JP2002102606A - Water treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment device in which an overflow amount is made constant and the rising of a sludge is prevented. SOLUTION: The water treatment device comprises a batch tank 1 provided with a flow-in means 6 and a discharge means 7; a supernatant discharge means 5 for introducing a supernatant to the discharge means 7; a driving means 4 for moving the supernatant discharge means 5; a batch tank water level measuring means 2 for measuring a water level in the batch tank; and a discharge control means 3 for controlling the driving means 4. A means for operating a descending amount of the supernatant discharge means based on an algorithm expressing a relationship of the water level in the batch tank and a discharge time of the processing water by inputting an output signal from the batch tank water level measuring means 2 to the discharge control means 5 is provided. The supernatant discharge means 5 is moved between the set highest position and the lowest position of the water level in the batch tank. It is preferable that a landing detection means for detecting that the supernatant discharge means 5 lands on the water level in the batch tank and a batch tank sludge interface measuring means for measuring a sludge interface are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch type water treatment apparatus and, more particularly, to a batch type water treatment apparatus capable of improving the quality of discharged water.

[0002]

2. Description of the Related Art As an example of a supernatant water discharge device in a conventional batch-type water treatment device, there is a device having a structure disclosed in Japanese Patent Publication No. 59-1362, as an example classified as a float arm type.

[0003] In the operation of the float arm type supernatant water discharge device, the lowering speed of the supernatant water discharge means changes depending on the arm position when the treated water is discharged in the discharge step. Therefore, by mechanically detecting the arm position and changing the descending speed each time the arm position changes, the descending speed of the supernatant water discharging device is kept as constant as possible to reduce the change in the overflow rate. The detection of this mechanical arm position
This is performed by the detection switches, and the accuracy is determined by the number of the detection switches.

[0004] The float arm type supernatant water discharger has a mechanical characteristic that the overflow amount increases as the float arm type supernatant water discharger descends. This is expressed as vcosθ (θ: 90 ° to 0 °) from the vertical velocity component of the arm and the angle θ of the arm with respect to the horizontal direction. As the vertical velocity component approaches the discharge end water level (θ becomes smaller). This is because the overflow speed increases. Activated sludge settles at the lower part of the batch tank, but activated sludge with poor sedimentation has a high activated sludge interface. When the activated sludge interface is at a high position due to such poorly sedimented activated sludge, a part of the activated sludge may be entrained along with the supernatant water with the increase in overflow, and the activated sludge may flow out. is there. Alternatively, when the supernatant water discharge proceeds and the activated sludge interface formed in the batch tank is near the discharge end water level, a part of the activated sludge is involved with the supernatant water, and the activated sludge may flow out. . The outflow of activated sludge degrades the treated water and is undesirable in water treatment equipment. Therefore, near the drainage end water level, fine adjustment of the descending speed is desired. However, as the float arm type supernatant water discharger approaches the discharge end water level as described above, the descending speed increases,
Fine adjustment is difficult.

[0005] In addition, the control of the conventional float arm type supernatant water discharge device is performed by a descending speed multi-stage switching type, and the number of shift stages is two to four, and the number of stages is limited. Therefore, the discharge process time cannot be made to correspond to the treated water amount (batch tank water level). For this reason, generally, it is necessary to set the discharge process time to the maximum so that the maximum treated water amount can be discharged, which causes waste time and further reduces the treated water amount (the batch tank water level becomes lower). At that time, even if it is desired to enter the stirring / aeration step or the precipitation step early, there is also a problem that the stirring / aeration step and the precipitation step cannot be lengthened because the discharge step time is set to the maximum for the above-described reason. .

[0006] Further, the conventional float arm type supernatant water discharge apparatus has an open loop control in which the batch tank water level is not utilized in the discharge step, so that the overflow rate tends to increase with time.

In the above prior art, although the descending speed multi-stage switching type is adopted, the descending speed of the float arm type supernatant water discharging means is large near the water level at the end of the discharging step because the number of shift steps is limited. The disadvantage of becoming was not improved.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a batch type water treatment apparatus which makes the overflow rate constant and prevents sludge from being rolled up.

SUMMARY OF THE INVENTION It is an object of the present invention to control a descending speed of a supernatant water discharging means of a float arm type or a float guide type according to a water surface position.

[0010]

In order to solve such a problem, the overflow rate from the batch tank is controlled by measuring the batch tank water level and arbitrarily controlling the descending speed of the supernatant water discharging means. .

That is, the batch type water treatment apparatus of the present invention comprises:
Batch tank with inflow means and drainage means, supernatant water discharge means for guiding the supernatant water to the drainage means, driving means to move the supernatant water discharge means, batch tank water level measurement means for measuring the batch tank water level, Discharge control means for controlling the driving means. An output signal from the batch tank water level measurement means is input to the discharge control means, and the descending amount of the supernatant water discharge means is calculated based on an algorithm expressing the relationship between the batch tank water level and the discharge time of the treated water. A means for performing this is provided.

