JPH0238243B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Purpose of the Invention [Industrial Application Field] The present invention relates to a method for controlling the injection of a flocculant, and in particular to a method for controlling the injection of a flocculant into a light emitting device through a suspension in a stirring region. After injecting the flocculant into the suspension while rapidly stirring the suspension while receiving light, the relationship between the suspension and the flocculant is determined from the flattened received light amount during slow stirring and the received light amount after the stirring is stopped. The present invention relates to a flocculant injection management method that optimizes the flocculant injection rate by detecting the flocculation state of a liquid mixture.

[Prior art] Conventionally, the injection control method for this type of flocculant is as follows:
Collect an appropriate amount of suspension such as tap water, industrial water, sewage, or industrial waste liquid, distribute it in equal amounts to multiple beakers, inject flocculant at different injection rates, and stir and let stand. It has been proposed that the flocculant injection rate is controlled to be appropriate by detecting the flocculation state through visual observation and experience of the tester.

[Problems to be solved] However, in the conventional flocculant injection control method, the agglomeration state was detected by visual observation and experience of the tester, so there were differences in the detection results of the agglomeration state depending on the tester. This method has the disadvantage that the injection rate of the flocculant cannot always be optimized, and it takes a lot of time to detect the flocculant state and determine the flocculant injection rate.

Therefore, in order to eliminate these drawbacks, the present invention injects a flocculant into the suspension and stirs it in the stirring area between the light emitting device and the light receiving device, and determines whether the suspension is liquid or not based on the amount of light received by the light receiving device. It is an object of the present invention to provide a flocculant injection management method that optimizes the flocculant injection rate by detecting the flocculating state of a mixed liquid with the flocculant.

(2) Structure of the invention [Means for solving the problems] The means for solving the problems provided by the present invention are as follows: ``(a) A first step of stirring a suspension; (b) A suspension during stirring. The second step is to inject a flocculant into the liquid.
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. a fourth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the step; (e) the amount of light received when the amount of light received measured in the fourth step is flattened; (f) a sixth step of determining an appropriate injection rate of the flocculant according to the agglomeration state detected in the fifth step. A coagulant injection management method characterized by the following.

Another solution to the problem provided by the present invention is that ``(a) the first step of stirring the suspension, and (b) the second step of injecting a flocculant into the suspension being stirred.
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. (e) after the amount of received light measured in the fourth step is flattened, the mixing (f) a sixth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the fifth step; (g) a fifth step of stopping stirring of the liquid; (h) determining the appropriateness of the flocculant according to the aggregation state detected in the seventh step; and an eighth step of determining the injection rate.''

[Function] The flocculant injection management method according to the present invention involves injecting the flocculant into the suspension being stirred, and then reducing the stirring speed of the suspension and preventing the mixing of the suspension and the flocculant. Measure the amount of light received by the light receiving device from the light emitting device through the liquid, detect the agglomeration state of the mixed liquid from the amount of light received when the amount of received light becomes flat, and respond according to the detected aggregation state. It has the function of determining the appropriate injection rate of flocculant, eliminates the visual observation and experience of the tester, and has the function of converting the detection result into an index. It acts to optimize the injection rate of the agent.

Another flocculant injection control method according to the present invention involves injecting the flocculant into the suspension being stirred, then reducing the stirring speed of the suspension, and dissolving the mixture of the suspension and the flocculant. The amount of received light given to the light receiving device from the light emitting device is measured through the light emitting device, and after the amount of received light becomes flat, stirring of the mixed liquid is stopped while measuring the amount of received light, and the amount of received light is determined from the amount of received light. The function is to detect the agglomeration state of the mixture and determine the appropriate injection rate of the flocculant according to the detected aggregation state, eliminating the visual observation and experience of the tester, and converting the detection result into an index. In addition to the function of optimizing the injection rate of flocculant according to the detection results expressed as an index, it also increases the number of detection items to improve the accuracy of the detection results and the accuracy of optimizing the injection rate of flocculant. Eggplant.

[Example] Next, the present invention will be specifically described with reference to the accompanying drawings.

