JP2001000994A - Anaerobic wastewater treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable operation by making it possible to return a part of the treated water in a treated water tank to both of a pH adjusting tank and an anaerobic wastewater treatment apparatus by a circulating pump. SOLUTION: A part of treated water is returned to the piping between a liquid supply pump 2 and an anaerobic wastewater treatment apparatus 3 (small circulating system) as circulating water. The setting of the operation method and flow rate of a circulating pump 5 is different by a circulating system and, in a large circulating system, the circulating pump 5 is stopped when the water level of a pH adjusting tank 1 is high and the water level of a treated water tank 4 is low. Herein, since a small circulating system is employed at a usual time and the circulating pump 5 is continuously operated, a freezing measure and the intermittent operation of a circulating line being the defects of the large circulating system are eliminated. Since a measure for adjusting the pH and temp. in the anaerobic wastewater treatment apparatus 3 due to trouble being the defect of the small circulating system can be taken by changing over the small circulating system to the large circulating system returning treated water to the pH adjusting tank 1 and adjusting the temp. and pH of treated water, a wastewater treatment plant can be stably operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an anaerobic wastewater treatment facility for treating wastewater with anaerobic bacteria.

[0002]

2. Description of the Related Art Anaerobic bacteria used in anaerobic wastewater treatment equipment are most activated when the pH is 7 and the temperature is 37 ° C., and the quality of wastewater sent to the anaerobic wastewater treatment equipment has a pH of 6.5. To 7.5 and the temperature is adjusted to 33 to 38 ° C.

However, in anaerobic wastewater treatment facilities, p
Since H and temperature are easily changed, a circulation line is often provided for the purpose of equalizing water quality in addition to the temperature adjustment and pH adjustment functions. Therefore, there is a demand for a system capable of stably operating the anaerobic wastewater treatment facility by establishing the arrangement of the circulation line and its control.

[0004] Conventional techniques for treating wastewater (raw water) are roughly classified into a circulation system and a non-circulation system. FIG. 4 (A)
A conventional wastewater treatment system will be described with reference to FIGS.
FIG. 4A shows what is called a general circulation system. That is, the wastewater flows into the pH adjustment tank 1, but a part of the treated water from the subsequent treatment water tank 4 is directly returned to the pH adjustment tank 1 via the valve 7 as circulation water by the circulation pump 5. In the pH adjustment tank 1, the circulating water and the wastewater are combined, and at the same time, the temperature and pH are adjusted.
Control. The wastewater whose pH has been adjusted in the pH adjustment tank 1 is sent to the anaerobic wastewater treatment device 3 by the liquid supply pump 2, where it is treated, and then sent to the treatment water tank 4.
In the treated water tank 4, a part of the treated water is directly returned to the pH adjusting tank 1 through the valve 7 as circulating water by the circulation pump 5, and most of the remaining treated water is sent to the subsequent treatment facility.

FIG. 4B shows a so-called small circulation system. That is, a part of the treated water in the treated water tank 4 is returned by the circulation pump 5 as circulating water between the liquid supply pump 2 and the anaerobic wastewater treatment device 3 via the valve 8. In this circulation system, the pH and temperature of the wastewater are adjusted in the pH adjusting tank 1. The circulating water returned by the circulation pump 5 through the valve 8 is combined with the wastewater between the liquid supply pump 2 and the anaerobic wastewater treatment device 3 and supplied to the anaerobic wastewater treatment device 3. The supplied wastewater is processed by the anaerobic wastewater treatment device 3 and then sent to the treated water tank 4. In the treated water tank 4, part of it is directly p
It is returned to the H adjustment tank 1 and most of the rest is sent to the subsequent processing facility.

FIG. 4 (C) shows that the wastewater is treated according to the treatment procedure without circulating a part of the treated water to the pH adjusting tank 1 or the anaerobic wastewater treatment apparatus 3 as in the above (A) and (B). This is a non-circulating method. That is, the wastewater is supplied to the pH adjusting tank 1
After the pH and temperature are adjusted in, the wastewater is treated by the anaerobic wastewater treatment device 3 and sent to the treated water tank 4. Treated water tank 4
Then, the treated water is sent to the subsequent treatment facility.

