S.EPA
United States
Environmental Protection
Agency
EPA/540/MR-92/OU
April 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Membrane Filtration
SBP Technologies, Inc.
Technology Description: SBP Technologies Inc. (SBP) has
developed a membrane-based separation technology that can
reduce the volumeof contaminated groundwater requiring treatment.
The SBP Filtration Unit consists of porous, sintered, stainless steel
tubes arranged in a shell-and-tube module configuration (Figure 1).
Multi-layered inorganics and polymeric"formed-in-place" membranes
are coated at microscopic thickness on the inside diameter of the
porous stainless steel tubing by the recirculation of an aqueous
slurry of membrane formation chemicals. This "formed-in-place"
membrane functions as a hyperfiltration unit, removing species with
molecular weights as low as 200. The formed-in-place membranes
can be easily and readily modified to conform to waste characteristics
and separation requirements.
The filtration unit is operated in a crossflow mode where the feed
stream is directed parallel to the surface of'the membrane. The
goal of the crossflow filtration is not to trap components within the
pore structure of the membrane. In crossflow filtration, particu-
lates and dissolved chemical species larger than the surface
porosity are temporarily retarded on the membrane surface, and
are then swept clean by the crossflow action. A portion of the
fluid stream, along with smaller species, passes through the
membrane. This process concentrates large species by reducing
the volume of fluid in the crossflow stream. The product crossflow
stream containing the excluded species is called the "concen-
trate." The material passing through the membrane is called the
"permeate."
In crossflow mode, the buildup of dissolved and particulate spe-
cies on the surface of the membrane (fouling) is minimized by the
parallel flow direction of the fluid. Periodic cleaning of the mem-
brane is necessary when the buildup of materials becomes ex-
cessive.
Stainless Steel
Tubular Housing
Space for
Permeate Removal
Porous Stainless
Steel Tubing
Formed-in-place
Membrane
Figure 1. Cross-section of shell-and-tube module
The test unit was operated with four modules. The filtration unit
used was approximately 13 ft long, 5 ft wide and 7 ft high. The
effective membrane area of each module is 72 ft2. Automatic
level controls provide for unattended operation with continuous
feed ito a tank. Temperature and concentrate recycle flow are
also controlled automatically.
A schematic of the filtration unit is shown in Figure 2. Contami-
nated water is fed into the filtration unit. The contaminant wastes
are contained within the .piping system while the permeate is
filtered through the tube walls and is captured within the system
outside the tubular bundle. Permeate may be disposed of in a
manner consistent with local permitting requirements. The con-
centrated contaminant stream can be repeatedly recycled to
achieive a desirable volume reduction level. The final concen-
trated waste is transferred to a holding tank to await subsequent
treatment.
Waslte Applicability: SBP states that their membrane filtration
technology is applicable to grpundwaters and process waters with
COD!leve|s between 100 and 500 mg/L where the molecular weight
of contaminants being concentrated are over 200. Based on the Site
demonstration, waste streams rich in polyaromatic hydrocarbons
(PAFjs) would probably be suitable while those with a goal of
concentrating phenols would probably not be appropriate.
Dilute feedwaters may require more permeate removal to achieve
desired concentrations, but the rate of permeate production would
likely be higher. Waste streams with contaminant concentrations
exceeding the desired range may require less permeate removal
to achieve desired concentrations, but the rate of permeate
production would likely be less due to accelerated fouling of the
membrane. More frequent downtime for washing may be required
with 'elevated levels of contaminants in the feedstream. In either
case^ operation should not be affected, since adjustments in
membrane surface, area and cleaning cycles allow for tailored
performance.
SBP believes the membrane can be customized to achieve
different rejection characteristics that could be applied to a wide
range of contaminants. For example, crossflow membrane filtration
may be applicable to wastestreams containing high molecular
weight or non-polar organic contaminants, such as polychlori-
nated biphenyls. The process may also be useful for separating
othef emulsified or dispersed organics which do not lend them-
selves to simple physical phase separation.
I . .
: , rS) Printed on Recycled Paper
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Demonstration Results: The SBP membrane microfiltration
process was demonstrated at the American Creosote Works
(ACW) Superfund site near Pensacola, Florida, in October, 1991.
Approximately 6,000 gallons of feedwater contaminated with wood
preserving wastes was treated over a six day period. The 6-day
average total semivolatile feed concentration was 88.5 mg/L, with
phenanthrene (17.1 mg/L) and naphthalene (12.9 mg/L) as the
major components.
Tha same test was essentially conducted for each of the six days
wHh small variations in operating conditions to account for mem-
brane fouling. The unit was cleaned every two days to eliminate
any contaminant buildup. Feedwater (approx. 1,000 gal) was
taken from a tank every day and initially run through the unit for 2
hr. Thereafter, the concentrate was recycled until the desired
80% volume reduction was achieved.
Process operating data were collected, including flow rates, tem-
peratures, pressures and electrical and potable water usage. The
feedwater, permeate, concentrate and washwater were all ana-
lyzed for volatile organic compounds, total dissolved and sus-
pended solids, oil and grease, total organic carbon and chemical
oxygen demand.
The key conclusions from the SBP SITE demonstration can be
summarized as follows:
The system can effectively concentrate the PAHs into a
smaller volume.
• The process is effective (>95%) at removing PAHs found
in creosote from the feed and producing a permeate stream
with concentrations low enough that it should be accept-
able for discharge to POTWs with little or no polishing
required.
The membrane is not very effective (25-35%) at removing
one-ringed compounds such as the phenolics.
Based on comparison of the total concentrations of creo-
sote constituents (phenolics and PAHs) in the feedwater
and permeate, the system removed an average of about
80% of these compounds instead of the claimed removal
efficiency of 90%. However, the major creosote constitu-
ents which contributed to the lower than claimed removal
"efficiency are less toxic, one-ringed compounds (pheno-
lics) which may be discharged or are easily treated.
Recycle
An Applications Analysis Report and a Technology Evaluation
Report describing the complete SBP SITE demonstration will be
available in the Fall of 1992.
For Further Information:
EPA Project Manager:
Kim Lisa Kreiton
U.S.Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7328/FTS: 684-7328
Figure 2. Filtration Unit Scfce/nafrc
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/540/MR-92/014
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