Vermont Dry Cleaner Remediation Using CL-Out

Cl-Out bioremediation was used to remove PCE from ground water at a dry cleaners in Vermont.  CL-Out micorbes were selected for bioremediation of the site because they are compatible with the natural aerobic aquifer conditions.  One application of CL-Out bioaugmentation reduced the PCE concentration by 90% in less than 6 months without increasing the vinyl chloride concentrations.

The following table summarizes the process of aerobic cometabolism of PCE.  The pre-bioaugmentation sampling showed aerobic conditions and a low population of Pseudomonas microbes.  After bioaugmentation the Pseudomonas population was higher.  As the microbes consumed the dextrose substrate and produced the oxygenase enzymes necessary for PCE destruction, the ORP and PCE concentrations decreased.  Six months after the bioaugmentation, the microbial population returned to the pre-bioaugmentation conditions.

Aerobic CL-Out Cometabolism Tracking

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

 

Bioaugmentation to Improve Oxygen Delivery Results

Many times oxygen is injected to improve natural attenuation of petroleum and other contaminants.  The results are often less than expected because the beneficial microbes that the oxygen addition is supposed to stimulate are absent or insufficient in numbers.  Bioaugmentation has been used to improve the results once the oxygen levels have increased but failed to improve the remediation rate.

The following table shows the results of Petrox bioaugmentation at a site in New Hampshire where the operation of an iSOC oxygen-delivery system failed to achieve stimulated bioremediation.  The table shows the improvement of the degradation rates and the achievement of reaching remediation goals.

Contaminant Pre-iSOC After iSOC Installation After Petrox Application
3/19/2002 1/9/2003 11/29/2004 2/9/2005 4/22/2005
Benzene 33 34 163 27 <2
Toluene 36 13 143 13 <2
Ethylbenzene 130 29 167 29 <2
Total Xylenes 500 141 336 109 <2
MTBE 60 24 61 35 1
Naphthalene 320 196 58 17 <2
1,2,4-Trimethylbenzene 110 40 238 110 <2
1,3,5-Trimethylbenzene 54 29 25 16 <2

Bioremediation of Dinitrotoluene

Dinitrotoluene (DNT) may occur in soil and ground water as the result of spills and historical use of the chemical as a solvent and industrial intermediary or as a residual of explosives at military facilities.  CL Solutions and SpecPro, Inc. conducted a treatability study to determine the effectiveness of CL-Out microbes in the removal of DNT from contaminated ground water at the Badger Army Ammunition Plant (BAAP) near Baraboo, Wisconsin.  The treatability study showed the removal of all six isomers of DNT, with a 53% to 91% removal in 21 days.  Intermediate by-products were detected only temporarily during the treatability study.  For more detailed information call CL Solutions.

Push-Pull Application of Aerobic Cometabolism

A CL-Out bioremediation push-pull pilot study was implemented  at a confidential dry cleaners site to verify the applicability of CL-Out bioremediation.

One unit of CL-Out was injected into the affected ground water in the source area.  One unit of CL-Out is a 55-gallon slurry with a microbial concentration of 1,000,000 cfu/ml.  The CL-Out microbes were injected with 50 pounds of dextrose to provide a carbon source to support the energy requirements of the population.   The post-treatment sample was taken after the monitoring well was purged of the injected volume.

The pilot study verified the applicability of CL-Out bioremediation to the site.  The total concentration of CVOCs  was reduced from 59,000 to 13,740 µg/L.