Fast Dry Cleaner Bioremediation

Case Study: Dry Cleaners Site, Southern California

Site Summary

CL-Out® fast dry cleaner bioremediation cost-effectively removed solvents from soil and ground water at a site in Soutern California.  After one application of CL-Out® bioremediation, the total chlorinated solvents concentration in ground water decreased by 90%. At the same time, the contaminant concentrations in soil decreased by an average of 85%. The remediation provided immediate risk reduction including avoiding vapor intrusion by vinyl chloride

Project Design and Implementation

Investigation found dry cleaning solvents in soil and groundwater around a dry cleaning machine. The solvent entered the soil below the building and percolated through the soil to a perched ground water.  The soil and sediments are interbedded alluvial and marine sediments with a high permeability.   The impacted soil volume covered approximately 80 cubic yards. The area of ground water impact and treatment covered approximately 2,000 square feet.

Based on the volumes of impacted soil and ground water, the remediation plan included five drums of hydrated CL-Out®.  Two drums treated the soil and perched ground water beneath the dry cleaning machine. Three drums treated the deeper ground water in the diffused area of the plume. The total injection volume was less than .1% of the pore volume of the treated soil and ground water.

CL-Out® bioremediation destroys chlorinated solvents by aerobic cometabolism. Dextrose provided the carbon source to support microbial growth. EHC-O by Adventus maintained the aerobic conditions to support cometabolism and prevent potential production of vinyl chloride.

Fast Dry Cleaner Bioremediation Results

Post–treatment soil and ground water sampling was approximately 30 days after the injection. The post-treatment soil samples came from locations adjacent to pretreatment sampling locations. The shallow soil samples all showed a decrease in solvent concentrations and no generation of vinyl chloride. Post-treatment ground water samples came from existing monitoring wells. The perched ground water showed a decrease in PCE concentrations but a slight increase in TCE and DCE concentrations. The deeper ground water showed a decrease in all concentrations. Vinyl chloride was not detected in either the perched or deep ground water. The following table shows the fast dry cleaner bioremediation results.

dry_cleaner_chart 6_11

The 30-sampling results show that the site progressing toward fast closure. Additional ground water treatment is unlikely to be necessary to achieve site closure after sufficient post-treatment monitoring.

Click here to learn more about CL-Out bioremediation.

Remediation of an Industrial Dry Cleaning Site

Site Summary

A CL-Out bioaugmentation pilot study verified the applicability of CL-Out remediation of an industrial dry cleaning site. The pilot study also determined whether the availability of oxygen to support cometabolism would limit the bioremediations.

Geology and Hydrology

Although the impacted ground water was relatively shallow, the site geology was complicated and varied across even this small site. In general the glacial deposits at the site were mainly till with interbedded sandy and silty zones. The impacted ground water was contained within the granular deposits.

Contamination

The main ground water contaminant was PCE with lower concentrations of TCE, cis -1,2 DCE and vinyl chloride. In the pilot study area, the PCE concentration was 44,200 μg/L and the total of the daughter products was 14,750 μg/L.

Pilot Study Design

A pilot study was completed in the source area in the fall of 2009. 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 109 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. Pre- and post -treatment samples were taken on February 19 and December 10, 2009. The post-treatment sample was taken after the monitoring well was purged of the injected volume. The following table shows the contaminant concentration trends in the treatment area.

dryclean8

Results

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. The CL-Out bioremediation was most effective in the removal of PCE and TCE. There was an increase in vinyl chloride suggesting some incomplete reductive dechlorination, probably by native dehalogenating organisms. Full-scale treatment will be most effective with the addition of an oxygen supplement to limit the dehalogenation and promote the cometabolism of the daughter products. Overall the push-pull pilot study verified the effectiveness of CL-Out bioremediation and provided insights for making full-scale application more effective.

