footprint of hazardous waste site cleanup response actions under the Massachusetts Contingency Plan.  Read more…

Click here for more information about Sustainability and Green Remediation.

Click here for more information about CL-Out bioremediation.



Aerobic PCE Bioremediation

CL-Out Aerobic PCE Bioremediation Pilot Study Results

A CL-Out bioremediation pilot study confirmed that aerobic PCE cometabolism removed dry cleaning solvent contamination from ground water.  The pilot study was located at a former dry cleaners.  At the site, the PCE in ground water was 27 parts per billion (ppb).  Bioaugmentation introduced CL-Out microbes and dextrose as the metabolic substrate by injected into the ground water up gradient from the sentinal monitoring well.  After 30 days the PCE concentration decreased to 20 ppb.  After 6 months the PCE concentration decreased to 16 ppb.

As the PCE was decreasing, the site conditions stayed aerobic.  The dissolved oxygen level in ground water decreased from 1.07 to 0.71 mg/l.  Meanwhile,  the ORP decreased from 99 to 45 mv.  These aerobic aquifer conditions support the conclusion that the PCE removal was through aerobic bioremediation.

CL-Out cometabolism uses a dioxygenase enzyme that is produced constituatively as the metabolic substrate is consumed.  The dioxygenase enzyme destabilizes the carbon bond in the PCE to convert the molecule to an organic acid that leads to complete mineralization. Click here to view the PCE and TCE cometabolic degradation pathways.

CL-Out is a consortium of naturally-occurring microbes.  The microbes have the benefits of metabolic diversity and environmental stability.  They are non-pathogenic and safe for human health and the environment. Click here to find out more about CL-Out bioremediation.