Using 2D MTBE Stable Isotopic Analysis to Optimize a Commercial -scale Pulsed Air Sparging/SVE System for MTBE Source Remediation
Xiaomin Yang, BP Corporation North America, Inc., Warrenville, IL
Shankar Subramanian, URS Corporation, Chicago, IL    
Timothy Dull, URS Corporation, Chicago, IL
Thomas Tunnicliff, Atlantic Richfield Company, A BP affiliated company, Warrenville, IL
David Tsao, BP Corporation North America, Inc., Warrenville, IL

Biodegradation of Tert-butyl Alcohol (TBA) using Biological Granular Activated Carbon (Bio-GAC)
Kayleigh Dunnett, University of Illinois at Urbana Champaign, Urbana, IL           
Kevin T. Finneran, University of Illinois at Urbana Champaign, Urbana, IL

Monitoring Ex situ MTBE and TBA Biodegradation using Stable Isotope Probing
Michael Hyman, North Carolina State University, Raleigh, NC
Kristy A. Salafrio, New York State Department of Environmental Conservation Region 1, Stony Brook, NY
Joseph Haas, New York Attorney General, New York, NY
Don Trego, Environmental Assessment and Remediation, Patchogue, NY
Ian Hofmann, Environmental Assessment and Remediation, Patchogue, NY

Biodegradation of MTBE and TBA Impacted Groundwater: Theories for Bio-GAC Vessel Design and Optimization
Kristy A. Salafrio, New York State Department of Environmental Conservation Region 1, Stony Brook, NY
Michael Hyman, North Carolina State University, Raleigh, NC
Burke Haywood, North Carolina State University, Raleigh, NC
Denise Aslett, North Carolina State University, Raleigh, NC
Joseph Haas, New York Attorney General, New York, NY
Ian Hofmann, Environmental Assessment and Remediations, Patchogue, NY 

Challenges Using Mass Flux at a Service Station
Ken Guttman, Gannett Fleming, Baltimore, MD                      

The Value of Compound Specific Stable Carbon and Hydrogen Isotope Analysis of a Long Island MTBE Mega-Plume
J. E. Haas, New York State Department of Law, New York, NY
K. A. Krajenke, Environmental Assessment and Remediation, Patchogue, NY
D.A. Trego, Environmental Assessment and Remediation, Patchogue, NY
T.C. Schmidt, University Duisburg-Essen, Duisburg, Germany
N. M. Hart, New York State Department of Environmental Conservation, Stony Brook, NY

Using 2D MTBE Stable Isotopic Analysis to Optimize a Commercial -scale Pulsed Air Sparging/SVE System for MTBE Source Remediation

Xiaomin Yang, BP Corporation North America, Inc.,Cantera I - MC 2N, 28100 Torch Parkway, Warrenville, IL 60555, USA, Tel: 630-836-7176, Fax: 630-836-7193, Email: Xiaomin.Yang@bp.com
Shankar Subramanian, URS Corporation, 100 S. Wacker Drive, Suite 500, Chicago, IL 60606, USA, Tel:  312-577-7410, Fax: 312-939-4198, Email: shankar_subramanian@urscorp.com
Timothy Dull, URS Corporation, 100 S. Wacker Drive, Suite 500, Chicago, IL 60606, USA, Tel: (312) 697-7227, Fax: 312-939-4198, Email: timothy_dull@urscorp.com
Thomas Tunnicliff, Atlantic Richfield Company, A BP affiliated company, Cantera I - MC 2N, 28100 Torch Parkway, Warrenville, IL 60555, USA, Tel: 618-254-9074, Fax: 618-254-8718, Email: thomas.tunnicliff@bp.com
David Tsao, BP Corporation North America, Inc.,Cantera I - MC 2N, 28100 Torch Parkway, Warrenville, IL 60555, USA, Tel: 630-836-7169, Fax: 630-836-7193, Email: david.tsao@bp.com

