NOVELTY - Livestock breeding wastewater such as anaerobic-fermented wastewater having phosphate ion concentration of 50-100 mg/l, magnesium ion concentration of 40 mg/l and ammonium ion concentration of 1000 mg/l is subjected to blow-off effective aeration using carbon dioxide, and the magnesium ion and ammonium ion are combined with phosphate ion to generate magnesium-ammonium phosphate crystal. The wastewater-treating reactor is operated in two modes such as interval flowing mode and continuous flowing mode to enable the effect of removing and recovering phosphorus in wastewater.    USE - Method for removing and recovering phosphorus from livestock-breeding phosphorus-containing wastewater, used for slow-release phosphate fertilizer.    ADVANTAGE - The method enables effective removal and recovery of phosphorus from livestock breeding wastewater, and provides magnesium-ammonium phosphate crystal of fertilizer.    DETAILED DESCRIPTION - Livestock breeding wastewater such as anaerobic-fermented wastewater having phosphate ion (PO43-) concentration of 50-100 mg/l, magnesium ion concentration of 40 mg/l, ammonium ion concentration of 1000 mg/l, chemical oxygen demand of 2000 mg/l, carbonate ion concentration of 4600 mg/l and pH of 7.1-7.4 is subjected to blow-off effective aeration using carbon dioxide, and the magnesium ion and ammonium ion are combined with phosphate ion to generate magnesium-ammonium phosphate crystal. The generation of magnesium-ammonium phosphate crystal is carried out due to high magnesium and ammonium ion concentrations in the wastewater. The addition of magnesium salt is not required, because the original magnesium concentration is sufficient to meet chemical reaction with phosphate radical crystal. When content of magnesium in wastewater is insufficient, the magnesium salt is added according to the analysis of water quality. The wastewater-treating reactor is operated in two modes such as interval flowing mode and continuous flowing mode to enable the effect of removing and recovering phosphorus in wastewater. The reactor is contributed to civil work, and processed into an integral shape by stainless steel.