WASTEWATER TREATMENT BY MAP METHOD USING SEA WATER

PROBLEM TO BE SOLVED: To provide a wastewater treatment method by MAP method using sea water by which not only phosphate ion contained in wastewater but also ammonium ion can simultaneously be removed. SOLUTION: This wastewater treatment method includes a first process of producing MAP from a part of phosphate ion and a part of ammonium ion contained in wastewater 10 by adding sea water 11 to the wastewater and separating and recovering the MAP, a second process of decomposing the MAP separated and recovered in the former process by heating and dissociating ammonia and giving magnesium phosphate compounds, a third process of adding the magnesium phosphate compounds produced in the second process to wastewater 10 treated in the former process to heighten the phosphate ion concentration and to produce MAP. The second process and the third process are repeated once or two times to gradually lower the ammonium ion concentration in the wastewater 10 and ammonium ion and phosphate ion are simultaneously removed from the wastewater 10.