JP4968420B2 - Flocculant injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flocculant injecting device for a water treatment system for solid-liquid separation of wastewater containing turbidity with a flocculant.
[0002]
[Related technical background]
Additives for condensing and precipitating turbid wastewater include inorganic flocculants and polymer flocculants such as aluminum chloride, polyaluminum chloride, aluminum sulfate, ferric chloride, and ferric sulfate. It is used. Conventional flocculant injection devices detect the flow rate and turbidity concentration of wastewater containing turbidity with a sensor, and perform condensation precipitation processing by controlling the addition rate of the flocculant (for example, Japanese Patent Publication No. 7). -29101).
[0003]
In addition, as a flocculant injection device for water purification treatment, turbidity of treated water, raw water flow rate and turbidity value are detected, and feedforward control using these values is performed (for example, Japanese Patent Application No. 58). -40114).
[0004]
[Problems to be solved by the invention]
However, since the flocculant injection device detects the turbidity of the wastewater, if dirt adheres to the turbidimeter provided on the raw water side of the wastewater, appropriate turbidity detection could not be performed, resulting in uncontrollability. . For this reason, maintenance of the turbidimeter must be performed frequently, and there is a problem that it is difficult to apply feedforward control in a wastewater treatment system.
[0005]
Of course, if feedback control is applied to the wastewater treatment system, a turbidity meter may be provided on the treated water side with high clarity after the wastewater is agglomerated, which can be said to be an effective means for preventing turbidity contamination. . However, since there is a time lag from the addition of the flocculant to the discharge of the treated water, it is difficult to perform appropriate control if feedback control is performed after detecting the turbidity of the treated water. There is a problem that a phenomenon that fluctuates.
[0006]
For this reason, when applying feedback control to a wastewater treatment system, sample value control is applied in which holding and control are repeated for a certain period of time so that the control amount does not vibrate due to the time lag. However, in the sample value control, it is necessary to hold the control for the time lag in the control system, and there is a drawback that the initial operation is delayed when a sudden water quality change occurs. For this reason, a method of shortening the hold time is also conceivable. However, in that case, there is a problem that the control amount vibrates due to hunting in the control output. Further, when the control amount vibrates, there is a concern that the waste water treatment system may cause excess or deficiency of the flocculant, causing deterioration of the quality of the treated water, wasteful consumption of the flocculant, and the like.
[0007]
The present invention has been made in consideration of the above-mentioned problems, and the object of the present invention is to perform quick flocculant injection control based on the treated water turbidity, and to keep the required amount of flocculant used, and to perform maintenance. An object of the present invention is to provide a flocculant injecting apparatus suitable for wastewater treatment capable of extending the cycle significantly.
[0008]
[Means for Solving the Problems]
To achieve the above object, coagulant injection device according to claim 1 of the present invention is an injection device of the coagulant in the water treatment system by injecting the flocculant to the water to be treated, solid-liquid separation, advance Quantify the pre- injected amount of flocculant in the water to be treated before solid-liquid separation by multiplying the turbidity concentration of 10 to 90% of the measured average turbidity of the water to be treated by the flow rate of the water to be treated previously measured. a first coagulant injection means for injecting a treatment liquid measuring means for measuring the turbidity of the treated water separated treated water to solid-liquid injected the flocculant, based on the measurement result of the treatment liquid measuring means, calculating means for calculating an injection amount of the coagulant deficiency to be added in addition to the treatment water before solid-liquid separation, before solid-liquid separation injection amount of the coagulant based on the result of said arithmetic means a second coagulant injection means for variable injected into water to be treated, consisting of coagulant injection To provide a location.
[0009]
A flocculant injection device according to claim 2 of the present invention is a flocculant injection device in a water treatment system for injecting a flocculant into water to be treated and performing solid-liquid separation, and measures the flow rate of the liquid to be treated. And a flocculant having an injection amount obtained by multiplying the turbidity concentration of 10 to 90% of the average turbidity concentration of the treated water measured in advance by the flow rate of the treated water measured by the flow measuring means. a first coagulant injection means for variable injection water to be treated before solid-liquid separation, and the processing liquid measuring means for measuring the turbidity of the treated water separated treated water to solid-liquid injected the coagulant, the based on the measurement result of the processing liquid measuring means, a calculating means for calculating an injection amount of the solid-liquid separation prior to treatment water shortage of the flocculant to be added in addition to the injection based on the result of said arithmetic means second coagulant injection hand to variate injecting said flocculant amount to the solid-liquid separation before the water to be treated When, it provides a coagulant injection device comprising a.
