Catalytic liquid-phase hydrogenation of aqueous nitrate solutions is presented as a potential, advanced treatment technology for the removal of excessive quantities of nitrate ions from polluted drinking water streams. Catalysts are briefly reviewed first, followed by mechanistic speculations and kinetics that have been proposed for the liquid-phase nitrate reduction. Subsequently, a novel process scheme consisting of integrated ion-exchange and catalytic denitrification steps is discussed. This paper reviews also the developments in the field of catalytic wet-air oxidation (CWAO). Particular attention was given to the heterogeneously catalyzed wet-air oxidation of real industrial wastewaters (such as Kraft bleach plant effluents) in batch and continuous-flow oxidation reactors. Finally, considerable potential of the CWAO process to ultimately destroy organic pollutants in industrial effluents and detoxify them by using novel titania-supported Ru catalysts is reported.