NOVELTY - An activated sludge is accommodated in denitrifying tank (12A). Adsorption of radioactive substance is carried out from nitrate waste liquid (11). The pH of nitrate waste liquid is adjusted, and carbon sources (22A,22B) are supplied. The processed denitrified liquid (24) and solid content containing sludge are separated. An oxygen-free gas is supplied to denitrifying tank, and microbe is reduced. Aeration mixing of denitrifying process liquid and activated sludge is carried out in reaeration tank (14). Thus, nitrate waste liquid is processed.    USE - Processing of nitrate waste liquid discharged from nuclear installation, such as reprocessing plant.    ADVANTAGE - The radioactive nitrate waste is efficiently processed. The amount of proliferation of activated sludge is reduced by supplying carbon source.    DETAILED DESCRIPTION - An activated sludge, in which anaerobic microbe capable of reducing nitric acid to nitrogen gas is grown is accommodated in a denitrifying tank. Adsorption or absorption of radioactive substance is carried out from nitrate waste liquid containing nitric acid and radioactive substance. The pH of nitrate waste liquid is adjusted in denitrifying tank, and a carbon source by which anaerobic microbe is propagated and a carbon source by which anaerobic microbe is not propagated are supplied. The processed denitrified liquid and solid content containing sludge are separated by solid-liquid separation unit (25). An oxygen-free gas is supplied to denitrifying tank, and microbe is reduced. The scrubbing of activated sludge adhered to separation unit is carried out. Aeration mixing of denitrifying process liquid and activated sludge is carried out in reaeration tank. The denitrified liquid is separated into surplus sludge and reaerated process liquid (27) by solid-liquid separation unit (28). Thus, the nitrate waste liquid is processed. An INDEPENDENT CLAIM is included for nitrate waste disposal apparatus (10A).    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of disposal apparatus. (Drawing includes non-English language text)    Disposal apparatus (10A)    Nitrate waste liquid (11)    Denitrifying tank (12A)    Reaeration tank (14)    Agent for adjusting pH (21)    Carbon source (22A,22B)    Denitrifying process liquid (24)    Solid-liquid separation unit (25,28)    Process liquid (27)