CONTROLLER FOR DISSOLVED OXYGEN IN AERATION VESSEL

摘要

PURPOSE:To keep the distribution of dissolved oxygen in the aeration vessel at optimum and simplify the maintenance of the controller, by separately providing dissolved oxygen control units for the inlet zone and other zone of the aeration vessel. CONSTITUTION:The first and the second control units are installed for the upstream part and middle and downstream part of the push flow type aeration vessel 10. Waste water is introduced into the upstream part of the vessel. The quantity of upstream aerating air is set from the intake quantity of the waste water by a ratio setting unit 15 whereon the index of the dissolved oxygen is set. The set quantity of upstream aerating air is compared with the measured value thereof. A valve 18 is operated depending on the difference. A signal of a sensor 22 provided at the middle and downstream part is supplied to the second control unit 24. The value measured by the sensor is compared with a setpoint and the difference is applied to a third control unit 26 to set the quantity of middle and downstream aerating air. The set quantity of this air is compared with the measured value thereof to control the rotation of a DC motor 28. Thereby, the quantity of middle and downstream aerating air from air pipes 36 can be varied.