(Description of the attached drawings) FIG. 1 is a sectional view showing a management device for carrying out an embodiment of the flocculant injection management method of the present invention.

FIG. 2 is a graph diagram showing temporal changes in the amount of received light when the embodiment of the present invention is executed by the management device shown in FIG.

FIG. 3 is a graph showing the relationship between the diameter d, number n, volume V and effective density ρ of the aggregates determined from the graph of FIG. 2 and the injection rate W _A1 of the flocculant.

FIG. 4 is a graph showing the relationship between the supernatant water turbidity τ, the settling velocity S and effective density ρ of the flocculant, and the flocculant injection rate W _A1 determined from the graph of FIG.

FIG. 5 is a sectional view showing a management device in which four management devices of FIG. 1 are arranged side by side.

FIG. 6 is a sectional view showing an actual suspension processing apparatus to which the management device of FIG. 1 or the management device of FIG. 5 is applied.

7a to 7c are graphs showing the results of controlling the injection rate of the flocculant according to an embodiment of the present invention in the suspension processing apparatus of FIG. 6.

(Management Device) First, a management device for carrying out the flocculant injection management method of the present invention will be described with reference to FIG.

Reference numeral 10 denotes a batch-type stirring tank having an appropriate capacity, for example, 1, and containing a mixed liquid 11 of a suspension and a flocculant. Reference numeral 12 denotes a stirring blade disposed in the stirring tank 10, which is appropriately attached to the free end of an output shaft 16 of a drive means, for example, an electric motor 14, arranged below the stirring tank 10.

A light emitting device 18 is connected to a suitable power source (not shown) by a lead wire 19, and is disposed on the side of the stirring tank 10, and is capable of emitting fluorescent lamps, tungsten lamps, halogen lamps, light emitting diodes, and laser light. Light generated by a suitable light source such as a light source is supplied to the mixed liquid 11 in the stirring tank 10 as a parallel beam bundle through a suitable optical system such as a slit. Reference numeral 20 denotes a light receiving device which includes a suitable photoelectric conversion element such as a phototransistor, photodiode, CdS, CCD, etc. as a light receiving means.
The light emitting device 18 receives the light supplied as a parallel beam bundle by the light emitting device 18 via the liquid mixture 11. Since the light provided by the light emitting device 18 is scattered or blocked by the aggregates or flocs 17 in the liquid mixture 11, the light receiving device 20 receives scattered light or attenuated transmitted light. . The light receiving device 20 may be placed opposite the light emitting device 18 in order to receive transmitted light, or may be placed at a predetermined angle with respect to the parallel light beam from the light emitting device 18 in order to receive scattered light. Good too. In addition, two light receiving devices 20 may be arranged to receive transmitted light and scattered light. Hereinafter, in order to simplify the explanation, it is assumed that the light receiving device 20 is opposed to the light emitting device 18. Although only one set of the light emitting device 18 and the light receiving device 20 are arranged in FIG. 1, the present invention is not limited to this, and multiple sets of the light emitting device 18 and the light receiving device 20 may be arranged as desired. good. Light emitting device 18 and light receiving device 20
It is convenient to measure the sedimentation state of the aggregates or flocs 17, especially if they are arranged on the same horizontal plane.

A measuring device 22 is connected to the light receiving device 20 via a lead wire 21, and measures the amount of light received by the light receiving device 20 (hereinafter referred to as "received light amount"). In addition, the measuring device 22 calculates the amount of received light _i (τ) before injection of the flocculant and the stirring blade 1 from the measured amount of received light.
2. The range of variation in the amount of received light when it is flattened due to slow stirring (i.e., the predetermined values _L and _H)
The difference between Δ) and the fluctuation period F are determined and output, and if desired, the amount of received light when flattened after slow stirring by the stirring blade 12 is stopped is output.
_f (τ) and the time T from when slow stirring by the stirring blade 12 stops until the amount of received light becomes flat may be determined and output.

