CLU-IN.ORG | Contaminant Focus: METHYL TERTIARY BUTYL ETHER (MTBE), Treatment Technologies

Methyl Tertiary Butyl Ether (MTBE)

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For more information on MTBE Treatment, please contact:

Linda Fiedler
Technology Assessment Branch
(703) 603-7194
fiedler.linda@epa.gov

Treatment Technologies

The effectiveness of remediation methods is directly linked to the physical and chemical characteristics of the constituent of concern. Because MTBE behaves differently in soil and water than other petroleum constituents, the choice of an effective remediation technology may be different when MTBE is present with other fuel contaminants at a site.

In soil, MTBE's very high vapor pressure and a low affinity for sorption to soil responds well to soil vapor extraction (SVE) and low-temperature thermal desorption (LTTD), typically without any costs beyond those needed for remediating other petroleum constituents. But because MBTE moves rapidly from the soil into the ground water, SVE or LTTD must be used soon after a release. Bioremediation methods for soil treatment (e.g., land-farming, bioventing, biopiles) currently are not recommended for removing MTBE because it is considered recalcitrant to biodegradation. This recommendation may change in the future as new research examines the efficacy of specific strains of bacteria and/or improved methods of biodegrading MTBE.

Because spills of conventional gasoline typically move slowly through ground water and are biodegraded over time, many are left in place to undergo bioremediation at no cost other than monitoring and temporarily replacing the water supply. MTBE, however, moves rapidly with ground water, is not readily degraded in the ground water environment, and can render ground water unpotable at low levels. Therefore, spills involving MTBE require much more aggressive management and remediation than do spills of conventional gasoline.

Pump and treat often can be an effective remediation technology for MTBE because the compound does not adsorb significantly to soil. As a result, fewer aquifer volumes are required to remove all of the MTBE than are required to remove other slowly desorbing petroleum hydrocarbons. Because of its high solubility, most of the MTBE mass can dissolve quickly into ground water, making pumping an efficient method for removing large quantities of the contaminant. As with petroleum hydrocarbons, however, diffusion is also a factor controlling the remediation timeframe. If micropores exist within the aquifer that are not readily influenced by ground-water flow, transfer of a contaminant from the micropores to the macropores will occur through the slow process of diffusion, which means that pump and treat will not always be an efficient remediation method for MTBE contamination.

The physical and chemical properties of MTBE limit the selection of ex situ treatment methods. MTBE is not a good candidate for removal via granular activated carbon (GAC) because it does not adsorb significantly to carbon. A 1991 American Petroleum Institute study (API Publication No. 4497) determined that air stripping alone was the most cost-effective technology for remediating water containing 20 ppm MTBE down to a level of 10 ppb, though MTBE's high solubility means that air strippers must use a higher volume of air than is required for other petroleum contaminants, such as benzene. MTBE remediation can require more extraction wells and associated equipment (e.g., pumps, lines) than for other fuel contaminants because MTBE travels farther and faster than the rest of the plume, resulting in a larger plume size. UV-catalyzed oxidation with hydrogen peroxide has been used to treat water and off-gases. Air sparging also has shown some promise, though the method typically is appropriate only in homogeneous sands, and also could require greater volumes of air to volatilize the MTBE than do other petroleum-related contaminants.

Though MTBE generally is believed to be resistant to biodegradation, preliminary research has shown that biodegradation can be an effective remediation option under certain conditions. Ex situ bioremediation in bioreactors has shown some initial promise. Research and development efforts are continuing to make them more reliable and cost-effective. New research is showing that in situ biodegradation may be an effective remediation alternative under specific environmental conditions that enable significant rates of biodegradation to occur. Phytoremediation approaches also are being investigated.

Under its MTBE Demonstration Project, EPA sponsored three MTBE treatment technology demonstrations on fuel-contaminated ground water at Naval Base Ventura County, Port Hueneme, California, from 2000 through 2002. The demonstrations examined propane biostimulation, high-energy electron injection (E-Beam), and the HiPOx advanced oxidation process. Links to the reports are provided on this page.

Adapted from:

MTBE Fact Sheet #2: Remediation of MTBE Contaminated Soil and Groundwater
U.S. EPA, Office of Underground Storage Tanks. EPA 510-F-97-015, 5 pp, 1998.

