Effect of Triethyl Phosphate on the Biodegradation of Diesel Fuel
Gary L. Mills, University of Georgia, Aiken, SC
Patterson  Nuessle, University of Georgia, Aiken, SC
Heather L. Lott, Texas A& M University, College Station, TX
Bruce E. Herbert, Texas A& M University, College Station, TX  

Degradation of 1,1,1-trichloroethane in Groundwater by Indigenous Microorganisms under Anaerobic Conditions
Paula R. Chang, GeoSyntec Consultants, Boxborough, MA 
Elizabeth Edwards, Ph.D., P.E., University of Toronto, Toronto, Ontario, Canada
Sandra Dworatzek, University of Toronto, Toronto, Ontario, Canada
David Major, GeoSyntec International, Inc., Guelph, Ontario, Canada
Peter Zeeb, GeoSyntec Consultants, Boxborough, MA  

Enhanced Bioremediation of DNAPL in Clay Formation
Willard Murray, Harding ESE, Wakefield, MA
Diana Tremaine, Harding ESE, Wakefield, MA
Maureen Dooley, Regenesis, San Clemente, CA

Cost and Performance of Vegetable Oil Injection for Enhanced In Situ Bioremediation at Two Air Force Sites
Bruce M. Henry, Parsons, Denver, CO
Daniel R. Griffiths, Parsons, Denver, CO                          Allison M. Love, Parsons, Denver, CO
Peter Guest, Parsons, Denver, CO
James R. Gonzales, AFCEE/ERT, Brooks AFB, TX 

A Bioremediation Case Study: Butane Biostimulation for the Remediation of Petroleum Contaminants
James F. Begley, Global BioSciences, Inc., North Attleboro, MA 
Joseph Longo, Horsley & Witten, Inc., Sandwich, MA
Felix A. Perriello, Global BioSciences, Inc., North Attleboro, MA
George DiCesare, Global BioSciences, Inc., North Attleboro, MA

Facilitated Desorbtion and Incomplete Dechlorination: Observations from 220 Applications of HRC
Stephen S. Koenigsberg, Regenesis Bioremediation Products, San Clemente, CA
Kevin Lapus, Regenesis Bioremediation Products, San Clemente, CA
Gunisha Pasrich, Regenesis Bioremediation Products, San Clemente, CA  

Effect of Triethyl Phosphate on the Biodegradation of Diesel Fuel

Gary L. Mills and Patterson Nuessle, Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, Tel: 803-725-5368, Fax: 803-725-3309
Heather L. Lott and Bruce E. Herbert, Department of Geology and Geophysics, Texas A& M University, College Station, TX 77843, Tel: 979-845-2405, Fax: 979- 845-6162

Nutrient availability is often the limiting factor in microbial growth and contaminant degradation.  Previous studies have shown that the use of an oleophilic, water-soluble, phosphorus fertilizer increased microbial growth and degradation hydrocarbons associated resulting from the T/V Exxon Valdez oil spill.  However, problems are often encountered with the delivery of nutrients to contaminated subsurface environments where vadose and aquifer sediments are heterogeneously distributed and hydraulic conductivity if often limited.  Injection of aqueous nutrient solutions to contaminated zones is often ineffectively dispersed causing local over stimulation, which may lead to problems such as formation clogging.  Injection via a gas phase offers higher diffusivity and more efficient delivery to the target zone. A 48-day experiment was conducted to analyze the effect of triethyl phosphate (TEP) on the biodegradation of diesel fuel.  Soil microcosms containing diesel only, diesel and TEP, and a sterile diesel  control were incubated in an environmentally controlled chamber which simulated subsurface conditions on the Department of Energy’s Savannah River Site in Aiken, South Carolina.  The microcosms were destructively sampled in triplicate on days 0, 3, 6, 12, 24, and 48.  Indigenous microbial populations were quantified by total heterotrophic plate counts.  Total petroleum hydrocarbons were analyzed by gas chromatography-flame with ionization detection (GC/FID). After 24 days, data showed that the diesel hydrocarbons in the TEP-treated soils were degraded at a significantly greater rate than the non-TEP treated soils.  However, by day 48 bacterial counts  had declined and there was no significant difference in diesel degradation  between TEP-treated and untreated soils.