24 has one end connected to the stirring tank 10 via the on-off valve 25.
The other end of the supply pipe is connected to a supply source (not shown) of a suspension liquid, such as tap water, industrial water, sewage, or industrial waste liquid. 26 is a flocculant supply pipe whose one end communicates with the flocculant supply source 28;
The other end is opened to the stirring tank 10 via an on-off valve 27. 30 is a drain pipe, one end of which is a stirring tank 10
The stirring tank 10 is opened at the bottom, and the other end is opened to a suitable storage tank (not shown) through an on-off valve 32 to remove the detected mixed liquid 11 from the stirring tank 10. 34 is a dark box which houses at least the stirring tank 10, the light emitting device 18 and the light receiving device 20;
Eliminates the effects of external light.

36 is a driving means 14, a measuring device 22, and an on-off valve 2
5, 27, the driving means 1
4 gives the circumferential speed υ of the stirring blade 12,
The measuring device 22 gives the amount of received light I _i (τ), the fluctuation range Δ and the fluctuation period F of the amount of received light, and if desired, the amount of received light _f (τ) and the time T. 25 and 27, the supply amount M of the suspension and the supply amount N of the flocculant are given. The arithmetic unit 36 operates on the aggregate or floc 1.
The parameters for determining the agglomeration state of No. 7 are calculated. That is, the arithmetic unit 36 calculates the diameter d (cm) of the aggregate, that is, the floc 17, as d=αΔ using the fluctuation range Δ (volts) of the amount of received light and the constant α, and calculates the fluctuation period F (seconds) of the amount of received light. Using the circumferential speed υ (m/sec) of the stirring blade 12 and the constant β, calculate the number n (1/cm ³ ) of aggregates, that is, flocs 17, as n=β (1/Fυ) ³ , and calculate the aggregates, i.e. Diameter d of flock 17
(cm), the number n (1/cm ³ ), and the constant ε, calculate the volume V (cm ³ ) of the aggregate, that is, the floc 17, as V=εd ³ n , and calculate the amount of received light I _i (τ) (volts). ), the initial concentration of suspended solids in the suspension, Wss (mg/), and the flocculant injection rate, W _A1 (mg/), determined from the supply amounts M and N.
^The effective density ρ (g/cm ³ ) is calculated as ρ=γ1/d ³ n (W _ss +aW _A1 ), and if desired, the settling velocity S (cm/min) of the flocs 17 is calculated using the time T and the constant δ. ) is calculated as S=δ1/T, and using the received light amount _f (τ) and constant λ, the supernatant water turbidity τ (degrees) after the flocs 17 have settled is calculated as τ=λ _f (τ) It is calculated as follows. Here, the relationship between the parameters calculated by the calculation device 36 and the actual aggregation state of the flocs 17 is as follows: diameter d or number n, volume V, effective density ρ, settling velocity S, and supernatant water turbidity τ. Therefore, if it is desired to accurately detect the aggregation state of the flocs 17, the latter parameter may be used, and if it is desired to detect the aggregation state even more precisely. For example, a combination of multiple parameters may be used.

38 is another arithmetic device connected to the arithmetic device 36, which calculates the diameter d, number n, volume V, effective density ρ, pouring speed S, and agglomerate of the floc 17 calculated by the arithmetic device 36. That is, at least one of the supernatant water turbidities τ after sedimentation of the floc 17 is stored in sequence for the flocculant injection rate W _A1 at that time, and the flocculant injection into the suspension at this time is The appropriate rate W _A1 ^* is calculated.
That is, the calculation device 38 calculates the flocculant injection rate W _A1 (given from the calculation device 36) calculated from the suspension supply amount M given from the on-off valves 25 and 27 and the flocculant supply amount N. When the diameter d, volume V, or effective density ρ of the flocculant body, that is, the floc 17, starts to change steeply in response to a change in , and the number n, sedimentation rate S, or supernatant water turbidity τ starts to change slowly. Correspondingly, the injection rate W _A1 of the flocculant is determined as the appropriate injection rate W _A1 ^* .

(Injection Management Method) Next, the flocculant injection management method of the present invention will be described in detail with reference to FIGS. 1 to 4, together with the operation of the management device shown in FIG.

After opening the on-off valve 32 and removing the mixed liquid 11 remaining in the stirring tank 10 through the drain pipe 30, the on-off valve 32 is closed.

