SEWAGE TREATING APPARATUS AND METHOD

摘要

PROBLEM TO BE SOLVED: To provide a sewage treating device capable of omitting the conventional air diffusion pipe and air piping, and adjusting the DO concentration to a derived value in a liquid mixture composed of sewage and activated sludge while preventing the precipitation of the activated sludge. SOLUTION: A reaction chamber 100 as this sewage treating device is a device for biologically treating the sewage by the activated sludge and has a water tank 3 which is formed with a circulating water path 8 consisting of a flow passage 8u (ascending flow passage) in which the liquid mixture W composed of the sewage and the activated sludge flows upward and a flow passage 8d (descending flow passage) which is communicated with the flow passage 8u and in which the liquid mixture W flows down and a vertical shaft aerator 10 which is arranged near the gas-air boundary of the liquid mixture W in the flow passage 8u and acts as a stirring aerator to lift the liquid mixture W, to supply oxygen to the liquid mixture W by causing gas-liquid contact and to admit the liquid mixture W subjected to the gas-liquid contact into the flow passage 8d.