| 摘要 |
Process for purifying waste water, in particular municipal waste water, the waste water to be purified being first introduced into a high-load activation stage operated as an adsorption stage, then introduced via an intermediate clarification stage with sludge withdrawal and subsequently thereto into a low-load stage, to which is connected a secondary clarification stage with sludge withdrawal. Microorganisms function in the adsorption stage. The sludge is kept in the assimilation phase with the aid of the sludge withdrawal from the intermediate clarification stage. In the low-load stage, nitrification and, subsequently thereto, denitrification can also be carried out. Sludge from the intermediate clarification stage can be reintroduced as return sludge into the adsorption stage; sludge from the secondary clarification stage can be reintroduced as return sludge into the low-load stage. Furthermore, excess sludge is withdrawn and thickened. The waste water in the adsorption stage, is first treated under facultatively anaerobic conditions and, prior to the discharge into the intermediate clarification stage, is treated under aerobic conditions. The microorganisms are subjected both to the anaerobic and the aerobic conditions. The turbid water of the sludge thickening and the sludge dewatering is treated with precipitants before it is returned to the inlet of the sewage treatment plant. <IMAGE>
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