REMOVAL OF DISSOLVED VOCS FROM WATER WITH AN AIR STRIPPER MEMBRANE VAPOR SEPARATION SYSTEM

Treatment of water contaminated with volatile organic compounds (VOCs) is a major problem for the United States chemical industry. Currently , VOCs are removed from moderately contaminated wastewater streams by processes such as steam stripping and from dilute wastewaters by air s tripping combined with a carbon adsorption off-gas treatment system. T his paper describes the development and performance of a hybrid proces s that combines air stripping with membrane organic-vapor separation t o recover VOCs from the stripper off-gas. A number of prototype system s have been constructed and evaluated. The optimum system appears to b e a tray stripper fitted with a high-pressure compression-condensation membrane separation unit. Such a system can remove 95 to 99% of the V OCs present in contaminated water; the removed VOCs are recovered as a liquid condensate. The economics of the technology are competitive wi th alternative processes, particularly for streams containing more tha n 500 ppm VOC and having flow rates less than 10 to 30 gal/min.