| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the over-aeration at a time when the load of the inflow water to an oxidation ditch is reduced (that is, when the amt. of inflow water is extremely reduced at night). SOLUTION: Sewage is introduced into the denitrification region (A) of an oxidation ditch 1 from an introducing port 2 and aerated by the aerating stirrer 3 arranged on the start end side of a nitration region (B) and purified water is led out of the final part of the nitration region B through a lead-out port 4. At this time, a dissolved oxygen controller 5 is arranged to the nitration region (B) of the oxidation ditch 1 and a submerged propelling device 6 is arranged to the denitrification region A and the operation of the aerating stirrer 3 is started or stopped on the basis of the dissolved oxygen measured value of the dissolved oxygen controller 5 and the operation of the submerged propelling device 6 is stopped or started.</p> |