The performance of a commercial-scale pulsed air sparging (AS) system for MTBE and TBA removal from a source area was investigated in this study. The results suggest that high flow, pulsed AS is an effective technology to remediate MTBE and TBA contaminated soil and groundwater. A novel engineering design approach based on stable isotope analysis was also developed to optimize the full-scale system that consists of 22 AS wells and 4 SVE wells. The MTBE and benzene groundwater concentrations in the source zone decreased at a rate of 0.9% and 1.2% per day, respectively, as a result of the pulsed AS/SVE system operation. The effectiveness of pulsed AS on benzene and MTBE source zone remediation was approximately equal. MTBE carbon and hydrogen stable isotope data was collected to quantify the contribution of MTBE aerobic biodegradation and volatilization to the mass reductions in soil and groundwater. A marginal delta C13 increase was observed in all three groundwater monitoring wells tested where the MTBE concentration dropped two orders of magnitude.  A dynamic delta H shift was also recorded in this study. The delta H rapidly decreased when only SVE was applied to the source zone, and then rapidly increased right after the AS was started. This field observation matches the findings recently documented in laboratory studies where volatilization caused a downward shift of delta H and biodegradation resulted in an upward shift. Our previous pilot test reported an MTBE aerobic biodegradation enrichment factor of 32 per mil.  The overall (volatilization and biodegradation) observed enrichment factor of MTBE in the field was 9.35 per mil. The measured enrichment factor of MTBE volatilization in this field study was -16.3 per mil.  MTBE volatilization caused a downward shift in the isotopic enrichment factor.  These measured delta H data suggest that both biodegradation and volatilization materially contribute to the MTBE mass removal. The AS/SVE operation was optimized using the 2D isotopic dynamics to maximize the system efficiency and to minimize the energy consumption of the remediation system.  

Biodegradation of Tert-butyl Alcohol (TBA) using Biological Granular Activated Carbon (Bio-GAC)

Student Presenter

Kayleigh Dunnett, University of Illinois at Urbana Champaign, 4162 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave, Urbana IL 61801- 2352, Tel: 217-333-8121, Email: dunnett2@illinois.edu
Dr. Kevin T. Finneran, University of Illinois at Urbana Champaign, 3221 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave, Urbana IL 61801- 2352, Tel: 217-244-7956, Email: finneran@illinois.edu

Tert-butyl alcohol (TBA), a metabolite of the gasoline additive methyl tert-butyl ether (MTBE), is a common groundwater contaminant encountered at petroleum remediation sites.  This work explored the capability of YZ2, a novel pure culture, to completely degrade TBA aerobically in both batch studies and in continuous-flow columns containing biologically activated granular carbon (bio-GAC), simulating an ex-situ remedial system.  YZ2 mineralized TBA from 0.5mM to 50mM, which is significantly higher than previously reported cultures.  The level at which TBA limited the cellular activity was 45mM; however, mineralization still proceeded up to 50mM.  YZ2 growth and corresponding TBA oxidation rates within saturated activated carbon were compared with rates quantified in pure aqueous media; results demonstrate that GAC decreases oxidation kinetics for TBA.  Batch studies quantified the kinetics of abiotic TBA sorption to activated carbon versus biological TBA oxidation using bio-GAC to compare the rates and efficiencies of physical removal processes to biological strategies.  Data demonstrate that adsorption may be more efficient at high TBA concentration, and that previously reported K_OC values for TBA were underestimates.  In addition, pH levels increased to as high as 10.2 once activated carbon was added to solutions containing TBA, which inhibited microbial growth.

The continuous-flow bio-GAC columns mimicked a field bio-GAC unit and focused on different potential inoculation strategies and the long-term capabilities of YZ2 to degrade TBA as a continuous culture.  Current data indicate lower effluent TBA concentrations within the bio-GAC column for 70 days, compared to a sterile GAC control column.  However, the overall stoichiometry of the mineralization pathway indicates that dissolved oxygen concentrations in influent water may limit TBA degradation in the bio-GAC column, preventing complete degradation.  We are using these data to develop a strategy for biological regeneration of GAC, which may be the most effective use of inoculated, TBA degrading cultures. 

Monitoring Ex situ MTBE and TBA Biodegradation using Stable Isotope Probing

Michael Hyman, Burke Haywood and Denise Aslett, Department of Microbiology, North Carolina State University, Raleigh NC 27695
Kristy A. Salafrio, New York State Department of Environmental Conservation Region 1, Division of Environmental Remediation, 50 Circle Road, Stony Brook, NY 11790
Joseph Haas, New York Attorney General, Environmental Protection Bureau, 120 Broadway, New York, NY 10271
Don Trego and Ian Hofmann, Environmental Assessment and Remediation, 225 Atlantic Ave., Patchogue, NY

¹³C-DNA stable isotope probing (SIP) is a culture-independent method used to identify bacteria with specific metabolic capabilities within complex microbial communities. We have used ¹³C-DNA-SIP to identify aerobic MTBE- and TBA-oxidizing bacteria in Bio-GAC reactors used to treat gasoline-impacted groundwater at two sites on Long Island, New York.

