Speciation analysis based design of mine water treatment technologies

The strong dependence of water treatment efficiency from pollutant speciation was demonstrated at the example of uranium removal from TMF seepage water by ion exchange. The pH dependence of carbonate equilibria was used to manipulate uranyl speciation in the investigated seepage water. Ion exchange experiments were carried out with TMF seepage feeds of the same origin but of different pH and thus of different uranyl speciation. Geochemical modeling and TRLFS measurements revealed calcium uranyl carbonate complexes to hamper sorption to ion exchange resins, whereas non-calcium uranyl carbonate complexes promote sorption. The manipulation of uranyl speciation by pH adjustment caused a rise in ion exchange efficiency from insignificant to technically feasible levels.