Struvite Production from Dairy Processing Waste

Food security depends on sustainable phosphorus (P) fertilisers, which at present are mostly supplied from a finite rock phosphate source. Phosphate (PO43−) and ammonium (NH4+) in dairy processing wastewater can be recovered as struvite (Mg + NH4+ PO43− 6H20), nutrient rich mineral for fertiliser application. The objectives of this study were to (1) quantify the effects of, pH, temperature Mg: dosing rates (PO43− NH4+) removal precipitation post anaerobic digested wastewater, (2) co-blend different wastewaters improve reactant stoichiometry optimal recovery removal. (>90%) production (>60%) was achieved across range synthesis conditions, significantly impacted by pH determined response surface modelling. A combination disproportionate molar ratios NH4+, presence calcium apparent mineralisation organic N, resulted co-precipitation hydroxyapatite elevated levels residual aqueous NH4+. In second phase study, successfully precipitated improved (~17%) however, higher concentrations blends greater (up 30%). While desired product formation multiple heterogenous P-rich products (struvite hydroxyapatite) has potential P produce blend with amenity value agricultural systems.