JP2017121601A - Coagulation method and coagulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coagulation method capable of determining the proper injection ratio of a coagulant injected into an undiluted solution including a suspended substance.SOLUTION: A coagulation method of the present invention includes a supply process of supplying an undiluted solution to an agitation tank from an undiluted solution supply pipe, an injection process of injecting a coagulant into the undiluted solution by supplying the coagulant to the agitation tank or the undiluted solution supply pipe, an agitation process of agitating the undiluted solution of injecting the coagulant by rotating the agitation blade, an optical measurement process of providing an optical measured value by radiating the light to the agitated undiluted solution, a numerical value analysis process of providing a numerical analysis value by numerically analyzing the optical measured value and an injection ratio determination process of determining the proper injection ratio of the coagulant based on the numerical analysis value. A value of the ratio to a flow rate Fb of the undiluted solution of passing through the agitation tank, of the volume Va of a rotary area formed by rotating a rotary body composed of the agitation blade and a rotary shaft in the agitation tank, falls within a range of 1-10.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for agglomerating a stock solution containing a suspended substance, and more particularly to a method for determining an appropriate injection rate of a flocculant injected into a stock solution containing a suspended substance. The present invention also relates to an aggregating apparatus using the aggregating method. In this specification, the stock solution refers to the liquid to be treated.

  In order to reduce the volume of waste and reduce environmental impact, it is necessary to reduce the volume of undiluted liquids (such as wastewater and sludge) containing suspended solids discharged from wastewater treatment facilities and water purification facilities. Dehydration is extremely important. Therefore, development of more efficient and low running cost dehydration technology is desired.

  The dehydration treatment of the stock solution containing the suspended substance is composed of an aggregating process in which flocs are formed by aggregating the suspended substance using an aggregating agent, and a dehydrating process in which the floc is dehydrated by a dehydrator. Most of the running cost in this dehydration process is the cost of the flocculant.

  In addition, agglomeration treatment (such as agglomeration sedimentation, agglomeration pressure flotation, agglomeration sand filtration, agglomeration membrane filtration) for purifying wastewater in a wastewater treatment facility, and agglomeration treatment (aggregation sedimentation, In the case of agglomerated sand filtration, agglomerated membrane filtration, etc.), most of the running cost is the cost of a flocculant. Therefore, it is desired to properly control the injection rate of the flocculant and reduce the amount of the flocculant used.

  The following prior arts are known as techniques related to a method for appropriately controlling the injection rate of the flocculant.

  In Patent Document 1, a sludge concentration meter that detects the concentration of sludge flowing through a sludge flow path, and sludge in a sludge storage tank is sent to a sludge dewatering machine according to the concentration of sludge detected by this sludge concentration meter. A concentration control device capable of controlling the concentration of sludge injected into the sludge dehydrator by operating at least one of the sludge injection pump and the coagulant injection pump that sends the coagulant in the coagulant storage tank to the sludge dewaterer; There is disclosed a wastewater treatment apparatus comprising:

  Patent Document 2 discloses a measuring unit that measures the amount of floc present in a dehydrated separation liquid supplied to a measurement tank, and a flocculant that minimizes the amount of floc based on measurement data of the amount of floc by the measuring unit. There is disclosed a flocculant injection amount determination device including a control means for determining an injection amount.

  Patent Document 3 discloses a flocculating means for injecting a flocculant into water or sludge in a reaction tank or in a flow path to flock suspended substances contained in the water or sludge in the reaction tank or in the flow path. And measuring means for measuring turbidity in the gap between flocs in the water or sludge using an agglomeration sensor provided in the reaction tank or in a flow path downstream of the agglomeration means, and this measurement And a control means for controlling the injection amount of the flocculant based on the change with time of the turbidity measured by the means. The aggregation sensor includes a probe that emits laser light into water or sludge and detects scattered light of the laser light generated by particles contained in the water or sludge.

  Patent Document 4 discloses a sludge treatment apparatus in which a flocculant is added to a stock solution in a flocculation mixing tank to form a suspended substance floc and the stock solution is supplied to a dehydrator. In this patent document 4, the size of the floc in the stock solution supply pipe for supplying the stock solution to the dehydrator is photographed, the luminance signal is converted into an electrical signal, and the magnitude of the floc is binarized from the electrical signal. Calculate the average area per floc from the binary image of floc, compare the average analysis area with the preset reference area of floc, calculate the appropriate value, and calculate the proportional set value based on the flock formation status A flocculant injection control method for controlling the flocculant injection rate is disclosed.

