Phosphorus recovery from pig manure fermentation supernatant by pH enhanced anaerobic fermentation and vivianite crystallization

Taking pig manure as the research object, anaerobic fermentation was carried out through different pH adjustments to collect phosphorus -rich supernatant. Under acidic conditions, the effect of promoting phosphorus(P) release was better. The highest Total P (TP) content in the supernatant was 1.46 times that of the control group(NC), and the highest PO 4 3− -P content was 1.71 times that of the control group. Under alkaline conditions, the effect of alkali promoting P release is poor, the maximum TDP content is only 0.89 times of that of the control group, and the maximum PO 4 3− P content is only 0.94 times of that of the NC. The fermentation supernatant was treated in a two-chamber electrolytic tank, and more than 90% of P was recovered, and 84.66% purity of vivianite was obtained.