JP4523731B2 - Water treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water treatment apparatus that performs an aggregation treatment using an inorganic flocculant and an organic polymer flocculant (hereinafter referred to as a polymer).
[0002]
[Prior art]
Conventionally, in water and sewage treatment and various wastewater treatment, agglomeration treatment has been widely performed in order to remove suspended solids and dissolved organic matter. In this aggregating treatment, aluminum-based and iron-based inorganic metal salt aggregating agents such as aluminum sulfate, PAC (polyaluminum chloride), and ferric chloride are usually used as the aggregating agent.
[0003]
However, depending on the quality of the raw water to be treated, these inorganic flocculants alone do not form sufficiently large flocs, and the solid-liquid separation rate in the subsequent precipitation and filtration processes is slow, so that good treated water quality cannot be obtained. There is.
[0004]
On the other hand, in the field of wastewater and sludge treatment, polymers such as polyacrylamide have been widely used to promote floc formation and sedimentation separation. In the field of water supply, since there is a possibility that harmful impurities (such as acrylamide monomer) are contained in the polymer, the use has not been approved so far. However, it is possible to keep these impurity concentrations sufficiently low, and in Japan, use has been approved since 2000 under conditions that keep the impurity concentrations below the reference value.
[0005]
In the coagulation treatment using the inorganic coagulant and the polymer in combination, first, the inorganic coagulant is injected and mixed in the inorganic mixing tank, and then the polymer is injected and mixed in the polymer mixing tank immediately thereafter. Stirring in this polymer mixing tank is performed by rapid stirring so that the polymer further binds to the fine flocs formed by the combination of the inorganic flocculant and the suspended substance in the raw water. Further, in the subsequent stage, the floc is grown by slow stirring. Slow agitation is usually performed in a series of 1 to 4 tanks, and the agitation conditions are such that the intensity of agitation is reduced toward the subsequent stage and the flocs are grown without breaking.
[0006]
[Problems to be solved by the invention]
Here, in conventional wastewater treatment, etc., polymers are used mainly for the purpose of enlarging flocs, increasing floc sedimentation speed, and reducing sedimentation tanks, and the target or standard of treated water quality is moderate. there were. Therefore, when polymer injection is performed, the amount added is controlled, but a constant value has been adopted for other conditions such as stirring intensity.
[0007]
However, as in the case of water purification treatment, not only coagulation sedimentation but also filtration is performed, and severe water quality such as turbidity of 0.1 degrees or less has been required as filtered water. As a result of various experiments, the present inventors have found that the stirring strength in the polymer mixing tank has a great influence on whether or not the required water quality can be achieved.
[0008]
In particular, the polymer solution has high viscosity and poor dispersibility in water. Therefore, the higher the injection rate, the stronger the stirring, and the more dispersible, the flocs grow and the fine particles grow. May not be removed. Even when the coagulated sediment treated water is passed through filtration, the quality of the treated water may be deteriorated. Conversely, if the injection rate is low, stirring with the same stirring intensity as in the case of a high injection rate will destroy the floc that has started to grow, and the floc will not grow sufficiently, leading to precipitation treatment. The effect may be reduced.
[0009]
Also, the viscosity of the water / polymer solution changes depending on the water temperature, the state of dispersion during injection and mixing, and the treatment effect also changes. In particular, when the water temperature is low, the viscosity of the water / polymer is high, so that it is difficult to disperse.
[0010]
In addition, if the raw water quality is relatively good, floc formation / sedimentation is good just by injecting the inorganic flocculant, and if the quality of the precipitated treated water / filtered water is good and stable, the polymer injection is not necessarily Not needed. When the treatment is performed only with the inorganic flocculant without injecting the polymer, it is necessary to inject the inorganic flocculant, perform rapid stirring for a short time, and then perform slow stirring. Therefore, when the polymer is not injected, if the stirring intensity in the polymer mixing tank is the same as when the polymer is injected, the rapid stirring time becomes too long and the floc does not become sufficiently large. In that case, there is a choice that a bypass line is provided and the polymer mixing tank is not used, but the apparatus becomes complicated and a valve switching operation is also required. Further, during that time, not only a part of the polymer mixing tank is allowed to play, but also the maintenance and restart are complicated.
