Electrochemical Ion Exchange Regeneration (ELIXR) and Rapid Electrochemical Crystallization Softening (RECS) for Chemical and Waste-Free Water Softening and Reclamation

1235596 (Farrell)。进行这项研究的直接原因是人们日益关注公共饮用水中盐的积累问题，以及社区越来越需要依靠水的再利用。该研究将测试两种新型电化学工艺去除饮用水和废水中硬度离子、二氧化硅和溶解有机物的可行性。ELIXR工艺利用电化学电池产生酸和碱，用于离子交换（IX）介质的再生。酸和碱是利用水中存在的离子产生的，因此不需要使用任何化学物质。RECS工艺是一种电化学增强的颗粒软化，其中电化学电池取代了用于pH调节的酸和碱。RECS工艺也可用于去除溶解的二氧化硅和有机物，作为反渗透（RO）的预处理，或作为反渗透浓缩物的后处理工艺。ELIXR和RECS工艺的结合可以消除IX再生过程中通常产生的盐水溶液的产生。因此，除了水软化之外，ELIXR和RECS工艺还可以用于水回收操作中实现零液体排放。本研究的目的是测试ELIXR和RECS流程的概念证明。实现这一目标将需要以下智力贡献：1)两种新的水处理技术的概念验证证明；2)在IX再生溶液中浓缩离子的方法的发展；3)测定离子浓度和形态对生成酸性再生溶液能量需求的影响；4)测定电流密度、氯化物和硫酸盐浓度对生产次氯酸盐和过硫酸盐的影响；5)块状炭过滤器去除次氯酸盐效果的测定；6)测定过硫酸盐对常规离子交换介质和聚丙烯基离子交换纤维的影响；7)测定RECS去除ELIXR和RO精矿中硬度离子、二氧化硅和溶解有机物的效果；8)测定直接阳极氧化和阳极氧化产生的氧化剂对RO精矿中溶解有机物和生物难降解污染物的破坏效果。这项研究最广泛的影响是它解决了该国干旱地区饮用水的两个最大问题，即：1)地下水供应的日益盐碱化；2)与反渗透和水回收活动相关的预处理和浓缩物处理问题。ELIXR和RECS工艺将对水的再利用处理产生直接影响，因为它们能够去除水中的离子、溶解固体和有机物，而无需化学添加或产生浓缩流。此外，ELIXR和RECS工艺将减轻与运输和储存大量危险化学品相关的污染和自然资源需求，减少传统处理方法的足迹，并降低净水成本。教育和多样性计划侧重于从代表性不足的群体中招募学生，并将研究成果纳入首席研究员目前管理的ENGR 102高中课程的能源、水和环境部分。

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.