However, in a general flocculation step, the rotation speed of the stirring blade provided in the stirring device is 10 to 300 min ⁻¹ , and the flocculant is dispersed in the stock solution under relatively gentle conditions. In this case, a relatively good floc is formed with a wide range of flocculant injection rates. Therefore, even if the techniques disclosed in Patent Documents 1 to 4 are used, it is difficult to determine an appropriate injection rate of the flocculant with high accuracy.

Patent Document 5 discloses a solution of sludge and first polymer flocculant by injecting a solution of the first polymer flocculant into sludge and performing high-speed stirring in which the rotation speed of the stirring device is set to 1000 min ⁻¹ or more. The first agitation step to prepare a mixed sludge by injecting the solution of the second polymer flocculant into the mixed sludge, and the agitation with the rotation speed of the agitator set to 10 to 500 min ⁻¹ , A method for coagulating sludge is disclosed, which includes a second stirring step of mixing the mixed sludge and a second polymer flocculant solution to form an aggregate floc.

However, generally, when the stock solution and the flocculant solution are mixed by high-speed stirring in which the rotation speed of the stirring device is set to 1000 min ⁻¹ or more, the floc is destroyed. Therefore, as described in Patent Document 5, after the high-speed stirring step, a slow stirring step is required in which the stock solution and the flocculant solution are mixed at a relatively gentle rotational speed to form a large floc. In this case, a relatively good floc is formed with a wide range of flocculant injection rates. Therefore, even if the technique disclosed in Patent Document 5 is used, it is difficult to determine an appropriate injection rate of the flocculant with high accuracy.

JP 2004-167401 A JP-A-11-347599 JP 2003-154206 A JP 2005-7338 A International Publication No. 2012/108312

  The present invention has been made in view of the above-mentioned conventional problems, and efficiently aggregates the suspended substance in the stock solution containing the suspended substance, and automatically sets the appropriate injection rate of the flocculant with high accuracy. The object is to provide an aggregation method which can be determined. Moreover, an object of this invention is to provide the aggregating apparatus which can implement such an aggregating method.

  One aspect of the present invention for solving the above-described problems includes a stirring tank, a rotating shaft rotated by a driving source, a stirring blade connected to the rotating shaft and disposed in the stirring tank, and the stirring In a coagulation method for aggregating a stock solution containing suspended solids using a stirrer provided with a stock solution supply pipe connected to a tank, a supply step of supplying the stock solution from the stock solution supply pipe to the stirring tank, An agitation step of supplying the flocculant to the agitation tank or the stock solution supply pipe and injecting the flocculant into the stock solution, a stirring step of rotating the agitation blade to agitate the stock solution injected with the agglomeration agent, and the agitation An optical measurement step of obtaining an optical measurement value by irradiating light to the undiluted solution, a numerical analysis step of obtaining a numerical analysis value by numerically analyzing the optical measurement value, and based on the numerical analysis value, Note to determine the proper injection rate of the flocculant A rate determining step, and a volume of a rotation region formed by rotation of a rotating body composed of the stirring blade and a rotating shaft in the stirring tank is Va [L], and passes through the stirring tank. When the flow rate of the stock solution is Fb [L / sec], the ratio value of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2, which is an aggregation method.

In a preferred aspect of the present invention, the rotation speed of the stirring blade is set to 400 min ⁻¹ or more.
In a preferred aspect of the present invention, the volume Va of the rotation region is in a range of 0.1L to 2.0L.
In a preferred aspect of the present invention, the injection rate determining step determines whether the injection rate of the flocculant is appropriate based on the numerical analysis value, and the appropriate injection rate of the flocculant is determined. Until the process, the supply process, the injection process, the stirring process, the optical measurement process, and the numerical analysis process are repeated while changing the injection rate.
In a preferred aspect of the present invention, the change of the injection rate is to change one or both of the flow rate of the stock solution flowing into the stirring device and the flow rate of the flocculant injected into the stock solution. It is characterized by.

In a preferred aspect of the present invention, the optical measurement step is a step of measuring the transmitted light intensity by irradiating the stirred stock solution with light.
In a preferred aspect of the present invention, the optical measurement step is a step of measuring the scattered light intensity by irradiating the stirred stock solution with light.
In a preferred aspect of the present invention, the optical measurement step is a step of measuring both transmitted light intensity and scattered light intensity by irradiating the stirred stock solution with light.

In a preferred aspect of the present invention, the dispersion of the optical measurement value is used as the numerical analysis value.
In a preferred aspect of the present invention, a peak area of the optical measurement value is used as the numerical analysis value.
In a preferred aspect of the present invention, a standard deviation of the optical measurement value is used as the numerical analysis value.
In a preferred aspect of the present invention, the numerical analysis value is a floc particle size of the suspended substance.

