Apparatus for sewage treatment, comprising: at least one tank (13), at least one inlet branch (14) to the tank (13), at least one outlet branch (15) from the tank (13), at least one microwave generator (9a) able to subject the sewage present internally of the tank (13) to at least one temperature raising treatment, at least a cooling circuit (19) of the microwave generator (9a), at least one blowing device (9b) connected to the tank (13). Blowing device (9b) is connected to an outlet (26) of the cooling circuit (19) and sending the heated gases arriving therefrom into the tank (13).