JPH0358761B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a stirring control method for a flocculation pond, and in particular a method for injecting a flocculant into a collected suspension while stirring it. Find the appropriate injection rate of the flocculant at that time, determine the velocity gradient and aggregate formation time corresponding to this injection rate, preferably determine the appropriate velocity gradient and appropriate aggregate formation time, and calculate the amount of suspension supplied to the mixing pond and the flocculation time. By detecting the volume of the aggregate formation pond,
The present invention relates to a method for controlling agitation in an agglomerate formation pond by controlling the amount of coagulant injected into a mixing pond and controlling agitation in the agglutination pond.

[Prior Art] Conventionally, as a stirring control method for this type of flocculation pond, a flocculant is injected into a beaker each time an appropriate amount of a suspension of clean water, industrial water, sewage, industrial waste liquid, etc. is collected. After injecting the flocculant at different rates, stirring and leaving it to stand still, the tester visually observes and experiences the condition of agglomeration to determine the appropriate injection rate of the flocculant. A flocculant was injected into the turbid liquid, and then the flocculant-injected suspension was actually slowly stirred in an agglomerate formation pond. It has been proposed to judge the state and adjust the agitation control in the aggregate formation pond according to the result.

[Problems to be solved] However, in the conventional agitation control method for the flocculation pond, the appropriate injection rate of flocculant or the agitation process in the flocculation pond was determined based on visual observation and experience of the tester. However, the judgment results differ depending on the tester, and the agitation process in the aggregate formation pond cannot be adequately optimized.Also, it takes more than 30 minutes to form aggregates in the aggregate formation basin, so it is difficult to form aggregates. It takes a lot of time to judge the condition and cannot respond quickly to changes in the suspension.In addition, stirring control in the aggregate formation pond cannot be performed with high precision, especially when the aggregate formation basin is in multiple areas. When the area is divided into two areas, there is also the drawback that once formed aggregates are destroyed by stirring in subsequent areas.

In order to eliminate these drawbacks, the present invention aims to inject a flocculant while rapidly stirring the suspension sampled in the stirring area between the light emitting device and the light receiving device, and then injecting the flocculant with slow stirring. The appropriate injection rate of the flocculant is determined by detecting the flocculation state of the suspension in which the flocculant has been injected from the amount of light received by the light receiving device during stirring and after the stirring has stopped, and then the speed corresponding to the appropriate injection rate is determined. Gradient and aggregate formation time Preferably, an appropriate velocity gradient and an appropriate aggregate formation time are determined, and a flocculant is injected into a mixing basin accordingly, and the agitation of the aggregate formation basin is controlled. The present invention aims to provide a method for controlling agitation in a pond.

(2) Structure of the Invention [Means for Solving Problems] The first means for solving problems provided by the present invention is as follows: ``After injecting a flocculant into a suspension while rapidly stirring it in a mixing basin, In an agitation control method for an aggregate formation pond in which aggregates are formed by slow stirring in an aggregate formation pond, (a) a flocculant is injected into the suspension collected upstream of the mixing basin; (b) a second step of stirring the suspension into which the flocculant was injected in the first step at a lower stirring speed than in the first step; (c) at least in the second step, a third step of measuring the amount of light received by the light emitting device through the suspension into which the flocculant was injected in the first step; (d) a fourth step of detecting the agglomeration state of the suspension in which the flocculant was injected in the first step from the amount of light received measured in the third step; (f) determining the appropriate injection rate of the flocculant in accordance with the flocculant state determined in the fifth step; a sixth step of determining the aggregate formation time of the injected suspension; (g) a seventh step of detecting the amount of suspension supplied to the mixing pond; (h) the amount of time determined in the sixth step; an eighth step of controlling agitation in the aggregate formation pond using the velocity gradient and aggregate formation time detected in the seventh step, the supply amount of the suspension detected in the seventh step, and the volume of the aggregate formation pond; (i) a ninth step of calculating the injection amount of the flocculant from the supply amount of the suspension detected in the seventh step and the appropriate injection rate of the flocculant determined in the fifth step; (j) a tenth step of injecting a flocculant into the mixing pond according to the amount of injection calculated in the ninth step. be.

Another solution to the problem provided by the present invention is to inject a flocculant into the suspension with rapid stirring in a mixing basin, and then slowly stir it in an aggregate formation basin to form aggregates. In the stirring control method for a flocculate formation pond, the method includes: (a) a first step of injecting a flocculant into a suspension collected upstream of the mixing basin and stirring the mixture in a stirring tank; (b) a second step of stirring the flocculant-injected suspension in the first step at a reduced stirring speed than in the first step; and (c) at least during the second step. (d) from the amount of received light measured in the third step; (e) determining the appropriate injection rate of the flocculant according to the flocculation state detected in the fourth step; (f) a sixth step of determining a velocity gradient corresponding to the appropriate injection rate determined in the fifth step; (g) a velocity gradient determined in the sixth step; (h) determining a velocity gradient that makes the agglomeration state detected in the fourth step appropriate as an appropriate velocity gradient; (h) determining a velocity gradient corresponding to the appropriate velocity gradient determined in the seventh step; An eighth step of determining the aggregate formation time of the suspension into which the flocculant has been injected in step 1 and setting it as an appropriate aggregate formation time; (i) detecting the amount of suspension supplied to the mixing pond; (j) the appropriate speed gradient determined in the seventh step and the eighth step;
The appropriate aggregate formation time determined in the process of
(k) a tenth step of controlling the agitation in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation pond; an eleventh step of calculating the injection amount of the flocculant from the supplied amount of the suspension and the appropriate injection rate of the flocculant determined in the fifth step; (l) the injection calculated in the eleventh step; and a twelfth step of injecting a flocculant into the mixing basin according to the amount thereof.''

