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Methyl tertiary butyl ether (MTBE) is a principal oxygenate used in reformulated gasoline to reduce smog. The reformulated gasoline program, which accounts for approximately 30 percent of gasoline use across the United States, covers 32 areas in 18 states. Although MTBE is credited with significantly reducing air emissions from gasoline-powered vehicles, it has also contaminated water supplies through accidental gasoline releases at pump stations and through leaks from underground storage tanks. In a recent study conducted by the US Geological Society (USGS), MTBE was detected (at 0.2 micrograms per liter) in 21 percent of the groundwater samples taken from areas using reformulated gasoline. Recently, the US Environmental Protection Agency (USEPA) advised water suppliers to ensure that MTBE levels do not exceed 20-40 micrograms per liter, a level most likely to avert the taste and odor of MTBE. Due to limitations of other treatment technologies (e.g., activated carbon and air stripping) to consistently and cost effectively reduce MTBE to low concentrations in drinking water, advanced oxidation processes (AOPs) have received increased interest. Under optimum operational conditions, AOPs can destroy MTBE and organic contaminants directly in the water through chemical oxidation, as opposed to simply transferring them from one phase to another as in the case of air stripping and carbon adsorption. Based on a technology and economical feasibility analysis, peroxone (ozone and peroxide) and ultraviolet (UV) light-catalyzed ozone were found to be the two most promising AOP technologies for MTBE removal. Extensive bench and pilot scale tests were performed to evaluate the effect of various water quality parameters (e.g., total organic carbon content, alkalinity, pH, bromide) and AOP operational factors (e.g., oxidant dose, contact time, UV) on the rate of MTBE and its byproducts reduction. Tests were also performed to identify the most effective type of UV application amongst the three available options: continuous wave low pressure mercury vapor lamp; continuous wave medium pressure mercury vapor lamp; and, pulsed UV xenon arc lamps. In order to determine the effectiveness of the various AOPs under changing water quality conditions, tests were conducted on Suffolk County (low alkalinity and low organic content), Miami-Dade (low alkalinity and high organic content), Santa-Monica (high alkalinity and low organic content) and Irvine Ranch (high alkalinity and high organic content) waters that were spiked with MTBE. Some results of this ongoing AWWARF research will be summarized in this paper. Preliminary results from bench-scale tests with ozone and medium pressure UV processes will be discussed in this paper. Preliminary results of bench-scale tests using pulsed UV technology will be presented in a separate paper. Includes 3 references, tables, figures.

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Edition: Vol. - No. Published: 06/01/2001 Number of Pages: 19File Size: 1 file , 440 KB