NOVELTY - Processing of nitrogen-containing drainage involves flowing nitrogen-containing drainage stored by raw water tank (3) into a denitrifying tank (7), carrying out denitrifying process in a denitrifying tank, adding organic substance of activated sludge to the denitrifying tank, carrying out oxidative decomposition treatment of organic substance which remained without used by the denitrifying treatment process and performing solid-liquid separation process in which the treated water after organic substance decomposition process is separated into solid and liquid.    USE - Processing of nitrogen-containing drainage discharged from foodstuff industry.    ADVANTAGE - The method efficiently enables the processing of nitrogen-containing drainage, by preventing denitrifying reaction and interface raise in the sedimentation tank.    DETAILED DESCRIPTION - Processing of nitrogen-containing drainage involves flowing nitrogen-containing drainage stored by raw water tank into a denitrifying tank, carrying out denitrifying process of the raw water which flowed in biologically with activated sludge in a denitrifying tank, adding organic substance used as the nutrient of the activated sludge to the denitrifying tank, carrying out oxidative decomposition treatment of the organic substance which remained without used by the denitrifying treatment process biologically with activated sludge in an aerator, converting into carbon dioxide and water, and performing solid-liquid-separation process in which the treated water after an organic substance decomposition process is made to flow into a sedimentation tank (13), and separated into solid and liquid in the sedimentation tank. The organic substance process involves performing organic substance addition amount calculation process by calculating addition amount of the organic substance by predetermined standard based on the total nitrogen or nitrate-nitrogen concentration of the raw water, and the amount of treated waters which flows into the denitrifying tank and performing organic substance addition amount correction process in which chemical oxygen demand or biological oxygen demand and total nitrogen concentration or nitrate-nitrogen concentration of treated water before flowing in into the sedimentation tank is detected. When total nitrogen and nitrate nitrogen are not detected and chemical oxygen demand or biological oxygen demand is detected, the organic substance addition amount in the organic substance addition amount calculation process is reduced. An INDEPENDENT CLAIM is included for apparatus (1) for processing of nitrogen-containing drainage.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the apparatus for processing of nitrogen-containing drainage. (Drawing includes non-English language text)    Apparatus for processing of nitrogen-containing drainage (1)    Raw water tank (3)    Denitrifying tank (7)    Aerator (11)    Sedimentation tank (13)