[0011]
This invention is made | formed in view of the said subject, and it aims at providing the water treatment apparatus which can perform favorable aggregation process.
[0012]
[Means for Solving the Problems]
The present invention has an inorganic flocculant mixing tank for mixing an inorganic flocculant, and an organic polymer flocculant mixing tank for mixing an organic polymer flocculant in the outflow water from the inorganic flocculant mixing tank, In a water treatment apparatus that performs an agglomeration treatment using an inorganic flocculant and an organic polymer flocculant, the stirring strength in the organic polymer flocculant mixing tank is set to a value larger than the stirring strength of the preceding inorganic flocculant mixing tank. In addition, the stirring strength in the organic polymer flocculant mixing tank is changed so as to increase as the injection rate of the organic polymer flocculant increases and to decrease as the water temperature increases .
[0013]
Thus, according to the present invention, the stirring strength in the organic polymer flocculant mixing tank is changed according to the injection rate of the organic polymer flocculant and the water temperature. Therefore, the stirring strength can be maintained at an appropriate level, effective agglomeration treatment can be performed, and good treated water can be obtained.
[0014]
The present invention also includes an inorganic flocculant mixing tank for mixing the inorganic flocculant, and an organic polymer flocculant mixing tank for mixing the organic polymer flocculant with the outflow water from the inorganic flocculant mixing tank. , together with the aggregation treatment using both inorganic coagulant and an organic polymer flocculant can row Ukoto, the amount of time the organic polymer flocculant to be added to the organic polymer flocculant mixing tank substantially 0 When adding an organic polymer flocculant to the organic polymer flocculant mixing tank in the water treatment apparatus capable of performing the same , the stirring strength in the organic polymer flocculant mixing tank is set to When the value is larger than the stirring strength and the addition amount of the organic polymer flocculant in the organic polymer flocculant mixing tank is substantially 0, the stirring strength of the organic polymer flocculant mixing tank is set to the inorganic strength. Use a value smaller than the mixing strength of the mixing tank And butterflies.
[0015]
Thus, in the present invention, when the addition amount of the organic polymer flocculant in the organic polymer flocculant mixing tank is substantially 0, the stirring strength of the organic polymer flocculant mixing tank is set to Set to a value smaller than the stirring intensity. Therefore, when the organic polymer flocculant is not added, the organic polymer flocculant mixing tank can be used as a part of the subsequent flock forming tank. Therefore, a bypass pipe or the like is not necessary, and a suitable aggregation process can be performed.
[0016]
Further, the organic polymer flocculant mixing tank has a flock formation tank that gently stirs the effluent of the organic polymer flocculant mixing tank to promote flock formation, and the addition amount of the organic polymer flocculant in the organic polymer flocculant mixing tank Is substantially 0, the stirring strength of the organic polymer flocculant mixing tank is preferably smaller than the stirring strength of the inorganic mixing tank and greater than the stirring strength of the floc-forming tank. It is. Thereby, suitable floc formation can be performed.
[0017]
In addition, it is preferable to change the stirring strength in the organic polymer flocculant mixing tank so as to increase as the organic polymer flocculant injection rate increases and to decrease as the water temperature increases .
[0018]
The organic polymer flocculant is an anionic or nonionic one using acrylamide monomer as a raw material, and preferably has a molecular weight of 1,000,000 to 3,000,000 daltons. With such an organic polymer flocculant, floc formation after the addition of the inorganic flocculant can be suitably performed. In addition, it is preferable to prepare a plurality of types of flocculants having different ionic properties and molecular weights in advance and use the most effective type according to the raw water quality.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
Drawing 1 is a figure showing the composition of the water treatment equipment of an embodiment. Raw water composed of surface water such as river water and lake water is introduced into the inorganic mixing tank 10. In the inorganic mixing tank 10, a stirrer 12 including a stirring blade 12a and a motor 12b for rotating the stirring blade 12a is disposed. In addition, an inorganic flocculant in the inorganic flocculant tank 14 is supplied to the inorganic mixing tank 10 by a pump 16. As the inorganic flocculant, for example, PAC (polyaluminum chloride: containing Al ₂ O ₃ 10%) is used. In addition, although the rapid stirring intensity | strength of this inorganic mixing tank 10 is usually less than 300 (S <^-1> ) and a residence time is less than 5 minutes, it is not limited to this.
