OXIDATION DITCH METHOD

PURPOSE:To make it possible to reduce treatment facilities or area of site therefor, by flowing sewage in a ring shaped ditch, which allows the same to flow round, in a meandering state by alternately projecting barrier plates from left and right or above and below in said ditch. CONSTITUTION:The bottom surface 4 of a ditch 1 has a gradient toward the flowing-round direction of sewage (a) which is, in turn, flowed along the gradient in the ditch 1. The sewage (a) reaching the deepest part (b) of the ditch 1 is pumped up by an underwater pump 6 or a rotor 3 so as to be flowed into the shallowest part (c) behind a partition wall 6 and again flowed round in the ditch 1. During the pumping-up of the sewage (a), air is mixed in the sewage (a) under stirring. Barrier plates 2a, 2b are alternately projected into the sewage (a) from above and below in the ditch 1 and the sludge (a) is flowed under the barrier plates 2a and above the barrier plate 2b while meandered up and down in nearly an S-shaped form.