Abstract: Particular aspects provide a method for recovering phosphate, comprising: obtaining an effluent or wastewater, etc. having calcium-sequestered phosphate; adding to the effluent or wastewater a calcium chelating or sequestration agent suitable to chelate or sequester Ca++ ions from the calcium-sequestered phosphate to facilitate release of phosphate from the calcium-sequestered phosphate; transferring, facilitated by said Ca++ ion capture and in the presence of sufficient concentrations of NH4+ and Mg2 ions, of the phosphate into struvite (magnesium ammonium phosphate hexahydrate or MgNH4PO4.6H2O), or hydrated magnesium ammonium complex of phosphate; and recovering the struvite, or the formed hydrated magnesium ammonium complex. Preferably, the method further comprises acidification of the effluent or wastewater to facilitate release of Ca++ ions from the calcium-sequestered phosphate and chelation of sequestration of the Ca++ ions by the calcium chelating or sequestration agent.

Abstract: Particular aspects provide a method for recovering phosphate, comprising: obtaining an effluent or wastewater, etc. having calcium-sequestered phosphate; adding to the effluent or wastewater a calcium chelating or sequestration agent suitable to chelate or sequester Ca++ ions from the calcium-sequestered phosphate to facilitate release of phosphate from the calcium-sequestered phosphate; transferring, facilitated by said Ca++ ion capture and in the presence of sufficient concentrations of NH4+ and Mg2 ions, of the phosphate into struvite (magnesium ammonium phosphate hexahydrate or MgNH4PO4.6H2O), or hydrated magnesium ammonium complex of phosphate; and recovering the struvite, or the formed hydrated magnesium ammonium complex. Preferably, the method further comprises acidification of the effluent or wastewater to facilitate release of Ca++ ions from the calcium-sequestered phosphate and chelation of sequestration of the Ca++ ions by the calcium chelating or sequestration agent.