In a preferred aspect of the present invention, the injection rate determination step repeats the supply step, the injection step, the stirring step, the optical measurement step, and the numerical analysis step a plurality of times while changing the injection rate. In this step, a plurality of numerical analysis values are acquired, and an appropriate injection rate of the flocculant is determined based on the plurality of numerical analysis values.
In a preferred aspect of the present invention, an injection rate at which a maximum value or a minimum value is obtained among the plurality of numerical analysis values is determined as the appropriate injection rate.
A preferred aspect of the present invention is an average value of an injection rate at which a maximum value is obtained among the plurality of numerical analysis values and an injection rate at which a second largest value is obtained, or a minimum value among the plurality of numerical analysis values. An average value of an injection rate at which a value is obtained and an injection rate at which the second smallest value is obtained is determined as the appropriate injection rate.
A preferred aspect of the present invention is characterized by further comprising a correction injection rate determining step of determining a correction injection rate by multiplying the appropriate injection rate determined in the injection rate determination step by a correction coefficient.
A preferred embodiment of the present invention further includes a dilution step of diluting the stirred stock solution with a diluent, and the dilution step is performed between the stirring step and the optical measurement step.

  Another aspect of the present invention includes a stirring tank, a rotating shaft rotated by a drive source, a stirring blade connected to the rotating shaft and disposed in the stirring tank, and a stock solution supply connected to the stirring tank And a stirrer that stirs a stock solution containing suspended solids infused with a flocculant; a supply device that feeds the stock solution to the stirrer; and a flocculant that feeds the stirrer or the stock solution supply pipe And an injection device for injecting the flocculant into the stock solution, an optical measurement device for obtaining an optical measurement value by irradiating the stirred stock solution with light, a numerical analysis of the optical measurement value, and a numerical analysis value A rotating body composed of the stirring blade and a rotating shaft in the stirring tank, and a control device that determines an appropriate injection rate of the flocculant based on the numerical analysis value. The volume of the rotation region formed by the rotation is Va [L], When the flow rate of the stock solution passing through the stirring tank is Fb [L / sec], the ratio of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2. .

In a preferred aspect of the present invention, the rotation speed of the stirring blade is set to 400 min ⁻¹ or more.
In a preferred aspect of the present invention, the stock solution inlet of the optical measuring device is located higher than the stock solution outlet of the stirring device.
In a preferred aspect of the present invention, the stock solution outlet of the optical measuring device is located higher than the stock solution inlet of the optical measuring device.

In a preferred aspect of the present invention, the control device determines whether or not an injection rate of the flocculant is appropriate based on the numerical analysis value, and until an appropriate injection rate of the flocculant is determined. , By operating any one or both of the flocculant injection device and the supply device, the stirring device, the optical measurement device, and the numerical analysis device, to supply the stock solution to the stirring tank, The injection of the flocculant into the stock solution, the stirring of the stock solution, the acquisition of the optical measurement value, and the acquisition of the numerical analysis value are repeated while changing the injection rate.
In a preferred aspect of the present invention, the optical measuring device measures the transmitted light intensity by irradiating the stirred stock solution with light.
In a preferred aspect of the present invention, the optical measurement device measures the scattered light intensity by irradiating the stirred stock solution with light.
In a preferred aspect of the present invention, the optical measuring device is both a measuring device for measuring transmitted light intensity and a measuring device for measuring scattered light intensity.

In a preferred aspect of the present invention, the numerical analysis device acquires a variance of the optical measurement value as the numerical analysis value.
In a preferred aspect of the present invention, the numerical analysis device acquires a peak area of the optical measurement value as the numerical analysis value.
In a preferred aspect of the present invention, the numerical analysis device acquires a standard deviation of the optical measurement value as the numerical analysis value.
In a preferred aspect of the present invention, the numerical analysis device acquires the particle size of floc of the suspended substance as the numerical analysis value.

In a preferred aspect of the present invention, the control device operates one or both of the flocculant injection device and the supply device, the stirring device, the optical measurement device, and the numerical analysis device. Supplying the stock solution to the stirring tank, injecting the flocculant into the stock solution, stirring the stock solution, obtaining the optical measurement value, and obtaining the numerical analysis value, while changing the injection rate. A plurality of numerical analysis values are acquired by repeating, and an appropriate injection rate of the flocculant is determined based on the plurality of numerical analysis values.
In a preferred aspect of the present invention, the control device determines an injection rate at which a maximum value or a minimum value is obtained among the plurality of numerical analysis values as the appropriate injection rate.
In a preferred aspect of the present invention, the control device is configured such that an average value of an injection rate at which a maximum value is obtained and an injection rate at which a second largest value is obtained among the plurality of numerical analysis values, or the plurality of numerical values. An average value of the injection rate at which the minimum value is obtained among the analysis values and the injection rate at which the second smallest value is obtained is determined as the appropriate injection rate.

