Nutrients Recovery by SPRR Process from Piggery Wastewater

PENG Jian-feng, SONG Yong-hui, YUAN Peng, YUAN Fang (Scientific and Technological Innovation Center for Water Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China)

sequencing-batch phosphorus recovery reactor; piggery wastewater anaerobic digestion effluent; MAP; nutrient

When adopting the crystallization technology of magnesium ammonium phosphate (MAP) for P recovery from high strength wastewater, fluid bed reactor is usually viewed as the most common choice. However, due to its poor hydrodynamics conditions, masses of MAP particles can not remain in the reactor but flow out the system with the effluent, which result in lower recovery efficiencies of phosphorus. For improving these recovery efficiencies, a new kind of sequencing-batch phosphorus recovery reactor (SPRR), which can accelerate the separation efficiencies of MAP particles from water, was designed. The nutrients recovery potential of SPRR from anaerobic digestion effluent of piggery wastewater was studied. Primary operational parameters of the SPRR were determined, and the influences of pollution components on the MAP crystallization were investigated. The results show that only through 3.0 h aeration stage, the anaerobic digestion wastewater can offer appropriate conditions for MAP crystallization. A running cycle of this SPRR including five stages, namely influent stage, pH increase stage, MAP crystal stage, MAP precipitation stage, effluent stage, it can be finished only in 3.6 h. The addition of Mg2+ could improve MAP production by 10.5%~11.6%; however, considering the cost of nutrients recovery, it is not necessary to add Mg2+ salt. Except some ions, such as NH, PO and Mg2+, the rest pollution components in anaerobic digestion effluent of piggery wastewater did not significantly restrain MAP formation. In conclusion, this kind of SPRR has a broad application future as a high-efficiency installation for direct nutrients recovery from anaerobic digestion effluent of the piggery wastewater.