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Enhanced Degradation <br /> of Dissolved Benzene and Toluene Using a Solid <br /> Oxygen-releasing Compound <br /> by Gino C. Bianchi-Mosquera, Richelle M. Allen-King, and Douglas M. Mackay <br /> Introduction <br /> Thousands of sites throughot. <br /> the United States contain groun <br /> Abstract `_ water that is contaminated with gas <br /> A <br /> field test to evaluate the applicability of an oline derivatives such as benzene <br /> oxvgen-releasing compound (ORC) to the reme- toluene, ethylbenzene, and xylenes <br /> This group of compounds ar <br /> field <br /> of ground water contaminated with ben- described collectively as BTE: <br /> zene and toluene was conducted in the Borden Aquifer in compounds. Many studies hav <br /> Ontario,Canada. Benzene and toluene were injected as shown that BTEX compound <br /> organic substrates to represent BTEX compounds,bromide present in ground water will degrad <br /> was used as a tracer, and nitrate was added to avoid under aerobic conditions, i.e., whe <br /> there is oxygen present in the syster <br /> nitrate-limited conditions. (e.g.. Barker et al. 1987). Howeve. <br /> The fate of the solutes was monitored along four lines it is also commonly known tha <br /> of monitoring points and wells.Two lines studied the BTEX-degrading bacteria will cor <br /> behavior of the solutes upgradient and downgradient of two sume oxygen during BTEX metabc <br /> large-diameter well screens filled with briquets containing lism,which often results in the syster <br /> ORC and briquets without ORC. One line was used to becoming anaerobic (Berwanger an <br /> Barker 1988).Anaerobic degradatio <br /> study the solute behavior upgradient and downgradient of of some BTEX constituents is posy <br /> columns of ORC powder placed directly in the saturated ible. particularly under denitrifyin <br /> zone.The remaining line was a control. conditions, but results have bee' <br /> The results indicate that ORC in both briquet and pow- mixed (Acton and Barker 1992 <br /> der form can release significant amounts of oxygen to con- Thus. to ensure rapid BTEX degrc <br /> dation, it is critical to maintain a <br /> taminated ground water passing by it. In the formulation adequate oxygen supply to th <br /> used in this work,oxygen release persisted for at least ground water.The intent of the f[el <br /> 10 weeks. Furthermore, the study indicates that the experiment described below was t <br /> enhancement of the available dissolved oxygen content of determine whether a proprietar <br /> at least 4 mg/L each of the ground water by ORC can sup- solid peroxide formulation(referre <br /> port biodegradation of benzene and toluene dissolved in or as an oxygen-releasing could <br /> provide <br /> compoun <br /> or ORC) could proeide dissolve <br /> ground water. Such concentrations are typical of those oxygen (D.O.) to BTEX-contain <br /> encountered at sites contaminated with petroleum hydro- nated ground water in a controller <br /> carbons; therefore,these results suggest that there is prom- steadv manner and result i <br /> ise for ORC to enhance in situ biodegradation of BTEX enhanced BTEX biodegradation. <br /> contaminants at such sites using passive (nonpumping) sys- <br /> tems to contact the contaminated ground water with the Site Characteristics <br /> oxygen source. The Borden Aquifer in Ontaric <br /> Canada. was selected for the f[el <br /> experiment. The site is locate <br /> immediately east of the natural grz <br /> 120 ■ WINTER 1994 GWMR Pales 120-12 <br />