In a preferred aspect of the present invention, the control device determines a correction injection rate by multiplying the determined appropriate injection rate by a correction coefficient.
In a preferred aspect of the present invention, the numerical analysis device is incorporated in the control device.
A preferred aspect of the present invention is characterized by further comprising a diluent supply device for supplying a diluent to the stirred stock solution.

The present invention has the following effects.
(1) According to the present invention, the control device determines that the floc is growing properly from a numerical analysis value obtained by numerical analysis of the optical measurement value. Thereby, the appropriate injection rate of the flocculant can be determined with high accuracy. As a result, the amount of the flocculant used can be reduced. Moreover, the injection rate of the flocculant can be appropriately controlled without the experience and intuition of the operator. Furthermore, even if the properties of the stock solution containing the suspended material (for example, the concentration of the suspended material in the stock solution) change, the injection rate of the flocculant can be controlled appropriately. In particular, in the present invention, the rotation speed of the stirring blade that stirs the stock solution containing the suspended solid material into which the flocculant is injected is set to 400 min ⁻¹ or more. By this stirring, the flocculant is instantaneously dispersed in the stock solution, and the flocculant is efficiently and uniformly mixed with the stock solution. As a result, the suspended substance contained in the stock solution is efficiently aggregated. When such agitation is performed, a high stress is applied to the stock solution into which the flocculant is injected. Therefore, if the flocculant is not injected at an appropriate injection rate, the flocs are destroyed before they grow. According to the present invention, it is possible to determine an appropriate injection rate of the flocculant capable of appropriately growing the floc.
(2) According to the present invention, the value of the ratio of the volume Va of the rotating region of the rotating body to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. Even if the stock solution flow rate Fb is changed, the stirrer is designed so that the value of the ratio of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2, or it is optimal by connecting a plurality of stirrers. Mixing conditions can be achieved. Alternatively, when the volume Va of the rotation region is fixed, the optimum mixing condition can be achieved by changing the stock solution flow rate Fb.
(3) According to the present invention, the value of the ratio of the volume Va to the stock solution flow rate Fb is in the range of 1.1 to 10.2, and the volume Va is in the range of 0.1L to 2.0L. If an agitator is designed under these conditions, an optimally sized agitator can be produced, eliminating the need to produce an unnecessarily large agitator, making the equipment production cost, equipment installation space, and agitation necessary. Can reduce the electricity bill.

It is a schematic diagram which shows the stirring apparatus which concerns on one Embodiment. Fig.2 (a) is a schematic diagram which shows the rotary body comprised from a stirring blade and the rotating shaft in a stirring tank, and FIG.2 (b) rotates the rotary body shown to Fig.2 (a). It is a schematic diagram which shows the rotation area | region formed by this. It is the schematic of the optical measuring device which measures the transmitted light intensity. FIG. 4 (a) shows an example of measurement of transmitted light intensity when flocs are not formed because the injection rate of the flocculant is not appropriate. FIG. 4 (b) shows an appropriate injection rate of the flocculant. Therefore, this is a measurement example of transmitted light intensity when a floc is formed. It is the schematic of the optical measuring device which measures scattered light intensity. FIG. 6A is an example of measurement of scattered light intensity when flocs are not formed because the injection rate of the flocculant is not appropriate, and FIG. 6B shows an appropriate injection rate of the flocculant. Therefore, this is an example of measurement of scattered light intensity when flocs are formed. It is a flowchart of a series of processes for determining an appropriate injection rate. A flow showing the process for determining the appropriate injection rate of the flocculant by calculating the absolute value of the difference between the numerical analysis value and the predetermined target value and comparing the absolute value of this difference with the allowable value FIG. Multiple injection rates were set, multiple numerical analysis values were acquired for each of these injection rates, and the process for determining the appropriate injection rate of the flocculant by comparing the acquired multiple numerical analysis values was represented. FIG. It is the schematic which shows one Embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the schematic which shows another embodiment of the aggregation apparatus of this invention. It is the graph which plotted the result of the 7th experiment.

Hereinafter, embodiments of the present invention will be described.
The flocculation method according to an embodiment of the present invention is a flocculation method for flocculating a stock solution containing a suspended substance, and is connected to a stirring tank, a rotating shaft rotated by a drive source, and the rotating shaft, A stirrer provided with a disposed stirring blade and a stock solution supply pipe connected to a stirring tank is used. This stirring device will be described later. Furthermore, the coagulation method of the present embodiment includes a supply process for supplying the stock solution from the stock solution supply pipe to the stirring tank, an injection process for supplying the flocculant to the stirring tank or the stock solution supply pipe, and injecting the flocculant into the stock solution, Stirring the stock solution in which the flocculant is injected by rotating the blade, optical measurement step of irradiating the stirred stock solution with light to obtain optical measurement values, and numerical analysis of the optical measurement values A numerical analysis step of obtaining a numerical analysis value, and an injection rate determination step of determining an appropriate injection rate of the flocculant based on the numerical analysis value.

