NOVELTY - A nitrification apparatus (10) has sludge nitrification tank (12), solid-liquid-separation tank (14) and carrier nitrification tank (16). Tank (12) nitrifies ammonia nitrogen using activated sludge (18) containing nitrifying bacteria. In tank (14), solid content in nitrification treated water obtained in tank (12) is separated, and supernatant liquid water is obtained. In tank (16), carrier separation screen (36) of entrapment fixation carrier (30) is provided where supernatant liquid water flows, and ammonia nitrogen remained in supernatant liquid water is nitrified.    USE - Nitrification apparatus is used for wastewater-treatment apparatus (claimed).    ADVANTAGE - The ammonia nitrogen contained in wastewater is efficiently and economically nitrified using the nitrification apparatus.    DETAILED DESCRIPTION - A nitrification apparatus has sludge nitrification tank, solid-liquid-separation tank, carrier nitrification tank, and sludge and carrier nitrification line(s) (58). The activated sludge contains nitrifying bacteria. The sludge nitrification tank nitrifies ammonia nitrogen using activated sludge into which wastewater flows. In the solid-liquid-separation tank, solid content in nitrification treated water obtained in sludge nitrification tank is separated into solid and liquid, and supernatant liquid water is obtained. In the carrier nitrification tank, carrier separation screen of entrapment fixation carrier is provided where supernatant liquid water flows, ammonia nitrogen remained in the supernatant liquid water is nitrified using entrapment fixation carrier which carries out blanket fixation of the nitrifying bacteria, and then, nitrification treated water is obtained. The nitrification apparatus forms nitrate nitrogen by carrying out nitrification process of ammonia nitrogen in wastewater using nitrifying bacteria under aerobic conditions. An INDEPENDENT CLAIM is included for wastewater-treatment apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the nitrification apparatus.    Nitrification apparatus (10)    Sludge nitrification tank (12)    Solid-liquid-separation tank (14)    Carrier nitrification tank (16)    Activated sludge (18)    Entrapment fixation carrier (30)    Carrier separation screen (36)