[Function] The first stirring control method of the flocculation pond according to the present invention is to inject the flocculant into the suspension while rapidly stirring it in the mixing basin, and then slowly stirring it in the flocculation basin. In a stirring control method for an aggregate formation pond in which aggregates are formed by The amount of received light given from the light emitting device to the light receiving device is measured, the agglomeration state of the suspension is detected from the amount of received light, and the appropriate injection rate of the flocculant is determined according to the detected aggregation state. , determine the velocity gradient and aggregate formation time corresponding to the determined appropriate injection rate, detect the amount of suspension supplied to the mixing basin, and calculate the suspension in the mixing basin according to the appropriate injection rate of the flocculant. A flocculant is injected into the turbid liquid, and stirring control of the aggregate formation pond is performed according to the velocity gradient, the aggregate formation time, the supply amount of the suspension, and the volume of the aggregate formation pond. This function eliminates the visual observation and experience of the tester, and allows the agitation control of the agglomerate formation pond to be properly controlled in a short time while avoiding the need to actually measure the results of the agitation process in the agglomeration formation pond. It has the effect of becoming

In addition, the second agitation control method of the flocculate formation pond according to the present invention is that after injecting the flocculant into the suspension while stirring rapidly in the mixing basin, the flocculant is injected into the suspension and then slowly stirred in the flocculation basin. In a stirring control method for an aggregate formation pond formed by forming aggregates, a flocculant is injected into a collected suspension, and then the stirring speed of the suspension is reduced, and the suspension into which the flocculant has been injected is The amount of received light given from the light emitting device to the light receiving device via the light emitting device is measured, the agglomeration state of the suspension is detected from the amount of received light, and the appropriate injection rate of the flocculant is determined according to the detected aggregation state. Then, a velocity gradient is determined corresponding to the determined appropriate injection rate, and among the velocity gradients, a velocity gradient that makes the detected aggregation state appropriate is determined as an appropriate velocity gradient, and a velocity gradient corresponding to the appropriate velocity gradient is determined. The aggregate formation time is determined as the appropriate aggregate formation time, the amount of suspension supplied to the mixing pond is detected, and the flocculant is added to the suspension in the mixing basin according to the appropriate injection rate of the flocculant. the aggregate forming pond according to the appropriate velocity gradient, the appropriate aggregate forming time, the supply amount of the suspension, and the volume of the aggregate forming pond. In addition to the function of eliminating the visual observation and experience of the tester and the effect of optimizing the stirring control of the flocculation pond in a short time while avoiding the actual measurement of the results of the stirring process in the flocculation basin, It not only detects the appropriate injection rate, but also determines the appropriate velocity gradient and appropriate aggregate formation time, thereby shortening the time required to control the stirring of the aggregate formation pond.

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

FIG. 1 is a sectional view showing an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by an embodiment of the agitation control method for an agglomeration formation pond according to the present invention.

FIG. 2 shows the appropriate injection rate W _Al ^* of flocculant to the suspension to carry out one embodiment of the present invention.
FIG. 2 is a sectional view specifically showing an example of the detection device of FIG. 1 that detects the appropriate aggregate formation time T _t ^* and the appropriate velocity gradient G _t ^* at that time.

FIG. 3 is an explanatory diagram for explaining the operation of the detection device shown in FIG. 2, and shows temporal changes in the amount of received light I. FIG.

FIG. 4 is a graph showing the relationship between the diameter d, number N _b , volume V, and effective density ρ of the aggregate obtained from the operation diagram in FIG. 3 and the injection rate W _Al of the flocculant. .

Figure 5 shows the supernatant water turbidity τ, sedimentation velocity S of aggregates, and effective density ρ obtained from the operation diagram in Figure 3.
FIG. 3 is a graph diagram showing the relationship between the coagulant injection rate W Al and the flocculant injection rate W _Al .

FIG. 6 is a sectional view showing a detection device in which four detection devices of FIG. 2 are arranged side by side.

First, with reference to FIG. 1, an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by the agitation control method for an agglomerate formation pond according to the present invention will be described.

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 mixing pond for the suspension and the flocculant, which are communicated through the mixing tank 08 .

Reference numeral 112 denotes an aggregate formation pond that is communicated with the mixing pond 106 via a supply pipe 114, and is divided into a desired number of regions, for example, three regions 112A, _{112C, each having a volume of V A ,} . Agitators 113A, . . . , 113C are provided respectively. Stirrer 113A, ~, 113C
are each driven by a driving means such as an electric motor 115.
A, . . . , 115C, and the rotational speed n _A , by means of a drive means such as an electric motor 115A, .
~, n Stirring blade 116A, ~1 rotated slowly at _C
Contains 16C. The suspension in which the flocculant is injected and mixed in the mixing basin 106 and supplied to the flocculation basin 112 through the supply pipe 114 is first fed to the first area of the flocculation basin 112, that is, the first area 112A. Stirring blade 1 of stirrer 113A
16A at a rotation speed _nA for a predetermined time, and then transferred to the second region 112B, where it is slowly stirred at a rotation speed _nB for a predetermined time by a stirring blade 116B of an agitator 113B. , further transferred to the third region 112C and stirred by the stirrer 113C.
The area is slowly stirred by the region blade 116C at a rotational speed n _C for a predetermined period of time.

Reference numeral 118 denotes a sedimentation tank connected to the flocculation basin 112, in which the flocs supplied from the final area of the flocculation basin 112, that is, the third area 112C, are used to stabilize the suspension in which the flocs have been sufficiently formed. The aggregates, or flocs, are precipitated and removed. Reference numeral 120 denotes a filter tank that is connected to the outlet of the sedimentation tank 118 via a supply pipe 122, and after removing fine aggregates, that is, flocs that could not be removed in the sedimentation tank 118, the water is passed through the treated water pipe 124 as treated water. It is sent to the appropriate subsequent equipment.

130 is specifically shown in FIG. 2 or FIG. 6, and the appropriate injection rate W _Al ^* of the flocculant into the suspension, the appropriate aggregate formation time T _t ^* , and the appropriate velocity gradient G _t at that time. ^* This is a detection device for detecting water, and is connected to the landing well 102 via a supply pipe 132 and a pump 134, and a drain pipe 133 is opened to an appropriate location such as the mixing pond 106.

