NOVELTY - The wastewater-treatment equipment has a natural-water tank (1), a denitrifying tank (3), a re-aeration tank (7) having a semi-anaerobic portion (8), a catalytic-oxidation tank (13), a sedimentation tank (15), an air-lift pump (5), and a mineral mixing tank (19). The mixing tank mixes the sludge obtained by biological treatment, and the calcium-containing mineral sludge from the sedimentation tank. The sludge and treated water from the mixing tank are then returned to the natural-water tank through a return piping (L20).    USE - The equipment is useful for treating wastewater, e.g. ammonia-containing wastewater, image development waste liquid, dimethylformamide waste liquid (all claimed), and waste liquid from chip fabrication factories.    ADVANTAGE - The equipment efficiently processes high-concentration aminoethanol-containing wastewater, saving energy and reducing the amount of waste material. The semi-anaerobic portion relieves the change of environment with respect to microorganisms, which enables easy breeding of microorganisms.    DETAILED DESCRIPTION - The wastewater-treatment equipment has a natural-water tank (1), a denitrifying tank (3), a re-aeration tank (7) having a semi-anaerobic portion (8), a catalytic-oxidation tank (13), a sedimentation tank (15), an air-lift pump (5), and a mineral mixing tank (19). Aminoethanol-containing wastewater introduced into the natural-water tank is introduced to the denitrifying tank and then to the re-aeration tank. The oxidation tank has a mineral source containing calcium, and to-be-processed water from the re-aeration tank is introduced to the oxidation tank and then to the sedimentation tank. The pump circulates to-be-processed water from the re-aeration tank to the denitrifying tank. The mixing tank mixes the sludge obtained by biological treatment, and the calcium-containing mineral sludge from the sedimentation tank. The sludge and treated water from the mixing tank are then returned to the natural-water tank through a return piping (L20).    An INDEPENDENT CLAIM is included for wastewater treatment method.    DESCRIPTION OF DRAWING(S) - The figure shows the wastewater-treatment equipment. (Drawing includes non-English language text)    Natural-water tank (1)    Denitrifying tank (3)    Air-lift pump (5)    Re-aeration tank (7)    Semi-anaerobic portion (8)    Catalytic-oxidation tank (13)    Sedimentation tank (15)    Mineral mixing tank (19)    Return piping (L20)