Sponge city low-lying land multistage cascading rotary purification system

The invention discloses a sponge city low-lying land multistage cascading rotary purification system. The system comprises a desilting water collection pool, a rotary purification canal and a reservoir. The desilting water collection pool is disposed at the top of a low-lying land. The rotary purification canal is in spiral downward arrangement along the periphery of the low-lying land, and is isolated into several purification units by several concrete baffle plates. Each purification unit is equipped with an antiscour layer, a soil layer, a coarse sand layer and a purification layer from top down in order, the soil layer and the purification layer are internally provided with water absorption discs, two sides of the purification layer extend to the purification unit surface layer, and the section is in U-shaped distribution. Water permeable geotextile is disposed at the contact part of the purification layer and the soil layer and the coarse sand layer. The reservoir is arranged at the bottom of the low-lying land, and the bottom is provided with a water pumping pump. The system provided by the invention not only can green and beautify the environment, but also can absorb heavy metals and other hazardous substances in water, and is of important reference significance for urban non-point source pollution control, rainwater purification recycling and sponge city construction.