Predicting ion exchange resin performance for contaminant removal from comingled groundwater plumes

• Published in: Journal of environmental chemical engineering 2024-12, Vol.12 (6), p.114820, Article 114820
• Main Authors: Saslow, Sarah A., Pearce, Carolyn I., Levitskaia, Tatiana G., Cordova, Elsa A., Hager, Jacqueline, Fang, Yilin, Escobedo, Nancy M., Johnson, Christian D., Boglaienko, Daria, Torgeson, Joshua, Freedman, Vicky L., Mackley, Rob D.
• Format: Article
• Language: English
• Subjects: 1-D flow; Dowex 21K; Hanford; Performance model; Purolite A532E; Technetium; Uranium
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.114820

At the U.S. Department of Energy’s Hanford Site, ion exchange (IX) resins Purolite A532E (A532E) and DOWEX 21 K (DOWEX) are used in the 200 West Area (200 W) pump-and-treat (P&T) facility to remove technetium-99 (99Tc, as TcO4-) and uranium (U, as anionic uranyl carbonates, UO2(CO3)n2–2n) from contaminated groundwater. Expansion of 200 W P&T operations will require treatment of new groundwater plumes with variable quantities of other anions, like nitrate, sulfate, carbonate, and chloride. Laboratory batch studies have quantified the impact of varying groundwater chemistry on IX resin performance. However, a demonstration that these laboratory-measured parameters can be used to provide operational feedback to the 200 W P&T facility is required. This work couples hydrologic transport and equilibrium IX coefficients to model contaminant breakthrough from laboratory-scale columns and evaluate scalability by modeling historical 200 W P&T facility data. The approach successfully captures breakthrough of competing groundwater anions, e.g., NO3- and SO42-, and co-contaminants with a lower affinity for the resin IX sites than the target anion. For TcO4- and U carbonate anions targeted by A532E and DOWEX, respectively, the model-derived exchange coefficients are magnitudes larger than those predicted by batch tests. This is attributed to the low, groundwater-relevant contaminant concentrations used in batch tests, where testing a range of contaminant concentrations would be required to confirm the model-derived exchange coefficients. The optimized modeling approach will predict the impact of changes in groundwater chemistry on A532E and DOWEX uptake of 99Tc and U, and open opportunities for predicting P&T response to changes in resin configuration(s) and evaluating the impact of potential new IX resins on P&T performance. •99Tc and U removal by A532E and Dowex 21 K resins quantified under flow conditions.•Exchange coefficients optimized to predict contaminant breakthrough from columns.•Models informed by lab-scale data describe contaminant breakthrough at field-scale.