Degradation of 1,1,1-trichloroethane in Groundwater by Indigenous Microorganisms under Anaerobic Conditions

Paula R. Chang, GeoSyntec Consultants, 629 Massachusetts Avenue, Boxborough, MA  01719
Elizabeth Edwards, Ph.D., P.E., University of Toronto, 200 College Street, Toronto, Ontario  M5S 3E5 Canada
Sandra Dworatzek, University of Toronto, 200 College Street, Toronto, Ontario  M5S 3E5 Canada
David Major, GeoSyntec International, Inc., 130 Research Lane, Suite 120, Guelph, Ontario, N1G5G3 Canada
Peter Zeeb, GeoSyntec Consultants, 629 Massachusetts Avenue, Boxborough, MA 01719

Results from a microcosm study using groundwater and soil from a Massachusetts Industrial Site (Site) show that indigenous microorganisms are capable of sequentially dechlorinating 1,1,1-trichlorethane (TCA) to 1,1-dichloroethane (1,1-DCA) and then to chloroethane under anaerobic conditions.  Degradation of co-disposed TCE in microcosms required augmentation with a microbial consortium containing dehalococcoides ethenogenes.  Waste chlorinated solvents were discharged to a drywell at this facility for approximately 10 years.  Compounds detected in groundwater at the Site include: 1,1,1-TCA, trichloroethene (TCE), associated biotic and abiotic degradation products as well as chlorobenzenes.  Shallow and deep groundwater zones are defined by a 7 to 20 foot thick semi-confining silt layer through which chlorinated solvents have migrated.  Aerobic and anaerobic microcosms were constructed using approximately 60 grams (g) of soil and 100 to 120mL of groundwater.  Both the aerobic and anaerobic microcosms were run in triplicate with active and intrinsic controls.  One set of aerobic microcosms was amended with butane and a second set was amended with methane.  One set of anaerobic microcosms was amended with methanol, ethanol, acetate and lactate (MEAL) and a second set was amended with MEAL and augmented with a non-pathenogenic microbial consortium known as KB-1.  The aerobic active control and methane amended microcosms showed 25 and 50% losses, respectively, of 1,1,1-TCA that is attributable to co-metabolic degradation, volatilization or adsorption.  The MEAL amended microcosms showed decreasing concentrations of 1,1,1-TCA and TCE with concomitant production of 1,1-DCA, and cis-1,2-DCE.  1,1-DCA was further degraded to chloroethane, however vinyl chloride was not detected.  The KB-1 augmented microcosms degraded 1,1,1-TCA, TCE, 1,1-DCA and cis-1,2-DCE faster in comparison to the electron donor-only amended microcosms, with complete dechlorination of TCE to ethene.

Enhanced Bioremediation of DNAPL in Clay Formation

Willard Murray and Diana Tremaine, Harding ESE, Wakefield, MA
Maureen Dooley, Regenesis, San Clemente, CA

DNAPL in clay is one of the most challenging environments to remediate.  In this presentation results from a full-scale enhanced bioremediation program will be presented from a site with reduced permeability that has shown evidence of DNAPL.  The site is located in Tennessee and is a clayey aquifer characterized by elevated levels of tetrachloroethene (PCE) and trichloroethene (TCE).  Concentrations of PCE and TCE have been detected above 100mg/L in the source area and at lower concentrations (20mg/L) in the plume.  A pilot test was conducted using Hydrogen Release Compound (HRC) to enhance biological degradation of the chlorinated solvents.   The pilot test included HRC injection into both a source and plume test area.  Complete destruction of PCE and TCE was observed in two test areas.  Biodegradation products dichloroethene, vinyl chloride and ethene were detected, and initially the total mass of ethenes increased suggesting an HRC-enhanced desorption effect.  It was apparent that the residual PCE and TCE located in the source area were continually being degraded to DCE and VC, which both remained at elevated concentrations.  The highest concentrations of DCE observed (greater than 200 mg/L) are equivalent to approximately 270 mg/L of TCE (25% of TCE solubility) and would be equivalent to a PCE concentration greater than its solubility. These facts indicate that there is residual dense non-aqueous phase liquid (DNAPL) within the aquifer in the source area.   In the plume area, where PCE/TCE levels began at 20mg/L, DCE levels increased, then decreased.  Little to no vinyl chloride was detected over the time course of the study and a reduction of greater than 90% in the total mass of ethenes was observed.  Based on these data a full-sale remedial was designed to treat both the source and plume.  The program was implemented in the Spring 2001 and results from the full-scale remedial effort will be presented. 

