A-CASS sewage processing system

The utility model discloses an A-CASS sewage processing system, which comprises a biological selection zone, an anaerobic zone, an aerobic zone, a high density sludge reaction zone, and a sludge collection diversion zone; during work, 20% sewage enters into the high density sludge reaction zone and mixes with the 40% residual sludge for reaction, and then the sewage enters the biological selection zone and mixes with backflow sludge, together with 80% sewage; after further processing, a sewage-sludge separation is carried out in the aerobic zone, and a supernatant is discharged through a decanter, and the discharged water is stable and reaches the discharge standard. According to the utility model, the sludge discharging area of the CASS aerobic zone is enlarged, thereby the sludge is discharged more uniformly, and the water content of the sludge is low, and the energy consumption of the sludge dehydration is reduced; moreover, the high density sludge reaction zone is added for strengthening denitrification a