A device for sewage treatment comprises a treatment tank, a power and electric control unit, a gas supply and tail gas recovery unit and a circular reaction treatment unit; the treatment tank is provided with a liquid inlet, a liquid outlet, a gas intake port and a tail gas exhaust port; the gas supply and tail gas recovery unit is communicated with the treatment tank through the gas intake port; the tail gas exhaust port is communicated with the gas supply and tail gas recovery unit; the circular reaction treatment unit comprises an external circulating device and a reaction treatment element arranged inside the treatment tank.