WATER TREATMENT APPARATUS AND WATER TREATMENT METHOD

This invention is concerning a water treatment apparatus having: an ozone injection facility configured to inject ozone gas into a treatment tank into which untreated water is introduced to be stored therein; a measuring unit configured to measure a spectral light intensity of the untreated water in a plurality of locations in the treatment tank by using at least a first wavelength; and a controller configured to estimate a residual rate of the spectral light intensity at a first wavelength for treated water, which has been treated with ozone in the treatment tank or for both the treated water and the untreated water, based on measurement results in the plurality of locations, measured by the measuring unit, and controls an ozone injection rate used by the ozone injection facility using the estimated residual rate.