Bruce M. Henry, Parsons, 1700 Broadway, Suite 900, Denver, Colorado  80290 , Tel: 303-831-8100, Fax: 303-831-8208, Email: bruce.henry@parsons.com                         
Chris A. Spitzer, Parsons, 1700 Broadway, Suite 900, Denver, Colorado  80290 , Tel: 303-831-8100, Fax: 303-831-8208, Email: chris.spitzer@parsons.com                                
Allison M. Love, Parsons, 1700 Broadway, Suite 900, Denver, Colorado  80290 Tel: 303-831-8100, Fax: 303-831-8208, Email: allison.love@parsons.com
Peter Guest, Parsons, 1700 Broadway, Suite 900, Denver, Colorado  80290 Tel: 303-831-8100, Fax: 303-831-8208, Email: peter.guest@parsons.com
Jerry E. Hansen, AFCEE/ERT, 3207 North Road, Bldg 532, Brooks AFB, Texas  78235-5363, Tel: 210-536-4353, Fax: 210-536-4330,  Email: jerry.hansen@brooks.af.mil

Remediating chlorinated solvents dissolved in groundwater to regulatory criteria is one of the United States’ greater environmental challenges.  Reductive dechlorination is known to degrade the common chlorinated solvents including tetrachloroethene, trichloroethene, carbon tetrachloride, and trichloroethane.  Many organic substrates have been used to stimulate reductive dechlorination of chlorinated solvents dissolved in groundwater.  Vegetable oil has been selected as a low-cost alternative and injected into the subsurface at over 15 sites across the country.  However, the technology is still being evaluated for its effectiveness and the physical and chemical properties of vegetable oil require careful design of the remedial application.  Therefore, performance and cost data are being collected to demonstrate its effectiveness under varied site conditions.  Cost and performance results from two large-scale Air Force technology demonstrations are evaluated for this study.  Both sites have over 18 months of post-injection monitoring, but vary significantly in terms of lithology and baseline geochemical conditions.  Performance monitoring indicates that in both cases, concentrations of chlorinated ethenes have declined significantly.  In addition, changing molar fractions of chlorinated compounds (i.e., sequential degradation of parent to daughter compounds) indicate that reductive dechlorination to ethene and ethane is occurring.  The cost of applying vegetable oil as an organic substrate at these sites is provided in terms of the cost of the substrate and the cost for emplacing the vegetable oil in the subsurface.  It is anticipated that only one full-scale application of the substrate will be required for remediation at these sites.  Therefore, operations and maintenance costs are limited to biannual groundwater monitoring.

A Bioremediation Case Study: Butane Biostimulation for the Remediation of Petroleum Contaminants   

James F. Begley, LSP, Global BioSciences, Inc., 91 George Leven Drive, North Attleboro, MA 02760 Tel: 508-643-7122, Fax: 508-643-7124
Joseph Longo, Horsley & Witten, Inc., 90 Route 6A, Sandwich, MA 02563, Tel: 508-833-6600, Fax: 508-833-3150
Felix A. Perriello, CHMM, CPG, LSP, Global BioSciences, Inc., 91 George Leven Drive, North Attleboro, MA 02760, Tel: 508-643-7122, Fax: 508-643-7124  
George DiCesare, Global BioSciences, Inc., 91 George Leven Drive, North Attleboro, MA 02760 Tel: 508-643-7122, Fax: 508-643-7124

