Water treatment apparatus and water treatment method

A water treatment apparatus comprising:

• a storage tank for water to be filtered for storing the water to be filtered that contains a substance to be treated that is subjected to filtration;
• an ozone water mixing tank for mixing, with ozone water, concentrated effluent of the substance to be treated in which the substance to be treated separated from the water to be filtered by the filtration is concentrated;
• and
• a pulse plasma discharge tank for supplying pulse plasma to a mixed liquid of the concentrated effluent of the substance to be treated and the ozone water,
• wherein the concentrated effluent of the substance to be treated is generated by subjecting the water to be filtered in the storage tank for the water to be filtered, in which activated sludge is retained, to filtration by a first filtration membrane to separate a first filtered water, and further subjecting the first filtered water to filtration by a second filtration membrane having a pore with a smaller diameter than that of the first filtration membrane.