Desalination of impaired water, reclaimed and plant (process) water exemplifies a resource-efficient, “fit-for-purpose” water service solution. Because of the interdependency between water and energy, method of reprocessing impaired water to replace fresh water must have very high energy-efficiency to make it sustainable.A reverse osmosis (RO), have low energy efficiency of near 12% for impaired water desalination.This is due to the nature of energy costs of the purification strategy, i.e., removing either the water or the salts from the aqueous mixture. Technologies with higher energy efficiency are in demand for reclaimed water and will have profound impact to the thermoelectric power plants, which are the single largest user of surface water in the United States (~40%) for cooling. The alternative source waters often contain undesirably high concentrations of specific constituents and may pose challenges with providing a reliable supply of water with that meets the water quality requirements for a specific application. Selective separation removes the key saline constitutes selectively for the recycled water therefore reduces the energy consumption. Silica is of particular concern for thermoelectric power plants because silica scaling, which limits the number of water reuse cycles in cooling tower operations. On the other hand, ammonia is a challenge for wastewater treatment, water reuse strategies, and also waste-to-energy production. High ammonium concentrations can have detrimental impacts on aquatic ecosystems and can inhibit anaerobic digestion processes that are used to produce biomass/bioenergy products. As an alternative to typical methods for silica and ammonia control that are chemical intensive and/or are highly dependent on influent water quality, electrodeionization (EDI) is an energy efficient method that utilizes an applied electric field to drive ionic separation. In a resin wafer EDI (RW-EDI) technology, the ion-conductive resins provide unique “simultaneous adsorption/desorption” sites to capture the weakly ionizable species, such as silica and ammonia in the brackish water. The porous resin wafer structure creates an “ion-channel” network that allows a continuous and low energy transport of the captured ions away from the process stream in an electric field. This presentation focuses on the adaptation and implementation of RW-EDI technology to remove silica and recover ammonia from aqueous streams.

Fit-for purpose water technology of selective desalination

2019 Fall National Meeting

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