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 ------- 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 ------- |