  In this specification, the stock solution refers to the liquid to be treated. Examples of the stock solution containing suspended solids include sludge discharged from a wastewater treatment facility or a water purification treatment facility, wastewater in a wastewater treatment facility, raw water in a water purification treatment facility, and the like. The sludge may be either organic sludge or inorganic sludge.

  Examples of the organic sludge include organic sludge generated in sewage treatment, human waste treatment, and wastewater treatment in various industries. More specifically, there may be mentioned first sedimentation basin sludge, surplus sludge, anaerobic digested sludge, aerobic digested sludge, human waste sludge, septic tank sludge, digestion desorbed liquid, coagulated sediment sludge, and the like. The organic sludge may contain an inorganic substance.

  Examples of the inorganic sludge include water purification treatment, construction wastewater treatment, and inorganic sludge generated in various industrial wastewater treatment. Here, the sludge generated in the water purification treatment is sludge discharged from a settling pond, a waste mud pond, a concentration tank, or the like in the water purification treatment facility. The inorganic sludge may contain organic matter.

  Examples of the wastewater in the wastewater treatment facility include wastewater from various industries such as sewage, food industry, drinking water industry, chemical industry, and machinery industry. Examples of raw water in water treatment facilities include river water, lake water, and groundwater.

  Furthermore, the stock solution containing suspended solids may be water prepared in the course of treatment such as waste water treatment or water purification treatment. For example, as an example of the undiluted solution in the wastewater treatment, wastewater adjusted pH, wastewater injected with an inorganic flocculant, wastewater injected with an organic coagulant, wastewater injected with a metal chelating agent, and the like can be mentioned. For example, as an example of the stock solution in the water purification treatment, raw water with adjusted pH, raw water into which an inorganic flocculant has been injected, and the like can be given.

  As the flocculant, any of an inorganic flocculant, an organic flocculant, and a polymer flocculant can be used. Examples of the inorganic flocculant include ferric chloride, aluminum sulfate, aluminum chloride, polyaluminum chloride, iron sulfate, and polyiron sulfate.

  Examples of organic coagulants include polyamine organic coagulants (such as polycondensates of dialkylamine and epichlorohydrin), diallyldimethylammonium chloride organic coagulants (such as polydiallyldimethylammonium chloride), and dicyandiamide organic coagulants (polydicyandiamide). Resin quaternary ammonium salt, etc.).

  As the polymer flocculant, any of an anionic polymer flocculant, a nonionic polymer flocculant, a cationic polymer flocculant, and an amphoteric polymer flocculant can be used. When treating organic sludge, it is particularly preferable to use a cationic polymer flocculant or an amphoteric polymer flocculant.

  Examples of the anionic polymer flocculant include sodium polyacrylate, a copolymer of sodium acrylate and acrylamide, polysodium methacrylate, a copolymer of sodium methacrylate and acrylamide, and the like.

  Examples of nonionic polymer flocculants include polyacrylamide and polyethylene oxide.

  Examples of cationic polymer flocculants include acrylate polymer flocculants (also referred to as “DAA polymer flocculants”), methacrylate polymer flocculants (also referred to as “DAM polymer flocculants”), and amide groups. , Nitrile groups, amine hydrochlorides, formamide groups, and the like, and polyvinylamidines (also referred to as “amidine polymer flocculants”), polyacrylamide Mannich modified products, and the like. Examples of the DAA polymer flocculant include a polymer of a quaternized product of dimethylaminoethyl acrylate, a copolymer of a quaternized product of dimethylaminoethyl acrylate and acrylamide, and the like. Examples of the DAM polymer flocculant include a polymer of a quaternized product of dimethylaminoethyl methacrylate and a copolymer of a quaternized product of dimethylaminoethyl methacrylate and acrylamide.

Examples of the amphoteric polymer flocculant include a quaternized product of dimethylaminoethyl acrylate and a copolymer of acrylamide and acrylic acid, a quaternized product of dimethylaminoethyl methacrylate, and a copolymer of acrylamide and acrylic acid. Can do.
However, the above is an example, and the present invention is not limited to these.

  In the supplying step, the stock solution containing the suspended substance is supplied from the stock solution supply pipe to the stirring tank, and in the injecting step, the aggregating agent as described above is injected into the stock solution containing the suspended material.

