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 Isomers Following ISCO Treatment

Background

CL-Out® bioaugmentation was used to remediate ground after ISCO was unsuccessful in remediation of chlorobenzene isomers, including chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and 1,2-dichlorobenzene. At the initiation of bioaugmentation, individual concentrations were as high as 50,000 µg/L. The CL-Out® treatment quickly reduced contaminant concentrations.

Remediation Approach and Results

CL-Out® was introduced into the contaminated ground water in November 2010 by injection through temporary well points surrounding the monitoring point. One drum of the CL-Out® was injected into the ground water.

The ground water treatment results were monitored by 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, 62% to 82% of individual contaminants were destroyed. The sampling results 30 days after bioaugmentation are compared to the pre-treatment concentrations on the following chart.

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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.

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Conclusions

This project demonstrates several of the benefits of aerobic bioaugmentation. 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.

Bioaugmentation Following In-situ Chemical Oxidation

Background

The chlorinated solvent trichloroethylene (TCE) was discovered in ground water at a manufacturing facility in eastern Massachusetts. ISCO was selected for remediation of the ground water. Although ISCO reduced TCE concentrations, the residual post-ISCO TCE concentrations were above the applicable remediation standards. The environmental consultant chose CL-Out® bioaugmentation to treat the residual ground water contamination. The CL-Out® treatment successfully achieved the remediation goal quickly and at a low cost.

Geology and Hydrogeology

The contaminated ground water was in a shallow, sandy, water-table aquifer. The residual contamination was located under a manufacturing building and adjacent to a river. The main receptor concerns were vapor migration into the building and contaminated ground water migration into the river.

TCE was the only contaminant in ground water. Post-ISCO TCE concentrations were as high as 54 µg/L. Daughter products were not detected. CL-Out® was selected for the treatment because it is capable of cometabolizing the TCE without producing daughter products such as vinyl chloride. Furthermore, the CL-Out® organisms are aerobic, so they were compatible with the natural oxygenated conditions of the aquifer.

Remediation Design

CL-Out® was introduced into the contaminated ground water by injection through temporary well points. Three drums of the CL-Out® were injected into the ground water through 14 injection points over an area of 1,200 square feet.

The ground water treatment results were monitored by analysis of ground water samples from five locations. The 30-day monitoring results show an immediate decrease in the TCE concentrations without the production of DCE or vinyl chloride. After 30 days as much as 97% of the TCE was destroyed and the ground water met applicable standards.

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Bioremediation Results

Dissolved oxygen (DO) concentrations and oxidation-reduction potentials (ORP) were also monitored to assess the growth environment for CL-Out® organisms. Before the bioaugmentation the DO concentration was 0.47 mg/L. After the bioaugmentation, the DO concentration dropped to 0.04 mg/L, which confirms active aerobic microbial metabolism. The ORP was 208 before and 272 after bioaugmentation, which shows positive redox potential was maintained even though oxygen was being utilized.

Ground water samples were tested for CL-Out® organisms by plate count analysis 30 days after the injection. The CL-Out® population was greater than 300,000 cfu/ml in 4 of 5 monitoring points 30 days after the inoculation, confirming a good distribution of the organisms and that the population was sustained at the planned level.

Conclusions

This project demonstrates several of the benefits of aerobic bioaugmentation. 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. The TCE was destroyed without production of daughter products, which accelerated site closure at minimal cost.

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.

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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.