136 is a flow meter 13 arranged in the supply pipe 108
8 and the detection device 130, the calculation device calculates the appropriate injection rate W _Al ^* of the flocculant for the suspension detected by the detection device 130, the appropriate aggregate formation time T _t ^* , and the appropriate speed at that time. The gradient G _t ^* , the flow rate detected by the flow meter 138 (i.e., the amount of supply to the mixing pond 106) Q, and the aggregate formation pond 112 inputted by manual operation or the like measured in advance
The volume of each area 112A, ~, 112C is V _A , ~,
Receives necessary information such as V _C and uses this information to form each region 112A, ~, of the aggregate formation pond 112.
The rotational speeds n _A , -, n _C of the stirrers 113A, -, 113C of 112C are calculated.

That is _, the ^calculation device ₁₃₆ ^calculates _{the relationship} ( However, α is a constant) From T _t ^* /T _r [G _t ^* /G _r ] ^1/2 = 1/α, each area 112A of the aggregate formation pond 112,
Velocity gradient G _r (A) at ~, 112C, ~, G _r (C)
By defining G _r (A) = α _A G _r G _r (B) = α _B G _r G _r (C) = α _C G _r using constants α _A , ~, α _{C r} (A) = [αT _t ^* /T _r ] ² α _A G _t ^* G _r (B) = [αT _t ^* /T _r ] ² α _B G _t ^* G _r (C) = [αT _t ^* / T _r ] ² α _C G _t ^* . However, the constant α _A , ~, α _C is
Each region 112A, ~, 11 of the aggregate formation pond 112
Considering the stirring intensity at 2C, α _A ≧ α _B ≧ α _C , and V _A α _A ² + V _B α _B ² + V _C α _C ² = V _A + V _B + V _C. Here, each region 112A, ~, 112C of the aggregate formation pond 112 has an equal volume, that is,
If V _A = V _B = V _C , there is a relationship between the constants α _A , . . . , α _C as follows: α _A ² + α _B ² + α _C ² = 3.

The velocity gradient G _r (A), ~, G _r (C) is the viscosity coefficient μ and specific gravity η of the suspension, the drag coefficient C, and the stirrer 113
A, ~, 113C stirring blades 116A, ~, 11
Area of 6C a _A , ~, a _C and circumferential speed υ _A , ~, υ _C TC
Each region 112A, ~, 11 of the aggregate formation pond 112
Using the volumes V _A , ~, V _C of 2C, G _r (A) = [Cηa _A υ _A ³ /2μV _A ] ^1/2 G _r (B) = [Cηa _B υ _B ³ /2μV _B ] ^{1 /2} G _r (C) = [Cηa _C υ _C ³ /2μV _C ] ^1/2 , so from this relationship a _A υ _A ³ =2μV _A /CηG _r (A) ² a _B υ _B ³ = 2μV _B /CηG _r (B) ² a _C υ _C ³ = 2μV _C /CηG _r (C) ² can be calculated. Here, the stirring blade 116A, ~, 1
The circumferential speed υ _A , ~, υ _C of 16C is calculated using the rotational speed n _A , ~, n _C and radius r _A , ~, r _C , υ _A = 2πr _A n _A υ _B = 2πr _A n _A υ _C ＝2πr _A n _A , and therefore a _A υ _A ³ , ~, a _C υ _C ³ can be expressed as a _A υ _A ³ = 8a _A π ³ r _A ³ n _A ³ a _B υ _B ³ = 8a _B π ³ r _B ³ n _B ³ a _C υ _B ³ = 8a _C π ³ r _C ³ n _C ³ , so 8a _A π ³ r _A ³ n _A ³ = 2μV _A /CηG _r (A) ² 8a _B π ³ r _B ³ n _B ³ = 2μV _B /CηG _r (B) ² 8a _C π ³ r _C ³ n _C ³ = 2μV _C /CηG _r (C) ² , and the rotation speed n _A , ~, n _C n _A = [2μV _A G _r (A) ² /8a _A π ³ r _A ³ Cη] ^1/3 n _B = [2μV _B G _r (B) ² /8a _B π ³ r _B ³ Cη] ^1/ It can be calculated as ³ n _C = [2μV _C G _r (C) ² /8a _C π ³ r _C ³ Cη] ^1/3 . Therefore, the rotational speed n _A , ~, n _C is n _A = [μV _A α ⁴ α _A ² (G _t ^* ) ² (T _t ^* ) ⁴ /4a _A π ³ r _A ³ CηT _r ⁴
] ^1/3 n _B = [μV _B α ⁴ α _B ² (G _t ^* ) ² (T _t ^* ) ⁴ /4a _B π ³ r _B ³ CηT _r ⁴
] ^1/3 n _C = [μV _C α ⁴ α _C ² (G _t ^* ) ² (T _t ^* ) ⁴ /4a _C π ³ r _C ³ CηT _r ⁴
] It can be calculated as ^1/3 . However, T _r is (V _A + V _B + V _C )/
It is Q. As a result, the rotational speed n _A , ~, n _C is determined based on the appropriate aggregate formation time T _t ^* and appropriate velocity gradient G _t ^* detected by the detection device 130 and the aggregate formation pond 1
12 aggregate formation time T _r (and thus the flowmeter 138
It can be determined by the flow rate Q) detected by Q).

140 is a controller connected to the calculation device 136, which controls the rotation speed output by the calculation device 136.
Stirrer 113A, ~, 113 according to n _A , ~, n _C
The rotational speed of the driving means 115A to 115C of C is controlled. Reference numeral 144 denotes an aggregate supply device, which supplies flocculant to the mixing basin 106 via a supply pipe 146 in accordance with the appropriate injection amount R ^* calculated as the product of the appropriate injection rate W _Al ^* and the flow rate Q in the calculation device 136. , injecting against a suspension.

Then, the suspension is collected from the landing well 102 via the pump 134 and the supply pipe 132, and the detection device 130 according to the present invention determines the appropriate injection rate W _Al ^* of the flocculant for the suspension and its timing. The calculation device 136 detects or calculates the appropriate aggregate formation time T _t ^* and the appropriate velocity gradient G _t ^* .
is being sent to.

