1235596 (Farrell). This research is being pursued in direct response to the growing concern of salt accumulation in public drinking water supplies and the increasing need for communities to rely on water reuse. The research will test the feasibility of two novel electrochemical processes for removing hardness ions, silica and dissolved organic matter from potable and waste waters. The ELIXR process utilizes an electrochemical cell for producing acids and bases for the regeneration of ion exchange (IX) media. The acids and bases are produced using the ions present in the water, and thereby does not require the use of any chemicals. The RECS process is an electrochemical enhancement of pellet softening, in which an electrochemical cell replaces the acids and bases used for pH adjustment. The RECS process can also be used for removing dissolved silica and organic matter as a pretreatment for reverse osmosis (RO), or as a posttreatment process on RO concentrates. Combination of the ELIXR and RECS processes can eliminate the production of brine solutions that are normally generated during IX regeneration. Thus, in addition to water softening, the ELIXR and RECS processes can be used to produce zero liquid discharge from water reclamation operations. The objectives of this research are to test the proofs of concept for the ELIXR and RECS processes. Achieving this objective will require the following intellectual contributions: 1) proof of concept validation for two new water treatment technologies; 2) development of methods to concentrate ions in IX regenerant solutions; 3) determination of ionic concentration and speciation effects on energy requirements for producing acid regenerant solutions; 4) determination of current density, chloride and sulfate concentration effects on the production hypochlorite and persulfate; 5) determination of the effectiveness of block carbon filters on hypochlorite removal; 6) determination of persulfate effects on conventional ion exchange media and on polypropylene based ion exchange fibers; 7) determination of the effectiveness of RECS for removing hardness ions, silica and dissolved organic matter from ELIXR and RO concentrates; and 8) determination of the effectiveness of direct anodic oxidation and anodically produced oxidant species for destroying dissolved organic matter and biologically recalcitrant contaminants in RO concentrates. The broadest impacts of this research are that it addresses the two biggest issues with potable water in arid regions of the country, namely: 1) the increasing salinification of the groundwater supplies; and 2) the pretreatment and concentrate disposal issues associated with RO and water reclamation activities. The ELIXR and RECS processes will have a direct impact on water reuse processing as they are able to remove ions, dissolved solids and organic matter from water without chemical addition or production of concentrate streams. In addition, the ELIXR and RECS processes will alleviate the pollution and natural resource requirements associated with the transport and storage of large quantities of hazardous chemicals, reduce the footprint of traditional treatment methods, and reduce the costs of purifying water. An education and diversity plan focuses on recruiting students from under-represented groups and integration of research results into the energy, water and the environment component of the ENGR 102-High School course that the principal investigator is currently managing.
