Limited phosphate resources, increasing fertilizer prices and unsustainable methods of treating phosphates in wastewaters have resulted in the need for phosphate recovery technologies. One method involves the precipitation of a magnesium ammonium phosphate mineral called 'struvite' (MgNH 4PO4·6HO). Wastewaters often require an additional source of Mg2+ and a solution pH between 8 and 11 in order to achieve orthophosphate (OP) removal as struvite. This research examined 3 effluents to determine an ideal pH for producing the lowest residual values of OP. Two types of MgO were also tested for their ability to reduce OP concentrations: a pure chemical source and ground MgO refractories. Optimal pH levels were not determined, as it was likely that the supersaturation was too high to produce differences in OP removal. Chemical-grade MgO was more reactive than the refractories, and was therefore more effective in removing OP as struvite in wastes where Mg2+ was limiting. OP removal rates of >90% were achieved in each effluent.