The supernatant water discharge means moves between the highest position and the lowest position where the batch tank water level is set, and the landing water detecting means detects that the supernatant water discharge means has reached the batch tank water level. It is preferable that an output signal from the water landing detecting means for detecting that the supernatant water discharging means has water is provided to the drain control means.

[0013] It is preferable to have a batch tank sludge interface measuring means for measuring a sludge interface, and to be able to input an output signal from the batch tank sludge interface measuring means to the discharge control means. The calculation preferably incorporates PID control.
Control factors are batch tank water level and sludge interface position.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a batch type water treatment apparatus according to the present invention is a batch tank 1 (dimensions :, for example, 6800 mm × 6800 mm × effective water depth) for storing and purifying water to be treated. 5000m
m), a supernatant water discharging means 5, a driving means 4 for moving the supernatant water discharging means 5, a batch tank water level measuring means 2 for measuring the batch tank water level and outputting it to the discharge control means 3, and a batch tank water level measuring means The apparatus includes a discharge control unit 3 that receives a signal from the control unit 2 and outputs the signal to the drive unit 4, an inflow unit 6, and a drain unit 7. Also,
The batch tank water level measuring means 2 preferably also has a function of detecting the landing position of the supernatant water discharging means 5, and outputs an output signal to the discharge control means 3.

The supernatant water discharge means 5 is configured as shown in Japanese Patent Publication No. 59-1362 to guide the supernatant water to the discharge means, and the amount of descent can be adjusted by the drive unit 4 between the highest position and the lowest position. Can go up and down.

The driving device 4 is provided with a mechanism for converting, for example, the rotation of a synchronous motor into a linear motion so that the supernatant water discharging means 5 is always horizontal and can move up and down.

The batch tank water level measuring means 2 measures a pressure sensing type water level meter installed below the lowest water level of the batch tank 1 and a round trip time when ultrasonic waves transmitted from the upper part of the batch tank are reflected on the water surface. An apparatus of a type that measures by converting to a water level may be used.

FIG. 4 is a block diagram showing the structure of the discharge control means 3. As shown in FIG.

The emission control means 3 includes a data collection unit 101
, An operation unit 102, a control signal conversion unit 103, a process control unit 104, a parameter setting unit 105, and a signal contact output unit 106. Specifically, it may be realized by an electronic arithmetic circuit, or may be realized by a commercially available electronic computer, software, and an appropriate program.

The batch tank water level measuring means 2 is connected to the data collecting unit 101 and stores data. Similarly, when a batch tank sludge interface measuring means described later is provided,
Connect to data collection unit 101. The arithmetic unit 102 uses the signal of the batch tank water level from the data collection unit 101, the set discharge time from the parameter setting unit 105, and the discharge process signal from the process control unit 104 to calculate the supernatant water
Calculate an appropriate descending amount of.

The lowering amount is input to the control signal converter 103, converted into a control signal, and then output to the driving means 4. In addition, the process control unit 104 sends an ascending / descending signal of the supernatant water discharging unit 5 via the signal contact output unit 106 to the driving unit
Output to

The amount of descent is calculated by the process controller 104 during the discharging step, after the supernatant water discharging means 5 starts to descent.
The detection of the landing of the supernatant water discharge means 5 is started at the same time as the detection of the change in the output signal from the batch tank water level measuring means 2.
The appropriate descending amount is calculated using the current batch tank water level and the set discharge time output from the parameter setting unit 105 as in the first embodiment described later.

In the batch type water treatment apparatus of the present invention, the batch tank water level is measured and output to the discharge control means 3 as described above.
Since the discharge control means 3 calculates the target value / control amount, sets the discharge time, and changes the control amount of the supernatant water discharge means 5 to control the overflow rate, it is possible to discharge the treated water satisfactorily. it can.

In a different embodiment of the batch type water treatment apparatus of the present invention shown in FIG. 2, in addition to the output signal of the batch tank water level measuring means 2 which measures the batch tank water level and outputs it to the discharge control means 3,
A circuit for detecting the landing of the supernatant water discharge means 5 based on a change in the water level and outputting an output signal to the discharge control means 3 is provided as a circuit. The landing detection means 8 may be a method using the above-mentioned batch tank water level measurement means 2 or may be attached to the supernatant water discharge means 5 and may be constituted by a float and a detection switch.
Other configurations, operations, and calculation of an appropriate descending amount are the same as those in the embodiment shown in FIG.

