JPH02291943A - Aggregation testing method based on measurment of aggregation speed and average floc diameter/number - Google Patents

Abstract

PURPOSE:To make it possible to judge the quality of aggregation reaction in a short time and to determine the optimum injecting amount of flocculant based on a continuously computed aggregation speed, a dimensionless total-cross-sectional-area decreasing speed, a floc diameter a floc number and the minimum or minimum values thereof. CONSTITUTION:In the first stage, the mixed liquid of suspension and flocculant is prepared. In the second stage, the mixed liquid is agitated at a specified agitating speed in an aggrega tion reaction tank wherein an agitator and a transmitted-light-intensity measuring device comprising a light source part and a light receiving part are provided. Thus aggregation reaction is made to progress. In the third stage, the intensity of the transmitted light emitted in the steps of the second stage is continuously measured. In the fourth stage, the aggregation speed, the dimensionless total-cross-sectional-area decreasing speed, the diameter of a floc and the number of the flocs are computed based on the change in intensity of the transmitted light which is continuously measured in the third stage. In the fifth stage, the quality of the aggregating reaction is judged and the optimum injecting amount of the flocculant is determined based on the aggregation speed, the dimensionless total-cross-sectional-area decreas ing speed, the diameter of the floc, the number of the flocs and the maximum or minimum values thereof which are continuously computed in the fourth stage.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of industrial application for the purpose of the invention> This invention is based on continuously measured changes in transmitted light intensity.
Since this is a suspension flocculation test method based on the calculation method of aa rate, dimensionless total cross-sectional area reduction rate, floc diameter, and floc number, it is possible to detect the growth process of various particles in the reaction tank,
It is effective for detection and analysis, and is particularly effective in the field of aa precipitation treatment in water supplies, sewage water, industrial wastewater, etc. BACKGROUND ART Conventionally, agglomeration tests for suspensions have mainly been carried out by the jar test method, and the amount of SaW concentrate to be injected has been determined based on the results. However, the jar test method is carried out in a batch manner, and has the drawback of requiring time, effort, and experience, and therefore does not respond quickly to changes in water quality. As countermeasures to this problem, there are experimental methods and feedback methods, but these are basically methods for determining the amount of coagulant to be injected in relation to several water quality items, and they lack responsiveness and reliability to changes in water quality. There are drawbacks. There are other methods, such as the fuzzy method and the PDA method, but they are still in the study stage and have little practical use. Problems to be Solved by the Invention> The optimum amount of coagulant to be injected in coagulation-sedimentation treatment depends on various factors such as water temperature, types and concentrations of various coexisting ions in water, quality and quantity of suspended matter, and stirring conditions. It changes from time to time due to fluctuations in factors, so it is necessary to determine the optimal amount of coagulant to be injected in response to the conditions at each point in time.
However, as mentioned above, the conventional 'a collection test method (
The method for determining the optimal coagulant injection amount based on the jar test method requires time, effort, and experience, and has the disadvantage of being unreliable and responsive to time fluctuations in water quality.

