NEW PILOT-PLANT STUDIES AT THE BUDAPEST WATERWORKS

The quality of water provided by the Budapest Waterworks should comply with the standards prescribed by the European Community. According to these provisions, on one of the major water-producing regions (Csepel Island), rows of wells of 60,000 m3/day yield have been closed recent ly, and in the immediate future further plants would have been closed because of the high iron and manganese content of the water. The raw w ater obtained from 100 different wells will be purified by a water tre atment plant of 150,000 m3/day capacity. Considering the high iron con tent (0.05-0.15 mg/L) and manganese content (0.05-0.2 mg/L), the raw w ater fails to comply with the requirements of the potable water standa rd. Since 1990, over a period of three years, we conducted water purif ication experiments in several stages. In these, three methods of oxid izing as well as single and double layer open rapid filters were appli ed to oxidize the manganese (and, to a lesser extent, the water) prese nt in dissolved form, resp., to destroy various living organisms. In t he course of the experiments, it became clear that the chlorine and ch lorine + air methods are efficient in case of a small quantity of iron to be oxidized and only 20-25% of the dissolved manganese content cou ld be oxidized. Neither of the two methods could ensure firm managemen t of microbiological and bacteriological characteristics. The best res ults were obtained by ozone oxidation, in which case the chemical oxid izing process was almost fully completed and even the chlorine-resista nt living organisms could be destroyed. On the basis of the experiment s carried out, the investment program of the water treatment plant was worked out and the conditions of an international tender were compile d whose winner will be commissioned to build up the water works in the time period 1993-1996. One of the main steps of the proposed technolo gy is the ozone treatment.