JPH0365297A - Control apparatus of aeration tank - Google Patents

Abstract

PURPOSE:To inject pure oxygen corresponding to the change of the quality of inflow water by providing the oxygen injection amount detector connected to an oxygen injection valve and an oxygen injection amount controller controlling the oxygen injection valve on the basis of the output signal of the oxygen injection amount detector, the output signal of a dissolved oxygen meter and the output signal of an inflow flowmeter. CONSTITUTION:The amount of inflow sewage is measured by an inflow flowmeter 1 and sewage flows in an aeration tank 3. The oxygen objective amount set to a ratio setting device 5 and the injection oxygen objective amount calculated from the difference between the outflow dissolved oxygen amounts of the dissolved oxygen meters 7 arranged on the inflow and outflow sides of the aeration tank 3 are added to the inflow flow rate signal 4 from flowmeter 1 by an adder 6 and an operation signal is inputted to an oxygen injection valve 12 by utilizing an oxygen injection amount controller 10 to control the injection of pure oxygen prepared by a pure oxygen making apparatus 2. Next, the value passed through a primary delay circuit 13 is set to the oxygen injection amount detected by a pure oxygen injection amount detector 11 as an objective value of an exhaust gas amount and an exhaust gas control valve, 16 is controlled by a controller 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a control device for an aeration tank used in a sewage treatment plant.

(Prior art) Conventionally, in a closed upper aeration tank at a sewage treatment plant, inflow sewage sent from a settling tank is first input, and pure oxygen produced by a pure oxygen production device is injected into the aeration tank. This is done by controlling the injection valve so that the pressure remains constant, and pure oxygen is dissolved in the inflowing sewage using a stirrer inside the tank.

Next, depending on the oxygen concentration in the aeration tank, the exhaust valve is controlled to discharge the exhaust gas inside the aeration tank.

However, if this oxygen injection pressure control and exhaust gas oxygen concentration control are performed at the same time, oxygen concentration decreases - discharge valve opens - tank pressure drops - injection valve opens - pure oxygen injection - oxygen concentration rises in the tank - discharge valve closes - tank inside The control system is unstable because the sequence of pressure increase, injection valve closing, and oxygen concentration decrease is repeated. Also, water treatment is not stable because the conditions of inflow water quality are ignored.

(Problems to be Solved by the Invention) An aeration tank control device that can inject pure oxygen in response to changes in inflow water quality and that does not repeat oxygen injection control and exhaust gas discharge control is essential.

[Configuration of the Invention (Means for Solving the Problems) The present invention provides a closed airage system 3 in a water treatment process.
In the tank, the amount of oxygen deficiency is calculated from the amount of change in water quality.
By injecting pure oxygen, organic matter is oxidized, stabilized, floc-formed, and adsorbed, and then in the final sedimentation tank.
A control device for an aeration tank for sedimentation is provided.

(Function) The present invention uses a substrate for the amount of pure oxygen to be injected by multiplying the amount of inflowing sewage by a certain ratio. Calculate the amount, apply correction to the base,
Further, the exhaust valve is controlled to discharge a value obtained by adding a first-order lag to the pure oxygen injection amount as the exhaust gas amount target value.

That is, determine the required amount of oxygen in the aeration tank,
This injection prevents excessive oxygen supply and provides stable water treatment.

(Example) Next, an example of the present invention will be described. Figure 1 shows an inflow flow meter 1 that measures the flow rate flowing into the aeration tank 3, a dissolved oxygen meter 7 that measures dissolved oxygen in the aeration tank 3, and an exhaust gas meter that measures the amount of exhaust gas generated from the aeration tank 3. an amount detector 15, an exhaust gas control valve te that adjusts the amount of exhaust gas released, a pure oxygen production device 2 that produces oxygen to be supplied to the aeration tank 3,
An oxygen injection valve 12 that adjusts the amount of oxygen supplied from the pure oxygen production device 2 to the aeration tank 3;
An oxygen injection valve 12 is controlled by an oxygen injection amount detector 1 connected in series with the oxygen injection amount detector 11, an output signal of the oxygen injection amount detector 11, an output signal of the dissolved oxygen meter 7, and an output signal of the inflow flow meter 1. 1 shows an aeration tank control device comprising a quantity control controller 10.

That is, the amount of inflowing sewage is measured by the inflow flow meter 1 and flows into the aeration tank 3.

Then, the oxygen target amount set by the ratio setting device 5 in the inflow flow rate signal 4 and the dissolved oxygen meter 7 in the aeration tank 3 were installed on the inflow side and the outflow side, and the difference between the outflow dissolved oxygen and the outflow dissolved oxygen was determined. The target amount of oxygen to be injected is added by an adder 6, and an operation signal is input to the oxygen injection valve 12 using an oxygen injection amount control regulator 10 to control the injection of pure oxygen produced by the pure oxygen production device 2.

Next, the value obtained by passing the oxygen injection amount detected by the pure oxygen injection amount detector U through the primary delay circuit 13 is set as the target value of the exhaust gas amount, and the exhaust gas amount controller 14
B is controlled to discharge the exhaust gas filling the aeration tank 3.

[Effects of the invention] There is no control imbalance in the aeration tank pressure control and oxygen concentration control, and by adding the inflow dissolved oxygen value to the control elements, it is possible to inject oxygen according to water quality conditions.
A stable aeration tank control device can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an aeration tank control device showing an embodiment of the present invention. 2... Pure oxygen production device 3... Airage 3 tank 7... Dissolved oxygen meter 10... Oxygen injection amount control regulator 11... Oxygen injection amount detector 12... Oxygen injection valve i5. ...Exhaust gas amount detector 16...Exhaust gas control valve

Claims (1)

[Claims] An inflow flow meter that measures the flow rate of water to be treated flowing into the aeration tank, a dissolved oxygen meter that measures dissolved oxygen in the aeration tank, and an exhaust gas amount detector that measures the amount of exhaust gas generated from the aeration tank. , an exhaust gas control valve that adjusts the amount of exhaust gas released; an oxygen injection valve that adjusts the amount of oxygen supplied from the pure oxygen production device to the aeration tank; and an oxygen injection amount detector connected in series with the oxygen injection valve. and an oxygen injection amount control controller that adjusts the oxygen injection valve according to the output signal of the oxygen injection amount detector, the output signal of the dissolved oxygen meter, and the output signal of the inflow flow meter. Device.