United States Environmental Protection Agency EPA/540/F-93/503 May 1993 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION Emerging Technology Bulletin A Cross-Flow Pervaporation System lor Removal of VOCs from Contaminated Wastewater 4. 'I Wastewater Technology Centre Technology Description: Pervaporation is a process for remov- ing volatile organic compounds (VOC) from contaminated water. The performance of the cross-flow pervaporation system in- creases with temperature, with an equipment limitation of 35 degrees Celsius. Permeable membranes that preferentially ad- sorb VOCs are used to partition VOCs from the contaminated water. The VOCs diffuse from the membrane and water interface through the membrane and are drawn off by a vacuum pump. Upstream of the vacuum pump, a condenser traps and contains the permeating vapors, condensing all the vapor, and allowing no fugitive emissions (see Figure 1). The condensed organic vapors represent only a fraction of the initial wastewater volume and may be sent for disposal at significant cost savings. Industrial waste streams may also be treated with this process, and sol- vents may be recovered for reuse. A pilot pervaporation system has been developed that is skid- mounted, compact, and rated for Class I, Division I, Group D environments. The membrane modules used in this system con- sist of beds of hollow fibers (much like a carbon bed) with well- Aqueous waste defined alignment that results in minimal pressure drop and operating costs per 1,000 gal of treated wastewater. The unit can reduce VOCs by 99%. Removal has been demonstrated to less than £} parts per billion (ppb). For flow rates of less than 1 gal/min this unit can achieve 99.999% removal of VOCs. This high removjal capacity plus containment of fugitive emissions are the primary advantages of this technology as compared with air stripping followed by gas-phase carbon adsorption. Wasto Applicability: Pervaporation can be applied to aqueous waste] streams (groundwater, lagoons, leachate, and rinse water) contaminated with VOCs, such as solvents, degreasers, and gasoline. The technology is applicable to the types of wastes currently treated by carbon adsorption, air stripping, and reverse osmosis separation. Test Results: A pilot plant with removal efficiency of 99% was built iand evaluated with toluene and trichlorethylene. The pervaporation module used in this plant consisted of hollow fibers (540 jim OD) spaced 1 mm center to center in both lateral and Treated effluent Feedpump Figure 1. Schematic of the Pervaporation process. Organic liquid Printed on Recycled Paper ------- tongiudinal directions. Toe" Klfavv: tiers i^mi^v^s.Mm'opb-.Il'.l^im^^ Developer Contacts: strudsd with a thick; and selfjflye; otAsJde layer of sfficone rubber f}25 {ttjj}. Triidughcitrt the ^|lg ptDgiim^there was rio evridence , — Bob Booti i :::=', ;= of foutlng or CRannailftig of feed in the tcansveirse nioclotes, fls- \fifes|ew§i|ai Tiefenojpg^ Centre mo\ral rales war® showa IQ tefeass beyond the rates reported in 867 LaReiitora Road, Box SQ68 For Further fnforraalton; EPA Profect Manager: John Mattfa '. U.S.EPA ffisk Reducion Engfaeerlng tSboratoiy 2S West Msalio Ualher King Chris I^dcT ' Suritegton, """Canada 416-639-6320 t»93— United States Erwfronmental Center for Envtenmeiili Cincinnati OH 45268 BULK RATE POSTAGE & FEES PAiD EPA PERMIT No. Q-35 Pwmjty for Private Use $300 ------- |