  In the stirring step, the stock solution containing the suspended solids is stirred together with the flocculant by the stirring device. Drawing 1 is a mimetic diagram showing stirring device 1 concerning one embodiment. As shown in FIG. 1, the stirring device 1 includes a stirring tank 2 to which a stock solution containing suspended solids is supplied, a stirring blade 8 for stirring the stock solution containing suspended solids, and a rotation to which the stirring blade 8 is connected. A shaft 17 and a drive source 9 (for example, a motor) that rotates the rotating shaft 17 integrally with the stirring blade 8 are provided. The stirring blade 8 has four blades 16 extending radially. However, the number of blades 16 is not limited to this embodiment, and the number of blades 16 may be smaller or larger than four. In addition, the shape of the blade 16 of the present embodiment is a rectangular shape, but may be other shapes such as a trapezoidal shape or a semicircular shape. A stock solution supply pipe 18 for supplying the stock solution to the stirrer 2 is connected to the stirrer 2 of the stirrer 1. Further, a discharge pipe 28 through which the stock solution discharged from the stirring tank 2 of the stirring device 1 flows is connected to the stirring tank 2. The undiluted solution discharged from the discharge pipe 28 flows into an optical measuring device to be described later.

  FIG. 2A is a schematic diagram showing a rotating body 15 composed of the stirring blade 8 and the rotating shaft 17 in the stirring tank 2. The rotating body 15 includes the stirring blade 8 and a part of the rotating shaft 17 located in the stirring tank 2. FIG. 2B is a schematic diagram showing a rotation region 15A formed by the rotation of the rotating body 15 shown in FIG.

The volume Va [L] of the rotating region 15A formed from the rotating rotator 15 is preferably determined in accordance with the type of stock solution, the properties of the stock solution, the physical properties of the flocculant, the dissolution concentration of the flocculant, and the like. In particular, when the volume of the rotation region 15A is Va [L] and the flow rate of the stock solution passing through the stirring tank 2 is Fb [L / sec], the value R of the ratio of the volume Va to the flow rate Fb is 1.1-10. .2 is important. The value R of the ratio of the volume Va to the flow rate Fb is expressed by the following equation (1).
R = Va / Fb (1)
The value R of the ratio of the volume Va to the flow rate Fb is preferably 1.1 to 10.2, and more preferably 2.0 to 7.0. More preferably, the value R of the ratio of the volume Va to the flow rate Fb is 3.0 to 8.0.

  The volume Va of the rotation region 15A is preferably in the range of 0.1L to 2.0L, and more preferably the volume Va is in the range of 0.15L to 2.0L. More preferably, the volume Va is in the range of 0.2L to 1.0L. The volume Va of the rotation region 15A can be changed by connecting a plurality of stirring devices 1 in series or in parallel.

  The volume Vc [L] of the rotating body 15 itself shown in FIG. 2A is preferably 0.5 times or less the volume Va [L] of the rotating region 15A. More preferably, the volume Vc of the rotating body 15 is not more than 0.3 times the volume Va of the rotating region 15A. Even more preferably, the volume Vc of the rotating body 15 is not more than 0.2 times the volume Va of the rotating region 15A.

  The volume Va of the rotation region 15A is preferably 0.4 times or more, more preferably 0.5 times or more the volume Vd (see FIG. 1) of the stirring tank 2.

The stock solution supplied from the stock solution supply pipe 18 to the stirring device 1 is stirred with the flocculant by the stirring blade 8 rotated by the drive source 9. The flocculant may be supplied to the stock solution supply pipe 18 as shown in FIG. 1 or may be supplied to the stirring tank 2. In the stirring device 1 of the present embodiment, the rotation speed of the stirring blade 8 is set to 400 min ⁻¹ or more. By this stirring, the flocculant is instantaneously dispersed in the stock solution, and the flocculant is efficiently and uniformly mixed with the stock solution. When an inorganic flocculant or an organic flocculant is used as the flocculant, the main purpose of the stirring step is to form fine flocs by neutralizing the surface charge of the suspended substance. When a polymer flocculant is used as the flocculant, the main charge of the stirring process is to neutralize the surface charge of the suspended substance and to form larger flocs by the adsorption and crosslinking action of the polymer flocculant. Purpose.

In the conventional aggregating method, the aggregating agent is dispersed in the stock solution by agitation where the rotation speed of the agitating blade of the agitator is set to about 10 to 300 min ⁻¹ . For this reason, it is difficult to uniformly disperse the flocculant in the stock solution. On the other hand, in the present embodiment, the flocculant can be uniformly dispersed in the stock solution by stirring in which the rotation speed of the stirring blade 8 of the stirring device 1 is set to 400 min ⁻¹ or more. As a result, the appropriate injection rate of the flocculant can be determined more accurately.

