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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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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