The on-off valve 25 is opened for a predetermined period of time, and the supply pipe 24 is opened.
A predetermined amount M (for example, 1) of the suspension is supplied into the stirring tank 10 from a suspension supply source (not shown) via the suspension.

When the supply of the suspension into the stirring tank 10 is completed,
At time t ₁ the drive means, e.g. electric motor 14
As a result, the stirring blade 12 begins to rotate rapidly, that is, at a high speed.

Thereafter, by opening the on-off valve 27 for a predetermined time at time t ₂ , a predetermined amount of flocculant is injected into the stirring tank 10 from the flocculant supply source 28 via the flocculant supply pipe 26 . As the flocculant, known flocculants such as polyaluminum chloride may be used as desired.

Prior to the start of rapid rotation of the stirring blade 12, the light emitting device 18, the light receiving device 20, and the measuring device 22 are started, and the amount of received light transmitted through the suspension in the stirring tank 10 is I _i (τ). is measured and provided to the arithmetic unit 36.

The amount of light received until time t ₂ , that is, the time when the flocculant is supplied, is a constant value I _i (τ) corresponding to the initial concentration W _ss of suspended matter contained in the suspension. When a predetermined amount N of flocculant is injected at time t ₂ , aggregates, that is, flocs 17 are gradually formed in the mixed liquid 11 , and the mixed liquid 11 is rapidly stirred and moved in the stirring tank 10 . , the amount of light received by the light receiving device 20 increases slowly.

At time _t3 , when the stirring blade 12 starts to rotate slowly, that is, at a low speed, the mixed liquid 11
Since aggregates or flocs 17 are formed within the agitation tank 10 and their diameter d increases, and the mixed liquid 11 is being stirred and moved slowly within the agitation tank 10, the light receiving device 20
The amount of received light increases and decreases little by little while increasing as a whole.

When time _t4 is reached, the flocs 17 are sufficiently agglomerated in the mixed liquid 11 and the diameter d does not change, and the mixed liquid 11 is being stirred and moved slowly in the stirring tank 10. The amount of light received by the light receiving device 20 is flattened and aggregates, that is, flocs 1
7, it begins to fluctuate periodically between predetermined values _L and _H.

Furthermore, at time _t5 , when the rotation of the stirring blade 12 is stopped to stop the stirring, the aggregates formed in the mixed liquid 11, that is, the flocs 17, start to settle, so that the amount of light received by the light receiving device 20 gradually decreases. The value _f is almost constant at time t ₆ while increasing and decreasing
(τ) is reached. After time _t6 , the flocs 17 in the mixed liquid 11 no longer settle, so the amount of received light maintains a constant value _f (τ).

For example, when using a kaolin suspension obtained by adding 25 mg of kaolin to fresh water in Step 1, and injecting polyaluminum chloride as a flocculant at an injection rate of 15 mg/1, the amount of light received by the light receiving device 20 is measured by the measuring device 22. The result was as shown in Figure 2.

Thereafter, the arithmetic unit 36 calculates the diameter d, the number n, and the number n of the aggregates or flocs 17 as described above.
The volume V and effective density ρ are calculated, and if desired, the sedimentation rate S and supernatant water turbidity τ are also calculated. Using these parameters calculated by the arithmetic unit 36, the aggregation state of the flocs 17 can be detected as described above.

The diameter d, number n, volume V, effective density ρ, sedimentation rate S, and supernatant water turbidity τ of the flocs 17 calculated by the calculation device 36 are determined by the calculation device 38 as the flocculant injection rate W _A1 is stored for. The calculation device 38 calculates when the diameter d, volume V or effective density ρ of the flocs 17 starts to change sharply, or when the number n, sedimentation velocity S or supernatant water turbidity τ starts to change slowly. Appropriate injection rate of flocculant W _A1
Determine W _A1 ^* and output as desired.

