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Ammonium removal from waste solutions by precipitation of MgNH4PO4 II. Ammonium removal and recovery with recycling of regenerate

1992; Elsevier BV; Volume: 6; Issue: 4 Linguagem: Inglês

10.1016/0921-3449(92)90057-9

1879-0658

T. Stefanowicz, S. Napieralska-Zagozda, Małgorzata Osińska, Katarzyna Samsonowska,

Phosphorus and nutrient management

It was found that the ammonium ion removal product MgNH4PO4·6H2O after drying and roasting becomes converted into the regenerate Mg3(PO4)2 suitable for recycling in the ammonium ion removal/recovery process. The gaseous ammonia expelled during roasting can be utilized according to known methods while the regenerate can be used as a source of PO43− and Mg2+ ions in MgNH4PO4·6H2O formation. After adding the regenerate to ammonium-laden waste solution, strong acid (HCl or H3PO4) is introduced to dissolve the regenerate (pH 1–2) and then pH is adjusted with NaOH to 9–10. Stirring is carried out preferably for 24 hours and the precipitated MgNH4PO4·6H2O is separated and returned for recycling. By this method the ammonium ion concentration in treated solutions can be reduced to below 1 mg/l.