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.i Microbubble Oxidation Smokes MTBE and BTEX Page 1 of 3 Microbubble Oxidation Smokes NITBE and BTEX C-Sparge TM Ozone Microsparging for Rapid Removal of MTBE and Benzene By William B. Kerfoot, Ph.D., LSP and Angus McGrath, Ph.D. A system called C-SpargingT which uses ozone/air injected periodically in conjunction with a pulsing pump has been demonstrated to reduce MTBE from over 1000 ppb to less than 100 ppb in less than 40 days. The rate of decay was cmass rxar found to be a ten-fold reduction in monitoring wells located 3 to 7 meters from the coaaaxasos p sowexsal injection point. Monitoring was performed weekly during and after treatment. r R mexN9ErsYurer; l=WW What is C-Sparginim ruaeauva ` The KVA process of C-SpargingTm, in sita air stripping with micro-encapsulated -� smsar e:uree ',^ CIAkt34Ni �i ozone, combines three- unit operations offering aone-two-three punch to knockout - MTBE. Firstly, fine bubbles with a high surface-to-volume ratio are injected into c the saturated zone to extract dissolved MTBE from contaminated groundwater. Secondly, ozone contained within the bubble and thin film around the bubble PUMP reacts extremely rapidly to decompose the MTBE into simple products, alcohols, acetate and formate. Thirdly, the residual oxygen from the reaction encourages azmin px bioremediation which consumes the breakdown products and converts them to carbon dioxide (CO2) and water (H2O). l r ri Ozone Microsparging is a Patented Technology for fn Situ Treatment of .ettvr Volatile Organic Compounds (VOCs) in Groundwater s smar t,wnt The reaction detoxifies groundwater containing MTBE and BTEX compounds, } rhssmoasT specifically benzene, rapidly to groundwater standards without producing hamif d c» u ALVE byproducts. The reaction is produced with very low ozone concentrations-molar ur uow zv ratios-compared to VOC concentrations in groundwater. The technology combines the unit operations of air stripping and oxidative decomposition in a single process asuatuwvmi.< which can be catalytically accelerated. In the C-SpargeTM process, air and ozone 'f' WAtSM1141 are injected directly into groundwater through specially-designed spargers to create "microbubbles" that have very high surface area-to-volume ratio. The Figure 1. master control unit Henry's Constant which regulates the partitioning of MTBE from aqueous to gaseous state is about one-tenth that of benzene derivatives. However, the surface-to-volume ratio increase of over 30- fold compensates to promote rapid in situ stripping of MTBE. As the "microbubbles" rise within a saturated column of groundwater, they extract or "strip" the VOCs from aqueous to gas partitioning. Upon entering the microbubbles, MTBE and BTEX compounds react with ozone in the gaseous state or in the aqueous "thin layer" surrounding the bubble to decompose. MTBE is rapidly degraded with time. The rate of decay is similar to that previously reported by Karpel vel Leitner, et. al. ( 1994). In both bench-scale testing and field testing, ozone microbubbles appeared effective _. in reducing MTBE concentrations to beyond 90% of original levels (Kerfoot, 2000). The rate of removal has been sensitive to ozone concentration, pressure, and iron silicate content. Site Specific System Set-up A-singlepargerg-master4ruit with-6-SpargepointsO wasinstalle -upgradie-nt of plume—region—. The—unit can-b installed with a dual-screened recirculation spargewell which has a lower Spargepoint® or with isolated Spargepoints®. The depth to groundwater was 2 to 3 meters. The general construction of a C-SpargeTM consists of a 100 mm casing leading to a 1 .5 meter screen with 0.5 meter above the water table, a blank casing which was bentonite-sealed in the annular space to prevent short-circuiting, and a lower 1 .5 meter screen (10 slot). Alongside this - .� was a 1 .5 cm diameter tubing leading from the wellhead region to a 50 mm microporous Spargepoint(k 46 cm long r_1 with a compression fitting situated below the lower double screen. -- The predominant soil type was gravelly sands. Water table level occurred at 2 to 3 meters. The predominant contaminated region extended vertically from 1 to 3 meters deep. The Spargepoints@ were installed at a depth of 10 — meters. i i http://www.kva-equipment.com/papers/microbub.htm 4/5/02