xvEPA
United States
Environmental Protection
Agency
EPA/540/MR-93/513
May 1993
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Microfiltration Technology
EPOC Water, Inc.
Technology Description: The EPOC mbrofiltratbn technology is
designed to remove suspended solids that are 0.1 microns in diameter
or larger from liquid wastes. Wastewaters containing dissolved metals
are treated by chemical precipitation, so that the metal contamination
present is greater than or equal to 0.1 microns. The precipitated
metals, along with all other particles down to 0.1 microns, are filtered
through a fabric crossfbw microfilter (EXXFLOW). The concentrate
stream is then dewatered in an automatic tubular filter press of the
same fabric material (EXXPRESS). Figure 1 presents a schematic of
EPOC's microfiltratbn system.
The EXXFLOW microfilter modules consist of an array of parallel
permeable textile tubes which are endosed in an outer tube shell.
Liquid wastes are pumped into the imbrofilter tubes, and suspended
matter in the liquid feed forms a membrane layer on the internal
surface of each tube. The membrane formed is dynamb, continually
formed and swept clean by the bngitudinal fbw of the feed liquid
through the tubes. Dynamic membranes of widely different characteris-
tics can be produced by using different pretreatment chemicais. Per-
meate, or treated product liquid, filters radially through the membrane
layer and out of the textile tube walls for collection in the outer tube
shell. The EXXFLOW concentrate stream is discharged to the
EXXPRESS feed tank.
The EXXPRESS portbn of the process dewaters the sludge from the
EXXFLOW concentrate. During operation, the discharge valve of the
EXXPRESS remains closed as the concentrate stream enters the
module. A layer of solids forms on the inside of the tubular cloth of the
EXXPRESS tubes similar to that of the EXXFLOW module. While in
the dead-end mode, the system builds pressure and the associated
water permeates through the slurry membrane layer. The water is
collected and recycled back to the EXXFLOW feed tank. When the
membrane layer reaches a controlled thickness, the discharge valve is
opened and the module is traversed by mechanical squeeze rollers.
The rollers separate the membrane layer from the tube wall to form
solid chips (filter cake). The cake is expelled from the tubes with flush
water and the solids are separated from the liquid with a gravity
dewatering screen. The discharge water is recycled back to the
EXXPRESS feed tank
In cases where the solids in the liquid feed are extremely high,
EXXPRESS can be used first, with EXXFLOW acting as a final polish
for the product water.
Waste Applicability: This technology is applbable to wastewaters
containing heavy metals, pesticides, oil and grease, suspended solids,
and constituents that can be precipitated into partble sizes greater
than 0.1 mbrons. The system can handle waste streams containing
2% to 5% solids.
Demonstration Results: A demonstration of the EPOC Water, Inc.
transportable, skid-mounted, pilot-scale Mbrofiltration Technology (2 to
7 gpm) has been performed under the Superfund Innovative Technol-
ogy (SITE) Program. The demonstratbn occurred during May and
June of 1992 at the Iron Mountain Mine Superfund site, located near
Redding, California.
During the Demonstratbn Test, the EPOC Mbrofiltratbn Technobgy
treated heavy metal contaminated acid mine drainage from the Old
Number 8 mine seep. The primary chemical composition of Old
Number 8 was approximately:
700 ppm aluminum;
0.5 ppm cadmium;
170 ppm copper;
1900 ppm copper;
7000 ppm sutfate;
60 ppm zinc; and
pH2-2.5
For each of the Demonstratbn Tests, different alkalies (treatment
chembals) were used to precipitate the metals from solution. These
alkalies included:
• Hydrated Lime (cabium hydroxide, Ca(OH)2);
• Sodium Hydroxide (50% liquid caustb soda, NaOH); and
• Magnesium Oxide (MgO).
Devebper claims for metal removals on Old Number 8, when neutral-
izing with NaOH and Ca(OH)2, were generally met or exceeded except
for aluminum. This was most likely due to the difficulty encountered
when using NaOH and Ca(OH)2 to control the pH of this waste stream.
The claims for all metals, including aluminum, were exceeded when
MgO was used as the neutralizing agent. In most cases, there were no
detectable concentratbns of heavy metals in the permeate samples.
Filter cake produced from the Demonstratbn Test contained approxi-
mately 12%, 31% and 30% solids when NaOH, Ca(OH) and MgO
were used as the treatment chembals, respectively. TCLP leaching
tests performed on the filter cake showed that teachable levels of
TCLP metals were below the regulatory limits for each of the treatment
chembals tested.
Printed on Recycled Paper
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An Applications Analysis Report and a Technology Evaluatbr Report
describing the complete Demonstratton Test will be available in the
Summer of 1993.
For Further Information:
EPA Project Manager:
Jack Hubbard
U.S. EPA Risk Reductbn Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7507
Technology Developer Contact:
K. Scott Jackson
EPOC Water, Inc.
3065 Sunnyside, #101
Fresno, CA 93727
(209)291-8144
Figure 1. Schematic diagram of EPOC's Micro-filtration System.
'U.S. Government Printing Office: 1993 — 750-071/80012
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGES FEES PAID
EPA
PERMIT No. G-35
EPA/540/MR-93/513
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