In the calculation device 136, each time the appropriate injection rate W _Al ^* of the flocculant from the detection device 130 is input, it is multiplied by the flow rate Q input from the flow meter 138 to determine the actual appropriate injection rate R ^* of the flocculant. It has been calculated,
In addition, the appropriate aggregate formation time T _t ^* is detected from the detection device 130.
Each time the appropriate velocity gradient G _t ^* is input or the flow rate Q is input from the flow meter 138, each region 1 of the aggregate formation pond 112 is input as described above.
Stirrers 113 installed at 12A, ~, 112C
The rotational speeds n A , . . . , n _C of _A , .about., 113C have been calculated.

The appropriate injection amount R ^* of the flocculant calculated by the calculation device 136 is provided to the flocculant supply device 144. The flocculant supply device 144 controls this appropriate injection amount.
R ^* (accordingly, flocculant is injected into the mixing basin 106 via the supply pipe 146.

The rotation speed n _A calculated from the arithmetic unit 136 , ~,
n _C is provided to controller 140. Controller 1
40 are agitators _113A , -, _113C of the aggregate formation pond 112, respectively, depending on the rotational speed nA, -, nC.
to drive.

By intermittently repeating the detection operation by the detection device 130 described above and correcting the agitation control of the aggregate formation pond 112, aggregate formation in the suspension processing device can be performed with appropriate efficiency, and the suspension can be further improved. Processing time can be shortened.

Further, the configuration of the detection device 130 will be explained in detail with reference to FIGS. 2 to 5.

Reference numeral 10 denotes a batch-type stirring tank, which has an appropriate capacity, for example, 1, and contains a suspension (hereinafter sometimes simply referred to as suspension) 1 into which a flocculant is injected.
1 is accommodated. Reference numeral 12 denotes a stirring blade disposed in the stirring tank 10, and an output shaft 16 of a drive means such as an electric motor 14 arranged below the stirring tank 10.
is suitably attached to the free end of the

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 suspension 11 in the stirring tank 10 as a bundle of parallel light rays through a suitable optical system such as a slit. Reference numeral 20 denotes a light receiving device which includes an appropriate photoelectric conversion element such as a phototransistor, photodiode, CdS, CCD, etc. as a light receiving means, and is arranged on the side of the stirring tank 10. The light supplied as a liquid is received through the suspension 11. Since the light provided by the light emitting device 18 is scattered or blocked by the aggregates or flocs 17 in the suspension 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 to receive transmitted light, or may be placed opposite the light emitting device 18 to receive scattered light.
They may also be arranged at a predetermined angle with respect to the parallel light beams from. In addition, two light receiving devices 20 may be arranged to receive transmitted light and scattered light. In order to simplify the explanation, the light receiving device 2 will be described below.
0 is opposed to the light emitting device 18. Further, in FIG. 2, only one set of the light emitting device 18 and the light receiving device 20 is arranged, but the present invention is not limited to this, and a plurality of sets of the light emitting device 18 and the light receiving device 20 may be arranged. Light emitting device 1
8 and the light receiving device 20 are preferably arranged on the same horizontal plane, in order to detect the sedimentation state of the flocs 17 with high precision.

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.

24 has one end connected to the stirring tank 10 via the on-off valve 25.
The other end of the supply pipe is open to the supply pipe 132 (see FIG. 1). 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
The detected suspension 11 is removed from the tank (see FIG. 1). 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 calculation device connected to the driving means 14, the measuring device 22, and the on-off valves 25, 27, which calculates the peripheral speed υ or rotational speed n of the stirring blade 12 from the driving means 14
is given, and the amount of light received from the measuring device 22 is
_i (τ), the fluctuation range △ of the amount of received light, and the fluctuation period F are given, and the on-off valves 25, 27
The supply amount M of the suspension and the supply amount N of the flocculant are given by . Arithmetic unit 36 calculates parameters useful in determining the state of formation of aggregates or flocs 17.

That is, the arithmetic unit 36 calculates the diameter d (cm) of the aggregate, that is, the floc 17, as d=α△ using the fluctuation width 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. ) and the circumferential speed υ (m/sec) or rotation speed n of the stirring blade 12
(1/sec) and the constants β and β', the number of aggregates or flocs 17 N _b (1/cm ³ ) is expressed as N _b = β (1/Fυ) ³ = β' (1/Fn) ³ Calculate the diameter d of the aggregate, that is, the floc 17.
(cm), the number N _b (1/cm ³ ), and the constant ε to calculate the volume V (cm ³ ) of the aggregate, that is, the floc 17, as V=εd ³ N _b , and the amount of received light _i (τ) ( The initial concentration of suspended solids in the suspension W _ss (mg/), which was determined from (Volt), and the injection rate of flocculant, W _Al (mg/), which was determined from the supply amount M and N.
) and the diameter d (cm) of the aggregate or floc 17
Then, using the number N _b (1/cm ³ ), the constant γ, and the coefficient a specific to the flocculant, the effective density ρ (g/cm ³ ) of the floc 17 can be calculated as ρ=γ1/d ³ N _b ( W _ss + aW _Al ), and if desired, the settling velocity S (cm/min) of the flocs 17 is calculated using time T and constant δ as S = δ1/T. The supernatant water turbidity τ (degrees) after the flocs 17 have settled is calculated as τ= _{λ f} (τ) using the amount of received light _f (τ) and the constant λ. Here, the relationship between the parameters calculated by the arithmetic unit 36 and the actual agglomeration state of the flocs 17 is as follows: diameter d or number N _b , volume V, effective density ρ, settling velocity S, and supernatant water turbidity τ. Therefore, if it is desired to accurately detect the agglomeration state of the flocs 17, the latter parameter may be used, and if it is desired to detect the aggregation state even more precisely. If so, you can use a combination of multiple parameters. Incidentally, the calculation device 36 may be configured not to calculate parameters that are not used.

