Process for the biological oxidation of organic carbon compounds (BOD reduction) by nitrification and denitrification of the nitrogen compounds of effluents without external H-donors for the denitrification and plant for carrying out the process

摘要

The invention relates to a process for the biological oxidation of organic carbon compounds (BOD reduction) by nitrification and denitrification of the nitrogen compounds of effluents without external H-donors for the denitrification and to a plant for carrying out the process. The effluent in this case is treated in at least three separate successive purification stages. In the first stage, for the biological oxidation of organic carbon compounds, the effluent is subjected to a highly loaded activation process known per se with intermediate clarification and internal activated sludge circulation. In the second stage, the effluent is completely nitrified after passing through a bio-film reactor known per se. In the third state, in a denitrification secondary treatment tank, the effluent flows through three zones functionally separated from each other vertically arranged so that sludge is thickened and surplus sludge is withdrawn in the bottom zone, the effluent is denitrified in the central zone and sludge is separated from the effluent in the top zone. During this, part of the return sludge from the first highly-loaded activation stage, with or without thickening, with or without washing, in an intermediate stage are introduced into the central zone of the secondary treatment tank as H-donor for the denitrification with the nitrate-containing efflux water of the biofilm reactor.