Circulating desanding device for sewage treatment and sewage treatment method

The invention discloses a circulating desanding device for sewage treatment, and relates to the technical field of sewage desanding, the circulating desanding device comprises a desanding unit, the desanding unit comprises a desanding cylinder and a sand screen, a desanding chamber is arranged in the desanding cylinder, the sand screen is detachably connected in the desanding chamber, and one end of the pipe wall of the desanding cylinder is provided with a water inlet communicated with the desanding chamber; the connecting unit comprises a first plug and a second plug, the two ends of the desanding cylinder are open, the first plug is in threaded connection with the open end, away from the water inlet, of the desanding cylinder, and the second plug is in threaded connection with the other open end of the desanding cylinder; sewage is guided into the sand removing chamber through the water inlet, the sand screening net is installed in the sand removing chamber, sand in water cannot penetrate through the sand