Photochemical destruction of tetrachloroethylene and trichloroethylene from the exhaust of an air stripper

A novel pilot-scale photochemical reactor is utilized to carry out vapor-phase tetrachloroethylene (PCE) and trichloroethylene (TCE) destruction experiments from the exhaust of a groundwater remediation air stripper. The cylindrical-shaped stainless steel photochemical reactor has an inner diameter of 32 cm and a length of 105 cm. Low-pressure mercury ultraviolet (UV) lamps are used as the photochemical energy source to initiate the destruction reaction within the reactor. A cylindrical-shaped air stripper with a volume of 15.7 L is constructed and utilized for transferring the contaminant from the aqueous phase to the vapor phase. Experiments are conducted using the air stripper to determine phase-transfer characteristics of PCE and TCE. The results show good contaminant phase transfer using clean airflow rates of 1.5 and 3.0 L/min. Next, groundwater remediation experiments are conducted with the air stripper exhaust flowing into the photochemical reactor for contaminant destruction. The first experiment use distilled water contaminated with dissolved PCE, the second experiment use distilled water contaminated with dissolved TCE, and the third experiment use distilled water contaminated with both dissolved PCE and TCE. All three experiments show excellent contaminant destruction efficiencies. This study demonstrates that the photochemical reactor should be included as part of an overall air-stripping PCE/TCE groundwater remediation scheme for complete contaminant destruction.