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

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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

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