The basis for this will be explained in more detail. That is, for example, using a kaolin suspension prepared by adding 25 mg of kaolin to 1 volume of fresh water, each time the above-mentioned measurements and calculations are repeated, the aggregates, i.e., flocs.
When the diameter d, number n, volume V and effective density ρ of 7 were calculated and plotted against the flocculant injection rate W _A1 , Figure 3 was obtained.

Similarly, using the above-mentioned kaon suspension, the effective density ρ, sedimentation rate S, and supernatant water turbidity τ of the flocs 17 are calculated each time the above-mentioned measurements and calculations are repeated. When plotted against the injection rate W _A1 , Figure 4 was obtained.

As is clear from FIGS. 3 and 4, as the flocculant injection rate W _A1 changes, the diameter d, number n, volume V, effective density ρ, and sedimentation velocity S of the flocs 17 change. The supernatant water turbidity τ is changing. To be more specific, the injection rate W _A1 of the flocculant is a predetermined value.
When the amount exceeds W _A1 ^* (in this case, 30 mg/), the number n of aggregates, that is, flocs 17, does not change much, but the diameter d and volume V become relatively large, and the effective density ρ decreases. It can be concluded that stable aggregates, ie, flocs 17, are formed. In addition, the flocculant injection rate W _A1 is the specified value.
When W _A1 ^* or more, aggregates or flocs 1
The sedimentation velocity S of No. 7 or the supernatant water turbidity τ after the flocs 17 have settled do not change much. Therefore, the injection rate W _A1 of the coagulant is the predetermined value.
Even if it exceeds W _A1 ^* , it can be judged that the amount of coagulation and sedimentation of the flocs 17 cannot be increased compared to the increase in the amount of coagulant injected, which is not preferable.

On the other hand, the flocculant injection rate W _A1 is the predetermined value.
When W _A1 ^* becomes significantly smaller, the number n of aggregates, that is, flocs 17, becomes extremely large, and their diameter d and volume V also become extremely small, resulting in an increase in effective density ρ, which results in a relatively stable It can be determined that aggregates, or flocs 17, are formed. However, at this time, the settling velocity S of the flocs 17 is low, and the turbidity τ of the supernatant water after the flocs 17 has settled is high. Consequently, the injection rate W _A1 of the flocculant is the predetermined value.
If it becomes significantly smaller than W _A1 ^* , it can be judged that the flocs 17 cannot be efficiently precipitated and removed even if the amount of coagulant injected can be reduced, which is not preferable.

Therefore, if the predetermined value W _A1 ^* at this time is used as the flocculant injection rate, the amount of flocculant injection can be reduced and the amount of flocculation and sedimentation of suspended matter in the suspension can be maintained at a relatively large value. Therefore, floating matter in the suspension can be efficiently flocculated and precipitated and removed.

For this purpose, the arithmetic unit 38 operates as described above.
W _A1 ^* has been determined as the appropriate injection rate of coagulant.

As described above, in the present invention, the injection rate of the flocculant into the suspension is controlled to be an appropriate injection rate.

(Modified Example) In the above description, a management device including only one stirring tank 10 has been described, but since this requires a large amount of time to detect the agglomeration state, multiple (hereinafter referred to as In this case, four stirring tanks may be arranged in parallel.

The management device shown in FIG. 5 has the following configuration and operation, except that the suspension liquid supply source (not shown), flocculant supply source 28, and calculation device 38 are common.
Since it is substantially the same as the management device of FIG. 1, the same reference numerals as in the management device of FIG. 1 are given to each member, and detailed explanation thereof will be omitted. The letters A, B, C, and D are added to the reference numbers to distinguish between the juxtaposed stirring vessels. The on-off valves 27A, -, 27D are open for different times, and the stirring tanks 10A, -, 27D are open for different times.
The injection rate of the flocculant to the mixed liquids 11A to 11D in 10D is adjusted.

(Application to suspension processing equipment) Referring to Figures 6 and 7, in order to more fully understand the flocculant injection management method of the present invention, the method was applied to an actual suspension processing equipment. Let me explain the case.

