| 摘要 |
<p>PROBLEM TO BE SOLVED: To set proper aeration quantity from a use start initial period, in controlling the operation of an aeration device automatically controlled on the basis of the measured value of a sensor, by repeating aeration and the stop thereof at the use start initial period by a timer and changing over automatic control to measuring control automatically at a point of time when load rises and the measuring control becomes possible. SOLUTION: An aeration tank 1 usually has an oval shape in many cases and is provided with one or more screw type aeration devices 2 and a measuring sensor 3, for example, a dissolved oxygen meter or a redox meter is provided in the aeration tank 1. The detected value of the sensor 3 is taken in a controller 4 and a time wherein the sensor value is more than a predetermined prescribed value is measured at every one cycle of the aeration by the aeration device 2, and the stop thereof and holding times are successively measured by a time measuring timer incorporated in the controller 4 and the sum total time of them is calculated at a point of time when a day is elapsed. At a time point when this sum total time becomes less than a set time, automatic control is changed over to measuring control.</p> |
