&EPA
United States
Environmental Protection
Agency
EPA/540/MR-96/507
December 1997
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Disc Tube™ Module Technology
Rochem Separation Systems, Inc.
Technology Description: Rochem Separation Systems, Inc.
has developed the Disc Tube Module (DIM) technology, an
innovative membrane separation process for removal of contami-
nants from liquid hazardous waste streams. Traditionally, mem-
brane separation processes have been used as a secondary or
polishing step in waste treatment schemes. However, Rochem's
DTM technology uses an innovative process configuration which
allows it to be the primary treatment for waste streams such as
landfill leachate. The DTM technology is designed to treat waste
that is higher in dissolved solids content, turbidity, and contami-
nant levels than waste treated by conventional membrane sepa-
ration processes.
The patented membrane module features larger feed flow chan-
nels and a higher feed flow velocity than other membrane sepa-
ration systems. According to the technology developer, these
characteristics allow the DTM greater tolerance for dissolved
solids and turbidity and a greater resistance to fouling and scal-
ing of the membranes. Suspended particulates are readily flushed
away from the membrane during operation. The high flow veloc-
ity, short feed water path across each membrane, and the circui-
tous flow path create turbulent mixing to reduce boundary layer
effects and minimize membrane fouling and scaling. According
to the developer, the DTM design allows easy cleaning and
maintenance of the membranes. Figure 1 details a cutaway
diagram of the Disc Tube Module. Membrane material for the
DTM is formed into a cushion with a porous spacer material on
the inside. The membrane cushions are alternately stacked with
hydraulic discs on a tension rod. The hydraulic discs support the
membranes and provide flow channels to pass the feed liquid
over the membranes. After passing through the membrane
material, permeate flows through permeate collection channels to
a product recovery tank. A stack of cushions and discs is housed
in a pressure vessel. Flanges seal the ends of the module in the
pressure vessel and provide the feed water input and the product
and reject output connections. The number of discs per module,
number of modules, and the membrane materials can be custom-
designed to suit the application. Modules are typically combined
in a treatment unit or stage. The DTM technology can use
reverse osmosis, ultrafiltration, or microfiltratipn membrane mate-
rials. These membranes are more permeable to water than to
contaminants or impurities. Water in the feed is forced through
these membranes by pressure and becomes permeate consist-
ing of a larger fraction of water with a lower concentration of
contaminants. The impurities are selectively rejected by the
membranes and are thus concentrated in the smaller fraction of
the concentrate left behind. The percentage of water that passes
through the membranes is a function of the operating pressure,
membrane type, and concentration of the contaminants.
Waste Applicability: According to the technology developer,
the DTM technology can treat liquid waste streams containing
hazardous wastes, volatile and semivolatile organic compounds,
metals, and radioactive wastes. The technology has been used
to treat landfill leachate, oil/water mixtures, and solvent/water
mixtures.
Demonstration Approach: The U.S. EPA Superfund Innova-
tive Technology Evaluation (SITE) Program conducted a Demon-
stration Test at the Central Landfill in Johnston, Rhode Island
where approximately 33,000 gallons of hazardous landfill leachate
were treated by the DTM technology using reverse osmosis
membranes. The leachate contained chlorobenzene and 1,2-
dichlorobenzene at average concentrations of 21 mg/L and 16
Feed water
Permeate Concentrate
(product) (reject)
Pressure vessel
End flange
Tension rod
Membrane Hydraulic
cushion disc
Figure 1. Cutaway Diagram of the Disc Tube Module.
Printed on Recycled Paper
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mg/L, respectively, and lower levels of toluene, xylenes, and
ethylbenzene; total organic carbon at an average concentration of
460 mg/L; low mg/L levels of heavy metals; and total dissolved
solids at an average concentration of 4,900 mg/L. For treatment
of this was|e, a three-stage DIM process was utilized. Two
stages were used in series to treat the landfill leachate and
produce the final permeate. The third stage was a high pressure
unit (HPU) which further treated the concentrate rejected by the
first stage to increase the system water recovery. Media and
cartridge filters were built into each unit to remove suspended
particulates, and acid was added at the first stage and at the HPU
for pH control.
The critical objectives of the Demonstration Test were to deter-
mine whether the technology was capable of meeting criteria for
(1) percent rejection of the contaminants, (2) treated water recov-
ery rate, and (3) resistance to scaling and fouling of membranes.
Sampling, analysis, and monitoring of the input and output streams
were conducted during treatment to evaluate system percent
rejection and recovery rate. Baseline testing was performed
before and after leachate treatment to compare the system's pre-
test and post-test flux (flow rate per unit membrane surface area),
and thereby evaluate resistance to scaling and fouling. The test
was designed to allow the system to operate for 21 days, 7 days
per week, and up to 10 hours per day, long enough to allow
several cycles of membrane cleaning.
Preliminary Results: Preliminary evaluation of the post-treat-
ment data suggest the following conclusions:
* Percent rejections were greater than the test criteria of 99% for
total dissolved solids, 92% fortotal organic carbon, and 99% for
all target metals. In addition, the average percent rejection for
volatile organic compounds was greater than the test criteria of
90%.
• The average water recovery rate forthe DTM technology during
the demonstration was approximately 75%. The test criteria
was 75% treated water recovery rate.
• The DTM technology operated for 19 days at up to 8 hours per
day. System operation conditions were not as long or as steady
as planned due to weather and field operational difficulties.
However, the system operated long enough to allow mem-
brane cleaning, which helped to maintain technology perfor-
mance.
Key findings from the demonstration, including complete analyti-
cal results, baseline test results, and an economic analysis will
be published in an Innovative Technology Evaluation Report.
This report will be used to evaluate the Rochem DTM technology
as an alternative for cleaning up similar sites across the country.
Results will also be presented in a SITE Technology Capsule
and a videotape.
For Further Information:
EPA Project Manager:
Douglas Grosse
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7784
Technology Developer Contact:
David LaMonica
President
Rochem Separation Systems, Inc.
3904 Del Amo Boulevard, Suite 801
Torrance, CA 90503
(310) 370-3160
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
EPA/540VMR-96/507
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
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