Removal of 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 U.S. chemical industry. Currently, VOCs are removed from moderately contaminated wastewater streams by processes such as steam stripping, and wastewaters containing low levels of VOCs are treated by air stripping combined with a carbon adsorption off-gas treatment system. Membrane Technology and Research, Inc.¿s research project involves the development of a process that combines air stripping with membrane separation to recover VOCs from the stripper off-gas. The optimum system appears to be a tray stripper fitted with a high-pressure membrane separation unit. Such a system could remove 95¿99 percent of the VOCs present in contaminated water; the removed VOCs are recovered as a liquid condensate. The economics of the technology are competitive with alternative processes, particularly for streams containing more than 100 ppm VOC and having flow rates less than 10¿30 gal/min.