Abstract

This study investigated the removal and recovery of ammonium ( NH4+ ) and phosphate ( PO43− ) from anaerobically digested slaughterhouse wastewater as struvite (MgNH4PO4; 6H2O). Nutrients removal experiments were conducted by the addition of magnesium sulfate MgSO4 as a Mg2+ source to the wastewater. The effects of Mg2+: PO43− ; Mg2+: NH4+ ; Mg2+: NH4+ : PO43−
molar ratios and pH on NH4+ and PO43− removal were monitored. To verify the recovery of NH4
+ and PO43− as struvite, the precipitates obtained during the experiments were analyzed by X-ray diffraction. The results showed that the increase of Mg2+ concentration and raising the pH to 10 leads to a significant improvement of NH4+ and PO43− removal. The molar ratio of Mg2+:NH4+ : PO43− = 1: 19: 0.58 and a pH=9 gave optimal removal of NH4+ and PO43− . The characterization of the precipitates byX-ray diffraction showed the presence of struvite crystals, confirming the recovery of NH4+ and PO43− in struvite.