The invention discloses an urban
sewage treatment method and device in a normal temperature operating mode and a low temperature operating mode, and belongs to the technical field of
water treatment. The device is composed of a grid, a desilting tank, a primary
settling tank, a three-section tank, secondary
settling tanks, a contact tank and
sludge collecting wells, wherein two groups of secondary
settling tanks and
sludge collecting wells are provided; each secondary settling tank is composed of a tank body, a water inlet
pipe, a central
pipe, a water outlet
pipe, a
sludge suction pipe and a sludge discharging main pipe; a sludge collecting hopper is arranged in the middle of the bottom; an inner end is connected with the central pipe; the central pipe is vertically mounted in the middle of the tank body; a bottom opening is located at a position of the sludge collecting hopper; one sludge suction pipe is mounted on each of four sides in the tank body close to an inner wall of the tank body; a bottom end of each sludge suction pipe is connected with the sludge discharging main pipe; the sludge discharging main pipe is connected with the sludge collecting wells. The treatment method comprises the following steps: the concentration of winter sludge in the three-section tank is controlled in 6000-8000 mg / L; and the two secondary settling tanks operate alternately and intermittently, namely, when one operates, the other performs static settling. The urban
sewage treatment method and device provided by the invention increases the concentration of
reflux sludge, increases dissolved
oxygen transferring efficiency, and adds a static settling link, so that a clear interface is present between sludge and water, and the quality of water discharged from the secondary settling tanks is improved.