Grantee Research Project Results
Final Report: Electrochemical Reduction of Perchlorates in Potable Water
EPA Contract Number: 68D03037Title: Electrochemical Reduction of Perchlorates in Potable Water
Investigators: Renock, Devon
Small Business: T/J Technologies Inc.
EPA Contact: Richards, April
Phase: I
Project Period: April 1, 2003 through September 1, 2003
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2003) RFA Text | Recipients Lists
Research Category: Watersheds , SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)
Description:
The U.S. Environmental Protection Agency (EPA) has identified perchlorate users and manufacturers in 44 states and perchlorate releases in 18 states. The EPA estimates that perchlorate contamination is present in the drinking water of 15 million people in the United States. T/J Technologies, Inc., proposed to develop a low-cost flow-through electrochemical reactor for reducing perchlorate concentrations in drinking water to less than 1 ppb. The first prototype will target point-of-use (POU) "under the sink" systems, and T/J Technologies plans to demonstrate the potential for cost-effective treatment of larger point-of-source (POS) systems.
T/J Technologies' approach destroys perchlorate ions by electrochemically converting them into harmless chloride (i.e., table salt). Electrochemical reduction is cost-effective for contaminants that are present in low (ppb) concentrations. Only small amounts of current are required, provided that inefficient side reactions are limited. T/J Technologies' innovative approach uses an electrically conductive ceramic catalyst that selectively destroys perchlorates while minimizing the electrolysis of water. To maximize interaction of the perchlorate contaminant with the electrode, the ceramic electrode materials are produced in very high surface area form. The catalyst then is incorporated into a flow-through reactor that optimizes electrode surface area to water volume. Contaminated water passes through several parallel plate electrodes, and perchlorate is converted to innocuous chlorinated byproducts and oxygen as shown in Figure 1. The compact reactor size, innocuous byproducts, and low maintenance requirements make this technology attractive to small POU systems but it also has the potential to be scaled-up to larger systems.
Figure 1. While contaminated water passes through several parallel plate electrodes, perchlorate is converted to innocuous chlorinated by-products and oxygen.
Summary/Accomplishments (Outputs/Outcomes):
T/J Technologies met all technical milestones in preparation for Phase II. The parameters for an "under the sink" device have been identified and an electrode structure has been selected based on a flow-through capacitor (FTC) design patented by Material Methods (Newport Beach, CA). T/J Technologies has synthesized and screened a wide variety of high surface area ceramic electrode materials for selectivity to perchlorate reduction. A transition metal carbide has been selected for Phase II development based on its increased perchlorate destruction rates relative to carbon and the other metal nitrides and carbides in laboratory test cells. This new material has shown high current efficiencies (greater than 75 percent) for conversion of perchlorate to chloride, which will translate to low power consumption in the commercial system. The candidate materials were produced in high surface area form (greater than 10 m2/g), and a scaled-up quantity was delivered to Material Methods for preliminary evaluation in a device.
Conclusions:
Because of its excellent conductivity, chemical stability, and high overpotential for hydrogen formation by water electrolysis, T/J Technologies' metal carbide is an excellent candidate for electrochemical destruction of perchlorate in an FTC reactor. This technology may enable the development of small and inexpensive perchlorate treatment systems. Unlike sorption- or membrane-based approaches, electrochemical treatment permanently converts the perchlorate into harmless species. Existing approaches such as reverse osmosis, activated carbon, or ion exchange require monitoring and periodic replacement or regeneration as well as subsequent disposal or destruction of perchlorate.
Potential uses include POU or POS treatment systems. The technology scales well for "under-the-sink" treatment systems. The treatment technology also may enable the integration with capacitive deionization systems, which would concentrate the perchlorate in the electrode structure for more efficient operation.
Supplemental Keywords:
perchlorate contamination, flow-through electrochemical reactor, drinking water, electrochemical reduction, point-of-use, point-of-source, chloride, electrically conductive ceramic catalyst, flow-through capacitor, carbide, small business, SBIR., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, INTERNATIONAL COOPERATION, Water, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Biochemistry, Physical Processes, Children's Health, Environmental Policy, Drinking Water, Environmental Engineering, alternative disinfection methods, health effects, public water systems, environmental health, other - exposure, exposure and effects, human health effects, drinking water filtration plants, perchlorate, developmental effects, exposure, perchlorates, chemical contaminants, children, community water system, tumors, electrochemical reduction, human exposure, children's vulnerablity, children's environmental health, contaminated groundwater, contaminant removal, drinking water contaminants, drinking water treatment, human health, water treatment, thyroid gland, groundwater, human health riskThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.