Sustainable Catalytic Treatment of Waste Ion Exchange Brines for Reuse During Oxyanion Treatment in Drinking WaterEPA Grant Number: R835174
Title: Sustainable Catalytic Treatment of Waste Ion Exchange Brines for Reuse During Oxyanion Treatment in Drinking Water
Investigators: Werth, Charles J , Strathmann, Timothy J.
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Hiscock, Michael
Project Period: December 1, 2011 through November 30, 2014 (Extended to November 30, 2016)
Project Amount: $500,000
RFA: Research and Demonstration of Innovative Drinking Water Treatment Technologies in Small Systems (2011) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Treating oxyanion contaminants poses a special challenge for smaller water systems. Drinking water systems that serve < 10,000 persons disproportionately utilize groundwater sources, many of which are contaminated by nitrate/nitrite, perchlorate, and chromate. The most common approach to remove oxyanions uses an ion exchange (IX) process. However. this technology only removes the oxyanions from water, and once contaminant breakthrough begins. resins are typically regenerated using a concentrated brine solution. Waste brines are usually disposed of. and they represent a considerable cost and negative environmental impact. A promising and emerging approach is to treat waste brines using catalytic reduction. and then reuse the brine multiple times for ion exchange resin regeneration. However, questions regarding catalyst longevity and economic viability are hindering adoption of this technology. The objective of this work are to 1) identify palladium (Pd) catalyst formulations with sufficient activity to reduce different target oxyanions in brine solutions, 2) determine if catalyst activity can be maintained for extended periods of operation, and 3) assess the economic and environmental life cycle costs of hybrid IX/catalysis treatment systems.
Meeting these objectives will allow us to test several key hypotheses; these are i) existing Pd bimetal catalyst formulations (e.g., supported Pd/In; Pd/Re) will be sufficient for reducing the major target oxyanions, but a staged approach of packing multiple catalysts in series into reactor beds may be necessary to optimize performance and minimize material costs, ii) catalyst activity will be maintained over months to years, and treated waste brines will maintain their ability to regenerate ion exchange res ins over multiple treatment cycles, iii) fouled catalysts can be regenerated by short-term flushing of reactor beds with regenerant solutions, and iv) catalytic brine treatment will significantly reduce operating costs and environmental impacts of ion exchange systems for small utilities. Our overall approach involves collecting a suite of oxyanion-contaminated waste brines from several small drinking water treatment plants, exploring the effects of brine characteristics, catalyst properties, and operating conditions on oxyanion reduction in packed- bed reactors, using oxyanion reduction rates from packed-bed reactors to design, build, and test a pi lot scale reactor at a small water treatment plant, and performing an economic and life cycle assessment of a full-scale reactor using results from the pilot scale reactor and information from the water treatment plant for scale up.
We expect the proposed work to result in the design of full-scale treatment systems for catalytic brine treatment that provides a more economical and sustainable option for removing mixtures of oxyanions from drinking water at small water treatment utilities. This will allow delivery of potable water at a lower cost, and reduce the risk of environmental impacts associated with global warming, acidification, carcinogens, non-carcinogens, respiratory effects, eutrophication, ozone depletion, ecotoxicity, smog, and fossil fuel depletion.