Therefore, we established a method to simultaneously and continuously estimate the flocculation rate, floc diameter, and floc number during the flocculation process, and based on this method, we can quickly respond to temporal changes in water quality.
The purpose of this invention is to establish a method that can automatically determine the i&appropriate amount of curdling agent to be injected in a short time and without requiring labor or experience. (2) Structure of the invention <Means for solving the problems> The means of the present invention for solving the above problems are "(a)
a first step of creating a mixture of the suspension and the flocculant; and (b) a predetermined stirring speed in a flocculation reaction tank comprising a stirrer and a transmitted light intensity measuring device consisting of a light source section and a light receiving section. (C) A third step in which the intensity of transmitted light is continuously measured during the second step; and (d) Continuously in the third step. A fourth step of calculating the aggregation rate, dimensionless total cross-sectional area reduction rate, floc diameter, and number of flocs from the measured transmitted light intensity change; and (e) the aggregation rate continuously calculated in the fourth step. A fifth step of determining whether the flocculation reaction is good or not and determining the optimal coagulant A injection amount based on the dimensionless total cross-sectional area reduction rate, floc diameter, floc number, and their maximum or minimum value. A suspension agglutination test method characterized by the following! & Method for determining the appropriate amount of coagulant to be injected. <Function> When aggregation reaction is progressed by stirring at a predetermined stirring speed in a flocculation reaction tank equipped with a stirrer and a transmitted light intensity measuring device consisting of a light source section and a light receiving section, as a28@ progresses, A continuous change in the transmitted light intensity (or voltage) occurs. The transmitted light intensity changes according to the following formula: 1 =
In exp (-KN π r2)I;
Transmitted light intensity In. Light source intensity K; constant N; number of particles r. Particle radius Here, the suspension with radius = r and number of particles = N aggregates,
If a particle grows to have a particle radius (qr) that is q times larger, the number of particles in the system is 1 / q 2, and the total particle cross-sectional area (Nπ
``2) is expected to be 1/q. That is, when flocs grow due to agglomeration reactions, the total cross-sectional area of floc particles in the system decreases as a result. Therefore, the transmitted light intensity increases according to equation (1). Although the floc growth process in the actual 'a aggregation reaction is more complicated than the above, the transmitted light intensity still changes continuously as aggregation progresses. In other words, the change in transmitted light intensity reflects the agglomeration rate, the rate of decrease in the dimensionless total cross-sectional area, the floc diameter, and the number of flocs, and it is possible to determine the optimal flocculant injection amount based on these indicators. The agglomeration test method of the present invention by measuring the aggregation rate, average floc diameter and number measures the transmitted light intensity given from the light source device to the light receiving device via the aggregation reaction tank, and from the transmitted light intensity, the aggregation rate and the number of flocs are measured. It has the function of measuring and calculating the dimensional total cross-sectional area reduction rate, floc diameter, and floc number, and also does not require the ability or experience to show the relationship between labor width, sedimentation rate, and J1gk agent injection amount in a short time. Its function is to provide a method for automatically determining the maximum amount of coagulant to be injected. <Example> Next, the present invention will be specifically explained with reference to the attached drawings. FIG. 1 is a sectional view showing a measuring device for carrying out the agglomeration test method of the present invention by measuring the agglomeration rate, average diameter and number of flocs. FIG. 2 is a diagram showing temporal changes in transmitted light intensity when the embodiment of the present invention is carried out using the measuring device shown in FIG. Figure 3 is a diagram showing the relationship between transmitted light intensity and total cross-sectional area of particles in the system. FIG. 4 is a diagram showing the relationship between the measured particle radius and the calculated value obtained by the method shown in FIG. 2. Figure 5 is a diagram showing the relationship between the measured value and the calculated value of the number of particles in a suspension determined by the method shown in Figure 2. Figure 6 is a diagram of the agglomeration rate and fluctuation obtained using the method shown in Figure 2. First, the measuring device shown in FIG. 1 will be explained.

The device basically consists of three parts: (1) a part for preparing a mixture of suspension and flocculant, (2) a flocculation reaction tank part, and (3) a light sensor part. In the mixed liquid preparation section, a predetermined amount of flocculant (20) is injected into a predetermined amount of suspension that is introduced via an on-off valve (12) and circulated through a pipe, water tank, etc. (16) and mixed. A liquid is prepared, and after a predetermined period of time, it is introduced into the aS reaction tank section via the on-off valve (14). On the other hand, the flocculation reaction tank part consists of a reaction vessel (2) and a stirrer (1).
0). The reaction vessel (2) is made of a transparent material such as glass, and has an appropriate capacity and shape, but it is preferably one that does not cause a lens effect and is convenient for calculating the stirring intensity. Furthermore, as shown in Figure 1, by deepening the space between the light source section and the light receiving section, the reaction container can be opened and observed from the outside, but even if it is covered, it can be placed in a dark box. You can. Furthermore, in order to facilitate semi-continuous measurement, a sample and flocculant injection device, a discharge device, and a constant temperature device may be added to the flocculation reaction tank. The stirrer (10) is equipped with stirring blades (8) to obtain the desired stirring speed and strength. Equipped with a stirring motor.

