NOVELTY - A nitrogen-containing organic wastewater-processing system has autotrophic denitrifying device (30) which denitrifies by performing nitrification, such that ammonia contained in to-be-treated water is oxidized to nitrous acid by autotrophic microbes, suspended organic matter separation device (10) which separates suspended organic matter contained in the to-be-treated water, sludge anaerobic digestion device (40) which anaerobically digests the separated suspended organic matter and transfer path (R1) which supplies digestive fluid from the device (40) to device (30).    USE - System is used for processing of nitrogen-containing organic waste water (claimed).    ADVANTAGE - The processing system efficiently performs anaerobic ammonia oxidation of nitrogen-containing wastewater using autotrophic microbes, even if waste water has low ammonia concentration and includes suspended organic matter.    DETAILED DESCRIPTION - A nitrogen-containing organic wastewater-processing system has an autotrophic denitrifying device which denitrifies by performing nitrification, such that ammonia contained in to-be-treated water is oxidized into nitrous acid by autotrophic microbes under aerobic conditions, and anaerobic ammonia oxidation by autotrophic microbes under anaerobic conditions using ammonia nitrogen as an electron donor and nitrate nitrogen as an electron receptor, a suspended organic matter separation device which separates suspended organic matter contained in the to-be-treated water is provided at stage before autotrophic denitrifying device, a sludge anaerobic digestion device which anaerobically digests the suspended organic matter separated by the suspended organic matter separation device and transfer path (R1) which supplies digestive fluid from the sludge anaerobic digestion device to the autotrophic denitrifying device. An INDEPENDENT CLAIM is included for processing of nitrogen-containing organic wastewater.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the nitrogen-containing organic wastewater-processing system. (Drawing includes non-English language text)    Suspended organic matter separation device (10)    Autotrophic denitrifying device (30)    Sludge anaerobic digestion device (40)    Transfer path (R1)