A different embodiment of the batch type water treatment apparatus of the present invention shown in FIG. 3 is provided with a batch tank sludge interface measuring means 9 for measuring a sludge interface 10 and outputting it to the discharge control means 3. The batch tank sludge interface measuring means 9 may be, for example, an “NU-AL” automatic sludge interface meter manufactured by Nishihara Environmental Sanitation Laboratory. This is because the amount of attenuation of the ultrasonic wave is
Utilizing the proportional relationship, the built-in motor operates to move the sensor up and down and output the sensor position (interface). Alternatively, any configuration can be used as long as the sludge interface 10 can be measured and output. Other configurations and operations are the same as those of the embodiment shown in FIGS. Then, the sludge interface 10 measured by the batch tank sludge interface measuring means 9 is added to the calculation of the appropriate descent amount, and the calculation is performed as in Example 2 described later.

The water treatment operation process in the batch type water treatment apparatus of the present invention is performed by the following method.

Sewage is fed into the batch tank 1 from the inflow means 6, passes through a stirring / aeration step and a sedimentation step, and in a discharge step, supernatant water is drained from the drainage means 7 via the supernatant water discharge means 5. The discharge control means 3 controls the batch tank 1 in the discharge step.
The batch tank water level is obtained from the batch tank water level measuring means 2 installed in the apparatus, and an appropriate amount of descent of the supernatant water discharging means 5 per unit time, that is, a descent speed, is calculated from a preset discharge time. A control amount is output from the discharge control means 3 to the drive means 4 so that the descending speed is attained, and the speed control of the supernatant water discharge means 5 is performed. Specifically, the speed is controlled by the number of rotations of the electric motor of the driving device 4. At the end of the discharging step, the supernatant water discharging means 5 is raised to end the discharging step.

An embodiment of the present invention will be described below.

(Example 1) The batch water treatment apparatus shown in FIG. 1 was used to carry out a constant overflow flow control operation of the supernatant water discharging means 5.

FIG. 5 is a conceptual diagram for explaining a temporal change of the batch tank water level during the constant overflow load control operation of the batch type water treatment apparatus. The figure focuses on the discharge time and the change in the batch tank water level during the discharge process.

HWL is the batch tank high water level at the start of the discharge step, and LWL is the batch tank discharge water level at the end of the discharge step. t1
Is the time from the start of lowering of the supernatant water discharge means 5 to the landing, and the time during which the supernatant water discharge means 5 moves in the air. t2
Is the time from landing to the end of discharge, and during this time t2, the overflow load constant control is performed. By monitoring the decrease in the water level of the batch tank during the discharging step, the landing of the supernatant water discharging means 5 is detected, and the time t2 from the landing to the end of discharging is calculated.

To make the overflow load constant is equivalent to making the time change of the batch tank water level constant when the batch tank is a rectangular parallelepiped.

(Equation 1) Becomes Here, ΔH is a minute water level change, and Δt is a minute time change.

Hereinafter, the speed type control and the position type control will be described.

In the case of the speed type control, the average batch tank water level change speed from HWL to LWL is expressed by the above (Equation 1), and the batch tank high water level HWL, the batch tank discharge water level LWL, the set discharge time Td,
When rewriting using the time t1 from the start of descent to landing,

(Equation 2) Becomes The constant value of (Equation 2) is the average gradient to be targeted when the treated water is discharged.

After the landing of the supernatant water discharge means 5, the constant value of (Equation 2) is set as the target value (SV), and ΔH measured in each control cycle is calculated.
From the above, the result of calculating ΔH / Δt is defined as the process value (PV),
The driving means 4 was subjected to PID control.

In the case of the position type control, the batch tank target water level H (t) at the time t is a function of the time t from the start of the descending of the supernatant water discharge means 5,

(Equation 3) Becomes

After the landing of the supernatant water discharge means 5, the batch tank target water level H (t) given by (Equation 3) is set as a target value (SV), and the batch volume obtained by the batch tank water level measurement means 2 for each control cycle. The tank water level was used as the process value (PV), and the driving means 4 was controlled by PID.

FIG. 6 is a graph showing the change over time in the batch tank water level during the constant overflow load control operation of the water treatment apparatus. For both the batch tank initial water level of 6.9 [m] and 5.8 [m], the set discharge time was 105 minutes and the overflow load constant control was performed. The results are the same in both the velocity type control and the position type control, and it can be seen that the discharge time is the same even though the initial water level differs by 1.1 [m].

In this embodiment, the shape of the batch tank is a rectangular parallelepiped, but any of the above-described speed-type control and position-type control can be applied to a batch tank other than a rectangular parallelepiped. However, when the horizontal cross-sectional area is not constant, the overflow amount is not always constant even if the descending speed of the batch tank water level is constant.