A part of the optical sensor consists of one or several pairs of light source parts and light receiving parts, and allows parallel light rays emitted from the light source parts to pass through the flocculation reaction vessel (2) in which flocs (6) are present, and the transmitted light is is received by the light-receiving part. The light source part consists of a light source (26) such as a tungsten lamp, a light intensity adjustment button (32), a filter <30>, and a lens (28>), and the light receiving part consists of a slit (33) and a photoelectric conversion element (34) such as a photodiode. ), amplifier (36>
, Sensitivity in button (38). In addition, a measuring device (40) is connected to the light receiving part by a lead wire (24), and the amount of transmitted light (1) or the time change in voltage (V) from before the start of the aggregation reaction to the end is measured. Each agglomeration index is calculated by the computer (42). Figure 2 shows an example of the change in transmitted light intensity over time during the aggregation process. The transmitted light intensity hardly changes for the first few minutes, but gradually increases as aggregation and floc formation occur. In other words, as flocculation progresses, the floc particle size increases, and as the total number of particles in the reaction tank decreases, the transmitted light intensity further increases. The amplitude also increases. After that, the transmitted light intensity and amplitude almost do not change. Therefore, the transmitted light intensity change rate (aggregation rate) is KIK2
, Ks. Also, the straight lines K1 and K
The time (T) until the intersection with 2 is regarded as the time until aggregation starts. On the other hand, when measuring the transmitted light from the aggregation reaction tank, when the particle size is 5 μm or more and the optical path length is constant, the transmitted light intensity (unit) is expressed by the following formula. log(l./T)”
k N xr2. ．． ．． ．．
(2) X: Transmitted light intensity (1)! . 2 Transmitted light intensity when the number of particles is 0 (-) N: Number of particles (particles/ml) r: Particle radius (cm) k: Constant (cnr”) Figure 3 shows the total when spherical resin particles are used. This shows the relationship between particle cross-sectional area and transmitted light intensity (scale on recording paper).Here, the reading of the recorder scale when there are no particles in the flocculation reaction tank (when only distilled water is present) is shown. L
o, the scale reading when there are particles is L (see Figure 2), and from the results in Figure 3, Io/I= Lo
/L holds true. This linear relationship can also be applied to particles such as flocs. Therefore, when calculating the change in the total particle area from the change in transmitted light intensity, the rate of change in the total particle cross-sectional area is divided into three parts (not shown), as in Figure 1. If standardized, the dimensionless total cross-sectional area reduction rate for each section is Kt+, as in Figure 2.
Kt2 and Kt3 are obtained. Also, the straight line Ktl
The time (Tt) until the intersection of and the straight line xt2 can be found. On the other hand, the amplitude 15 (D) of the transmitted light intensity shown in FIG.
1 and L2, which is a measure of the particle radius. However, since the total cross-sectional area is proportional to log (L0/L), the difference in total cross-sectional area is used as an indicator of particle size:
It is more appropriate to use log (Lo/L+) - log (L0/L2) - log (Ll/L2). Here, spherical resin of known particle size and number (average particle size is within the range of 3.2 to 8.9 x 10-2cm) is used.
The experimentally determined number of particles in the system and the log
The leap factor of (Ll/L2) is expressed by the following formula.