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General Information

Advances in MTBE Remediation and Treatment Strategies
Malcolm Pirnie, Inc.
The Methanol Institute, 10 pp, 2001.
Contact: The Methanol Institute, MI@methanol.org

Comparative Treatment Study of MTBE and Alternative Fuel Oxygenates
C.D. Adams, J. Sutherland, and J. Kekobad.
Missouri Petroleum Storage Tank Insurance Fund, 69 pp, 2002.
Contact: Craig Adams, adams@umr.edu

Comparison of air stripping, carbon adsorption, hydrogen peroxide/ozone advanced oxidation, and hydrogen peroxide/UV advanced oxidation treatment processes for MTBE at the pilot scale under a variety of treatment conditions to develop key design parameters used to calculate estimated treatment costs. Also compared the treatability and associated costs of treating alternative fuel oxygenating agents.

Evaluation of MTBE Remediation Options
R.A. Deeb, A.E. Flores, A.J. Stocking, S.E. Thompson, M.C. Kavanaugh, D.N. Creek, and J.M. Davidson.
National Water Research Institute, Center for Groundwater Restoration and Protection, Fountain Valley, CA. 150 pp, 2004

Provides an evaluation and case study summaries of a range of strategies and technologies applicable to MTBE remediation: pump and treat, soil vapor extraction, multiphase extraction, air sparging, in situ chemical oxidation, bioremediation, natural attenuation, advanced oxidation processes, synthetic resin sorbents, thermal processes, phytoremediation, and chemical reduction.

Groundwater Remediation Strategies Tool
American Petroleum Institute, Publ. No. 4730, 80 pp, 2003.

This guide provides strategies for focusing remediation efforts on 1) the change in MTBE mass flux in different subsurface transport compartments (e.g. the vadose zone, smear zone or a zone within an aquifer of interest) and 2) the change in remediation timeframe.

MTBE: Effects on Soil and Groundwater Resources
James J. Jacobs and Jacques Guertin (eds.).
Lewis Publishers/CRC Press, Boca Raton, FL. 264 pp, 2001.

MTBE Remediation Handbook
Moyer, Ellen and Paul T. Kostecki (eds.).
Springer, New York. ISBN: 1-88494-029-3, 712 pp, c2004. [Originally published by Amherst Scientific Publishers in 2003.]

Provides an overview of MTBE history, properties, occurrence, and assessment, followed by a survey of applicable remediation technologies—soil vapor extraction, bioventing, air sparging, in situ chemical oxidation, aerobic and anaerobic in situ bioremediation, phytoremediation, pump and treat, and monitored natural attenuation—and over a dozen remediation case studies.

MTBE Training Tool
U.S. Navy, Naval Facilities Engineering Command, Environmental Restoration Technology Transfer, Multimedia Training Tools website, 30 pp.

This Web tool provides an overview of MTBE, its chemical and physical properties, its fate and transport in the environment, and successful MTBE remediation technologies. An MTBE Treatment Technology Decision Tool is provided at the end of the training session to help screen potential cleanup technologies for a particular site.

Overview of Groundwater Remediation Technologies for MTBE and TBA
Interstate Technology and Regulatory Cooperation Work Group MTBE and Other Fuel Oxygenates Team.
Interstate Technology Regulatory Council (ITRC), 131 pp, 2005.

Technologies For Treating MtBE and Other Fuel Oxygenates
U.S. EPA, Office of Superfund Remediation and Technology Innovation, Technology Innovation Program
EPA 542-R-04-009, 109 pp, 2004

This report provides an overview of the treatment technologies used to remediate groundwater, soil, and drinking water contaminated with MtBE and other fuel oxygenates. The treatment methods discussed include air sparging, soil vapor extraction, multi-phase extraction, in situ and ex situ bioremediation, in situ chemical oxidation, pump-and-treat, and drinking water treatment. Information in the report can be used to help evaluate those technologies based on their effectiveness at specific sites. The report summarizes available performance and cost information for these technologies, examples of where each has been used, and additional sources of information.

Cost Studies

An Estimate of the National Cost for Remediation of MTBE Releases from Existing Leaking Underground Storage Tank Sites
Frank Sweet et al.
Association for Environmental Health and Sciences, Amherst, MA. 46 pp, 2005.

Cost and Performance Evaluation of Treatment Technologies for MTBE-Contaminated Water
Arturo A. Keller, et al.
Health and Environmental Assessment of MTBE: Report to the Governor and Legislature of the State of California as Sponsored by SB 521. Volume V: Risk Assessment, Exposure Assessment, Water Treatment & Cost-Benefit Analysis.
University of California Toxic Substances Research & Teaching Program, Davis, CA. 41 pp, 1998.

In-Situ Bioremediation of MTBE in Groundwater. ESTCP Cost and Performance Report
2003. Environmental Security Technology Certification Program. ESTCP Project CU-0013, 43 pp.

