A pilot plant for removal of radioactivity from solutions has been built and tested. In an initial trial, uranium remaining in a Davies-Gray-analysis waste solution was reduced 300,000-fold to 0.2 ppb by passing the solution through Diphonix(TM) ion-exchange columns. The columns were regenerated (and the uranium was recovered) with HEDPA (1-hydroxyethane-1, 1-diphosphonic acid). The latter was destroyed with H2O2, and the uranium was reduced and precipitated as a phosphate. Final purification of the dissolved precipitate employed a U/TEVA . Spec(TM) (dipentyl pentylphosphonate) extraction chromatographic column. Studies of matrix effects upon the uptake of uranium by the Diphonix(TM) led to an initial dilution of the waste solution and to a reduction of ferric ion.