At the Hampton Bays site in eastern Long Island, samples of “self-inoculated” Bio-GAC were exposed to ¹³C₅-TBA. After consumption of the TBA, total microbial DNA was extracted from the activated carbon and ¹³C- and ¹²C-DNA were separated by density gradient centrifugation.  The 16S rRNA genes in the ¹³C-DNA fraction were amplified and the products were analyzed by denaturing gradient gel electrophoresis (DGGE). Individual DGGE bands were excised, re-amplified, sequenced and then compared to rRNA databases. This analysis identified five novel TBA-oxidizing bacteria including strains of Cupravidus, Polaromonas and Hydrogenophaga. Further analysis of the ¹³C-DNA using DGGE demonstrated these organisms harbor several key genes previously identified in the MTBE-degrading bacterium, Methylibium petroliphilum PM1.

At a site in Ronkonkoma in central Long Island, ¹³C-DNA-SIP was used to follow temporal changes in the distribution of both MTBE- and TBA-oxidizing bacteria in another “self-inoculated” Bio-GAC reactor initially operated to treat only TBA. Measurements of total DNA indicate microbial biomass was concentrated in the upper 40% of the reactor. Introduction of MTBE into the influent resulted in an MTBE-oxidizing zone in the upper portion of the reactor. Our results suggest two different groups of organisms oxidize MTBE and TBA in this reactor. Our ongoing studies are identifying these organisms using DGGE and quantifying the distribution of genes associated with fuel oxygenate biodegradation using quantitative molecular approaches. The results will be used to help improve the design and operation of Bio-GAC systems for ex-situ fuel oxygenate bioremediation.

Biodegradation of MTBE and TBA Impacted Groundwater: Theories for Bio-GAC Vessel Design and Optimization

Kristy A. Salafrio, New York State Department of Environmental Conservation Region 1, Division of Environmental Remediation, 50 Circle Road, Stony Brook, NY 11790, USA, Tel: 631-444-0334, Email: kasalafr@gw.dec.state.ny.us
Michael Hyman, Department of Microbiology, North Carolina State University, Raleigh, NC 27695, USA, Tel: 919-515-7814, Email: mrhyman@ncsu.edu
Burke Haywood, Department of Microbiology, North Carolina State University, Raleigh, NC 27695, USA, Tel: 919-515-7814
Denise Aslett, Department of Microbiology, North Carolina State University, Raleigh, NC 27695, USA, Tel: 919-515-7814
Joseph Haas, New York Attorney General, Environmental Protection Bureau, 120 Broadway (26th Floor) New York, NY 10271,USA, Tel: 212-416-8481, Email:  Joseph.Haas@oag.state.ny.us
Ian Hofmann, Environmental Assessment and Remediations, 225 Atlantic Ave., Patchogue, NY, USA, Tel: 631-447-6400, Email: IHofmann@enviro-asmnt.com

A treatment system involving granular activated carbon fixed film bioreactors (Bio-GACs) was employed to treat groundwater containing methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA). One reactor was modified to investigate where and how MTBE and TBA biodegradation was occurring. The modifications included seven access ports facilitating the installation of GAC-filled stainless steel screens (carbon samplers) that spanned the depth of the reactor vessel and a system of six depth discrete reactor pore water sampling ports. Dissolved MTBE and TBA concentrations entering, leaving and at six depth discrete ports within the bioreactor were monitored regularly. Individual carbon samplers were removed at strategic times and the cores were segmented vertically to correspond to one of the six pore water sampling depths. Samples from each core segment were analyzed using ¹³C-DNA stable isotope probing (SIP) and other microbiological tools to quantify changes in the distribution of the microorganisms responsible for MTBE and TBA biodegradation. The SIP results identified the MTBE and TBA degraders present in each core segment and while measurements of total DNA indicated that the majority of the microbial biomass was concentrated in the upper 40% of the reactor. Shifts in the populations of MTBE- and TBA-degraders and total biomass that corresponded to shifts in the proportion of MTBE and TBA entering the bioreactor were also identified.

Our new understanding of the changing nature and distribution of the MTBE and TBA-degrading microbial populations and total biomass within the bioreactor suggests the need for several improvements to the design and operation of similar Bio-GAC systems. These design and operational improvements, which include bioreactor geometry, influent flow mixing and contaminant loading manipulation, are discussed with regard to their potential to optimize effectiveness of Bio-GAC reactors by enhancing the accumulation of MTBE- and TBA-degrading biomass more evenly throughout the entire reactor.

Challenges Using Mass Flux at a Service Station 

Ken Guttman, P.E., Gannett Fleming, 4701 Mt Hope Drive, Suite A, Baltimore, MD 21215, Tel: 410-585-1460, Email: kguttman@gfnet.com

Mass flux estimates are useful to predict potential impacts to potable wells.  A comprehensive transect of monitoring points positioned perpendicular to groundwater flow is required, along with reasonable estimates of specific discharge (i.e. transect approach).  Alternatively, pump and treat system data can be used to estimate mass flux rates assuming pumping wells capture the plume between the source and potable well receptor (i.e. pumping approach).