38 is another arithmetic device connected to the arithmetic device 36, which calculates the diameter d, number N _b , volume V, effective density ρ, sedimentation velocity S, and aggregate 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 _Al at that time, and the flocculant injection into the suspension at this time is performed. The appropriate value of the injection rate (that is, the appropriate injection rate) W _Al ^* is calculated. That is, the arithmetic device 3
8 is a change in the flocculant injection rate W _Al (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. On the other hand, the diameter d, volume V, or effective density ρ of the flocs 17 begins to change sharply, and the number N _b and sedimentation velocity S
Alternatively, in response to when the supernatant water turbidity τ starts to change slowly, the flocculant injection rate W _Al is determined to be the appropriate injection rate W _Al ^* , and this is output to the arithmetic unit 136 (first (see figure).

Further, the calculation device 38 sets the number N _b corresponding to the appropriate injection rate W _Al ^* to the appropriate number N _b ^* , and then sets the peripheral speed υ and rotational speed n of the stirring blade 12 corresponding to the appropriate number N _b ^* to appropriate values. Assuming the circumferential speed υ ^* and the appropriate rotational speed n ^* , calculate from the above as υ ^* = 1/F [β/N _b ^* ] ^1/3 n ^* = 1/F [β'/N _b ^* ] ^1/3 , When detecting the subsequent appropriate aggregate formation time T _t ^* , the driving means 14 is applied to slowly rotate the stirring blade 12 which is in the process of slow stirring at an appropriate circumferential speed υ ^* and thus at an appropriate rotational speed n ^* .

In addition, the arithmetic circuit 38 uses the volume of the stirring tank 10 (here M+N), the viscosity coefficient μ and specific gravity η of the suspension, the drag coefficient C, the area a of the stirring blade 12, and the appropriate peripheral speed υ ^* , The appropriate speed gradient G _t ^* is calculated as G _t ^* = [Cηa (υ ^* ) ³ /2μ (M+N)] ^1/2 , and this is output to the arithmetic unit 136 (see FIG. 1).

39 is a control device arranged between the on-off valve 25 and the arithmetic unit 38 and the on-off valve 27;
Therefore, the product MW _Al of the suspension supply amount M and the appropriate injection rate W _Al ^* given from the calculation device 38
^* Open/close valve 2 so that the supply amount N of flocculant matches
The time to open 7 is adjusted.

40 is another measuring device connected to the measuring device 22, which measures the appropriate injection rate W _Al given from the arithmetic device 38.
^* With the flocculant injected into the suspension in the stirring tank 10 according to
While driving the stirrer 2 to perform slow stirring at an appropriate circumferential speed υ ^* and thus an appropriate rotational speed n ^* , the amount of received light measured by the measuring device 22 becomes flat from the start time _t3 of slow stirring of the stirring blade 12. The time up to time _t4 , that is, the aggregate formation time _Tt , is determined and outputted to the arithmetic unit 136 as the appropriate aggregate formation time _Tt ^* (see FIG. 1).

In addition, the operation of the detection device 130 will be explained in detail with reference to FIGS. 2 to 5.

After the on-off valve 32 is opened and the suspension 11 remaining in the stirring tank 10 is removed via 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 collected from a suspension supply source (not shown) through the suspension and supplied into the stirring tank 10 .

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 _t2 , a predetermined amount N of flocculant is released.
The flocculant is injected from the flocculant supply source 28 into the stirring tank 10 via the flocculant supply pipe 26 . As a flocculant,
Known flocculants such as polyaluminum chloride may be used if 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 received light amount I of the transmitted light is measured through the suspension in the stirring tank 10. It is given to the arithmetic unit 36.

The amount of received light I until time t ₂ , that is, the time when the flocculant is supplied, is a constant value I _i (γ) 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 _t2 , aggregates, that is, flocs 17 are gradually formed within the suspension 11, and the suspension 11 is rapidly stirred and moved within the stirring tank 10. Therefore, 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 suspension 11
Agglomerates or flocs 17 are formed in the stirring tank 1 and the diameter d thereof gradually increases, and the suspension 11 flows into the stirring tank 1.
Since the light is stirred and moved slowly within 0, the amount of light received by the light receiving device 20 increases and decreases little by little, but increases as a whole.

When time t ₄ is reached, the flocs 17 are sufficiently agglomerated in the suspension 11 and their diameter d does not change, and the suspension 11 is being stirred and moved slowly in the stirring tank 10. Therefore, the amount of light I received by the light receiving device 20 is flattened, and the aggregate, that is, the floc 1
7, the predetermined values I _L and I _H begin to fluctuate periodically.

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

For example, when a kaolin suspension prepared by adding 25 mg of kaolin to fresh water in step 1 is used, and polyaluminum chloride is injected at an injection rate of 15 mg, the amount of light received by the light receiving device 20 is measured by the measuring device 22. , as shown in Figure 3.

Thereafter, the arithmetic unit 36 determines the diameter d, the number N _b , and
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 state of formation of the aggregates, that is, the flocs 17, can be detected as described above.

The calculation device 38 calculates the diameter d, the number N _b , and
At least one of the volume V, the effective density ρ, the sedimentation rate S, or the supernatant water turbidity τ is memorized for the flocculant injection rate W _Al as desired, and the diameter d and volume V of the floc 17 are stored. Or effective density ρ
when the change starts to become steep or the number of
The flocculant injection rate W _Al at which changes in N _b , sedimentation velocity S, or supernatant water turbidity τ start to slow down is determined as the appropriate injection rate W _Al ^* , and is output to the subtraction device 136 (Fig. 1 reference).

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 _b , volume V and effective density ρ of No. 7 were calculated and plotted against the flocculant injection rate W _Al , the result shown in FIG. 4 was obtained.

Similarly, each time the above measurements and calculations are repeated using the kaolin suspension, the effective density ρ of the aggregates or flocs 17 and the sedimentation velocity S
and the supernatant water turbidity τ, and the flocculant injection rate W _Al
Figure 5 was obtained by plotting against .