[0007]

In the treatment system employing the large circulation system shown in FIG. 4A, the valve 7 is always fully opened to return the treated water to the pH adjusting tank 1. It is possible to supply wastewater of pH and temperature to the anaerobic wastewater treatment device 3. When raw water cannot flow into the anaerobic wastewater treatment device 3 due to a trouble in the anaerobic wastewater treatment device 3, the circulating water from the treatment water tank 4 is adjusted to adjust the temperature and pH of the anaerobic wastewater treatment device 3. By returning to the pH adjustment tank 1 and heating and adjusting the pH, the activation of the anaerobic bacteria in the anaerobic wastewater treatment device 3 is promoted.

In the case of this large circulation system, the control of the circulation pump 5 is stopped when the water level in the pH adjusting tank 1 is high or the water level in the treatment water tank 4 is low. If the water level in the pH adjustment tank 1 is high, the circulation pump 5 stops and the wastewater cannot be circulated, so that high-concentration wastewater directly flows into the aerobic treatment device and the like, leading to deterioration of the treated water quality. There is.

Further, the mass balance may be lost due to the effect of the stop of the circulation pump 5, and the liquid supply pump 2 may stop. In such a case, since the treated water is in the pipe, the pipe may freeze in winter or the like.

In the system employing the small circulation system shown in FIG. 4B, the valve 8 is always fully opened, and the treated water is circulated between the liquid supply pump 2 and the anaerobic wastewater treatment device 3. In the general circulation system, the circulation pump 5 is operated in conjunction with the water level of the pH adjustment tank 1. Therefore, when the water level of the pH adjustment tank 1 becomes high, the circulation pump 5 stops, and thus the circulation pump 5 is stopped. However, since the small circulation method is continuous and the circulation pump 5 is not stopped, such a phenomenon does not occur, and stable water treatment can be performed.

However, when the small circulation system is used, when an abnormality occurs in the anaerobic wastewater treatment apparatus 3, the anaerobic wastewater treatment apparatus 3
It is necessary to promote the activation of the anaerobic bacteria in the anaerobic wastewater treatment apparatus 3 by keeping the pH and the temperature constant so as to activate the anaerobic bacteria. Because even if sending treated water in the circulation line,
It takes a long time to control the temperature and pH in the anaerobic wastewater treatment device 3.

Therefore, in order to stabilize the processing system, it is necessary to attach a pH meter, a thermometer and devices for controlling them to the treatment water tank 4 as well. As a result, p
The consumption of NaOH in the H adjustment tank 1 increases, the number of control and monitoring points increases, the maintenance becomes complicated, and the initial cost increases. In the non-circulation system without a circulation line shown in FIG. 4C, if there is a sudden change in pH or temperature, it cannot be dealt with immediately, and the stability of the processing system is lost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the drawbacks of each by combining both circulation systems instead of the conventional large circulation system or small circulation system. Another object of the present invention is to provide an anaerobic wastewater treatment facility capable of stable operation.

[0014]

Means for Solving the Problems To achieve the above object, a first aspect of the present invention is to adjust wastewater to a pH at which anaerobic bacteria are activated in a pH adjusting tank and send the adjusted wastewater to an anaerobic wastewater treatment apparatus. In this anaerobic wastewater treatment equipment, the BOD in wastewater is reduced to 80
In an anaerobic wastewater treatment facility in which 〜95% is removed and sent to a treatment water tank, a part of the treatment water stored in the treatment water tank is circulated by a circulation pump to either the pH adjustment tank or the anaerobic wastewater treatment apparatus. It is also characterized by being configured to be able to be returned.

According to the first aspect of the present invention, since the small circulation system is always employed, the measures against freezing and the intermittent operation of the circulation line which are disadvantages of the large circulation system are eliminated. By switching to the general circulation system, it is possible to cope with the situation, so that stable operation of wastewater treatment equipment becomes possible.