A Review of Cost Estimates of MTBE Contamination of Public Wells
American Water Works Association, Denver, CO. 33 pp, 2005.
Contact: AWWA, 303-794-7711

Biological Methods

Bioremediation of MTBE, Alcohols, and Ethers
Victor S. Magar, et al. (eds.).
Sixth International In Situ and On-Site Bioremediation Symposium, Volume I.
Battelle Press, Columbus, Ohio. 249 pp, c2001.

Envirogen Propane Biostimulation Technology for In-Situ Treatment of MTBE-Contaminated Ground Water. Innovative Technology Evaluation Report
Ann Azadpour-Keeley, U.S. EPA.
EPA 600-R-02-092, 152 pp, 2002.
Contact: Ann Azadpour-Keeley, keeley.ann@epa.gov

Factors Influencing Biological Treatment of MTBE Contaminated Ground Water
William T. Stringfellow, Robert D. Hines Jr., Dirk K. Cockrum, and Scott T. Kilkenny.
LBNL-48941, 49 pp, 2001.
Contact: William Stringfellow, wstringfellow@lbl.gov

In Situ Bioremediation of MTBE in Groundwater
2003. P. Johnson and C. Bruce (Arizona State Univ.); K. Miller (NFESC). Naval Facilities Engineering Service Center, Port Hueneme, CA. NFESC TR-2222-ENV, 118 pp.

In-Situ Remediation of MTBE Contaminated Aquifers Using Propane Biosparging: Cost and Performance Report
2003. Naval Facilities Engineering Service Center, Port Hueneme, CA. Environmental Security Technology Certification Program (ESTCP) Project CU-0015. NFESC-TR-2230-ENV, 59 pp.

In-Situ Remediation of MTBE Contaminated Aquifers Using Propane Biosparging: Technology Demonstration Final Report, Revision 1
2003. Environmental Security Technology Certification Program (ESTCP), 244 pp.

Methyl tert-Butyl Ether (MTBE): Its Movement and Fate in the Environment and Potential for Natural Attenuation
Air Force Center for Environmental Excellence, Brooks Air Force Base, TX. 221 pp, 1999.
Contact: Sylvia Ortega, sylvia.ortega@brooks.af.mil

Methyl Tertiary Butyl Ether (MTBE) Bioremediation. Technical Data Sheet
Naval Facilities Engineering Command (NAVFAC), Washington, DC.
NFESC TDS-2081-ENV, 4 pp, 2000.
Contact: Naval Facilities Engineering Service Center, 805-982-1299; DSN: 551-1299

Natural Attenuation of MTBE in the Subsurface under Methanogenic Conditions
John T. Wilson, Jong Soo Cho, Barbara H. Wilson, and James A. Vardy.
EPA 600-R-00-006, 59 pp, 2000.
Contact: John T. Wilson, wilson.johnt@epa.gov

A Practical Approach to the Design, Monitoring, and Optimization of In Situ MTBE Aerobic Biobarriers
P.C. Johnson, K.D. Miller, and C.L. Bruce. NFESC-TR-2257-ENV, 31 pp., 2004.

Summary of Workshop on Biodegradation of MTBE, February 1-3, 2000
U.S. EPA, Office of Research and Development, Technology Transfer and Support Division.
EPA 625-R-01-001A, 45 pp, 2001.

Technical Memorandum: Estimated Cost Associated with Biodegradation of Methyl Tertiary-Butyl Ether (MTBE)
Brett M. Converse and E. D. Schroeder.
Health and Environmental Assessment of MTBE: Report to the Governor and Legislature of the State of California as Sponsored by SB 521. Volume V: Risk Assessment, Exposure Assessment, Water Treatment & Cost-Benefit Analysis.
University of California Toxic Substances Research & Teaching Program, Davis, CA. 7 pp, 1998.

Technical Protocol for Evaluating the Natural Attenuation of MtBE
API Publication 4761, 2007

Physical/Chemical Methods

Demonstration of the HiPOx Advanced Oxidation Technology for the Treatment of MTBE-Contaminated Groundwater
T.F. Speth, G. Swanson.
EPA 600-R-02-094, NTIS: PB2003-103275, 36 pp, 2002.
Contact: Thomas Speth, speth.thomas@epa.gov

Engineering Issue Paper: In Situ Chemical Oxidation
EPA 600-R-06-072, 2006

This issue paper was produced by the EPA Risk Management Research Laboratory and the Engineering Forum. It provides an up-to-date overview of ISCO remediation technology and fundamentals, and is developed based on peer-reviewed literature, EPA reports, web sources, current research, conference proceedings, and other pertinent information.

