JPH03151099A - Method for controlling batch operated activated sludge treatment - Google Patents

Abstract

PURPOSE:To improve operating efficiency by measuring the oxygen utilization speed value of the activated sludge in water to be treated, computing the change rate of this measured value and determining the point of the time when the aeration treatment is completed in accordance with the computed value. CONSTITUTION:The oxygen utilization speed value rr is measured at every specified time in an oxygen utilization speed control section 12 and this value is sent as an output signal S2 to an arithmetic control section 11 at the time of the aeration of a batch tank 1. The subsequent change rate is computed by the rr value sent from an arithmetic section 10 in the arithmetic control section 11 which stops the operation of a blower 3 by making judgment that the treatment is completed when the value attains the preset value or below. The setting of the optimum aeration time which is free from excess or shortage is possible in this way and the operation dealing with a change in the mass and volume of the inflow water is executed. The stable treated water 10 thus obtd. and the electric power of the blower occupying the greater part of the energy required for the treatment is minimized. The efficient operation is thus possible.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a water treatment method, and particularly to a batch activated sludge treatment control method.

B0 Summary of the Invention The present invention provides a batch sludge treatment method that controls aeration based on the oxygen utilization rate of water to be treated in a batch tank having both the functions of an aeration tank and a settling tank. By calculating the rate and calculating the completion point of aeration treatment from the calculation result, a batch type sludge treatment control method that improves treatment efficiency is obtained.

C1 Prior Art The standard activated sludge method is the standard activated sludge method for wastewater treatment today, which is applied to most fields of wastewater treatment and has been established as a highly reliable technology. However, in recent years, wastewater treatment in large cities and large-scale business establishments has become widespread, and as a result, the proportion of small-scale sludge wastewater sources in the pollution load on public water bodies has increased relatively. The focus of buildings is shifting to smaller and more decentralized structures. Furthermore, there is a problem of eutrophication in closed water bodies, and the removal of nitrogen and phosphorus from wastewater is also required. The batch activated sludge process is currently attracting attention as a treatment method that can cope with the above situations. In the batch activated sludge method, the same tank functions as both an aeration tank and a settling tank. And it has the following characteristics.

l) Sludge bulking is less likely to occur.

2) If an aeration stop period is introduced during the treatment process, the power cost for the blower required for aeration can be reduced.

3) The configuration of the device is simple, and the installation and maintenance costs are cheaper than continuous type.

4) Biological denitrification and dephosphorization are possible through appropriate operation.

D0 Problems to be Solved by the Invention The operating method in the batch activated sludge treatment method takes different treatment cycles depending on whether the main objective is to remove organic matter or whether nitrogen and phosphorus are also to be removed. However, since the time setting of the operation cycle is fixed, it is not possible to operate the system in response to changes in the mass of inflow water, which would be necessary to operate the batch activated sludge treatment more efficiently.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an activated sludge treatment control method that improves operational efficiency by controlling aeration treatment based on oxygen utilization rate values. be.

Means and Effects for Solving the E0 Problem In order to achieve the above object, the present invention controls aeration based on the oxygen utilization rate of the water to be treated in a batch tank equipped with the functions of an aeration tank and a settling tank. In the batch sludge treatment control method, the oxygen utilization rate value of activated sludge in the water to be treated is measured, the rate of change of this measured value is calculated, and the completion point of the aeration treatment is determined based on this calculated value. .

F. Example In order to operate batch activated sludge treatment more efficiently,
It is necessary to operate according to the mass of inflow water. For this purpose, it is necessary to monitor changes in the concentration of a substance during the treatment process and determine the time at which the treatment ends.

However, since it is sufficient to determine whether or not the treatment has been completed as long as it is possible to determine whether or not organic matter to be biooxidized remains, it is as simple as possible to measure the organic matter concentration indirectly, even if it is not necessary to directly measure the organic matter concentration. It is sufficient if the concentration changes can be grasped visually.

Therefore, the present invention measures the oxygen utilization rate of the mixed liquid in the batch activated sludge treatment tank at regular intervals, determines whether the treatment has been completed based on changes in the value, and controls the operation. It is something.

The oxygen utilization rate (hereinafter referred to as r1) is generally expressed by the following formula.

r r” a ”△S + b −M −−−−−−
(1) However, △S is the amount of removed substrate, M is the amount of activated sludge, a
is the oxygen consumption per unit removed substrate, and b is the endogenous respiration rate of activated sludge.

In batch processing, there is usually no inflow of new organic matter, so as the organic matter is purified, the amount of residual organic matter also decreases, so the oxygen utilization rate rr decreases accordingly, and there is no organic matter that can be biologically treated. (1
) In the equation, r,=b-M (2), and thus takes an approximately constant value.