According to a second aspect of the present invention, in the anaerobic wastewater treatment equipment according to the first aspect, a speed controller is attached to the circulation pump so as to control the rising flow rate in the anaerobic wastewater treatment apparatus to be constant. It is characterized by having comprised so that it may perform. According to the second aspect, by controlling the speed of the circulation pump, the ascending flow rate in the anaerobic wastewater treatment apparatus is kept constant, and stable wastewater treatment can be performed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment (corresponding to claim 1) of the present invention. As shown in the figure, in the anaerobic wastewater treatment equipment of the present embodiment, wastewater (raw water) is supplied to the pH adjustment tank 1 so that the anaerobic bacteria in the anaerobic wastewater treatment apparatus 3 at the subsequent stage have appropriate pH and temperature. As described above, the pH is adjusted to 6.5 to 7.0 by the pH meter 15 and the thermometer 16 installed in the pH adjusting tank 1.
5 and the temperature is adjusted between 33-38 ° C. The wastewater thus adjusted is sent to the anaerobic wastewater treatment device 3 by the liquid supply pump 2. This sent wastewater is adjusted by a valve attached to the secondary side of the feed pump 2 so as to have a rising flow velocity of about 1 m / h in the anaerobic wastewater treatment device 3, and is monitored by flow meters 9 and 10. You. In the anaerobic wastewater treatment apparatus 3, the BOD contained in the wastewater is reduced by 8%.
Removed to 0-95%. The wastewater treated in the anaerobic wastewater treatment device 3 (hereinafter referred to as treated water) is sent to the treated water tank 4 and stored in the treated water tank 4. The treated water in the treated water tank 4 is sent to the subsequent treatment equipment and the like, and part of the treated water is returned by the circulation pump 5 between the pH adjusting tank 1 or the liquid supply pump 2 and the anaerobic wastewater treatment device 3. .

By the way, regarding the selection of the circulation line,
The selection is made each time according to the situation, but the switching is performed by the switching valves 7 and 8. The valve 6 is provided for maintenance of the switching valves 7 and 8. A flow meter 14 is attached to monitor the discharge amount from the circulation pump 5. In the case of operating in the general circulation system, the amount returned to the pH adjustment tank 1 is confirmed by the flow meter 13 to determine how much is returned. When operating in the small circulation system, the flow rate of the small circulation is measured by the flow meter 11. Furthermore, a thermometer 1 is used for monitoring the quality of the circulating water.
9. A pH meter 20 is installed in the treatment water tank 4.

Next, the operation of the present embodiment will be described.
First, how to use the two circulation lines will be described. The wastewater enters the pH adjusting tank 1, where the pH and temperature are controlled based on the instructions of the pH meter 16 and the thermometer 15.
The controlled wastewater is sent to the anaerobic wastewater treatment device 3 by the feed pump 2, where the BOD of the wastewater is 80 to 9
5% is removed. The removed wastewater is sent to the treated water tank 4 as treated water, from which it is sent to the subsequent treatment equipment.
A part of the treated water is returned as circulating water to a pipe (small circulation system) between the liquid supply pump 2 and the anaerobic wastewater treatment device 3.

The operation method and the flow rate setting of the circulation pump 5 are as follows.
Depending on the circulation system, the pH adjustment tank 1
The operation stops when the water level is high and the water level in the treatment tank 4 is low. In the small circulation system, since the circulation pump 5 is operated continuously, the measures against freezing and intermittent operation of the circulation line, which are disadvantages of the large circulation system, are eliminated. In addition, measures for pH and temperature adjustment in the anaerobic wastewater treatment apparatus 3 due to troubles, which are a drawback of small circulation, are as follows: return the treated water to the pH adjustment tank 1, heat the treated water, and adjust the pH. We can cope by changing. In addition, when the anaerobic bacteria in the anaerobic wastewater treatment device 3 are activated and the treatment situation is improved, the switching to the small circulation system is performed by switching the switching valves 7 and 8.

As described above, in this embodiment, since the small circulation system is always employed, the measures against freezing and the intermittent operation of the circulation line, which are disadvantages of the large circulation system, are eliminated. In addition, trouble countermeasures, which is a disadvantage of small circulation, can be dealt with by switching to a large circulation system, so that a stable operation of a wastewater treatment plant can be realized. Further, by attaching a pH meter and a thermometer to the treatment water tank, the anaerobic wastewater treatment device 3
Monitoring of the internal processing status can be performed.

FIG. 2 is a block diagram of a second embodiment (corresponding to claim 1) of the present invention. This embodiment is different from the embodiment of FIG. 1 in that the switching valves 7a and 8a are electrically operated valves, Since the configuration is switched to the general circulation mode and other configurations are the same, the same portions are denoted by the same reference numerals and described.

As shown in the figure, in the present embodiment, in the processing state of the anaerobic treatment device 3 by the small circulation method, the indication of the thermometer 19 and the pH meter 20 attached to the treatment water tank 4 is as follows.
When the pH becomes lower than 6.0 and the temperature becomes lower than 30 ° C., since the anaerobic bacteria in the anaerobic wastewater treatment apparatus 3 are not activated, the flow rate changing mechanism is automatically changed from the small circulation system by the electric valves 7a and 8a. It is configured to switch to the circulation system. Further, the electric valve 7 is controlled so that the flow rate of the circulation is set to 0.7 to 1.2 m / h at the rising flow rate of the anaerobic wastewater treatment apparatus 3.
The configuration is such that the opening degrees of a and 8a can be automatically controlled.

