BTEX, groundwater contamination

The monoaromatic compounds benzene, toluene, ethylbenzene and xylene, commonly found in crude oil, are often jointly called BTEX compounds. The most harmful of these compounds is benzene, which is a known carcinogen. BTEX compounds occur naturally near natural gas and petroleum deposits and are detected in the fumes of forest fires. Most of the highly volatile BTEX compounds released by human activity originate from fuel use and end up as pollutants in the air. Inhaling BTEX-polluted air is also the greatest hazard to humans by these compounds. BTEX compounds are water-soluble, and therefore, improper handling can also cause groundwater contamination. 

At a service station in Carson City, Nevada, a 30-kW Rayox system was used to treat groundwater contaminated with BTEX and petroleum hydrocarbons. Operating costs for this system were 2.25 per 1000 gal of water treated (D17097S, Appendix II). 

At the Mustang-Shadow Mountain Gas Station, in Grand Lake, Colorado, FOREMOST installed 3 BioNets containing 3 BioLuxes to remediate soils and groundwater contaminated with BTEX. The design and installation of this system cost 130,000 (D213332, Appendix... 

ISOTEC is a technology that uses the periodic injection of hydrogen peroxide and proprietary catalysts to oxidize organic contaminants in situ. According to the vendor, this technology can treat soil and groundwater contaminated with chlorinated compounds, petroleum hydrocarbons, polychlorinated biphenyls (PCBs), trichloroethene (TCE), tetrachloroethene (PCE), pesticides, herbicides, as well as benzene, toluene, ethylbenzene, and xylene (BTEX). The ISOTEC technology is commercially available. 

According to the vendor. Microbial Fence has been used to treat groundwater contaminated with polycyclic aromatic hydrocarbons (PAHs) benzene, toluene, ethylbenzene, and xylenes (BTEX) and volatile organic hydrocarbons (VOCs) at petroleum, chemical, and wood treating facilities and manufactured gas plants. Microbial Fence was used alone or in conjunction with soil venting/bioventing, aquifer aeration, pump-and-treat methods, and/or recovery of non-aqueous-phase liquids (NAPLs). 

More than 20 years ago, the need to separate and deteet VOCs was accomplished by placing a PID in series with a EICD in whieh aromatic VOCs could be detected on the PID and CIVOCs could be detected on the EICD. This was the principal basis for the EPA Methods 501/502 for drinking water and 601/602 for wastewater. The lowering of GC IDEs from the low-ppm level afforded by the FID to the low-ppb level was first accomplished on a routine basis with the PID, EICD, and ECD detectors. An instrument that incorporated a cap column and ECD, C-GC-ECD, first detected DDT in the environment and a cap column with a PID, C-GC-PID, first found ppb levels of BTEX in contaminated groundwater. 

Johnston, C.D., Rayner, J.L., Patterson, B.M. and Davis, G.B., Volatilisation and biodegradation during air sparging of dissolved BTEX-contaminated groundwater, J. Contam. Hydrol., 33, 377-404, 1998. 

The United States Environmental Protection Agency (U.S. EPA) has identified several hundred MTBE-contaminated sites that have performed treatment of soil and groundwater to remove or destroy MTBE.1 Many of these sites have also treated other fuel components, primarily benzene, toluene, ethylbenzene, and xylene (BTEX), and some have treated fuel oxygenates other than MTBE. Although others have reported about treatment technologies for MTBE cleanup,2 only limited information has been published about cleanup of other oxygenates. These oxygenates include ether compounds, such as ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), diisopropyl ether (DIPE), and tert-amyl ethyl ether (TAEE), as well as alcohol compounds, such as tert-butyl alcohol (TBA), tert-amyl alcohol (TAA), ethanol, and methanol. 

A full-scale cleanup was performed using in situ bioremediation to treat MTBE and BTEX at a service station in Massachusetts. Soil at the site consists of a layer of sand and gravel underlain by peat, silt, and clay. The in situ bioremediation system consisted of 12 injection wells and two butane injection panels used to stimulate cometabolic aerobic biodegradation of the contaminants in groundwater. The system was operated between October 2000 and January 2001. MTBE concentrations were reduced from 370 to 12 pg/L and BTEX contamination in groundwater was reduced by approximately two orders of magnitude during the 4-month period.74... 

Landmeyer, J.E., Vrblosky, D.A., and Bradley, P.M., MTBE and BTEX in trees above contaminated groundwater, Battelle International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, 2000. 

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