Reference numeral 102 denotes a landing well, into which a suspension is supplied via a supply pipe 104 from an appropriate suspension supply source (not shown). 106 is the supply pipe 1 for the landing well 102
A stirring blade 110 that is rapidly rotated by a driving means, such as an electric motor 109, is disposed in the coagulant mixing basin communicated through a coagulant 08. 112
is an aggregate formation pond that is connected to the mixing pond 106 via a supply pipe 114, and has three areas 112A,
stirring blades 116A, 116A, 112C, which are divided into stirring blades 116A, 112C, which are rotated slowly by driving means such as electric motors 115A, 115C, respectively.
6C is installed. The mixed liquid of the flocculant and the suspension formed in the mixing pond 106 and supplied to the flocculation basin 112 through the supply pipe 114 is first stirred in the first region 112A of the flocculation basin 112. It is slowly stirred by the blade 116A for a predetermined time, then transferred to the second area 112B, slowly stirred by the stirring blade 116B for a predetermined time, and further transferred to the third area 112C, where the stirring blade 116C for a predetermined period of time. 118 is aggregate formation pond 1
A sedimentation tank connected to 12, and a flocculation tank 112
The flocculant is supplied from the third region 112C in which the aggregates or flocs are sufficiently formed and the mixture of suspension and flocculant is allowed to stand, and the aggregates or flocs are settled and removed. 120
is a filter tank connected to the outlet of the sedimentation tank 118 via a supply pipe 122, in which fine aggregates, or flocs, that could not be removed in the sedimentation tank 118 are removed by filtration, and then treated water is passed through the treated water pipe 124 to the subsequent water. It is sent to the appropriate equipment.

Reference numeral 130 denotes a management device for carrying out the flocculant injection management method of the present invention shown in FIG. 1 or FIG. immersed in liquid,
The other end of the drain pipe 30 is open to a mixing pond 106 or an aggregate formation pond 112. 13
A multiplier 4 is connected to a flow meter 136 disposed in the supply pipe 108 and the management device 130, and is used to calculate the flow rate of the suspension detected by the flow meter 136, that is, the amount Q supplied to the mixing pond 106, and the management device 130, and the appropriate injection rate W _A1 ^* of the flocculant is calculated to calculate the appropriate injection amount R ^* of the flocculant. 138 is a flocculant supply device, which supplies an amount of flocculant to a pipe 140 according to the appropriate injection amount R ^* calculated by the multiplier 134.
The suspension is supplied to the mixing pond 106 via the mixing pond 106 and injected into the suspension.

The suspension is then collected from the landing well 102 via the pump 132 and the supply pipe 24, and the management device 130 according to the present invention calculates the appropriate injection rate W _A1 ^* of the flocculant according to the above-mentioned method. This appropriate injection rate W _A1 ^* is multiplied by the flow rate Q detected by the flow meter 136 in a multiplier 134 to calculate the appropriate injection amount R ^* of the flocculant. A flocculant is supplied from the flocculant supply device 138 to the mixing pond 106 according to the appropriate injection amount R ^* , and is injected into the suspension.

By repeating the above operation intermittently, the flocculant injection rate in the suspension processing device can be maintained at the appropriate injection rate W _A1 ^* , which in turn shortens the suspension processing time, and at the same time reduces the flocculant injection rate. Unnecessary injections can be avoided.

To explain with more specific numerical values, when the turbidity τ of the suspension changes as shown in Figure 7a, according to the injection control method of the present invention, the injection rate W _A1 of the flocculant changes as shown in Figure 7b. According to the change in the turbidity τ of the suspension, it can be managed more appropriately than in the comparative example.
The turbidity τ of the treated water discharged from 18 can be improved compared to the comparative example as shown in FIG. 7c.

(3) Effects of the invention As is clear from the above, the flocculant injection control method according to the present invention includes: (a) the first step of stirring the suspension; and (b) the injection control method for the suspension during stirring. The second to inject the flocculant
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. a fourth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the step; (e) the amount of light received when the amount of light received measured in the fourth step is flattened; (f) a sixth step of determining an appropriate injection rate of the flocculant according to the agglomeration state detected in the fifth step. Therefore, (i) it has the effect of eliminating the visual observation and experience of the tester, and (ii) it has the effect of optimizing the injection rate of the coagulant so that the detection results can be converted into an index.

