To prevent the ocean from being contaminated by disposer waste water of high concentration by respectively providing an aeration air pipe communicated with pressure air source in a pre-treatment chamber and an aeration air pipe communicated with a pressure air source and a contact oxidization plate in a contact oxidization chamber.

A treatment tank 7 is filled with water beforehand, and waste water of high concentration discharged from a disposer is introduced to a pre- treatment chamber 8. On the other hand, pressure air from an air pipe 20 is supplied to an aeration air pipe 14, continuously jetted out into water from small holes after being changed into bubbles, water articles are broken by aeration action, a number of aerobic microbes are produced by the supplying of oxygen and organic materials are decomposed into carbonic acid gas and water. Also, contact oxidization plates 19 are arrayed on the full width of a first contact oxidization chamber 9, bubbles are divided into small pieces by clashing with a number of wrinkles, the concentration of oxygen solved in water is increased, aerobic microbes are produced in the contact oxidization plates 19 in a film shape and cleaning efficiency is improved by adding oxygen thereto.