PURPOSE: A sewage treating system is provided to enhance efficiency for disposing the sewage regardless of a frost penetration depth by keeping a sewage treatment room warm using waste heat caused by all kinds of drive units within a machine room. CONSTITUTION: A sewage treating system comprises: a machine room(100) in which all kinds of drive units for disposing the sewage; a sewage treatment room(200) in which a plurality of contact aeration tanks(220) and settling tank(230) are divided to have a respective place; a heat storage tank(300) which is formed in order to have a space storing the heat in the inside; a heat offer part which storages the heat generated when all kinds of drive units within the machine room are driven in the heat storage tank.
