NOVELTY - Inflow sewage and return sludge are mixed in an activated sludge adsorption tank and maximum portion of carbon and minimum portion of nitrogen in sewage are transferred to return sludge. Effluent is supplied to settling pond for solid-liquid separation, and clear water and residual sludge are drained. Residual sludge is supplied to efficient anaerobic digestion reactor and processed to obtain hydrogen or biogas and digested sludge. Biogas slurry produced after dehydrating digested sludge is treated in anaerobic ammonium oxidation, denitrification and oxidation system respectively.    USE - Sewage treatment (claimed).    ADVANTAGE - The method is carried out with high phosphorus and nitrogen recovery rate, in short period of time.    DETAILED DESCRIPTION - Inflow sewage and return sludge are mixed in an activated sludge adsorption tank for 35 minutes by controlling activated sludge adsorption concentration to 3000 mg/L, and maximum portion of carbon and minimum portion of nitrogen in the sewage are transferred to the return sludge. The effluent is supplied to a settling pond for solid-liquid separation for 2 hours, and clear water and residual sludge are drained. The residual sludge is supplied to an efficient anaerobic digestion reactor and processed at 35 degrees C for 20 days to obtain hydrogen or biogas and digested sludge. The biogas slurry produced after dehydrating the digested sludge is conveyed into a fluidized bed reactor provided with a settling zone through magnesium ammonium phosphate (MAP) crystallization method, and portion of residual biogas slurry obtained with an MAP method and clear water drained from the settling pond is treated in an anaerobic ammonium oxidation, denitrification and oxidation system respectively at 30-37 degrees C or the clear water drained from the settling pond and the biogas slurry are combined, and denitrification treatment is performed using Chlorella as dominant algae and nitrogen-fixing bacteria to adjust ammonia concentration to less than 750 mg/L, and then treated water is discharged.