As is clear from FIGS. 4 and 5, as the flocculant injection rate W _Al changes, the diameter d, number N _b , volume V, effective density ρ, and sedimentation velocity S of the flocs 17 change. and supernatant water turbidity τ are changing. In detail, the flocculant injection rate W _Al is a predetermined value.
When W _Al ^* (here, 30 mg/) or more, the number N _b 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 unstable aggregates, or flocs 17, are formed. Further, when the flocculant injection rate W _Al exceeds the predetermined value W _Al ^* , the sedimentation velocity S of the flocs 17 or the supernatant water turbidity τ after the flocs 17 have settled do not change much. As a result, the flocculant injection rate W _Al is the predetermined value.
Even if it exceeds W _Al ^* , 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 _Al is at its predetermined value.
When W _Al ^* is significantly smaller than W Al *, the number N _b 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, making it relatively stable. It can be concluded that fine 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. As a result, the flocculant injection rate W _Al is the predetermined value.
If it becomes significantly smaller than W _Al ^* , 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 _Al ^* 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.

To this end, the arithmetic unit 38 operates as described above.
W _Al ^* has been determined as the appropriate injection rate of coagulant.

When the calculation device 38 determines the appropriate injection rate W _Al ^* , the calculation device 38 determines the appropriate circumferential speed υ ^* of the stirring blade 12 in accordance with this.
Furthermore, the proper rotational speed n ^* is determined and sent to the drive means 14, and then the proper speed gradient G _t ^* is calculated and sent to the arithmetic unit 136 together with the proper injection rate W _Al ^* (see FIG. 1).

When the proper injection rate W _Al ^* is output from the calculation device 38, the detected suspension 11 in the stirring tank 10 is removed via the on-off valve 32, and then the on-off valve 25 is opened and the stirring tank 10 is removed. stirring blades 12
Appropriate injection rate for suspensions under rapid stirring
A flocculant is injected via the on-off valve 27 so that W _Al ^* .

Thereafter, the driving means 14 controls the appropriate circumferential speed υ ^* calculated by the arithmetic unit 38 in accordance with the appropriate injection rate W _Al ^* .
Alternatively, the stirring blade 12 is controlled to perform slow stirring at an appropriate rotational speed n ^* .

In this state, the amount of received light I is measured by the measuring device 22, and then the amount of received light I is measured in the measuring device 40 from time _t3 when slow stirring is started to time _t4 when the amount of received light I measured by the measuring device 22 becomes flat. The time, that is, the aggregate formation time T _t is detected and output as the appropriate aggregate formation time T _t ^* to the arithmetic unit 136 (see FIG. 1).

In the above description, the detection device 130 including only one stirring tank 10 has been described, but with this, a large amount _of ^time is required to detect the state of agglomeration _. Since it takes time to detect ^* and the appropriate velocity gradient G _t ^* , a plurality of (four in this case) stirring tanks may be arranged side by side as shown in FIG.

The detection device 130 in FIG.
The configuration and operation are substantially the same as the detection device shown in FIG. 2, except that the measuring device 8 to the measuring device 40 are common. On the other hand, the same reference numerals as those given in the detection device of FIG. 2 are given, and detailed explanation thereof will be omitted. Reference numbers include A, B,
The symbols C and D are added. On-off valve 27A,
~, 27D are open for different times, and the suspensions 11 in the stirring tanks 10A, ~, 10D
The injection rate of flocculant for A, ~, 11D is adjusted.

When the calculation device 38 determines the appropriate injection rate W _Al ^* , the control device 39 determines this appropriate injection rate W _Al ^* for the suspension being rapidly stirred in the stirring tank 10A.
The flocculant is injected so that the agitating blade 12A is slowly stirred at the appropriate circumferential speed υ output from the calculation device 38 ^* and the appropriate rotational speed n ^* while the measuring device 22A
The amount of received light I is measured by the measuring device 4.
0, the appropriate aggregate formation time T _t ^* is measured from the received light amount I at this time.

In addition, the calculation device 38 calculates the appropriate circumferential speed υ * and thus the appropriate rotational speed ^{n *} calculated corresponding to the appropriate injection rate W _Al ^* .
The appropriate speed gradient G _t ^* is calculated using

In the case of the detection device 130 shown in FIG. 6, a fifth stirring tank is additionally arranged to allow proper aggregate formation time.
It may be used only to measure T _t ^* , which further reduces processing time.

In the above description, after determining the appropriate injection rate W _Al ^* and the appropriate circumferential speed υ ^* (and thus the appropriate rotational speed n ^* ) and calculating the appropriate speed gradient G _t ^* in the arithmetic unit 38, the operation is performed again in the stirring tank 10 or 10A. A test is performed to detect the appropriate aggregate formation time T _t ^* by supplying a suspension liquid to the sample. Rate W _Al ^* and proper velocity gradient G _t ^*
A similar operation or effect can be achieved even if the appropriate aggregate formation time T _t ^* is determined from past data and sent to the arithmetic unit 136.

In addition, in the above, the appropriate injection rate of coagulant W _Al
Although the agitation control of the aggregate formation pond ¹¹² is performed by determining the appropriate speed gradient G _t ^* and appropriate aggregate formation time T _t ^* in accordance with *, the present invention is not limited thereto. , if desired, in order to reduce calculation operations and so on, instead of the appropriate velocity gradient G _t ^* and the appropriate aggregate formation time T _t ^* , a velocity gradient that does not yet fully optimize the agglomeration state of the suspension. G _t and aggregate formation time T _t may be used. That is, after determining the appropriate injection rate W _Al ^* of the flocculant in Figure 2 or Figure 6, this appropriate injection rate W _Al
^* The amount of light received is measured by simply stirring the flocculant-injected suspension in a stirring tank slowly to form aggregates, and the velocity gradient is adjusted in response to this slow stirring.
Calculate G _t and calculate the aggregate formation time T _t from the amount of received light.
You may also ask for

In addition, in the above description, the stirrers 113A, . . .
Although the agitation control of the aggregate formation pond 112 is executed by controlling the rotational speed n _A , ~, n _c of the agitator 113C, the present invention is not limited to this, and the The agitation control of the aggregate forming pond 112 may be achieved by controlling the rotational speed of the aggregate forming basin 112C or the volume of the aggregate forming basin 112C.