[0021]
Next, the water mixed with the inorganic flocculant is introduced into the polymer mixing tank 18. The polymer mixing tank 18 is provided with a stirrer 20 including a stirring blade 20a and a motor 20b for rotating the stirring blade 20a. The polymer flocculant in the polymer flocculant tank 22 is supplied by a pump 24. The As the polymer flocculant, for example, a nonionic acrylamide polymer is used. Moreover, although an anionic acrylamide polymer may be suitable, it is not limited to these. In addition, it is preferable to prepare a plurality of types of flocculants having different ionic properties and molecular weights in advance and use the most effective type according to the raw water quality. The rapid stirring strength of the polymer mixing tank 18 is set to 300 (S ⁻¹ ) or more and a residence time of about 1 to 10 minutes.
[0022]
Water mixed with the inorganic flocculant and the polymer flocculant from the polymer mixing tank 18 is introduced into the floc forming tank 28. The floc forming tank 28 is composed of three tanks, each of which is provided with a horizontal axis paddle type slow agitator 26. The slow stirrer 26 can set the stirring strength for each tank, and the stirring strength is usually set so as to gradually decrease. Then, the flocs are coarsened by gently stirring in the floc forming tank 28. The stirring strength in the floc forming tank 28 is set so as to gradually decrease from the tank on the entrance side, for example, 100-60-40 (S ⁻¹ ).
[0023]
Then, water flocked with the inorganic flocculant and the polymer flocculant is introduced into the precipitation tank 30, where the solid matter is precipitated. Solid matter precipitated in the settling tank 30 is excluded from the system as sludge, and the supernatant water is supplied to the sand filter 32. The sand filter 32 has a filter medium layer inside, and the floating solids remaining by the filter medium layer are separated by filtration. As a result, water-treated filtered water that can be distributed as tap water is stably obtained. The filter medium layer is formed of, for example, three layers of anthracite, two-layer anthracite of silica sand, silica sand, and garnet.
[0024]
The filtered treated water is stored in the treated water tank 34 and distributed after being disinfected. Further, the treated water in the treated water tank 34 can be supplied to the bottom of the sand filter 32 by the backwash pump 36, whereby the sand filter 32 can be backwashed. In addition, air from the blower 38 can be supplied to the bottom of the sand filter 32, whereby air backwashing is also performed.
[0025]
And the thermometer 40 is provided in the inflow path | route to the inorganic mixing tank 10 of raw | natural water, and raw | natural water water temperature is measured. In addition, since this temperature does not change so much in each tank, you may provide in any tanks, such as the inorganic mixing tank 10, the polymer mixing tank 18, and the flock formation tank 28. FIG. In particular, the water temperature in the polymer mixing tank 18 is important, and it is preferable to provide a thermometer in the polymer mixing tank 18.
[0026]
The detection result of the thermometer 40 is supplied to the controller 42. The controller 42 is also supplied with a signal regarding the flow rate of the pump 24 for adding the polymer flocculant. And this controller 42 controls rotation of the motor 20b based on water temperature and the addition amount of a polymer flocculant, and controls the stirring intensity | strength of the stirrer 20. FIG.
[0027]
The injection rate of inorganic flocculant, the injection rate of polymer flocculant, the type of polymer flocculant, etc. are determined by the jar test for raw water, etc., and the optimum conditions are determined and changed according to the raw water turbidity etc. ing.
[0028]
In this embodiment, PAC is used as the inorganic flocculant. However, if the raw material is iron or aluminum such as sulfate band, ferric chloride, ferric sulfate, polyaluminum sulfate / iron, There is no particular limitation. It is also preferable to add sulfuric acid, hydrochloric acid, carbonic acid, sodium hydroxide, slaked lime, etc. as an agglomeration aid.
