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A METHOD FOR PRODUCING AN AQUEOUS SOLUTION OF HIGH PHOSPHOROUS CONTENT, RECOVERING IRON COMPOUNDS CONSTITUTING PRECIPITATING AGENTS, AND SEPARATING HEAVY METALS IN A SEWAGE-WATER OR RAW-WATER PURIFICATION PLANT
A METHOD FOR PRODUCING AN AQUEOUS SOLUTION OF HIGH PHOSPHOROUS CONTENT, RECOVERING IRON COMPOUNDS CONSTITUTING PRECIPITATING AGENTS, AND SEPARATING HEAVY METALS IN A SEWAGE-WATER OR RAW-WATER PURIFICATION PLANT
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机译:一种生产高磷水溶液的方法,回收构成沉淀剂的铁化合物,并分离污水或原水净化厂中的重金属
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摘要
The invention relates to a method of producing an aqueous solution rich in phosphorous and recovering metal compounds in the purification of sewage-water or raw-water, in a plant which includes at least one chemical treatment stage in which an iron compound is supplied to the water to precipitate phosphorous present therein. The method is characterized in that the sludge from the chemical treatment stage is treated with hydrogen sulphide under anaerobic conditions, phosphorous compounds being dissolved from the sludge and metal sulphide being formed. The metal sulphides are dissolved to form metal salt solutions, of which at least the iron salt solution is separated and recycled to the chemical treatment stage. It is also possible prior to separating the iron salt solutions to recycle the metal salt solutions one or more times. The dissolved phosphorous can be removed in the form of an aqueous solution and treated in accordance with the so-called Donnert-process, to form calcium phosphate.
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