An extensive set of experimental and modeling studies was completed to investigate the potential performance of a sorbing permeable treatment wall comprised of natural zeolite for the removal of strontium-90 from groundwater. Multiple column tests were performed at the University at Buffalo and on-site West Valley Environmental Services for periods ranging from 6 months to 2 years; UB columns were supplied with synthetic groundwater referenced to anticipated field conditions and radioactive groundwater obtained on-site was used for the West Valley columns. The results from the column studies yielded an extensive data set containing aqueous and sorbed concentrations over time and along the column length, respectively. This research project supported the deployment of the first full-scale natural zeolite permeable treatment wall at West Valley Environmental Services in November of 2010.

The primary focus in this work was on quantifying the competitive cation exchange reactions among five cations (Na⁺, K⁺, Ca²⁺, Mg²⁺, and Sr²⁺) and Sr-90; the data obtained from the column studies were used to support the robust estimation of zeolite cation exchange parameters; to obtain an improved understanding of cation exchange in natural zeolites, clinoptilolite-rich rock. This research produced a five-solute cation exchange model describing the removal efficiency of the natural zeolite, using the various column tests to calibrate and evaluate the contaminant transport model. The resulting field-scale transport model will provide flexibility to explore the influence of design parameters and variations in groundwater geochemistry on long-term performance of a permeable treatment wall at any site contaminated with Sr-90.