In other words, as shown in the changes in water quality in the batch activated sludge method in Figure 2, the organic matter concentration decreases as the aeration progresses.
After X o'clock, it becomes almost constant. Therefore, this time point of X is r
If the aeration is stopped based on the r value, unnecessary aeration energy can be reduced.

FIG. 1 shows a batch type activated sludge treatment control device for carrying out the above-mentioned control method, and this device is roughly divided into a batch type activated sludge treatment section and an oxygen utilization rate measurement section.

In Figure 1, Sato is a batch tank, 2 is a diffuser installed in batch tank I, 3 is a blower (B), and 4 is a batch tank! A float-type supernatant water suction section disposed inside, 5 a supernatant water discharge pump (PI), 6 a level switch, and 7 an excess sludge extraction pump, these constitute a batch-type activated sludge treatment section 8. . In FIG. 1, reference numeral 9 indicates an oxygen utilization rate measuring sensor, IO indicates an oxygen utilization rate measuring device that calculates the oxygen utilization rate using the detection signal S1 of the measuring sensor 9 as human power, and 11 indicates an oxygen utilization rate measuring device that uses the measurement signal S2 of the measuring device IO as human power. Batch activation processing section 8
These components constitute an oxygen utilization rate control section 12.

In the control device with the above configuration, raw water is first introduced into the batch tank 1, and the upper limit level (HWL) is set by the level switch 6.
When detected, the inflow of raw water is stopped and the blower 3 is operated to supply dissolved oxygen into the batch tank 1. In addition to supplying dissolved oxygen, activated sludge and incoming raw water are mixed to purify the water quality. When the treatment is completed, the blower 3 is stopped and activated sludge and treated water are separated into solid and liquid. When the solid-liquid separation is completed, the supernatant water discharge pump 5 is operated to discharge the treated water from the float-type supernatant water suction section 4 above the water surface in the batch tank 1 to the outside of the tank. At this time, as the treated water is discharged, the supernatant water suction section 4 also follows the drop in the water surface, but the level switch 6 is set at the lower limit level (LWL).
) is detected, the supernatant water discharge pump 5 stops. In addition, the excess sludge extraction pump 7 is operated as necessary to discharge excess sludge. This is the end of one processing cycle, and the operations of these devices are executed by the arithmetic control section 2.

The operation of the oxygen utilization rate control unit 12 is to measure the oxygen utilization rate value rr at regular intervals during aeration of the batch tank l, and output the value as an output signal S2 to the arithmetic control unit I! send to In the calculation control unit 11, based on the rr value sent from the calculation unit IO,
The subsequent rate of change is calculated, and when the rate of change is below a preset value, it is determined that the process is complete, and the operation of the blower 3 is stopped. Therefore, the overall operation is basically the same as that of the batch activated sludge treatment apparatus, but the operation time of the blower 3, that is, the aeration time is controlled by the measured value of the r1 meter.

G1 Effects of the Invention The present invention is as described above, and calculates the rate of change of the constant value measured by the oxygen utilization rate measurement unit at regular intervals during the aeration process, and determines whether the blower continues to operate or stops based on the result. By doing this, it is possible to set the optimal aeration time without excess or deficiency, and the quality of the inflow water can be improved.

It is possible to operate in response to changes in the amount of water, and stable treated water can be obtained, and the electric power of the blower, which accounts for most of the energy required for treatment, can be minimized, allowing for efficient operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus for carrying out a batch activated sludge treatment control method according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing changes in water quality in the batch activated sludge process. ■...batch tank, 2...diffuser, 3...block,
4...Supernatant water suction section, 5...Supernatant water discharge pump, 6
...Level switch, 7...Excess sludge extraction pump,
8...Batch type activated sludge treatment section, 9...Oxygen utilization rate measuring sensor, lO...Oxygen utilization rate measuring device, 11...
- Arithmetic control unit, 12...Oxygen utilization rate measurement unit. FIG. 1 Batch-type activated sludge treatment control device according to the embodiment 0! ... Batch tank 2 ... Air diffuser 3 ... Blower 4 ... Upper water suction section 5 ... Supernatant water discharge pump 6 ... Level switch 7 ... Excess sludge extraction pump 8 ... Batch type activated sludge treatment section 9...Oxygen utilization rate measurement sensor lO/Al element utilization rate measuring device 11...Calculation control section I2...Oxygen utilization rate measurement section

Claims (1)

[Claims] (1) In a batch sludge treatment control method in which aeration is controlled based on the oxygen utilization rate of treated water in a batch tank having the functions of an aeration tank and a settling tank, the oxygen utilization rate of activated sludge in the treated water 1. A batch activated sludge treatment control method, comprising: measuring a value, calculating a rate of change of the measured value, and determining a completion point of aeration treatment based on the calculated value.