[0029]
Next, the setting of the stirring intensity of the stirrer 20 in the polymer mixing tank 18 will be described.
[0030]
In the present embodiment, when the polymer injection rate is 0.01 mg / L or more, the stirring strength in the polymer mixing tank 18 is changed according to the polymer injection rate and the water temperature. That is, an appropriate G value is calculated according to the temperature and the polymer injection rate, and the G value in the stirrer 20 or the rotation speed of the stirrer 20 is controlled. The stirring strength G2 in the polymer mixing tank 18 is larger than the stirring strength G1 of the preceding inorganic mixing tank 10, and when the G1 value is less than 300S- ¹ , the G2 value is 300 (S- ¹ ) or more in terms of G value. And
[0031]
On the other hand, when the polymer injection rate is 0 mg / L, the stirring strength G2 of the polymer mixing tank 18 is made smaller than the stirring strength G1 of the inorganic mixing tank 10 in the preceding stage and functions as one of the slow stirring tanks. Thereby, in the polymer mixing tank 18, the coarsening of the inorganic floc is promoted.
[0032]
First, the stirring intensity G2 value is increased as the polymer injection concentration is increased. Further, it is preferable to increase the concentration of the polymer stock solution to be used.
For example, when performing control in which G2 is proportional to the injection rate,
[Expression 1]
G2 (S ⁻¹ ) = Ga × d + Gb (1)
Here, d: polymer injection rate (mg / L), Ga and Gb are constants, and Ga and Gb are determined in advance by an experiment using an experimental machine or a jar test.
[0033]
Further, when the water temperature is low, the polymer is difficult to mix. Therefore, the stirring intensity is increased as the temperature is lowered.
[Expression 2]
G2 (S ⁻¹ ) = Ga × d + Gb + Gc (T0−T) (2)
Here, Gc is a predetermined constant, T0 is a standard temperature, and T is a water temperature at that time. According to this equation (2), the third term on the left side of the water temperature is zero when the water temperature is T0, but when the water temperature T is higher than T0, the predetermined value is negative, and when the water temperature T is lower, the predetermined value is positive. Therefore, the stirring intensity G2 can be determined by this equation (2) in consideration of not only the polymer injection amount but also the water temperature at that time. Here, the constant Gc is also determined by a jar test at various temperatures. Note that this equation (2) may be applied only when the water temperature T falls below T0.
[0034]
When switching the type of polymer flocculant to the most effective type according to the raw water quality, the constants Ga, Gb, Gc of the above formulas are determined in advance for each type, and the flocculant used at the time of switching is determined. It is preferable to calculate the stirring intensity from the conditions of the constant and the injection rate water temperature.
[0035]
Thus, according to the present embodiment, the stirring intensity in the polymer mixing tank 18 is changed to an appropriate value according to the polymer injection rate and the water temperature. As a result, the polymer agglomeration effect is effectively exhibited, and a good treated water quality is obtained.
[0036]
On the other hand, depending on conditions, sufficient treated water quality may be obtained only by agglomeration with an inorganic aggregating agent. In such a case, it is not necessary to add a polymer. However, when the addition of the polymer is stopped, if strong stirring is performed in the polymer mixing tank 18, the floc becomes fine and the quality of the treated water cannot be made sufficient. Therefore, it can be considered that a bypass pipe is provided and the polymer mixing tank 18 is bypassed and introduced into the flock forming tank 28. However, when such a bypass pipe is provided, a device for controlling the switching must be provided, and a problem occurs when the addition of the polymer is resumed.
[0037]
In the present embodiment, even when no polymer is used, not only does the flock formation not be inhibited by merely changing the stirring strength, but also the formation can be promoted. That is, for example, the stirring strength in the polymer mixing tank 18 is set to about 100 (S ⁻¹ ), which is equivalent to the stirring strength in the first tank of the flock formation tank 28. As a result, better treated water quality can be obtained than when the polymer mixing tank 18 is bypassed and not used. Further, since only the agitation intensity is changed, the effect of simplifying the apparatus and facilitating operation management can be obtained.
