NOVELTY - Purifying and processing domestic sewage comprises removing sewage with suspension via grizzly screen and sand settling sand, introducing into a first section of processing system that comprises a hydrolytic acidification tank, a contact oxidation pond and an anaerobic sedimentation tank; introducing the sewage into a second section of processing system comprising a biomembrane band aeration pipe oxidization pond; and introducing the sewage into a third section of processing system comprising a biomembrane band deep processing oxidization pond.    USE - Method for purifying and processing domestic sewage via biological section.    ADVANTAGE - The method can deeply process the domestic sewage with high removal rate of nitrogen and phosphorus, and makes use of degradation function of natural organisms to purify and improve water quality; and uses a system that can stably run, which is strong in impact resisting loading ability, high in security, high in adjusting and controlling property and easy to improve water amount and water quality, and can be used for landscape and building park-type sewage processing plant.    DETAILED DESCRIPTION - Purifying and processing domestic sewage comprises removing sewage with suspension via grizzly screen and sand settling sand, introducing into a first section of processing system comprising a hydrolytic acidification tank, a contact oxidation pond and an anaerobic sedimentation tank; introducing the sewage into a second section of processing system comprising a biomembrane band aeration pipe oxidization pond; and introducing the sewage into a third section of processing system comprising a biomembrane band deep processing oxidization pond. Three sections of organisms used for continuously purifying and processing domestic sewage comprise bacteria, algae, protozoa, metazoan, large plant, fish, and zoobenthos, which can form food chain and ecosystem to deeply process the domestic sewage. In the first section, the domestic sewage can flow into a biochemical reaction device after being settled and processed by adjusting pond and grizzly screen. The biochemical reaction device comprises hydrolytic acidification tank, contact oxidation pond and anaerobic sedimentation tank. The domestic sewage flows through the hydrolytic acidification tank, contact oxidation pond and anaerobic sedimentation tank in sequence with inner parts that are provided with biomembrane bands and can quickly remove pollutants via the metabolism of bacterium. The hydrolytic acidification tank is 3-5 m deep, where sewage is treated for 2-4 hours. It is provided with a water distribution system to uniformly distribute water to make the sewage contact the biomembrane band. The concentration of dissolved oxygen is at 0.1-0.3 mg/L. The microbial community on biomembrane is anaerobic microbe. Part of organic matters can be degraded via metabolism of anaerobic microbe. The macromolecular organic matters difficult to degrade are degraded into small molecular organic matters, which are good for subsequent technique. Efficient polyphosphate-accumulating organism in sludge can release phosphorus in anaerobic state, which can prepare for contact oxidization section for absorbing phosphorus. The contact oxidation pond is 3-5 m deep, where sewage is treated for 4-8 hours. The bottom of the pond is mounted with aeration plate; and concentration of dissolved oxygen is kept for more than 2 mg/L via blasting and aeration. In aerobic condition, active sludge and microbe in biomembrane band can quickly degrade organic matters in sewage to make the concentration of chemical oxygen demand and biological oxygen demand greatly reduced. Ammonia and nitrogen in water can be transformed into nitrate nitrogen with the effect of nitrifying bacteria; at the same time, the polyphosphate-accumulating organism can efficiently absorb phosphorus in sewage in aerobic state. The anaerobic sedimentation tank is 4-7 m deep, where lower part of it is provided with active sludge settling groove with a bottom that is provided with inclined plane for collecting active sludge, and optimally, the inclined plane is funnel-shaped. The active sludge settling groove is 1.5-2.5 m deep, where the sewage is treated for 2-3 hours. The anaerobic sedimentation tank is mounted with a biomembrane band, which can accelerate settlement of sludge via the buffer effect of biomembrane band to the water flow; and besides, the sewage still can keep certain dissolved oxygen in the sedimentation tank after running through the contact oxidation pond to make the sedimentation tank in the state of anaerobic state. The microbe on biomembrane band can further degrade the organic pollutant; at the same time, the biomembrane band is provided with denitrifying bacteria for denitrification, that is, they can transform the phosphorus in sewage into nitrogen, which can completely remove nitrogen in sewage. Phosphorus in sewage also can be removed via discharging the sludge. Outlet water of anaerobic sedimentation tank enters the second section of processing system. The discharged sludge enters the sludge processing system. The biomembrane band aeration pipe oxidization pond comprises oxidization pond body, biomembrane band and microporous aeration mechanism. The oxidization pond body comprises cement structure and earth pond material, where sewage is treated for 8-24 hours. The oxidization pond body adopts flow guiding type structure to prevent short circuit and increase contact between biomembrane band and sewage. The microporous aeration mechanism comprises microporous aeration tube, wind pipe and blast blower. The blast blower is arranged at outer side of a wet pond body and is connected with wind pipe. The main wind pipe stretches into the wet ground pond body and provided with microporous aeration tube. Diameter of microporous aeration tube is 18-50 mu m. Periphery of microporous aeration tube is provided with microholes, each having a diameter of 0.5-2 mm. The blast blower can convey air into the microporous aeration tube via the wind pipe. Concentration of dissolved oxygen in water can be increased via aeration. In third section, the biomembrane band deep processing oxidization pond comprises oxidization pond body, biomembrane band and microporous aeration mechanism. The oxidization pond body comprises cement structure and earth pond material, where sewage is treated for 12-48 hours. The biomembrane band aeration pipe oxidization pond can be added with a plant filtering frame, which is a three-dimensional filtering frame filled with filtering material and can be planted with hygrophytes.