(3) Effects of the invention As is clear from the above, the first agitation control method for the flocculate formation pond according to the present invention involves injecting the flocculant into the suspension while rapidly stirring it in the mixing basin, and then injecting the flocculant into the suspension.
A stirring control method for an aggregate formation pond in which aggregates are formed by slow stirring in an aggregate formation pond, which method includes: (a) a suspension collected upstream of the mixing basin; The first step is to inject the flocculant and stir it in the stirring tank.
(b) a second step of stirring the flocculant-injected suspension in the first step at a reduced stirring speed than in the first step; and (c) at least a second step. (d) measuring the amount of light received by the light receiving device from the light emitting device through the suspension into which the flocculant was injected in the first step; a fourth step of detecting the flocculation state of the suspension into which the flocculant was injected in the first step from the amount of received light; (e) proper injection of the flocculant according to the flocculant state detected in the fourth step; (f) determining the velocity gradient and aggregate formation time of the suspension injected with flocculant in the first step, corresponding to the appropriate injection rate determined in the fifth step; (g) a seventh step of detecting the amount of suspension supplied to the mixing pond; (h) a seventh step of determining the velocity gradient and aggregate formation time determined in the sixth step; an eighth step of controlling agitation in the aggregate formation pond using the supply amount of the suspension detected in step 7 and the volume of the aggregate formation pond; (i) detected in the seventh step; a ninth step of calculating the injection amount of the flocculant from the supplied amount of the suspension determined in the calculation and the appropriate injection rate of the flocculant determined in the fifth step; and a tenth step of injecting the flocculant into the mixing basin according to the injection amount, () it has the effect of eliminating the visual observation and experience of the tester, and () the flocculation basin. This has the effect of optimizing the agitation control of the aggregate formation pond in a short time while avoiding actually measuring the result of the agitation process.

Further, the second agitation control method for the aggregate formation pond of the pond according to the present invention is to inject the flocculant into the suspension while rapidly agitating it in the mixing basin, and then slowly agitating it to form aggregates. A stirring control method for an aggregate formation pond formed by forming aggregates, in particular: (a) a flocculant is injected into the suspension collected upstream of the mixing basin and the mixture is stirred in the stirring tank; First thing to do
(b) a second step of stirring the flocculant-injected suspension in the first step at a reduced stirring speed than in the first step; and (c) at least a second step. (d) measuring the amount of received light given to the light receiving device from the light emitting device via the liquid mixture created in the first step; (e) determining the appropriate injection rate of the flocculant according to the flocculation state detected in the fourth step; (f) a sixth step of determining a velocity gradient corresponding to the appropriate injection rate determined in the fifth step; and (g) a velocity gradient determined from among the velocity gradients determined in the sixth step. , a seventh step of determining a velocity gradient that makes the aggregation state detected in the fourth step appropriate as an appropriate velocity gradient; (h) a first step corresponding to the appropriate velocity gradient determined in the seventh step; (i) an eighth step of determining the aggregate formation time of the suspension into which the flocculant has been injected and determining the appropriate aggregate formation time; (i) an eighth step of detecting the amount of suspension supplied to the mixing pond; (j) the appropriate speed gradient determined in the seventh step and the eighth step;
The appropriate aggregate formation time determined in the process of
(k) a tenth step of controlling the agitation in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation pond; an eleventh step of calculating the injection amount of the flocculant from the supplied amount of the suspension and the appropriate injection rate of the flocculant determined in the fifth step; (l) the injection calculated in the eleventh step; A twelfth step of injecting the coagulant into the mixing basin according to the amount, in addition to the effects of () and () above, it not only detects the appropriate injection rate but also detects the appropriate velocity gradient and It has the effect of shortening the time required for stirring control of the aggregate formation pond by determining the appropriate aggregate formation time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by an embodiment of the agitation control method for an agglomerate formation pond according to the present invention, and FIG. is the appropriate injection rate of flocculant into the suspension to carry out an embodiment of the present invention.
A sectional view specifically showing an example of the detection device shown in FIG. 1 for detecting W _Al ^* , appropriate aggregate formation time T _t ^* and appropriate velocity gradient G _t ^* at that time, and FIG. 3 is similar to FIG. 2. An operation explanatory diagram for explaining the operation of the detection device _shown in FIG. A graphical diagram showing the relationship between the rate W _Al ,
FIG. 5 is a graph showing the relationship between the supernatant water turbidity τ, the sedimentation velocity S and effective density ρ of the flocculant, and the flocculant injection rate W _Al obtained from the operation diagram in FIG.
FIG. 6 is a sectional view showing a detection device in which four detection devices of FIG. 2 are arranged side by side. 102...Water landing well, 106...Mixing pond, 112
... Aggregate formation pond, 118 ... Sedimentation pond, 120...
... Overflow pond, 130 ... Detection device, 136 ... Arithmetic device, 138 ... Flowmeter, 140 ... Controller, 1
44... Coagulant supply device, 10... Stirring tank, 11
... Suspension liquid, 12 ... Stirring blade, 14 ... Drive means, 16 ... Output shaft, 18 ... 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, 3
2... Opening/closing valve, 34... Dark box, 36, 38... Arithmetic device, 39... Control device, 40... Measuring device.

Claims (1)