Bioaugmentation to Reduce Ammonia, Nitrate and Organics in Wastewater

Case Study: Improving Poultry Wastewater Treatment

Site Summary

Petrox DN® bioaugmentation was implemented at a poultry processing plant to deal with a recurring problem of excessive ammonia levels in wastewater discharge. Petrox ND® bioaugmentation reduced the organic carbon load in the wastewater and converted the ammonia to nitrogen gas. Within 48 hours of treatment the ammonia levels in the wastewater were reduced to acceptable levels and discharge limits were maintained.

Nature of the Problem

Wastewater treatment requires the treatment of a variable waste stream with limited control over the volume and concentration of the raw material and only moderate control over the operating conditions. The goals for organic wastes include the removal of organic pollutants, reducing the total organic load, reducing nutrient concentrations including nitrogen, and odor control. Removal of ammonia and nitrogen compounds are typically achieved by a two- step process of nitrification of the ammonia and denitrification of the nitrate. The autotrophs Nitrosomas sp. and Nitrobacter sp. are typically involved in these steps. As autotrophs these microbes use carbon dioxide instead of organic carbon to build cells, organic wastes are not treated by this process.

The Pseudomonas sp. in Petrox DN® oxidize the organic carbon wastes converting it to cell mass, carbon dioxide and water and generating stored cellular energy.  Simultaneously, the Pseudomonas sp. in Petrox DN® remove ammonia and nitrogen by utilizing these compounds as a nitrogen source for cell growth and electron acceptors during the consumption of the organic wastes. The benefit of Petrox DN® bioaugmentation is the removal of both the organic waste, nutrients and elimination of ammonia odors.

Pseudomonas sp. are also cold water tolerant, so Petrox DN® can be used year round under most under natural conditions.

Implementation

The plant generates 0.85 million gallons of wastewater per day with ammonia levels of 80 to 120 ppm. The wastewater after primary treatment and equalization flows into a 7.5 million gallon anaerobic lagoon and subsequently four sequencing batch reactors (SBRs). At the end of the settling cycle, the supernate discharges to a receiving stream.

Bench-scale laboratory studies showed that nitrate could be removed at a rate of 17 mg/L/hr under aerobic conditions and at a rate of 12 mg/L under anaerobic conditions. TOC could be removed at a rate of 45 mg/L/hr. Petrox DN® bioaugmentation was initiated in the aeration basin and the SBRs.

After less than 48 hours the wastewater met and maintained the wastewater discharge limits.

Bioremediation of Chlorobenzene Following ISCO

Compatable Techology To Finish Remediation

CL-Out® micorbes bioremediation of chlorobenzene continued treatment after ISCO remediation stalled.  The target isomers included chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and 1,2-dichlorobenzene. Before bioaugmentation, individual concentrations exceeded 50,000 µg/L. The CL-Out® treatment quickly reduced contaminant concentrations by as much as 82% more.

Remediation Approach and Results

Injection through temporary well points introduced CL-Out® micorbes into the contaminated ground water in November 2010. Only one drum of the CL-Out® was injected into the ground water.

The ground water monitoring included analysis of ground water samples for the contaminants of concern, microbial population, and known functional genes, including naphthalene dioxygenase, phenol hydroxylase, and toluene dioxygenase. The 30-day monitoring results show an immediate decrease in the contaminant concentrations. After 30 days, bioremediation reduced 62% to 82% of individual contaminants. The sampling results 30 days after bioaugmentation are compared to the pre-treatment concentrations on the following chart.

isco-1

The total biomass increased from 1.5 million to 12.8 million cells per milliliter following the bioaugmentation. The concentration of the naphthalene dioxygenase functional gene also increased by more than ten fold, as shown on the following table.

isco-2

Conclusions

This project demonstrates several of the benefits of bioremediation of chlorobenzene. Bioaugmentation provides active control of the site as effective organisms compatible with the site conditions were injected where they were needed. Furthermore, the CL-Out® aerobic cometabolism was compatible with the residual conditions following ISCO treatment. Treatment will continue to reduce the contaminant concentrations to acceptable levels.

Click Here to read more about CL-Out bioremediation.

 

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.