(Embodiment 2) Using the batch type water treatment apparatus shown in FIG.
And the measurement signal from the batch tank sludge interface measuring means 9 were input, and the lowering speed of the supernatant water discharging means 5 was reduced so as to be closer to the sludge interface, and an operation to reduce the overflow was performed. . However, sludge interface is lower than LWL (LWL ≧ DWL)
It is necessary.

The batch tank target water level H ′ (t) at time t is a function of the time t from the start of lowering of the supernatant water discharge means 5 and the water level DWL at the sludge interface,

(Equation 4) And Here, k is an adjustment parameter.

After the landing of the supernatant water discharge means 5, the batch tank target water level given by the time t and the sludge interface water level DWL (Equation 4) is set as a target value (SV), and the batch tank water level measured at each control cycle. Is a process value (PV), and PID control of the driving means 4 is performed. (Equation 4) is set so that when the sludge interface water level DWL is high, the deceleration is early, and when the sludge interface DWL is low, there is almost no deceleration.

FIG. 7 is a graph showing the change over time in the batch tank water level during the control operation of the batch type water treatment apparatus using the batch tank sludge interface measuring means 9 together. When the sedimentation of sludge is good (a)
However, even in the bad case (b), it can be seen that the discharge time is equal.

Little lifting of sludge due to discharge of supernatant water was observed. Therefore, sludge outflow accompanying the rise of the sludge interface could be prevented.

Further, it is possible to stop the descending of the supernatant water discharging means 5 by the change of the output of the batch tank sludge interface measuring means 9 so as to prevent the sludge from flowing out. As a result, it is possible to prevent the water quality of the discharged water from being deteriorated due to the sludge flowing out due to the rise of the sludge interface due to bulking or the like.

[0046]

According to the present invention, the following effects can be obtained.

(1) The supernatant water can be discharged at a constant overflow flow rate.

(2) Since any discharge time can be set,
The setting time of the stirring / aeration step and the precipitation step can be set longer. Therefore, the range of response under a high load is expanded.

(3) Sludge roll-up is reduced and water quality is improved. Furthermore, the combined use of the batch tank sludge interface measuring means makes it possible to prevent the quality of the discharged water from deteriorating due to the sludge flowing out due to the rise of the sludge interface.

(4) The detection of the landing of the supernatant water discharge means can be replaced by a batch tank water level gauge. Further, the present invention can be applied to a liquid discharge device that wants to keep a discharge speed constant, other than the water treatment device.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing one embodiment of a batch type water treatment apparatus of the present invention.

FIG. 2 is a schematic vertical sectional view showing another embodiment of the batch type water treatment apparatus of the present invention.

FIG. 3 is a schematic longitudinal sectional view showing another embodiment of the batch type water treatment apparatus of the present invention.

FIG. 4 is a configuration block diagram showing one embodiment of a discharge control means of the batch type water treatment apparatus of the present invention.

FIG. 5 is a conceptual diagram of an overflow load constant control operation.

FIG. 6 is a graph at the time of an overflow load constant control operation by the batch type water treatment apparatus of the present invention.

FIG. 7 is a graph of a batch type water treatment apparatus of the present invention during a control operation using a batch tank sludge interface measuring means.

[Explanation of symbols]

 1 batch tank 2 batch tank water level measurement means 3 discharge control means 4 drive means 5 supernatant water discharge means 6 inflow means 7 drainage means 8 water landing detection means 9 batch tank sludge interface measurement means 10 sludge interface 101 data collection unit 102 arithmetic unit 103 Control signal conversion unit 104 Process control unit 105 Parameter setting unit 106 Signal contact output unit

Claims (3)

[Claims] A batch tank provided with an inflow means and a drainage means, a supernatant water discharge means for guiding the supernatant water to the drainage means,
In a batch type water treatment apparatus comprising a driving means for moving a supernatant water discharging means, a batch tank water level measuring means for measuring a batch tank water level, and a discharge control means for controlling the driving means, the discharge control means includes a batch tank water level. An output signal from the measuring means is input, and a means for calculating a descending amount of the supernatant water discharging means is provided based on an algorithm expressing a relationship between a batch tank water level and a treated water discharging time. Batch type water treatment equipment. 2. The apparatus according to claim 1, wherein the supernatant water discharge means has a water landing detection means for detecting that water has reached the batch tank water level, and outputs an output signal from the water landing detection means for detecting that the supernatant water discharge means has landed. 2. A batch type water treatment apparatus according to claim 1, wherein said apparatus can be inputted to said discharge control means. 3. A batch tank sludge interface measuring means for measuring a sludge interface, wherein an output signal from the batch tank sludge interface measuring means can be inputted to the discharge control means. The batch type water treatment apparatus according to claim 2.