[0010]
Therefore, according to the present invention, it is possible to provide a flocculant injecting apparatus suitable for wastewater treatment that can perform quick flocculant injection control based on the treated water turbidity and can greatly extend the maintenance cycle.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the flocculant injection device according to claim 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a flocculant injection device.
This coagulant injecting apparatus includes a reaction tank 1 into which raw water (treated water) of inorganic wastewater containing turbidity is continuously introduced. Further, the flocculant stored in the flocculant storage tank 2 is supplied to the reaction tank 1 continuously or intermittently from the flocculant storage tank 2 by the metering injection pump 3 in a certain amount with respect to the raw water. The The raw water and the flocculant are stirred in the reaction tank 1 and flow into the precipitation tank 5. The raw water and the flocculant that have flowed into the settling tank 5 are separated into solid and liquid in the settling tank 5. At this time, the solid material separated in the precipitation tank 5 is discharged as sludge, and the liquid is discharged as treated water. The turbidity of the treated water discharged from the sedimentation tank 5 is monitored by a turbidimeter 6. The monitored turbidity is calculated by a controller (calculation means) 7, and the inverter 8 is controlled to drive the variable injection pump 4 at a variable speed so as to inject an amount of flocculant corresponding to the turbidity.
[0012]
In the flocculant injection device configured as described above, when the raw water flows into the reaction tank 1, the minimum necessary amount of flocculant is injected into the reaction tank 1 in advance by the metering injection pump 3.
Here, the minimum amount of flocculant injected can be obtained by the following equation.
Minimum required flocculant injection amount [g / H] = raw water flow rate [l / H] × turbidity concentration [g / l] × safety factor The turbidity concentration in the above equation is 90 to 10 of the average turbidity concentration. [%], Preferably 80 to 50 [%]. In addition, the safety factor in the above equation means a factor (> 1) that provides a margin for the coagulation treatment with respect to changes in the concentration and flow rate of raw water of drainage.
[0013]
Then, the turbidity of the treated water in which the raw water and the flocculant are stirred in the reaction tank 1 and solid-liquid separated in the precipitation tank 5 is monitored by a turbidimeter 6. When the controller 7 determines that the flocculant is insufficient from the monitor value of the turbidimeter 6, the inverter 8 is controlled to drive the variable injection pump 4, and the amount of flocculant suitable for the turbidity is An additional injection is made to 1. On the other hand, when the additional flocculant is unnecessary from the turbidity concentration of the treated water, the variable injection pump 4 is not driven.
[0014]
Now, the drainage turbidity in the above-described coagulant injection will be described with reference to the drawings. FIG. 2 is a diagram showing changes in turbidity of wastewater by a conventional feedback method. In FIG. 2, PV is a turbidity value detected by a turbidimeter, and SV is a turbidity control target value. Moreover, MV shows the amount of flocculant injection.
When raw waste water (treated water) flows into the flocculant injection device, it is discharged as treated water via the reaction tank 1 and the settling tank 5. The water to be treated at this time is detected by the turbidimeter 6 with a time lag TD corresponding to the time for passing through the reaction tank 1 and the sedimentation tank 5. When the detected value of the turbidimeter 6 for the water to be treated exceeds the target value SV, the flocculant is injected. However, because of the time lag, the detected value of the turbidimeter 6 continues to increase even after the flocculant is injected. For this reason, the injection amount of the flocculant is further increased. At this time, the wastewater concentration in the reaction tank 1 is equal to or less than the target value, but the flocculant is continuously injected due to the time lag, so that the flocculant is excessively injected. Then, the injection of the flocculant is stopped when the detected value of the turbidimeter 6 falls below the target value SV. However, since the flocculant is excessively injected, it further falls below the target value SV. And since the flocculant is not inject | poured into the reaction tank 1, the waste water turbidity of the reaction tank 1 will rise again, and the same operation | movement as mentioned above will be repeated hereafter. For this reason, drainage turbidity changes in vibration.
