Resin wafer electrodeionization for the removal of weakly ionized species: silica and ammonia

Y.J. Lin, L. Valentino
Argonne National Laboratory,
United States

Keywords: waste water treatment, cooling water, desalination


The global water demand, which originates from energy production, agriculture, industrial uses, and human consumption, is projected to increase by up to 33 percent by 2050. As a result, there is a growing need to manage available water supplies more efficiently and even consider alternative sources. However, these 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. Silica is of particular concern for thermoelectric power plants, which account for ~40 percent of total water withdrawals in the United States. This is because the cooling water systems in power plants are susceptible to 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 ion exchange phenomena and an applied electric field to drive ionic separation. EDI is especially advantageous for the removal of weakly ionizable species, such as silica and ammonia, due to in-situ water splitting that continuously occurs within the EDI stack under the application of an applied potential. This presentation focuses on the adaptation and implementation of EDI technology to remove silica and recover ammonia from aqueous streams, therefore, enabling the use of non-traditional cooling source waters and energy-efficient biomass production, respectively.