Several benchscale column tests (resin bed volume less than or equal to75mL) have been conducted with SuperLig((R)) 639 resin and simulated U.S. Department of Energy tank waste supernates. Rhenium (surrogate for technetium in actual waste samples) breakthrough profiles were determined for three simulant compositions, which are representative of the basic waste categories requiring treatment in the Hanford River Protection Project Waste Treatment Plant. Considerable loading performance variability was observed between the three waste types, although the resin is effective at rhenium. removal from each solution. Careful and frequent analysis during elution studies conducted at the conclusion of the column loading tests confirmed that sodium nitrate and sodium perrhenate ion pairs are primary sorbing species on SuperLig((R)) 639 resin. Furthermore, it was discovered that potassium nitrate and potassium perrhenate salts are significant competitors for sorption sites on the resin. Successive desorption profiles were identified for all four salt species during elution tests. Integration of the desorption profiles revealed that the resin is selective for removal of the potassium salts over the sodium salts.