Method for purifying water body by utilizing bioretention facility with three-dimensional structure

The invention relates to the technical field of water treatment, in particular to a method for purifying a water body by using a bioretention facility with a three-dimensional structure. Comprising the following steps: manufacturing a biological retention facility prefabricated member, measuring the pH value, the total nitrogen content, the total phosphorus content, the ammonia nitrogen content and the chemical oxygen demand of a water body to be purified, comparing measured related values with expected values, configuring a composite filler according to standard-exceeding indexes, arranging the composite filler on a multi-layer grating plate layer and on a path of a water flow flowing to a pond based on terrain, the pit slot forming direction and the number of the prefabricated parts are determined, the depth of the pit slot is dug according to the height of the prefabricated parts, and the prefabricated parts are sequentially connected through the connecting auxiliary structures and finally placed in the pi