Moreover, in the conventional coagulation method, since the rotational speed of the stirring blade of the stirring device is set to about 10 to 300 min ⁻¹ , the coagulant is dispersed in the sludge under mild conditions. According to this conventional agglomeration method, the time required for floc formation is long and a large capacity agglomeration tank is required. In the conventional agglomeration method, a relatively good agglutination reaction occurs at a wide range of aggregating agent injection rates. On the other hand, in this embodiment, the flocculant is dispersed in the sludge under severe conditions by stirring with the rotation speed of the stirring blade 8 set to 400 min ⁻¹ or more, so that it is good only when the injection rate is appropriate. Agglutination occurs. Therefore, an appropriate injection rate can be determined with higher accuracy from the result of the aggregation reaction. In the present embodiment, the flocculant can be instantaneously dispersed in the stock solution, and flocs can be formed in a short time. Therefore, the appropriate injection rate of the flocculant can be determined more quickly.

  A line mixer may be used as the stirring device. A line mixer is a mixer built in piping. The advantage of the line mixer is that the mixer is hermetically sealed, so if there are two pumps, one for the stock solution upstream of the line mixer and the other for the flocculant pump, the liquid can be sent downstream of the line mixer. is there. On the other hand, as shown in FIG. 1, in the case of the stirring device 1 in which the stirring blade 8 is installed in the stirring tank 2, the upper part of the stirring tank 2 is open, so that the stock solution is sent downstream of the stirring device 1. In addition to the undiluted solution pump and the flocculant pump upstream of the stirring device 1, another pump or a device equivalent to a pump is required. For this reason, usually, a pump is not installed and the liquid is generally sent downstream with a height difference.

In the agitation step, it is important to agitate the stock solution containing suspended solids into which the flocculant has been injected by rotating the agitation blade 8 at a rotation speed of 400 min ⁻¹ or more. Preferably, the rotation speed of the stirring blade 8 is 400 min ⁻¹ or more. More preferably, the rotation speed of the stirring blade 8 is 600 min ⁻¹ or more. Preferably, the peripheral speed of the outer edge portion 16A (see FIG. 2) of the blade 16 of the stirring blade 8 is 1 to 5 m / second.

The rotational speed of the stirring blade 8 depends on the type of stock solution containing suspended solids (for example, drainage and sludge), the nature of the stock solution (for example, SS (Suspended Solids concentration, viscosity, etc.)), and the type of flocculant (for example, Based on inorganic flocculants, organic flocculants, polymer flocculants, etc.), it is preferable to adjust at 400 min ⁻¹ or more. Flock formation in the stirring step may be performed in the stirring tank 2 or in the discharge pipe 28. The flocculant to be injected into the stock solution containing the suspended substance in the injection step may be injected into the stirring tank 2 or may be injected into the stock solution supply pipe 18 connected to the stirring tank 2.

  An optical measurement process is performed in order to irradiate light to the stock solution containing the floc formed by the stirring process, and to obtain an optical measurement value. Examples of the optical measurement values to be acquired include transmitted light intensity, transmittance, scattered light intensity, diffracted light intensity, diffracted / scattered light intensity, absorbance, and reflected light intensity. Multiple types of optical measurements may be measured simultaneously. For example, the transmitted light intensity may be measured and the scattered light intensity may be measured. In this case, both an optical measurement device that measures the transmitted light intensity and an optical measurement device that measures the scattered light intensity are provided.

  In the optical measurement method, generally, an optical measurement device including a light source that emits light and a photodetector that receives light emitted from the light source is used. As a light source used in the optical measurement method, various lamps (mercury lamp, xenon lamp, krypton lamp, metal halide lamp, halogen lamp, etc.), various lasers (solid laser, semiconductor laser, liquid laser, gas laser, etc.), various An LED or the like can be used. As the photodetector, a CCD, photodiode, phototransistor, photomultiplier tube, photoconductive element, infrared sensor, CMOS, or the like can be used. In any case, a commercially available optical measuring device can be used as the optical measuring device.

