| 摘要 |
<p>PROBLEM TO BE SOLVED: To automatically calculate the optimum values of aeration and stirring times in an intermittent aeration tank to obtain stable treated water. SOLUTION: In a purifying tank having at least an aeration tank, an aerator, a stirrer and a thermometer are provided in the aeration tank and a nitration speed KN and a denitrification speed KDN are calculated from the water temp. T in the aeration tank obtained from the thermometer and one cycle time (the sum total time of an aeration time and a stirring time) is preset to perform the time allotment of the aeration time and the stirring time on the basis of the speeds KN, KDN, and the first purification tank operation is performed according to the time allotment and, at this time, the time required in the rising of the DO value in the aeration tank to a predetermined value from the start of aeration is set to t1 and the time required in the falling of the DO value to the predetermined value by stirring from the stop of aeration is set to t2 and, by adding t1 and t2 to the aeration time and the stirring time used at the first time or subtracting them therefrom, the second purifying tank operation is performed and, on and after, the above time setting is successively repeated to set the aeration time and the stirring time.</p> |
