Recyclage chimique du phosphore des lisiers de porcs

Abstract

International audienceThe technical feasibility of a dissolution/precipitation chemical phosphorus recycling process from piggery wastewater was assessed. Several combinations of acidifying/precipitating reactants were evaluated for their impact on liquid effluent quality and solids formed. Chloride and sodium concentration in the liquid effluent, which could contribute to soil salinisation, were reduced by a third by using acetic acid/magnesium oxide when compared to hydrochloric acid/sodium carbonate. Finally more than 95% of the initial dissolved phosphorus from the acidified supernatant was recovered. Struvite crystals and amorphous calcium phosphate were the main components in the solid, identified by X-ray diffraction, optical and SEM-EDS microscopy. The size and the shape of struvite crystals were increased by increasing the magnesium or ammonium/phosphate ratio which made them more suitable for the filtration and drying steps required to export phosphorus as a dry mineral product