[0015]
Next, FIG. 3 is a figure which shows the waste-water turbidity change in this invention. When raw waste water (treated water) flows into the coagulant injection device, a predetermined amount of coagulant predetermined by the metering injection pump 3 is injected into the reaction tank 1. This treated water is detected by the turbidimeter 6 with a time lag TD after passing through the reaction tank 1 and the sedimentation tank 5. The detection value of the turbidimeter 6 shows a value close to the target value SV because a predetermined amount of the flocculant is injected into the reaction tank 1 by the metering injection pump 3 in advance. Therefore, it is sufficient to compensate for the deficiency of the flocculant by the variable injection pump 4, and the target value can be reached quickly. In addition, it becomes possible to control stably without causing the vibration phenomenon of drainage turbidity.
[0016]
That is, a predetermined minimum required amount of flocculant is charged first, and the adjustment of the deficiency may be adjusted by the variable injection pump 4, so that the control delay due to the time lag as seen in the conventional feedback control system is reduced. Can be minimized.
That is, according to the flocculant injection device of the present invention, it is possible to reach the optimum injection amount in the shortest time, and it is also possible to prevent surrounding fluctuations in processing water turbidity and hunting phenomenon.
[0017]
Furthermore, since the turbidimeter 6 is provided on the treated water side separated from the solid and liquid in the sedimentation tank 5 so that the contamination of the turbidimeter 6 due to contamination of raw water is extremely reduced, the maintenance cycle of the turbidimeter 6 is greatly increased. Can be extended to
Next, an embodiment of the invention according to claim 2 of the present invention will be described. FIG. 2 is a schematic configuration diagram of the present flocculant injection device. This embodiment is different from the first embodiment in that it includes a flow meter 9 that measures the inflow amount of raw water of inorganic wastewater, and further performs feedforward control that controls the injection amount of the flocculant based on this flow rate information. It is that it was provided.
[0018]
This flocculant injection device has a reaction tank 1 into which raw water of inorganic wastewater containing turbidity flows continuously, and a flow meter 9 for measuring the amount of flow of the raw water. Then, an amount of the flocculant corresponding to the inflow amount of the raw water measured by the flow meter 9 is continuously or intermittently injected from the flocculant storage tank 2 into the reaction tank 1. Specifically, in order to inject the flocculant in an amount corresponding to the inflow amount of the raw water by the first controller (calculation means) 10 based on the flow rate information of the flow meter 9, the first inverter 11 is controlled, One variable injection pump 12 is driven at variable speed.
[0019]
The raw water and the flocculant are stirred in the reaction tank 1 and flow into the precipitation tank 5. The raw water and the flocculant that have flowed into the settling tank 5 are separated into solid and liquid in the settling tank 5. At this time, the solid substance separated in the settling tank 5 is discharged as sludge, and the liquid is discharged as treated water. The turbidity of the treated water is monitored by a turbidimeter 6. The monitored turbidity is calculated by the second controller 13, and the second inverter 14 is controlled to inject the flocculant corresponding to the turbidity, and the second variable injection pump 15 is driven at a variable speed.
[0020]
In the flocculant injection device configured as described above, when raw water flows into the reaction tank 1, the minimum necessary flocculant proportional to the inflow amount is injected into the reaction tank 1 in advance by the first variable injection pump 12. The flocculant and the stirred stock solution are solid-liquid separated in the precipitation tank 5, and the treated water is monitored by the turbidimeter 6. Then, the second variable injection pump 15 is driven to change speed so that the injection amount of the flocculant suitable for the turbidity is obtained. That is, when the second controller 13 determines that the coagulant is insufficient from the monitor value of the turbidimeter 6, the second inverter 14 is controlled to drive the second variable injection pump 15 to coagulate. The agent is additionally injected into the reaction vessel 1. On the other hand, when the additional flocculant is unnecessary from the turbidity concentration of the treated water, the second variable injection pump 15 is not driven.