A basic overview of mass flux is presented, followed by a case study and lessons learned.  With tentative approval from the regulator, mass flux is being used as a performance metric to establish onsite groundwater cleanup goals for MTBE at a service station site in the mid Atlantic.  MTBE impact to a community supply well downgradient from the site is driving the cleanup.  SVE in the suspected source area coupled with a line of three pump and treat wells near the down gradient property line comprise the source removal and containment strategy, respectively.  Both methods of mass flux estimation were employed.  (1) A simple spreadsheet tool was used to calculate mass flux using the transect approach.  (2) MTBE influent concentrations and flow rates were used to calculate mass flux using the pumping approach.  Results were interesting and useful to some degree, but several shortcomings prevented a robust and thorough evaluation of the mass flux technique.  A review of lessons learned will be presented including tips for understanding uncertainty when using mass flux at future service station sites.

The Value of Compound Specific Stable Carbon and Hydrogen Isotope Analysis of a Long Island MTBE Mega-Plume

J. E. Haas, New York State Department of Law, 120 Broadway, New York, NY, USA, Tel: 212-416-8481, Fax: 212-416-8446, Email: joseph.haas@oag.state.ny.us
K. A. Krajenke, Environmental Assessment and Remediation, 225 Atlantic Avenue, Patchogue, NY, USA, Tel: 631-447-6400, Fax: 631-447-6497
D.A. Trego, Environmental Assessment and Remediation, 225 Atlantic Avenue, Patchogue, NY, USA, Tel: 631-447-6400, Fax: 631-447-6497
T.C. Schmidt, University Duisburg-Essen, Chair of Instrumental Analysis, Lotharstr. 1, MF 147, D-47057 Duisburg, Germany, Tel: +49,203 379-3311, Fax: +49,203 379-2108
N. M. Hart, New York State Department of Environmental Conservation, 50 Circle Rd., SUNY @ Stony Brook, Stony Brook, NY 11790-3409, USA, Tel: 631-444-0325, Fax: 631-444-0328

The relative enrichment of the heavier stable isotopes of both carbon and hydrogen within the remaining undegraded fraction of a mass of an organic compound which has undergone bio-degradation has been widely documented. The quantification of biologically induced enrichment of these heavier stable isotopes by Compound Specific Isotope Analysis (CSIA) has gained credibility as a tool to assess and or to quantify the role of natural biodegradation at sites contaminated with fuel oxygenates. Due to a combination of factors, including cost and limited analysis availability, the application of CSIA to the assessment of fuel oxygenate biodegradation is frequently limited to determining the ratio of ¹³C  / ¹²C in the residual Methyl Tertiary Butyl Ether (MTBE) (i.e. reporting δ¹³C in the remaining undegraded MTBE) at a site. Although such applications of CSIA can yield useful information regarding the percentage of MTBE that has been degraded at a site, they do not provide data indicative of the degradation pathway that can be gained by combined MTBE δ ²H and MTBE δ ¹³C analysis.

The value of combined MTBE δ ²H and MTBE δ ¹³C data in developing the biodegradation component of a Conceptual Site Model (CSM) for a MTBE plume is illustrated by three successive applications of CSIA to a 1,372 meter long, 244 meter wide and 41 meter thick groundwater plume containing 5,164 kg of dissolved MTBE. The distribution of MTBE and Tertiary Butyl Alcohol (TBA) within the plume was extensively monitored by a three dimensional network consisting of 1617 concentration monitoring points. Initially, 53 MTBE δ ¹³C values were determined for samples taken from within the MTBE plume over two sampling events. The initial MTBE δ ¹³C data, along with the distribution of MTBE, TBA and dissolved oxygen, failed to provide sufficient understanding of the relationship between biodegradation and the observed MTBE and TBA distributions to support remedial treatment technology selection and design. The third CSIA application included combined MTBE δ ²H and MTBE δ ¹³C values for 13 monitoring locations. The combined MTBE δ ²H and MTBE δ ¹³C data confirmed that transformation of MTBE to TBA likely took place under both anaerobic and aerobic conditions prevailing within different portions of the plume. The data also helped explained the 1:1 MTBE to TBA concentration ratio observed in the anaerobic portion of the plume which strongly influenced potential treatment designs. In addition to providing the level of understanding of site specific MTBE to TBA bio-transformation needed to support remedial treatment technology selection and design, the CSIA data provided the basis of new site specific estimates of the MTBE anaerobic and aerobic degradation rates that will influence the application of the selected remedial technology.

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