log(L+/L2)=C+Np. ．．
．． ．． (3) N: Number of particles in the system (number of particles) CI: Coefficient that changes depending on particle size p: Coefficient coefficient p is almost constant regardless of the particle size.
Also, the coefficient C! is a variable that changes depending on the particle size, and its relationship with the particle radius is shown by the following equation. C+=C2rq
．． ．． ．． ．． - <4) C2: Coefficient r: Particle radius q: Coefficient Therefore, equation (3) becomes as follows. log (
LL/L2) = C2r qN p Therefore, from equation (2) and (5) 2, the following equation is obtained. <kff)”
(q-2p) (log(L+/L2) }l
/(q-2p) In this way, by removing the upper and lower ends of the amplitude of the transmitted light intensity and their median value using equation (6). The particle size of the particles in the reaction tank is determined. In addition,
While it is desirable to set the upper end (L2) and lower end (L1) of the amplitude of the transmitted light intensity based on the frequency of their appearance, once the particle radius (r) is determined from equation (6), (3 )
From equations and equations (4), the number of suspended particles in the system (N>) can be found using the following equation: shows the relationship between the measured value using the method shown in Figure 2, the calculated value of the particle radius (r) obtained from equation (6), and the actual measured value. Here, the same spherical resin as above was used. The calculation accuracy is about ±9% on average, but similar results can be obtained for aluminum flock. Figure 5 shows the measured values using the method shown in Figure 2 and the system internal values obtained from equation (7). It shows the relationship between the calculated value and the actual measured value of the number of particles (N).The calculation accuracy is about ±19% on average.In this way, from equation (6), particle radius < r) is also expressed as (
7) The number of particles (N) in the system is calculated from the formula, but the calculation accuracy depends on the elucidation of the aggregation mechanism in a heterogeneous system such as a suspension, the analysis of the aggregation reaction, and the determination of the optimal amount of flocculant injection. It has sufficient accuracy for such purposes.

Figure 6 is a diagram showing the relationship between each index and the amount of flocculant injected when a flocculation reaction using aluminum salt was performed on artificial turbid water containing 50 mg/I of kaolin. From Figure 6 1a, the amount of coagulant injected (Cro) 8 -10
It is shown that at mg/l, the aggregation rate K2 reaches the maximum value, and the aggregation rate K3 and the darkness at the start of aggregation (T) reach the minimum values. On the other hand, as shown in Figure 6-b, the above 'a'
In 4A agent injection i (Co), the transmitted light intensity Mhi
D = L2-Ll (see Figure 2), particle radius r
(not shown) and sedimentation velocity V (see Figure 2) take the maximum value, and the number of particles in the system N (not shown) takes the minimum value. Therefore, in order to determine the optimum amount of atA agent to be injected to form flocs with good sedimentation properties, which is the purpose of the IL2 collection and sedimentation treatment of the suspension, it is necessary to The optimum flocculant injection amount is determined so that the particle radius r takes the maximum value, the aggregation rate K3, the dimensionless total cross-sectional area reduction rate Kt3, the aggregation start time T, Tt, and the number of particles in the system N take the minimum values. It will be a good thing if you decide.

Effects of the Invention The flocculation test method of the present invention, which measures the flocculation rate and average floc diameter/number, has the above-mentioned effects. (11) It has the effect of easily responding to changes in the quality of raw water; (II+) The flocculation reaction used in the present invention has the following effects: Indicators can be automatically measured, calculated, and output, and therefore,
(IV) Since the test method is based on a large number of indicators, it has the effect of improving judgment and decision accuracy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a measuring device for carrying out the agglomeration test method of the present invention by measuring the agglomeration rate and average floc diameter number. FIG. 2 is a diagram showing temporal changes in transmitted light intensity when the embodiment of the present invention is carried out using the measuring device shown in FIG. Figure 3 is a diagram showing the relationship between transmitted light intensity and total cross-sectional area of particles in the system. FIG. 4 is a diagram showing the relationship between the actual and calculated particle radius values determined by the method shown in FIG. 2. Figure 5 is a diagram showing the relationship between the measured value and the calculated value of the number of particles in a suspension determined by the method shown in Figure 2. Figure 6 shows the relationship between the collection rate, fluctuation rate and sedimentation rate determined using the method shown in Figure 2 and the amount of flocculant injected. 2. ．． ．． ．． ．． ．． ．． ．． Coagulation # & reaction vessel 10, 12.14 22.24 26, 30. 33. 34. 36. 38. Mixed liquid floc Stirring blade Stirrer Open/close valve Mixing tank Circulation pipe 'AS agent tank Lead line Light source Lens filter Light intensity adjustment button Slit Photoelectric conversion element Amplifier Sensitivity adjustment button Measuring device Diagram 2 ports 'r-srn nb+ro NWr' Co (1/λ)