A remediation system developed by Global BioSciences (GBI) of North Attleborough, Massachusetts was applied to the cleanup of a fuel oil contaminated site in Fairhaven, Massachusetts using GBI’s innovative Butane Biostimulation TechnologyÔ including Butane BiospargingÔ and Butane BioventingÔ. Eight underground storage tanks originally installed in the 1930s were removed from the site in 1989. A recent investigation at the site identified contaminant concentrations exceeding applicable Massachusetts risk based standards for petroleum hydrocarbons and discovered floating product in one location. Butane BiostimulationÔ was selected as the preferred remedial alternative. This patented bioremediation process stimulates naturally occurring butane-utilizing bacteria to metabolize and cometabolize pollutants. In the Butane Biosparging treatment system, butane and air are introduced into the groundwater via a specialized gas delivery system, the Butane Injector 2000Ô . This system injects low volumes of butane gas at a predetermined rate into the air stream from an air compressor. The butane/air mixture is distributed into the groundwater via a set of injection wells. The butane dissolves into the groundwater and provides a food source for butane and petroleum degrading bacteria, and along with increased dissolved oxygen, stimulates an increased biomass and treatment by direct metabolism of hydrocarbons and cometabolism of more recalcitrant compounds such as MTBE. Above the water table, the Butane Bioventing system degrades contaminants in the unsaturated zone. The system provides soil treatment by circulating butane and air through the contaminated area and promoting the growth of butane-utilizing bacteria. Baseline sampling for contaminant concentrations, dissolved oxygen, and the microbial community was completed before system startup. Analyses of groundwater samples have documented system effectiveness by achieving groundwater remedial goals within seven months of system start up.

Facilitated Desorbtion and Incomplete Dechlorination: Observations from 220 Applications of HRC

Stephen Koenigsberg, Kevin Lapus and Gunisha Pasrich, Regenesis, 1011 Calle Sombra, San Clemente, CA  92673, www.regenesis.com

The use of a variety of electron donors to accelerate natural attenuation is becoming a standard procedure.  As the frequency of use of these protocols increases, certain issues are surfacing and becoming the subject of more intense examination.  Two that are identified herein are 1) the ability for electron donor enhancement to facilitate the desorbtion of residual DNAPL and 2) incomplete dechlorination, i.e., the inability for PCE or TCE to rapidly degrade past DCE.

Observations on the performance of Hydrogen Release Compound (HRC), a time-release electron donor, at over 220 sites can contribute to the discussion of these issues. Clear evidence that enhanced bioremediation is facilitating the desorbtion of DNAPL is not abundant in this venue because the usual intention is to employ HRC in dissolved phase plume management.  Nevertheless, residual DNAPL is still present on about 5% of the treated sites (sometimes discovered after the fact).  In this relvant sub-population there is clear evidence that enhanced bioremediation facilitates DNAPL desorbtion.  The basis of this conclusion is that parent contaminants and the daughter products cycle through reduction and replenishment in ways that which cannot be readily explained by hydrogeological changes in plume dynamics.  Furthermore, the fact that this pattern is being observed with some frequency - as will be shown with representative data sets - enhances the likelihood that we are documenting desorbtion driven by bioremediation. 

With regard to incomplete degradation of the daughter products, with specific reference to chlorinated ethenes, it is apparent that reductive dechlorination can slow down and appear to be incomplete on about 80% of the sites.  The important thing, however, it to differentiate the degree of slowdown so that the sites that are truly recalcitrant and require further intervention can be identified.  In many cases, particularly when the kinetic disparity appears to be linked to elevated dissolved iron (which blocks electron flow to DCE), the phenomenon is very transient.  Based on the above referenced data set we believe that a truly problematic inability for DCE to degrade further is only present on about 10% of the time.  Aside from the physical reasons for elevated DCE, such as a DNAPL-mediated “constant feed”, the other explanations can be classified as geochemical (elevated dissolved ferric iron fed by highly bioavailable ferrous and ferric sources) or biological (the absence of microbes necessary for complete dechlorination).  In the latter case the solution may be to bioaugment or, if the pool of DCE is present without significant parent materials, the addition of oxygen can be considered in order to drive the intermediates to less toxic endpoints.

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