CATALYTIC ABATEMENT OF WATER POLLUTANTS

The paper reviews solid-catalyzed oxidation and reduction processes fo r the treatment of wastewater that contains small concentrations of to xic compounds and for which separation is not economical while biologi cal treatment is not feasible. Specifically, the objectives are (1) to understand the interactions between catalytic materials and various p ollutants, (2) to provide a database for catalyst selection, and (3) t o assess the potential of these processes for commercialization. The r eview suggests tl-le following well-investigated; solutions: (1) Suppo rted metal (Ru/CeO2, Pt/CeO2, and Ru/C) and metal oxides (CuO-ZnO-CoO, MnO2/CeO2, CoO/Bi2O3, and V2O5/Al2O3) are the most promising catalyst s for the destruction of refractory organic compounds with nearly 100% selectivity to CO2; (2) CoO/CeO2 and MnO2/CeO2 are the most active ca talysts for ammonia oxidation at temperatures of 263-400 degrees C; (3 ) activated carbon, preferably in the presence of copper ions, Is an a ctive catalyst for the oxidation of cyanides and sulfur-containing com pounds; (4) catalytic hydrodechlorination (HDC) of chloroorganics and hydrodenitrification (HDN) of nitrates emerge as promising processes f or wastewater treatment. To overcome mass-transfer resistance, catalys ts should be constructed as fibers, cloth, or powder. Novel processes that incorporate separation at room temperature (e.g., by adsorption) and reaction at elevated temperatures are de:scribed. Suggestions for new directions of research are made.