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Converting aluminum phosphate to calcium phosphate, useful as fertilizer, comprises adding aluminum salts to phosphates in sludge and reacting aluminum phosphate-precipitate with suspension containing sodium and calcium hydroxide
Converting aluminum phosphate to calcium phosphate, useful as fertilizer, comprises adding aluminum salts to phosphates in sludge and reacting aluminum phosphate-precipitate with suspension containing sodium and calcium hydroxide
Converting aluminum phosphate from sewage sludge to calcium phosphate by wastewater treatment plants comprises (a) precipitating phosphates in the sewage sludge by adding aluminum salts to obtain aluminum phosphate precipitate, and (b) single step reaction of the aluminum phosphate-containing sewage sludge with a suspension containing sodium hydroxide containing solution and calcium hydroxide in a reactor such that calcium phosphate precipitate is formed by the recrystallization of aluminum phosphate in the sewage sludge. Independent claims are included for: (1) a device for preparing calcium phosphate precipitate and sodium aluminate solution from sludge by wastewater treatment plants comprising a reactor comprising at least one inlet for sewage sludge, and at least one inlet for calcium hydroxide, sodium hydroxide and/or wash-filtrate (sodium aluminate) and an outlet for calcium phosphate-containing sewage sludge, and a solid separation device comprising at least one inlet for calcium phosphate containing sludge, an outlet for wash-filtrate and an outlet for dehydrated calcium phosphate containing sludge; and (2) a phosphate fertilizer comprising calcium phosphate obtained by the above method. ACTIVITY : Fertilizer. MECHANISM OF ACTION : None given.
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