[0038]
Therefore, in this embodiment, when the polymer addition amount is 0.1 mg / L or more, the stirrer 20 is controlled based on the above formula (2), and the polymer addition amount is 0.1 mg / L or less. When it can be regarded as substantially 0 mg / L, the stirring strength is set to a value equivalent to the stirring strength of the floc forming tank 28 (particularly, the stirring strength of the first tank). As a result, it is possible to perform a treatment that always provides good treated water.
[0039]
【Example】
In order to confirm the effect of the present invention, a treatment experiment was conducted for 6 months by using the water of a certain lake as raw water in the following experimental apparatus.
[0040]
1. Experimental conditions (1) Coagulation sedimentation filtration apparatus of comparative example / Raw water flow rate: 1,000 m ³ / hour / Inorganic mixing tank: Residence time 3 minutes, stirring strength 200 (S ⁻¹ )
-Polymer mixing tank: Residence time 5 minutes, stirring strength 400 (S ^-1 )
・ Flock formation tank: Horizontal axis paddle 3-stage type, Residence time 30 minutes G value ・ Retention time 1st stage 100 (S ⁻¹ ) 10 minutes 2nd stage 60 (S ⁻¹ ) 10 minutes 3 stages 40 (S ⁻¹ ) · 10 minutes (In addition, a pipe capable of bypassing the polymer mixing tank and a valve associated therewith are provided between the inorganic mixing tank and the floc-forming tank).
・ Sedimentation tank: Precipitation tank with upward flow type inclined plate, residence time 40 minutes, ascending speed 3 m / hour ・ Sand filter: Anthracite 400 mm Effective diameter 1.0 mm Uniformity factor 1.4, Silica sand 400 mm Effective diameter 0. 5mm uniformity coefficient 1.3, filtration rate 200m / day, backwash once every 48 hours · Inorganic flocculant: PAC (polyaluminum chloride), injection rate 40-60mg / l · Polymer: nonionic polyacrylamide, solution concentration 1000mg / L
[0041]
(2) Coagulation / precipitation filtration apparatus of the present invention In the apparatus of the present invention, (i) the stirring intensity of the polymer mixing tank is automatically controlled, and (ii) there is no pipe bypassing the polymer mixing tank, which is simple it is Do apparatus, but differs from the device of the comparative example, in other respects, it is the same as the apparatus configuration and processing conditions of Comparative example.
[0042]
Details of the automatic control of the stirring intensity are as follows.
-The stirrer is a flash mixer system with variable rotation speed. The stirring intensity is controlled by the G value, and automatically changed to the number of rotations corresponding to the G value.
-Stir strength makes the G value linearly proportional to the polymer injection rate.
The G value determination conditional expression is
[Equation 3]
G (S ⁻¹ ) = 500 × d + 350 (3)
It is. Here, d is the polymer injection rate (mg / L), and this equation corresponds to the above-described equation (1), and constants Ga = 500 and Gb = 350. This condition was determined based on the results of jar tests conducted in advance.
[0043]
In addition, when the water temperature is less than 15 degrees after the sixth month, the G value is set to a value obtained by adding 5 (S ⁻¹ ) to the value of the expression (3) every time the water temperature decreases by 1 degree. This formula (4) was applied only when the water temperature was below 15 degrees.
That is,
[Expression 4]
G (S ⁻¹ ) = 500 × d + 350 + 5 × (15−T) (4)
And This equation (4) corresponds to the above equation (2), and constants Gc = 5 and T0 = 15. This condition was determined based on the results of jar tests conducted in advance.
[0044]
Further, when the polymer was not injected, the G value was set to 100 (S ⁻¹ ).
[0045]
In this experiment, either without added polymer, when added, it was added amount 0.1 mg / L or more.
[0046]
2. Experimental raw water, 1 month from start of experiment: The average turbidity was about 20 degrees, and about 2000 algae were generated. The water temperature was 20-25 degrees.
2 months to 3 months from the start of the experiment: Algae bred as large as 10,000 to 20,000 cells / mL with an average turbidity of 30 degrees. The water temperature was 25-30 degrees.
