| 摘要 |
<p>PROBLEM TO BE SOLVED: To effectively perform the nitrifying and denitrifying treatments of sewage by treating org. sewage with activated sludge and setting a plurality of automatic operation modes corresponding to the stage of inflow load quantity when the operation of an aeration device is automatically controlled by using a dissolved oxygen value, a redox potential value or the like as input factors. SOLUTION: A plurality of aeration devices 2 are arranged in the circulating water channel of an aeration tank to stir and aerate sewage and the sensor 3 for controlling the operation of the aeration devices 2 is arranged. The measured value by the sensor 3 is inputted to a control circuit 4 to control the aeration devices 2 but, at this time, in order to always automatically operate the aeration devices 2 under the optimum condition, a planned inflow sewage amt. is set to 100% and, for example, four modes are separately set to input to the operation conditions, respectively. That is, kinds of machines and the number of them proper to a condition of a use start initial period are selected to be preliminarily inputted to the mode lowest in load quantity and, thereafter, a sewage amt. is gradually increased, and in this process, the operation kinds of the aeration devices and the number of them are stepwise increased.</p> |
