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Iron phosphate production wastewater is usually divided into washing water, mother liquor and other wastewater. The washing water usually has pH = 1.5-4.0, salt concentration of 0.5% - 2%, ammonia nitrogen content of several hundred and contains a large amount of heavy metals; The mother liquor usually has high ammonia nitrogen content, high sulfate / phosphoric acid content, pH = 0.5-1.0 and contains a lot of heavy metals; At present, new projects require wastewater recycling or zero discharge.