-From 3 months to 4 months from the start of the experiment: The turbidity was about 10 degrees, and the number of algae was greatly reduced to about 500 / mL. The water temperature was 25 to 20 degrees.
-5 months after the start of the experiment: The turbidity increased to 20 degrees again. The water temperature was 20-15 degrees. The number of algae was about 500 / mL.
-Six months after the start of the experiment: The turbidity was about 20 degrees and the water temperature was 15 to 10 degrees.
[0047]
3. Experimental results-1 month from the start of the experiment: A treatment with 0.1 mg / L of polymer injected was performed. The stirring intensity was set to the same value as the G value 400 (S ⁻¹ ) for both the comparative device and the device of the present invention. The treatment results were the same in both apparatuses, and the precipitation treatment water turbidity was 0.3 to 0.4 degree and the filtered water turbidity was 0.03 degree.
[0048]
・ 2nd to 3rd months: Algae with poor cohesion grows in raw water, and when the polymer injection rate is 0.1 mg / L, sufficient water quality cannot be obtained for both the turbidity of the precipitated treated water and the filtered water. In particular, the filtered water turbidity cannot stably achieve the treatment target of 0.1 degree.
[0049]
For this reason, the injection rate was raised to 0.3 mg / L. Accordingly, the apparatus of the present invention automatically raised the stirring intensity of the polymer mixing tank to a G value of 500 (S ⁻¹ ) according to the conditional expression (4). The stirring intensity of the comparison device remains at 400 (S ⁻¹ ). Precipitation water turbidity was slightly unstable at 0.4 to 0.7 degrees in the comparison device, whereas the apparatus of the present invention was stable at 0.3 to 0.4 degrees. . In addition, the turbidity of the filtered water was 0.04 degrees in the comparative apparatus, whereas it was 0.03 degrees in the apparatus of the present invention, and the same treatment effect as the first month was obtained. .
[0050]
・ 4th month: The generation of algae in the raw water has stopped, the turbidity of the raw water has decreased, and the water has become relatively easy to treat, so the polymer injection was stopped. The precipitation water turbidity was slightly higher than when the injection was performed, but the polymer injection was stopped from the judgment that sufficient treatment could be performed by filtration.
[0051]
In the apparatus of the present invention, the stirring G value of the polymer mixing tank was automatically lowered to 100 (S ⁻¹ ), thereby forming one tank for the flock formation tank. The comparative apparatus did not pass water through the polymer mixing tank, but directly passed water from the inorganic mixing tank to the floc-forming tank through a bypass pipe. The turbidity of the precipitation-treated water changed from 0.9 to 1.1 degrees in the comparison device, whereas it changed from 0.8 to 1.0 degrees in the device of the present invention. In the apparatus of the present invention, the agglomeration was carried out for a longer time, so that the precipitation treatment water turbidity was slightly better. The filtered water turbidity was 0.04 to 0.05 degree for the comparison device, and 0.04 degree for the device of the present invention, which was better than the comparison device.
[0052]
-5th month: Since the raw water turbidity increased again, it was decided to inject 0.1 mg / L of polymer. In the apparatus of the present invention, the precipitation-treated water turbidity gradually improved from 1.0 degree to 0.4 degree simply by increasing the stirring G value of the polymer mixing tank after the start of injection. On the other hand, in the comparison device, the coagulation sedimentation treatment by passing water through the polymer mixing tank that has not been used for about one month is temporarily affected by the water remaining in the mixing tank. It became unstable such as rising to 1.2 degrees, and it took about 4 hours to stabilize.
[0053]
6th month: Since the raw water temperature was below 15 ° C., the mechanism was such that the stirring intensity was automatically adjusted according to conditional expression (3) with water temperature correction. The polymer injection rate is 0.1 mg / L. During the period when the water temperature decreased from 20 degrees to 15 degrees, the G value of the present apparatus changed from 400 to 425 (S ⁻¹ ). On the other hand, the G value of the comparison device remains 400 (S ⁻¹ ). During this period, the turbidity of the precipitation-treated water changed stably at 0.5 to 0.6 degrees of the apparatus of the present invention, whereas it changed at 0.5 to 0.7 degrees of the comparison apparatus. Was good.