Another flocculant injection management method according to the present invention includes (a) a first step of stirring a suspension, and (b) a second step of injecting a flocculant into the suspension being stirred.
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. (e) after the amount of received light measured in the fourth step is flattened, the mixing (f) a sixth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the fifth step; (g) a fifth step of stopping stirring of the liquid; (h) determining the appropriateness of the flocculant according to the aggregation state detected in the seventh step; In addition to the effects (i) and (ii) above, (iii) the detection items can be increased to improve the accuracy of the detection results, and the injection rate of the flocculant can be increased. This has the effect of improving the optimization accuracy of.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a management device for implementing an embodiment of the coagulant injection management method of the present invention, and FIG. 2 is a cross-sectional view showing an embodiment of the present invention using the management device shown in FIG. Figure 3 is a graph showing the temporal change in the amount of received light when
Figure 4 shows the relationship between the supernatant water turbidity τ, flocculation velocity S, effective density ρ, and flocculant obtained from the graph in Figure ₂ . 5 is a cross-sectional view showing a management device in which four of the management devices shown in _FIG . 1 are arranged side by side, and FIG. 7a to 7c are cross-sectional views showing an actual suspension processing apparatus in which the management device shown in the figure is arranged.
FIG. 2 is a graph diagram showing the results of controlling the injection rate of a flocculant according to an embodiment of the present invention in the suspension processing apparatus shown in the figure. 10... Stirring tank, 11... Mixed liquid, 12... Stirring blade, 14... Drive means, 16... Output shaft, 1
8... Light emitting device, 20... Light receiving device, 22... Measuring device, 24... Supply pipe, 25, 27... Opening/closing valve, 26... Flocculant supply pipe, 28... Flocculant supply source, 30... ...Drain pipe, 32...Opening/closing valve, 34...
Dark box, 36, 38...Arithmetic device.

Claims (1)

