For both direct potable reuse and indirect potable reuse applications, there are two prevailing treatment approaches: one centered on reverse osmosis, known as reverse osmosis-based advanced…

The Department of the Interior Bureau of Reclamation awarded a $1,001,044.18 Cooperative Agreement to Carollo Engineers Inc. on August 24, 2023 under the SECURE Water Act - Research Agreements program (CFDA 15.560). The project will test an in-situ resin regeneration process using bicarbonate for potable water reuse applications. This approach aims to remove dissolved organic matter and inorganic anions such as nitrate, nitrite, phosphate, and others from the water without producing the large volumes of waste concentrated generated by reverse osmosis-based treatment. By coupling ion exchange and softening processes, the in-situ resin regeneration method is expected to provide multiple treatment barriers for both inorganic and organic contaminants, thereby improving the overall treated water quality compared to traditional carbon-based advanced treatment. The project will run through March 31, 2025.

For both direct potable reuse and indirect potable reuse applications, there are two prevailing treatment approaches: one centered on reverse osmosis, known as reverse osmosis-based advanced treatment, and the other known as carbon-based advanced treatment and based on a combination of ozone-biologically active filtration and granular activated carbon adsorption. Yet, these status QUO treatment technologies can only meet potable reuse water quality goals while generating large volumes of residual waste streams and consuming intensive amounts of energy. This project proposes the testing of in-situ resin regeneration using bicarbonate, which consists of suspended ION exchange for dissolved organic matter and inorganic anion (e.g., nitrate, nitrite, phosphate, sulfate, bromide, chloride, etc.) removal, in-situ resin regeneration using bicarbonate, and softening for hardness and further total dissolved solids removal. Compared to reverse osmosis-based advanced treatment, in-situ resin regeneration using bicarbonate addresses chemical and potentially pathogenic contaminants without producing a large volume of reverse osmosis-based advanced treatment concentrate. By coupling ION exchange and softening processes, in-situ resin regeneration using bicarbonate provides multiple treatment barriers for both inorganic and organic contaminants and thus improving the overall treated water quality as compared to carbon-based advanced treatment.