PURPOSE: To enable water saving, perfect incineration of garbage and energy saving by mixing living waste water with the garbage, wet-burning the waste water reduced in quantity and concd. by primary treatment and supplying generated hot treated water for district heating to houses.

CONSTITUTION: Waste water from generating sources 1 is mixed with crushed garbage and filtered in a primary treating apparatus 2. The filtered waste water is burned in water with air under a high pressure of about 100atm in the body of a wet burner for secondary treatment. A high efficiency catalytic system by which ammonia in waste water is decomposed to utilize heat is advantageously applied to the wet burning and the rationalization and acceleration of district heating are expected.