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INTEGRATION OF PHOTOCATALYTIC OXIDATION WITH AIR STRIPPING OF CONTAMINATED AQUIFERS
Citation:
Changrani, R., G. B. Raupp, AND C. Turchi. INTEGRATION OF PHOTOCATALYTIC OXIDATION WITH AIR STRIPPING OF CONTAMINATED AQUIFERS. EPA/540/R-98/504 (NTIS PB99-127920), 1999.
Impact/Purpose:
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Description:
Bench scale laboratory studies and pilot scale studies in a simulated field-test situation were performed to evaluate the integration of gas-solid ultaviolet (UV) photocatalytic oxidation (PCO) downstream if an air stripper unit as a technology for cost-effectively treating water from an aquifer contaminated with chlorinated volatile organic compounds (VOCs). Chlorinated ethylenes such as trichloroethylene (TCE) can be destroyed in a wide process window, although chlorinated ethanes such as trichlorethane (TCA) are non-reactive. Water vapor significantly inhibits the chlorinated ethylene destruction rate. For this reason, PCO units should be placed downstream of a dehumidification unit located between air strippers and the PCO unit, with targeted reduction of the relative humidity in the contaminated air stream to less than 50%. Principal carbon-containing products of PCO identified experimentally at the bench scale include carbon dioxide, carbon monoxide, and phosgene (COCl2). Failure to close carbon mass balances under some process conditions suggests that not all byproducts were identified. Further studies are needed in this area. A panel bed was identified as the preferred photoreactor configuration. This unit is characterized by simplicity of construction, ease of maintenance, and high UV photon utilization efficiency.
