CATALYTICAL REMOVAL OF NITRATE AND NITRITE FROM DRINKING-WATER .1. SCREENING FOR HYDROGENATION CATALYSTS AND INFLUENCE OF REACTION CONDITIONS ON ACTIVITY AND SELECTIVITY

The rising concentrations of nitrate in ground water make it necessary to use processes to remove nitrate from drinking water. Nitrate is re moved at present either by physicochemical or biological processes. We describe here an efficient and rapid method to reduce nitrate and nit rite with hydrogen to nitrogen using supported precious metal catalyst s. First, we screened for appropriate hydrogenation catalysts. Palladi um on alumina was found to be favourable to reduce nitrite mainly to n itrogen. Ammonia as a by-product is formed only in small amounts (98% nitrogen, 2% ammonia). Reduction of nitrate is possible by using bimet allic catalysts. We found the best results with a copper-palladium bim etallic catalyst (nitrate removal activity of 3.13 mgNO3-/(mingcat), ammonia formation of 18%. Compared to the biological denitrification, the catalysts show a 30 times higher nitrate removal activity.