JPS6344037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an oxidation date, which is a type of aeration tank used in sewage treatment.

In small-scale sewage treatment plants (approximately 30,000 tons/day or less),
Oxidation tanks are generally used as aeration tanks. (References: "Sewerage Facility Design Guidelines and Explanations," p. 342377, etc.; published by Japan Sewage Works Association, 1972) As is well known, in oxidation dates, the retention time or treatment time for the amount of inflow water, i.e. The amount of inflow water per unit time per unit time reaches about 24 to 48 hours. This value corresponds to approximately 6 times that of a typical aeration tank. However, as is clear from its structure, the time required for the inflow water to go around the oxidation date waterway once and reach the outlet is approximately 5 to 10 minutes.
minutes, which is extremely short.

Although the newly inflowing sewage is mixed with the water stagnant in the waterway, some of the inflow water will flow out within a short treatment time of 5 to 10 minutes. This has the disadvantage that untreated water flows out.

In addition, in small-scale treatment plants where oxidation dates are used, the amount of inflow water often fluctuates greatly from day to day, and the amount of inflow water decreases to almost zero at night, and rapidly increases from 6 a.m. to 8 a.m. The inflow pattern is expected to increase.

Therefore, considering the fact that the inflow water reaches the outlet in 5 to 10 minutes after going around the waterway of the oxidation date as mentioned above, the time at which the amount of inflow water increases rapidly can be determined. It is very likely that a significant amount of influent water will flow out with little or no treatment.

In order to deal with the inconvenience caused by such rapid fluctuations in the amount of inflow water, a retention pond has traditionally been installed before the aeration tank or oxidation date, or after the inflow sewage pump. Methods have been proposed in which the amount of water flowing into the tank or oxidation date is constant.

However, the method of installing such a retention pond is
It is difficult to realize this in terms of land and costs, and at present it is hardly put into practice.

The purpose of the present invention is to stabilize the treatment effect even in the face of rapid fluctuations in the amount of inflow water without installing a retention pond in a small-scale treatment plant using an oxidation date as described above. The object of the present invention is to provide a sewage treatment control device that can perform the following tasks.

The present invention focuses on the fact that the capacity of an oxidation date type aeration tank is large compared to the inflow amount, and the water area is also large, and by operating the overflow gate on the outflow side, the aeration tank is The feature is that the effective capacity of the tank or oxidation date is variable to cope with rapid fluctuations in the amount of inflow water.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic plan view of an embodiment of the present invention.

In Figure 1, 1 is an oxidation date (hereinafter referred to as a date) which is a type of aeration tank, 2 is a paddle (stirrer) installed in the waterway of date 1, and 3 is a paddle 2. Drive motor, 4 is a sewage inflow channel, 5 is an outflow channel, 6
7 is a return sludge inlet waterway, and 7 is an overflow gate provided according to the present invention.

The sewage flowing in from the sewage inlet waterway 4 is mixed with the water circulating in the waterway and circulated, as indicated by arrows in the figure. A part of the water overflows over the upper end of the overflow gate 7 and is discharged from the outflow channel 5.

Figure 2 shows a cross-sectional view taken along the - line in Figure 1.
It is a diagram shown together with a vertical drive device for an overflow gate 7. In the figure, the same reference numerals as in FIG. 1 represent the same or equivalent parts.

In the figure, 10 is a water level gauge, 11 is an overflow gate driver, 12 is a gate upper end position detector, 13 is a subtraction calculator, 14 is an overflow water depth setting device, 15 is a comparison controller, and 16 is a gate control. It is a device.

The water circulating in the waterway of the date 1 in the direction of the arrows flows out into the outflow waterway 5 over the upper end of the overflow gate 7, as shown in FIG. In this case, the overflow water depth H is determined by calculating the difference between the output signal of the water level gauge 10 of date 1 and the signal from the gate upper end position detector 12 using, for example, a potentiometer.
3.

On the other hand, the overflow water depth target value H ₀ is set by the setting device 14 . This set value H ₀ and the value H of the overflow water depth obtained by the calculator 13 are input to the comparison controller 15 .

Here, if the actual water depth H is greater than the set value H ₀ , a signal to raise the gate is output to the gate control device 16, and if it is smaller, a signal to lower the gate is output to the gate control device 16, respectively. Then, the control device 16 moves the overflow gate 7 up and down based on this signal.

By continuously performing the above operations, the overflow water depth H is maintained at a constant value H ₀ or within a constant range. Therefore, based on the well-known relationship between the overflow water depth H and the outflow amount, the outflow water amount is approximately constant.

Therefore, when the amount of water flowing into the dew 1 increases, the water level of the dew 1 rises, and the overflow gate 7 is accordingly raised by the gate control device 16. As a result, the water level (water depth) of the date 1 increases, and the effective volume of the date 1 increases.

This suppresses fluctuations in the residence time or processing time of inflow water, which is defined by the ratio of the volume of the deutch to the amount of inflow water per unit time.

In other words, even if the amount of inflow water increases rapidly, the amount of water flowing out can be reduced in the short treatment time required to go around the waterway, achieving better sewage treatment and improving the quality of treated water. can be improved.

In addition, although the case where the overflow water depth H is controlled to be almost constant has been described above, the overflow water depth H is
Naturally, it may be controlled as a function of the amount of sewage inflow.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an embodiment of the oxidation date according to the present invention, and FIG. 2 is a cross-sectional view of the outflow channel portion of FIG. 1, and a block diagram showing an embodiment of the control device of the present invention. be. DESCRIPTION OF SYMBOLS 1...Oxidation date, 2...Buddle, 3...Buddle drive motor, 4...Sewage inflow channel, 5...Outflow channel, 6...Return sludge inflow channel, 7...Overflow gate, 10...Water level gauge, 11...
... Overflow gate drive machine, 12 ... Gate upper end position detector, 13 ... Subtraction calculator, 14 ... Overflow water depth setting device, 15 ... Comparison controller, 16 ... Gate control device.

Claims (1)

[Claims] 1. An oxidation system comprising a circulation waterway, a sewage inflow waterway and an outflow waterway communicating with the circulation waterway, a paddle disposed within the circulation waterway, and an overflow gate provided on the outflow waterway. A control device for a station date, comprising means for detecting the water level in the waterway, means for detecting the upper end position of the overflow gate, and means for calculating the overflow water depth from the outputs of the two detection means. , a means for setting a target value of the overflow water depth, a means for comparing the overflow water depth with the target value, and a signal for raising an overflow gate when the overflow water depth is greater than the target value;
Conversely, when the overflow water depth is smaller than the target value, a gate control device outputs a signal to lower the overflow gate, and a means for driving the overflow gate according to the gate raising and lowering signals. An oxidation date control device comprising: 2. The oxidation date control device according to claim 1, wherein the target value of the overflow water depth is set to a constant value.