[0054]
Summing up these experimental results,
(I) The treated water quality of the apparatus of the present invention that automatically changes the stirring strength of the polymer mixing tank in accordance with the polymer injection rate was constantly better and more stable than the comparative apparatus.
(Ii) In the case of the treatment without injecting the polymer, this apparatus using the polymer mixing tank as one tank of the agglomeration tank has a better quality of the treated water, and the shift to the polymer injection process is easier.
(Iii) It can be said that the quality of the treated water of the device of the present invention that changes the stirring intensity depending on the water temperature was better than that of the comparative device.
[0055]
【The invention's effect】
As described above, according to the present invention, the stirring strength in the organic polymer flocculant mixing tank is changed according to the injection rate of the organic polymer flocculant and the water temperature. Therefore, the stirring strength can be maintained at an appropriate level, effective agglomeration treatment can be performed, and good treated water can be obtained.
[0056]
In the present invention, when the addition amount of the organic polymer flocculant in the organic polymer flocculant mixing tank is substantially 0, the stirring strength of the organic polymer flocculant mixing tank is set to the stirring strength of the inorganic mixing tank. Set to a smaller value. Therefore, when the organic polymer flocculant is not added, the organic polymer flocculant mixing tank can be used as a part of the subsequent flock forming tank. Therefore, a suitable aggregation process can be performed without using a bypass pipe or the like.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an overall configuration of a water treatment apparatus according to an embodiment.
[Explanation of symbols]
10 Inorganic mixing tank, 18 Polymer mixing tank, 20 Stirrer, 28 Flock forming tank, 30 Precipitation tank, 32 Sand filter, 40 Thermometer, 42 Controller.

Claims (5)

An inorganic flocculant mixing tank for mixing the inorganic flocculant, and an organic polymer flocculant mixing tank for mixing the organic polymer flocculant with the outflow water from the inorganic flocculant mixing tank. In a water treatment device that uses an organic polymer flocculant for agglomeration treatment,
The stirring strength in the organic polymer flocculant mixing tank is set to a value larger than the stirring strength of the preceding inorganic flocculant mixing tank, and the stirring strength in the organic polymer flocculant mixing tank is set to the injection rate of the organic polymer flocculant. Water treatment device that changes so that the larger the water is, the smaller the water temperature is . An inorganic flocculant mixing tank for mixing the inorganic flocculant and an organic polymer flocculant mixing tank for mixing the organic polymer flocculant in the effluent water from the inorganic flocculant mixing tank. with aggregation process using both of the polymeric flocculant can row Ukoto, water treatment capable of substantially zero the amount of time the organic polymer flocculant to be added to the organic polymer flocculant mixing tank In the device
When an organic polymer flocculant is added to the organic polymer flocculant mixing tank , the stirring strength in the organic polymer flocculant mixing tank is set to a value larger than the stirring strength of the preceding inorganic flocculant mixing tank. When the addition amount of the organic polymer flocculant in the organic polymer flocculant mixing tank is substantially 0, the stirring strength of the organic polymer flocculant mixing tank is set to a value smaller than the stirring strength of the inorganic mixing tank. Water treatment equipment. The apparatus of claim 2.
Further, the organic polymer flocculant mixing tank has a floc forming tank that gently stirs the effluent water to promote flock formation, and the amount of organic polymer flocculant added to the organic polymer flocculant mixing tank is substantially In particular, when the organic polymer flocculant mixing tank is 0, the stirring intensity of the organic polymer flocculant mixing tank is smaller than the stirring intensity of the inorganic mixing tank and is equal to or higher than the stirring intensity of the floc-forming tank. The apparatus according to claim 2 or 3,
The water treatment apparatus which changes the stirring intensity | strength in the said organic polymer flocculant mixing tank so that it may become so large that the organic polymer flocculant injection rate is large and water temperature is high . In the device according to any one of claims 1 to 4,
Organic polymer flocculating agent is one of the anionic or nonionic which the acrylamide monomer as a raw material water treatment device.

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