[Scope of Claims] 1. A flocculant forming pond in which a flocculant is injected into a suspension while being rapidly stirred in a mixing basin, and then a flocculant is formed by slow stirring in a flocculating basin. In the agitation control method, (a) a first step of injecting a flocculant into a suspension collected upstream of the mixing pond and stirring it in a stirring tank; (b) from the first step; (c) at least during the second step, stirring the suspension in which the flocculant has been injected in the first step at a reduced stirring speed; (d) Injecting a flocculant in the first step based on the amount of received light measured in the third step. (e) a fifth step of determining an appropriate injection rate of the flocculant according to the aggregation state detected in the fourth step; (f) ) a sixth step of determining the velocity gradient and the aggregate formation time of the suspension in which the flocculant was injected in the first step in accordance with the appropriate injection rate determined in the fifth step; a seventh step of detecting the amount of suspension supplied to the mixing pond; (h) the velocity gradient and aggregate formation time determined in the sixth step and the supply of suspension detected in the seventh step; an eighth step of controlling agitation in the flocculate formation pond using the amount and the volume of the flocculation pond; a ninth step of calculating the injection amount of the flocculant from the appropriate injection rate of the flocculant determined in the step; (j) adding the flocculant to the mixing pond according to the injection amount calculated in the ninth step; and a tenth step of injecting the agglomerate formation pond. 2 () In the fourth step, the aggregation state of the suspension 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 second step, and ( ) In the fifth step, the injection rate of the flocculant corresponding to when the change in the number of aggregates starts to become slow is determined as the appropriate injection rate. A method for controlling agitation in an aggregate formation pond. 3 () In the fourth step, the aggregation state of the suspension is detected by calculating the diameter of the aggregate from the fluctuation range when the amount of received light is flattened, and () In the fifth step, the The agitation control method for an aggregate formation pond according to claim 1, characterized in that 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. . 4 () In the fourth step, the number of aggregates is calculated from the fluctuation period when the amount of received light is flattened and the stirring speed in the second step, and the number of aggregates is calculated from the fluctuation range when the amount of received light is flattened. The aggregation state of the suspension is detected by calculating the diameter of the aggregates and the volume of the aggregates from the number and diameter of the aggregates, and () in the fifth step, the number of aggregates is calculated. The injection rate of the flocculant corresponding to when the change 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 become steep is determined as the appropriate injection rate. A stirring control method for an aggregate formation pond according to claim 1, characterized in that: 5 () In the fourth step, the number of aggregates is calculated from the fluctuation period when the amount of received light is flattened and the stirring speed in the second step, and the number of aggregates is calculated from the fluctuation range when the amount of received light is flattened. The aggregation state of the suspension is detected by 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 () In the fifth step, the injection rate of the flocculant corresponding to when the change in the number of the aggregates starts to slow down and the changes in diameter and effective density start to become steep is determined as the appropriate injection rate. A method for controlling agitation in an aggregate formation pond according to claim 1. 6 In an agitation control method for an aggregate formation pond, in which a flocculant is injected into a suspension while being rapidly stirred in a mixing basin, and then aggregates are formed by slow stirring in an aggregate formation basin, ( a) a first step of injecting a flocculant into the suspension collected upstream of the mixing pond and stirring it in a stirring tank; (b) a stirring speed lower than that of the first step; a second step of stirring the suspension into which the flocculant was injected in the first step; (c) at least during the second step, stirring the suspension into which the flocculant was injected in the first step; (d) measuring the amount of light received from the light emitting device to the light receiving device; (d) measuring the amount of light received from the light emitting device measured in the third step; a fourth step of detecting the agglomeration state; (e) a fifth step of determining an appropriate injection rate of the flocculant according to the aggregation state detected in the fourth step; (f) in the fifth step. (g) determining the appropriateness of the aggregation state detected in the fourth step from among the velocity gradients determined in the sixth step; (h) coagulating the suspension into which the flocculant was injected in the first step in accordance with the appropriate velocity gradient determined in the seventh step; An eighth step of determining the aggregate formation time and determining the appropriate aggregate formation time; (i) a ninth step of detecting the amount of suspension supplied to the mixing pond; and (j) determined in the seventh step. The appropriate speed gradient and the 8th
The appropriate aggregate formation time determined in the process of
(k) a tenth step of controlling the agitation in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation pond; an eleventh step of calculating the injection amount of the flocculant from the supplied amount of the suspension and the appropriate injection rate of the flocculant determined in the fifth step; (l) the injection calculated in the eleventh step; A twelfth step of injecting a flocculant into the mixing basin according to the amount thereof. 7 () In the fourth step, by calculating the supernatant water turbidity after the aggregates have been precipitated from the amount of light received when the amount of light received becomes flat after the stirring in the second step is stopped, It is characterized by detecting the flocculation state of the suspension, and () in the fifth step, determining the injection rate of the flocculant that corresponds to when the change in supernatant water turbidity starts to become slow as the appropriate injection rate. A stirring control method for an aggregate formation pond according to claim 6. 8 () In the fourth step, the aggregation state of the suspension is detected by calculating the sedimentation rate of the aggregate from the time until the amount of received light becomes flat after the stirring in the second step is stopped. and () In the fifth step, the injection rate of the flocculant corresponding to when the change in the sedimentation rate of the aggregates starts to become slow is determined as the appropriate injection rate. A stirring control method for an aggregate formation pond as described in Section 1. 9 () In the fourth step, the number of aggregates in the suspension is calculated from the fluctuation period when the amount of received light measured in the third step becomes flat and the stirring speed in the second step. A patent claim characterized in that the aggregation state is detected, and () in the fifth 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 controlling agitation in an aggregate formation pond according to item 6. 10 () In the fourth step, the agglomeration state of the suspension is detected by calculating the diameter of the aggregate from the fluctuation range when the amount of received light measured in the third step is flattened, and ( ) In the fifth 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. Stirring control method for aggregate formation ponds. 11 () In the fourth step, calculate the number of aggregates from the fluctuation period when the amount of received light becomes flat after the stirring in the second step is stopped and the stirring speed in the second step, and 3
The aggregation state of the suspension can be determined by calculating the diameter of the aggregates from the range of variation when the amount of received light measured in the process is flattened, and by calculating the volume of the aggregates from the number and diameter of the aggregates. is detected, and () in the fifth step, 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. The agitation control method for an aggregate formation pond according to claim 6, wherein a corresponding injection rate of the flocculant is determined as an appropriate injection rate. 12 () In the fourth step, calculate the number of aggregates from the fluctuation period when the amount of received light measured in the third step becomes flat and the stirring speed in the second step, and calculate the number of aggregates in the third step. The diameter of the aggregates is calculated from the range of variation when the measured amount of received light becomes flat, and the effectiveness 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 density, the aggregation state of the suspension is detected, and () In the fifth step, it is possible to respond when the change in the number of aggregates starts to slow down and the change in diameter and effective density starts to become steep. 7. The agitation control method for an aggregate formation pond according to claim 6, wherein the injection rate of the flocculant is determined as the appropriate injection rate.