JPS5840115A - Flocculant pouring control apparatus in water treatment - Google Patents

Abstract

PURPOSE:To obtain the flocculant pouring control apparatus capable of easily controlling the outlet turbidity of a precipitation basin to a set value even if the flow amount of raw water is varied, by a method wherein the signal of the flow amount of raw water is put in a treated water set turbidity operator and the set value of treated water turbidity is calculated in accodance with the flow amount of raw water. CONSTITUTION:The set value of the outlet turbidity of a precipitation basin 2 by a precipitation basin outlet turbidity setting device 11 and the flow amount of raw water by a raw water flowmeter 3 are put in a treated water set turbidity operator 12 to calculate treated water set turbidity. This treated water turbidity set value is sent to a ratio operator 9 and compared to the treated water turbidity value by a treated water turbidimeter 8 to calculate a flocculant pouring ratio and this calculated value is sent to a pouring amount controller 6. A proper pouring amount of a flocculant is poured into a rapidly stirring basin 1 by the controller 6, the feedback signal of a flocculant flowmeter 4 and a manipulation device 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to injection control of a flocculant in water treatment. Conventionally, there has been an apparatus of this type as shown in FIG. 1.

Figure 1 shows a conventional example using a feedback injection control device. In the figure, (1) is a rapid stirring tank that injects a flocculant into raw water, and (2) is a sedimentation tank that includes a flocculator that mixes the raw water suspended matter and the flocculant. Pond (3) is the above rapid stirring pond (1)
(4) is a flocculant flow meter, (6) is a flocculant injection operator that operates the flocculant flow rate, (6) is a controller that controls the flocculant flow rate, (7)
is the raw water flow rate using the raw water flow meter (8) and the ratio calculator (9)
(8) is a treated water turbidity meter that measures the treated water turbidity, which is a control amount; and the ring is the sedimentation by the settling tank outlet turbidity setting device (b). This is a treated water setting turbidity calculator that calculates the desired treated water turbidity setting value based on the pond outlet turbidity setting value.

In the configuration shown in Fig. 1, when the operator sets the set value of the turbidity at the outlet of the settling tank (2) using the setting device CI, the signal is sent to the treated water setting turbidity calculator and is then controlled by feedback control. The set value of the turbidity of the treated water is calculated using a predetermined functional formula. The calculated treated water turbidity set value is sent to the ratio calculator (9), where it is compared with the treated water turbidity value measured by the treated water turbidity meter (8), and flocculant is injected according to the deviation between the two. A rate (ratio) is calculated and sent to the injection amount calculator (7). The injection amount calculation unit (γ) calculates the amount of flocculant injection from the injection rate determined by the ratio calculation unit (9) and the raw water flow rate determined by the raw water flow rate needle (3). Then, this injection amount is sent to the injection amount controller (6), and a feedback signal from this controller and the flocculant flow meter (4) and an operation device (5) are sent to the injection amount controller (6).
), an appropriate amount of flocculant is injected into the rapid stirring basin (1) and mixed with the raw water. moreover,
After this, the raw water forms a 7μ filter in a flocculator, and the flocs are settled in a settling tank behind it to reach the desired outlet turbidity before entering the next filter tank.O Conventional flocculant injection control Because the device is configured as described above, the raw water flow rate signal is not input to the treated water turbidity calculator. Therefore, when the raw water flow rate changes, the settling tank (2) outlet turbidity and the treated water turbidity change. It has the disadvantage that it cannot follow the changes in the functional formula and can only be used when the raw water flow rate is constant.

The present invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by sending changes in the raw water flow rate to a treated water setting turbidity calculator, it is possible to adjust the treated water turbidity according to the raw water flow rate. It is an object of the present invention to provide a flocculant injection control device that can calculate a set value and thereby control the turbidity of a sedimentation tank.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 2, in which the same parts as in FIG. 1 are denoted by the same reference numerals.

In Fig. 2, the treated water setting turbidity calculator (to) in the present invention includes the setting value of the settling tank outlet turbidity by the settling tank outlet turbidity setting device (b), as well as the raw water flow rate by the raw water flow meter (8). 0, which is inputted, and others are the same as before.

Therefore, in the configuration shown in Figure 2, when the operator sets the set value of the settling tank outlet turbidity using the setting device (B), the signal is sent to the treated water setting turbidity calculator, and here the predetermined value is The set turbidity of the treated water is calculated using the functional formula (residence time differs depending on the raw water flow rate, so the functional formula differs depending on the raw water flow rate), the raw water flow rate from the raw water flow meter (81), and the set value from the setting device Ql.

The subsequent operation is the same as before, and the calculated treated water turbidity set value is sent to the ratio calculator (9), where it is compared with the treated water turbidity value measured by the treated water turbidity meter (8). The flocculant injection rate (ratio) is calculated according to the deviation between the two, and the injection amount is calculated.
is sent to the container (γ). The flocculant injection amount is calculated from the injection rate by the injection amount calculator (9) and the raw water flow rate by the raw water flow meter (8) ◇Then, this injection amount is sent to the injection amount controller (6). An appropriate amount of coagulant is injected into the rapid stirring basin (1) by means of feedback signals from the flocculant flow meter (4) and the operating device (6), and is mixed with the raw water. Furthermore, after this, the raw water forms 70 filters in the flocculator, and settles 70 filters in the settling tank behind it to reach the desired outlet turbidity before entering the next filter tank. Although feedback control has been described in the embodiment, it goes without saying that the same effect can be achieved by combining feedback control and feedback control.

As described above, according to the present invention, since the raw water flow rate signal is input to the treated water setting turbidity calculator, the sedimentation tank outlet turbidity can be easily controlled to the set value even if the raw water flow rate changes, and stable turbidity can be maintained. of water.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a conventional flocculant injection control device, Figure 2
The figure is a configuration diagram showing a flocculant injection control device according to an embodiment of the present invention. (1)... Rapid stirring tank (2)... Sedimentation tank (3)...
Raw water flow meter (4)...Flocculant flow meter (5)...Flocculant injection operator (θ) fist/injection rate controller ())...Injection rate calculator (8)...Treatment water turbidity meter (9) - Ratio calculator acid, (2) - Treated water setting turbidity calculator o3J+1, Sedimentation tank outlet turbidity setter

Claims (1)

[Claims] A raw water flow meter that measures the flow rate of raw water to remove turbidity, a treated water turbidity meter that measures the turbidity of treated water, a setting device that sets the turbidity at the outlet of the sedimentation tank, and the settings by the above setting device and the raw water. a calculator that calculates the flow rate and the turbidity set value of the treated water; and a ratio calculator that calculates the flocculant injection ratio from the turbidity of the treated water collected by the treated water turbidity meter and the set value by the calculator. , an injection amount calculator that calculates the flocculant injection amount based on the ratio by the ratio calculator and the raw water flow rate, an injection amount controller that controls the flocculant injection amount, a flocculant injection operator, and a flocculant flow meter. A flocculant injection control device for water treatment.