[Claims] 1. (a) A first step of stirring the suspension; (b) A second step of injecting a flocculant into the suspension being stirred.
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. a fourth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the step; (e) the amount of light received when the amount of light received measured in the fourth step is flattened; (f) a sixth step of determining an appropriate injection rate of the flocculant according to the agglomeration state detected in the fifth step. A coagulant injection management method characterized by: 2 (i) In the fifth step, the aggregation state of the mixed liquid is detected by calculating the number of aggregates from the fluctuation period when the amount of received light is flattened and the stirring speed in the third step, and ( ii) In the sixth step, the injection rate of the flocculant corresponding to when the change in the number of aggregates starts to slow down is determined as the appropriate injection rate. How to manage the injection of flocculant. 3 (i) In the fifth step, the aggregation state of the mixed liquid is detected by calculating the diameter of the aggregate from the fluctuation range when the amount of received light is flattened, and (ii) In the sixth step, the The injection of the flocculant according to claim 1 or 2, wherein the injection rate of the flocculant corresponding to when the change in the diameter of the aggregate starts to become steep is determined as the appropriate injection rate. Management method. 4 (i) In the fifth step, the number of aggregates is calculated from the fluctuation period when the amount of received light becomes flat and the stirring speed in the third step, and the number of aggregates is calculated from the fluctuation range when the amount of received light becomes flat. (ii) detecting the aggregation state of the liquid mixture by calculating the diameter of the aggregates and calculating the volume of the aggregates from the number and diameter of the aggregates, and (ii) in the sixth step, determining the number of the aggregates; The appropriate injection rate is determined to be the injection rate of the flocculant corresponding to when the change in the diameter of the aggregate starts to become slow, the change in the diameter of the aggregate starts to become steep, and the change in the volume of the aggregate starts to steepen. A method for managing injection of a flocculant according to claim 1, characterized in that: 5 (i) In the fifth step, calculate the number of aggregates from the fluctuation period when the amount of received light becomes flat and the stirring speed in the third step, and calculate the number of aggregates from the fluctuation range when the amount of received light becomes flat. The aggregation state of the mixed liquid is detected by calculating the diameter of the aggregates and calculating the effective density of the aggregates from the number and diameter of the aggregates, the suspended solids concentration of the suspension, and the injection rate of the flocculant. , and (ii) in the sixth step, the injection rate of the flocculant corresponding to when the change in the number of aggregates starts to slow down and the change in diameter and effective density starts to become steep is determined as the appropriate injection rate. A method for managing injection of a flocculant according to claim 1, characterized in that: 6 (a) A first step of stirring the suspension; (b) A second step of injecting a flocculant into the suspension being stirred.
(c) a third step of stirring the suspension and flocculant mixture at a lower stirring speed than in the first step after the injection of the flocculant; and (d) at least a third step. (e) after the amount of received light measured in the fourth step is flattened, the mixing (f) a sixth step of measuring the amount of light received from the light emitting device to the light receiving device through the mixed liquid during the fifth step; (g) a fifth step of stopping stirring of the liquid; (h) determining the appropriateness of the flocculant according to the aggregation state detected in the seventh step; and an eighth step of determining an injection rate. 7 (i) In the seventh step, the turbidity of the supernatant water after the aggregates have been precipitated is calculated from the amount of light received when the amount of light received measured in the sixth step is flattened. Detects the state of aggregation,
and (ii) in the eighth step, the injection rate of the flocculant corresponding to when the change in supernatant water turbidity starts to become slow is determined as the appropriate injection rate. The injection management method of the described flocculant. 8 (i) In the seventh step, the sedimentation rate of the aggregates is calculated from the time it takes for the amount of light received measured in the sixth step to flatten after the stirring is stopped in the fifth step. It is characterized by detecting the flocculating state of the liquid, and (ii) determining, in the eighth step, the injection rate of the flocculant that corresponds to when the change in the sedimentation rate of the aggregates starts to become slow as the appropriate injection rate. A method for managing the injection of a flocculant according to claim 6 or 7. 9 (i) In the seventh step, the number of aggregates is calculated from the fluctuation period when the amount of received light measured in the fourth step becomes flat and the stirring speed in the third step. A patent characterized in that the aggregation state is detected, and (ii) in the eighth step, the injection rate of the flocculant corresponding to when the change in the number of aggregates starts to slow down is determined as the appropriate injection rate. A method for managing injection of a flocculant according to any one of claims 6 to 8. 10 (i) In the seventh step, the agglomeration state of the mixed liquid is detected by calculating the diameter of the aggregate from the fluctuation range when the amount of received light measured in the fourth step is flattened, and ( ii) In the eighth step, the injection rate of the flocculant corresponding to when the change in the diameter of the aggregate starts to become steep is determined as the appropriate injection rate. 9. A method for managing injection of a flocculant according to any one of Item 9. 11 (i) In the seventh step, calculate the number of aggregates from the fluctuation period when the amount of received light measured in the fourth step becomes flat and the stirring speed in the third step, and calculate the number of aggregates in the fourth step. The agglomeration state of the mixed liquid can be detected by calculating the diameter of the aggregate from the fluctuation range when the amount of light received is flattened, and by calculating the volume of the aggregate from the number and diameter of the aggregate. and (ii) in the eighth step, when the change in the number of the aggregates starts to slow down, the diameter of the aggregates starts to change steeply, and the volume of the aggregates starts to change steeply; 7. A flocculant injection management method according to claim 6, characterized in that a corresponding flocculant injection rate is determined as an appropriate injection rate. 12 (i) In the seventh step, calculate the number of aggregates from the fluctuation period when the amount of received light measured in the fourth step becomes flat and the stirring speed in the third step, and calculate the number of aggregates in the fourth step. The diameter of the aggregates is calculated from the range of variation when the amount of light received is flattened, and the diameter of the aggregates is calculated from the number and diameter of the aggregates, the suspended matter concentration of the suspension, and the injection rate of the flocculant. By calculating the effective density, the aggregation state of the mixed liquid is detected, and (ii) in the eighth step, when the change in the number of aggregates starts to slow and the changes in diameter and effective density start to become steep; 7. A flocculant injection management method according to claim 6, characterized in that a corresponding flocculant injection rate is determined as an appropriate injection rate.