Chang H.-CHuang L.-SCheng M.-PHsiao T.-HLee H.-JKAI-YIN LOSHAN-LI WANG2022-12-142022-12-14202116052471https://www.scopus.com/inward/record.uri?eid=2-s2.0-85131374374&doi=10.6578%2fTJACFS.202106_59%282%29.0004&partnerID=40&md5=a118ac14901be2dd6e4c13f56b287b17https://scholars.lib.ntu.edu.tw/handle/123456789/626025High contents of phosphorus in discharged wastewater can cause eutrophication of rivers and lakes. Therefore, how to reduce phosphorus content effectively is important in wastewater treatment. Magnesium ammonium phosphate (MAP), also known as struvite, is a slow-release phosphate fertilizer. MAP does not dissolve well like chemical fertilizers, so it is friendly to the environment. In this research, we conducted a field study to test the recovery of phosphorus from wastewater as MAP. Anaerobic digestion effluent was used for the mass production test of struvite using a traditional sedimentation tank, and an up-flow type MAP fluidized crystallization bed. By using a traditional precipitation tank, 80-90% of the phosphorus could be recovered. However, the product contained only about 50% struvite and the others were mostly calcium and magnesium carbonate (dolomite) precipitates. MAP recovery rate can be improved when the up-flow MAP fluidized crystallization bed was used. When a decalcification tank was added, calcium ions, but not the magnesium ions, could be selectively precipitated by addition of oxalic acid. Consequently, 80-90% of the phosphorus could be recovered as MAP after pH adjustment of the decalcified fermentation broth. Therefore, after the decalcification treatment, the up-flow MAP fluidized crystallization bed can effectively recover the dissolved phosphorus from wastewaters in the form of MAP with higher purity and yield. © 2021 Chinese Agricultural Chemical Society. All rights reserved.Magnesium ammonium phosphate; Pig manure wastewater; Sedimentation tank; Upflow fluidized crystallization bed[SDGs]SDG2[SDGs]SDG14journal article10.6578/TJACFS.202106_59(2).00042-s2.0-85131374374