High Energy Electron Injection (E-Beam) Technology for the 'Ex-Situ' Treatment of MTBE-Contaminated Groundwater
Tetra Tech, Inc., San Diego, CA.
EPA 600-R-02-066, 88 pp, 2002.
Contact: Al Venosa, venosa.albert@epa.gov

In-Well Vapor Stripping Technology. Innovative Technology Summary Report
U.S. DOE, Office of Environmental Management, Office of Science and Technology.
DOE/EM-0626, 50 pp, 2002.

MTBE Remediation Using Hollow Fiber Membrane and Spray Aeration Vacuum Extraction Technologies
M. Kram, S. Sirivithayapakorn, M. Joy, E. Lory, and A. Keller.
NFESC-CR-00-004-ENV, NTIS: ADA382396, 52 pp, 2000.
Contact: Ernest Lory, loryee@nfesc.navy.mil

Removal of MTBE from Drinking Water Using Air Stripping: Case Studies
R. Deeb, E. Hawley, A. Stocking, M. Kavanaugh, A. Flores, S. Sue, D. Spiers, M. Wooden, G. Crawford, and G. Garcia.
National Water Research Institute, NWRI-2006-03, 92 pp, 2006

Design, performance, and cost summary data were collected from nine packed-tower and low-profile air stripper treatment systems that address MTBE contamination in ground-water supplies in the 1990s to develop a series of cost and reliability curves and assess the accuracy of two models designed to predict the cost and performance of packed-tower and low-profile air strippers. Results indicate that a variety of different treatment train configurations can use air strippers successfully to remove a range of MTBE concentrations (i.e., from 10 to 2,400,000 ug/L). Removal efficiencies ranged from 65% to greater than 99.9%. The commercially available models predicted actual removal efficiencies within 15%.

Removal of MTBE with Advanced Oxidation Processes
Michael Kavanaugh, et al.
American Water Works Association (AWWA) Research Foundation, Denver, CO. 236 pp, c2003.

Sorption for Removing Methyl Tertiary Butyl Ether (MTBE) from Drinking Water
Irwin (Mel) Suffet, et al.
Health and Environmental Assessment of MTBE: Report to the Governor and Legislature of the State of California as Sponsored by SB 521. Volume V: Risk Assessment, Exposure Assessment, Water Treatment & Cost-Benefit Analysis.
University of California Toxic Substances Research & Teaching Program, Davis, CA. 27 pp, 1998.

Technical and Regulatory Guidance for In Situ Chemical Oxidation of Contaminated Soil and Groundwater
Interstate Technology and Regulatory Cooperation Work Group In Situ Chemical Oxidation Work Team.
Interstate Technology Regulatory Council (ITRC), 71 pp, 2001.

Technology Demonstration Report: PolyGuard™, Guardian Environmental Technologies, Inc.
Eric Winkler.
Center for Energy Efficiency and Renewable Energy, Univ. of Massachusetts, Amherst. The Massachusetts Strategic Envirotechnology Partnership (STEP). 69 pp, 1999.
Contact: Eric Winkler, winkler@ceere.org

Describes a 1998 demonstration pilot of the granular absorption media that constitute PolyGuard™ to quantify its absorption potential for MTBE and other organic contaminants associated with gasoline-contaminated ground water, evaluate its stability, and monitor its performance.

Thermal Treatment

Electrical Resistance Heating (ERH) Technology Coupled with Air Sparging and Soil Vapor Extraction for Remediation of MTBE and BTEX in Soils and Groundwater in Ronan, Montana
J. Kuhn, K. Manchester, and P. Skibicki.
Montana Department of Environmental Quality, Butte, MT. 8 pp, 2004.

Site-Specific Information

MTBE Treatment Profiles

Contains information about completed and ongoing applications of treatment for MtBE in drinking water and media at contaminated sites.

Cost and Performance Case Studies from the Federal Remediation Technologies Roundtable

The FRTR Remediation Case Study Searchable Database provides capability to search all 342 case studies by keyword and category, including media/matrix, contaminant type, primary and supplemental technology type, specific site name, or state.

Literature References

Technology Innovation News Survey Archives
The Technology Innovation News Survey archive contains resources gathered from published material and gray literature relevant to the research, development, testing, and application of innovative technologies for the remediation of hazardous waste sites. The collected abstracts date from 1998 to the present, and the archive is updated twice each month.