Further, a piping having a flow rate changing mechanism is attached to the circulation line, and pH meters 16 and 20 attached to the pH adjustment tank 1 and the treatment water tank 4 are used to check the treatment status of the anaerobic wastewater treatment apparatus. By using the thermometers 15 and 19, the processing status of the anaerobic bacteria inside the anaerobic wastewater treatment device 3 can be confirmed.

FIG. 3 is a block diagram of a third embodiment (corresponding to claim 2) of the present invention. This embodiment is different from the embodiment of FIG. 1 in that the speed control of the liquid supply pump 2 and the circulation pump 5 is performed. Apparatus 1
2 and 18 are attached, and the flow rate changing pipe 17 is attached, and the other configuration is the same.

As shown in the figure, in this embodiment, the flow rate signals obtained by the flow meters 9 and 10 are taken into a speed control device 12 to control the feed pump 2, and at the same time, the flow meters 9 and 1 are controlled.
The flow rate signals obtained at 0, 11, 13 are
By controlling the circulation pump 5, the wastewater is controlled so as to have a rising flow rate of 0.7 to 1.2 m / h in the anaerobic wastewater treatment apparatus 3. Further, it can be easily switched to the large circulation system in which the circulating water from the treated water tank 4 is returned to the PH adjustment tank 1 by the flow rate changing pipe 17 or the small circulation system in which the circulating water is returned to the inlet pipe of the anaerobic wastewater treatment device 3.

As described above, by controlling the flow rate of the wastewater, the efficiency of the wastewater treatment in the anaerobic wastewater treatment apparatus 3 is improved, the stable operation of the wastewater treatment equipment becomes possible, and the running cost such as the electricity charge is reduced. it can. Further, by using a motor-operated valve as the valve, the system can be switched to the large circulation system or the small circulation system according to the treatment state of the anaerobic wastewater treatment apparatus, so that a stable wastewater treatment plant can be operated.

[0028]

As described above, the present invention (Claim 1)
According to the countermeasure), the small circulation system is always used, eliminating the problems of freezing and the intermittent operation of the circulation line, which are the disadvantages of the large circulation system. Since switching can be dealt with, stable operation of a wastewater treatment plant can be realized. Further, by using a motor-operated valve, the system can be automatically switched to the large circulation system or the small circulation system according to the wastewater treatment status, so that a more stable operation of the wastewater treatment plant can be performed.

According to the present invention (corresponding to claim 2),
By controlling the speeds of the liquid supply pump and the circulation pump, the ascending flow rate in the anaerobic wastewater treatment apparatus is kept constant, stable wastewater treatment becomes possible, and running costs such as electricity charges can be saved. In addition, by performing the opening control of the electric valve, the ascending flow rate in the anaerobic wastewater treatment device is kept constant,
Stable wastewater treatment becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a process flow diagram of a conventional wastewater treatment apparatus, wherein FIG. 4A is a flow diagram of a large circulation system, FIG. 4B is a flow diagram of a small circulation system, and FIG. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... pH adjustment tank, 2 ... Supply pump, 3 ... Anaerobic wastewater treatment apparatus, 4 ... Treatment water tank, 5 ... Circulation pump, 6,7,8 ... Electric valve, 9,10,11,13,14 ... Flow rate 12,1
8. Speed control device, 15, 19 Thermometer, 16, 20 ...
pH meter, 17 ... flow rate change piping.

Claims (2)

[Claims] 1. The wastewater is adjusted to a pH at which anaerobic bacteria are activated in a pH adjusting tank and sent to an anaerobic wastewater treatment apparatus, where BOD in the wastewater is removed by 80 to 95% in the anaerobic wastewater treatment apparatus. In the anaerobic wastewater treatment equipment that is sent to the treatment water tank, a part of the treatment water stored in the treatment water tank can be returned to either the pH adjustment tank or the anaerobic wastewater treatment device by a circulation pump. An anaerobic wastewater treatment facility characterized by comprising. 2. The anaerobic wastewater treatment equipment according to claim 1, wherein a speed control device is attached to the circulation pump to control the anaerobic wastewater treatment device so as to keep the rising flow rate constant. An anaerobic wastewater treatment facility characterized by the following.