Pure biofilm/A3AO mud film combined dual-mode sewage treatment system and operation method thereof

The invention provides a pure biological membrane/A3AO mud membrane combined dual-mode sewage treatment system and an operation method thereof, and belongs to the technical field of sewage treatment. The invention discloses a pure biological membrane/A3AO mud membrane combined dual-mode sewage treatment system. The system comprises a selection zone A, a selection zone B, an anoxic zone A, an anoxic zone B, an aerobic zone, a settling zone, a soft filtering zone and a clear water zone which are connected in sequence, the selection zone A can be used as an anoxic zone C or a pre-denitration zone by adjusting the operation mode; and the selection zone B can be used as an anoxic zone D or an anaerobic zone by adjusting the operation mode. By arranging the selection area A and the selection area B and matching the selection area A and the selection area B with the anaerobic area A, the anaerobic area B, the aerobic area, the backflow pipeline and the like, a switching mode of a pure biological membrane mode and an