Tuesday, November 6, 2007 : 10:30 a.m.

MTBE and TBA Remediation using Fluidized Bed Bioreactors

Joseph E. O'Connell, Sc.D., P.E., Environmental Resolutions Inc and Ellen E. Moyer, Ph.D., PE, Greenvironment LLC

Bioreactors are being used to treat methyl tertiary butyl ether (MTBE), tertiary butyl alcohol (TBA), and other fuel oxygenates at over twenty gasoline release sites in California.  The bioreactors rely on naturally occurring bacteria to mineralize gasoline constituents to carbon dioxide and water.  The bacteria are provided with oxygen and essential nutrients such as nitrogen, phosphorus, and potassium, and pH is maintained between 6.5 and 8.5 standard units.  Incoming concentrations of TBA/MTBE have ranged from 5,000 to 1,500,000 micrograms per liter.  The concentrations of fuel oxygenates in bioreactor effluent are generally non-detect for TBA and MTBE.  Most bioreactors are followed by granular activated carbon canisters for final polishing in the event that gasoline constituents exit the bioreactor.  Bioreactor operating principles and field operation experiences are discussed.  The process and the equipment are described, and capital and operating costs are reviewed.  Specialized equipment for removal of sticky bio-solids containing iron, manganese, and hardness precipitates is also discussed.  Analytical performance data are presented for a number of California sites.  Bioreactors are also treating groundwater at several sites in the Northeast.  The process has been in operation in New Hampshire for over two years where the biomass had to adapt to New England groundwater temperatures and high iron and manganese concentrations.  The bioreactor has effectively treated groundwater at temperatures as cool as 49 oF, the lowest influent water temperature measured at this site.  This bioreactor is treating MTBE, TBA, and petroleum hydrocarbons such as benzene, toluene, ethylbenzene, and xylenes (BTEX).  The cleaned, aerated, seeded effluent is currently being re-injected into the subsurface in the source area to flush the smear zone and promote in situ bioremediation.  Contaminant concentrations in source area wells have decreased significantly.  Another bioreactor operating at a site in Maryland is effectively treating MTBE, TBA, and BTEX.

Joseph E. O'Connell, Sc.D., P.E., Environmental Resolutions Inc Joseph E. O’Connell, Sc.D., P.E., is President of ERI. With approximately 33 years of professional experience, he has been the Principal Engineer for designing, permitting, installing and operating numerous remediation systems. Systems installed include air sparging, vacuum extraction, pump and treat, shoring and excavation, bioremediation and fixation. Contaminants range from chlorinated hydrocarbons to gasoline-range hydrocarbons to metals. He worked with researchers at UC Davis in California to develop bio-culture, adapt the fluidized bed bioreactor to handle the slow growing biomass, and develop the overall design and control features of the bioreactors.

Ellen E. Moyer, Ph.D., PE, Greenvironment LLC Ellen Moyer, Ph.D., P.E is a recognized expert in the assessment and remediation of VOC contamination. She has an M.S. in Environmental Engineering, a Ph.D. in Civil Engineering, and over 20 years of professional experience. Dr. Moyer has managed all phases of assessment and remediation work, and her numerous projects have employed a wide range of in situ and ex situ remediation technologies at diverse sites with organic and inorganic contaminants. She was the lead editor of an MTBE Remediation Handbook, now in its second printing. Her Ph.D. research investigated soil vapor extraction, air sparging, and bioventing of gasoline VOCs.


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Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection, and Remediation® Conference