Method for treating wastewater with high phosphorus content and obtaining coated struvite slow-release fertilizer and application of coated struvite slow-release fertilizer

The invention provides a method for treating wastewater with high phosphorus content and obtaining a coated struvite slow-release fertilizer, which comprises the following steps: (1) adding alkali into ardealite leachate for pretreatment to obtain supernate; (2) adding a nitrogen-containing salt and a magnesium salt into the supernate, and adjusting the molar ratio of N to P to Mg to obtain a mixed solution; alkali is added into the mixed solution to further adjust the pH value, and struvite crystal sediment is obtained; (3) mixing the struvite crystal precipitate with gelatinized water-insoluble starch to prepare a granular struvite fertilizer core; (4) coating the struvite fertilizer core with a coating material to obtain coated struvite particles; and (5) carrying out sealing treatment on the coated struvite particles, and then carrying out drying treatment to obtain the coated struvite slow-release fertilizer. According to the method, nitrogen, phosphorus and magnesium elements in the phosphogypsum leacha