Claims (5)

[Claims] (1) (a) The first step of creating a mixture of the suspension and the flocculant
(b) a second step in which the aggregation reaction is progressed by stirring at a predetermined stirring speed in a coagulation reaction tank equipped with a stirrer and a transmitted light intensity measuring device consisting of a light source section and a light receiving section; c) A third stage in which the transmitted light intensity is continuously measured during the second stage; and (d) From the changes in the transmitted light intensity continuously measured in the third stage, the rate of aggregation and floc formation ( (hereinafter referred to as aggregation rate)
, a fourth step of calculating the dimensionless total cross-sectional area reduction rate, floc diameter, and number of flocs; and (e) agglomeration rate, dimensionless total cross-sectional area reduction rate, and floc diameter continuously calculated in the fourth step; number of flocks, and
A suspension flocculation test method and optimal flocculant injection characterized by comprising a fifth step of determining whether the flocculation reaction is good or not and determining the optimal flocculant injection amount based on the maximum or minimum value thereof. Quantity determination method (2) In the third step, a method of dividing the aggregation reaction into three categories from the continuously measured changes in transmitted light intensity and calculating the aggregation rate (X_1, X_2, and X_3) within each category; , a method for calculating the aggregation start time (T) from the time of coagulant injection to the time when the aggregation rate K_1 in the first section changes to the aggregation rate X_2 in the second section;
calculated agglomeration rates (K_1, K_2, and K_3),
The suspension according to claim (1), characterized by a method of determining whether the aggregation reaction is good or not and determining the optimum amount of coagulant to be injected from the aggregation start time (T) and the maximum or minimum value thereof. Liquid flocculation test method and optimal flocculant injection amount determination method (3) In the third step, a method of calculating the change in the total cross-sectional area of the particles in the system from the continuously measured changes in transmitted light intensity using the following formula, I=I■ exp(-KNπr^2) Furthermore, The aggregation reaction was divided into three categories based on the change in the total cross-sectional area,
Kt value (Kt
_1, Kt_2, and Kt_3); Furthermore, the aggregation start time (Tt) from the time of coagulant injection to the time when the dimensionless total cross-sectional area reduction rate Kt_1 of the first section changes to Kt_2 of the second section. Furthermore, the calculated dimensionless total cross-sectional area decreasing speed Kt value (Kt_1
, Kt_2, and Kt_3), aggregation onset time (Tt)
The suspension according to claim (1) or (2), characterized by a method for determining whether the flocculant reaction is good or not and determining the optimal flocculant injection amount from the maximum value or minimum value thereof. Liquid flocculation test method and optimal flocculant injection amount determination method (4) In the third stage, the floc diameter (r_t) at each time point is calculated from the fluctuation range of the continuously measured transmitted light intensity.
How to calculate by the following formula, r_t=[(kπ)^p^/^(^q^-^2^p^)
{log(L_1/L_2)}＾t＾/＾(＾q＾-＾
2^p^)]/[C_2^t^/^(^q^-^2^p
^) {log (L_0/L)}^p^/^(^q^-^
2^p^)] Furthermore, it is characterized by a method of determining the quality of the flocculation reaction and the optimal flocculant injection amount based on the temporal change of the calculated floc diameter (r_t), r_t at a desired time, and its maximum value. A suspension flocculation test method and a method for determining the optimum flocculant injection amount according to claim (1) (5) In the third step, the floc diameter (r_t) at each time point calculated by the method described in paragraph (4) from the fluctuation range of the transmitted light intensity that was continuously measured is used. A method of calculating the number of flocs (N_t) using the following formula, N_t=[{log(L_1/L_2)}^1^/^p
]/[(C_2^1^p)・(r^q^/^p)] Also, from the time change status of the calculated number of flocs (N_t), N_t at the desired time, and its minimum value, the aggregation reaction can be determined. Claim (1) or (4) characterized by a method for determining quality and determining the optimum amount of coagulant to be injected.
Aggregation test method for suspension and method for determining optimal flocculant injection amount described in section