Sewage treatment system

The invention discloses a sewage treatment system, which comprises a selection area, an anaerobic tank, an anoxic tank, an aerobic tank, a precipitation adjusting tank and an aerobic membrane tank, which are connected in turn through an effluent weir, wherein the precipitation adjusting tank is arranged between the aerobic tank and the aerobic membrane tank. The sewage treatment system is technically characterized in that the system has two-stage oxidation and the precipitation adjusting tank is arranged between the aerobic tank and the aerobic membrane tank, so the membrane loss is greatly reduced, the membrane flux of the membrane tank is ensured, and the impact resistant loading capacity of the system is obviously improved while reducing the running cost; basically the consumption of the membrane is saved, and meanwhile the treatment efficiency of AA0 is improved; and composition units of the process device are built integrally in sequence and the units share the same wall, so the design can save investment and save space, and meanwhile the running cost can also be saved due to interconnection of the units. The integral device has low investment and running costs and ultrahigh yield water quality, and is particularly suitable for the requirements of water-lacking large and medium cities for recycling sewage.