[0021]
That is, according to the flocculant injection device of the present invention, even if the raw water inflow amount of the waste water fluctuates, an amount of the flocculant proportional to the inflow amount can be injected into the reaction tank 1 in advance. For this reason, it becomes possible to improve the control delay at the time of performing feedback control according to the turbidity of treated water after detecting the turbidity of treated water. In addition, since the optimum amount of the flocculant is quickly injected, the flocculant is not wasted.
[0022]
In the example described above, one example of the storage tank for the flocculant is taken up. For example, as the flocculant, there are an inorganic flocculant and a polymer flocculant, which are combined with a single storage tank or a plurality of storage tanks and a plurality of pumps, respectively. It is good also as a structure. In this case, as described above, one flocculant may be supplied as a fixed amount, and the other flocculant may be supplied as a variable amount. Or it is good also as a structure which has a fixed_quantity | specification injection pump and a variable_quantity | specification injection pump in each storage tank of a plurality of flocculants. In addition, you may comprise in various combinations in the range which does not deviate from the meaning of this invention.
[0023]
【Effect of the invention】
As described above, according to the flocculant injection device of the present invention, since the minimum amount of flocculant necessary for processing raw water of wastewater containing turbidity is supplied in advance by a metering injection pump, the treatment water turbidity detection Even with the feedback control according to the above, the flocculant injection control based on the treated water turbidity can be performed quickly and the required amount of the flocculant can be kept. In addition, since there is no turbidimeter installed on the raw water side of the wastewater, it is possible to avoid the influence of contamination of the turbidimeter due to the raw water of the wastewater, to achieve stable control, and to greatly extend the maintenance cycle of the turbidimeter. And the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a flocculant injection device according to an embodiment of the present invention.
FIG. 2 is a diagram showing an outline of a change in turbidity of drainage in a conventional flocculant injection device.
FIG. 3 is a diagram showing an outline of a change in turbidity of drainage in the flocculant injection device according to one embodiment of the present invention.
FIG. 4 is a diagram showing a schematic configuration of a flocculant injection device according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Coagulant storage tank 3 Fixed injection pump 4, 12, 15 Variable injection pump 5 Precipitation tank 6 Turbidimeter 7, 10, 13 Controller 8, 11, 14 Inverter 9 Flowmeter

Claims (2)

An apparatus for injecting a flocculant in a water treatment system for injecting a flocculant into water to be treated and performing solid-liquid separation,
The pre-measured turbidity concentration of 10 to 90% of the average turbidity concentration of the treated water is multiplied by the pre-measured flow rate of the treated water, and a preset amount of flocculant is added to the treated water before solid-liquid separation. First flocculant injection means for quantitative injection;
A treatment liquid measuring means for measuring the turbidity of the treated water wherein flocculant was solid-liquid separated water to be treated is injected,
A calculating means for calculating a measurement result based on the injection amount of the solid-liquid separation prior to shortage of the flocculant to be added in addition to the water to be treated of the treatment liquid measuring means,
Injection amount of the second coagulant injection means for variable injected into the water to be treated before the flocculant to solid-liquid separation, consisting coagulant injection device based on the result of said arithmetic means. An apparatus for injecting a flocculant in a water treatment system for injecting a flocculant into water to be treated and performing solid-liquid separation,
A flow rate measuring means for measuring the flow rate of the liquid to be treated;
The flocculant of the injection amount obtained by multiplying the turbidity concentration of 10 to 90% of the average turbidity concentration of the treated water measured in advance by the flow rate of the treated water measured by the flow rate measuring means is obtained before the solid-liquid separation. First flocculant injection means for injecting a variable amount into treated water;
A treatment liquid measuring means for measuring the turbidity of the treated water wherein flocculant was solid-liquid separated water to be treated is injected,
A calculating means for calculating a measurement result based on the injection amount of the solid-liquid separation prior to shortage of the flocculant to be added in addition to the water to be treated of the treatment liquid measuring means,
Injection amount of the second coagulant injection means for variable injected into the water to be treated before the flocculant to solid-liquid separation, consisting coagulant injection device based on the result of said arithmetic means.

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