Removal and Disposal of Perchlorate from Drinking Water by Novel Capacitive

The leading treatments for perchlorate removal are ion exchange with catalytic destruction and bioreactors. These treatments require significant labor and material inputs. The associated operating costs prohibit scaling to small systems (fewer than 25 people or 15 service connections). Even in large systems, the leading treatments are expensive, costing $100-$200/acre-ft, or 20-40 percent of wholesale water costs. The Awwa Research Foundation investigated an effective alternative electrochemical reduction of perchlorate. The study showed that perchlorate could be electrochemically converted into water and harmless chloride ions. It concluded that a practical device "would require that the number of reactive sites on the electrode surface relative to the solution volume be increased by several orders of magnitude." Material Methods, LLC, has developed such a device. Material Methods' research during the past several years has focused on water purification with the flow through capacitor (FTC). High surface area, nanostructured electrodes, and thin layer reactor designs have been developed. This is exactly the platform recommended in the Awwa Research Foundation study. Electrochemical desalting, softening, and arsenic removal with the FTC have been demonstrated. Initial experiments demonstrated continuous perchlorate removal and destruction over a wide range of feed concentrations. This Phase I research project will enhance the initial rates of removal and destruction. Research conducted by Material Methods will produce a novel, heterogeneous electrode design and optimal electrochemical modulation. These advances will prove the concept of a low-cost, low-maintenance perchlorate treatment system suitable for small water systems. This electrochemical approach will be effective for the removal of perchlorate and inorganic ions at 200 ppm total dissolved solid levels with greater than 95 percent rejection using a single-stage reactor. It will be particularly suitable for use as a polishing unit to remove or reduce low levels of perchlorate in small drinking water systems from 0.05-5 ppm to below 4 ppb levels, and greater than 90 percent of perchlorate waste will be destroyed. In Phase I, the focus will be on the technical feasibility. Phase II research will test the prototype at a small water treatment facility. The proposed technology relates to drinking water treatment, nanomaterials, and clean technology, which are of special interest to the U.S. Environmental Protection Agency. It will have considerable commercial use potential as an efficient, cost-effective, and environmentally benign method for the treatment of perchlorate from drinking water in small systems. This technology also can be developed into point of entry drinking water purification devices for home and commercial applications.