  FIG. 3 is a schematic diagram of an optical measuring device for measuring transmitted light intensity. As shown in FIG. 3, a pair of transparent windows 40, 40 through which light can pass is provided in the discharge pipe 28 through which the stock solution containing floc flows. A light source 41 is disposed at a position where light can be emitted into the discharge pipe 28 through one of the transparent windows 40, 40, and light detection is performed at a position where light emitted from the discharge pipe 28 can be received through the other transparent window 40. A container 42 is arranged. The light transmitted through the stock solution containing floc is detected by the photodetector 42. The transmitted light intensity is measured for a predetermined time, and the measured transmitted light intensity is used as an optical measurement value. The measurement of the transmitted light intensity is performed once or a plurality of times while changing the injection rate of the flocculant, thereby obtaining at least one optical measurement value. The transmitted light intensity detected by the photodetector 42 is accumulated in the data logger 50 and then sent to the numerical analysis device 5 described later. The numerical analysis value obtained by the numerical analysis device 5 is sent to the control device 6, and the control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value. The data logger 50, the numerical analysis device 5, and the control device 6 may be provided separately. Alternatively, the data logger 50 and the numerical analysis device 5 may be incorporated in a control device 6 configured as one computer or one programmable logic controller (for example, a sequencer).

  A measurement example in which the transmitted light intensity of a stock solution (for example, sludge) containing a suspended substance is measured will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4 (a) shows an example of measurement of transmitted light intensity when flocs are not formed because the injection rate of the flocculant is not appropriate, and FIG. 4 (b) shows an appropriate injection rate of the flocculant. Therefore, an example of measurement of transmitted light intensity when a floc is formed will be shown. 4A and 4B, the horizontal axis represents measurement time, and the vertical axis represents transmitted light intensity.

  As shown in FIG. 4A, if the floc is not formed, the light emitted from the light source 41 is blocked by the suspended matter and hardly reaches the photodetector 42. As a result, the measured transmitted light intensity changes at a low value as the measurement time elapses. On the other hand, when the floc is formed, the suspended substance is collected as a floc. Therefore, as shown in FIG. 4B, the time when the light emitted from the light source 41 is blocked by the flock and does not reach the light detector 42 and the time when the light reaches the light detector 42 through the gap between the flocks are as follows. Exists. As a result, a plurality of transmitted light intensity peaks are measured. The plurality of peaks are used in a numerical analysis process described later.

  FIG. 5 is a schematic diagram of an optical measuring device for measuring scattered light intensity. As shown in FIG. 5, an irradiator 43 </ b> A and a light receiving unit that receives scattered light caused by collision of light emitted from the irradiator 43 </ b> A with a suspended substance inside the discharge pipe 28 through which a stock solution containing floc flows. The container 44A is spaced apart by a minute gap S. For example, the irradiator 43A and the light receiver 44A are arranged such that the central axis of the irradiator 43A and the central axis of the light receiver 44A intersect at an angle of 90 °. The irradiator 43A is an optical fiber that guides light from the light source 43B such as a laser into the discharge pipe 28, and the light receiver 44A is an optical fiber that guides scattered light to a photodetector 44B such as a phototransistor. Light scattered by colliding with suspended matter or floc is detected by the photodetector 44B through the light receiver 44A. The photodetector 44B measures the scattered light intensity, and uses the measured scattered light intensity as an optical measurement value. The measurement of the scattered light intensity is performed once or a plurality of times while changing the injection rate of the flocculant, whereby at least one optical measurement value is obtained. The scattered light intensity detected by the photodetector 44B is accumulated in the data logger 50 and then sent to the numerical analysis device 5 described later. The numerical analysis value obtained by the numerical analysis device 5 is sent to the control device 6, and the control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value. The data logger 50, the numerical analysis device 5, and the control device 6 may be provided separately. Alternatively, the data logger 50 and the numerical analysis device 5 may be incorporated in a control device 6 configured as one computer or one programmable logic controller (for example, a sequencer).

  A measurement example in which the scattered light intensity of a stock solution containing a suspended substance is measured will be described with reference to FIGS. 6 (a) and 6 (b). FIG. 6A shows an example of measurement of scattered light intensity when flocs are not formed because the injection rate of the flocculant is not appropriate. The upper graph shows the measured scattered light intensity at the lower level. The graph shows the average intensity of scattered light. FIG. 6B is a measurement example of the scattered light intensity when flocs are formed because the injection rate of the flocculant is appropriate, and the upper graph shows the measured scattered light intensity at the lower level. The graph shows the average intensity of scattered light. 6A and 6B, the horizontal axis represents the measurement time, and the vertical axis represents the scattered light intensity or the average intensity of the scattered light. Here, the average intensity is an average intensity for a predetermined time.

  If no floc is formed, a lot of suspended matter enters the minute gap S, and more light is reflected from the suspended matter. Therefore, the intensity of the scattered light measured by the photodetector 44B becomes high as shown in FIG. On the other hand, when the floc is formed, the suspended substance is collected as a floc. In this case, the amount of the suspended substance entering the minute gap S is reduced, and the light reflected from the suspended substance is reduced. Therefore, the intensity of the scattered light measured by the photodetector 44B becomes low as shown in FIG. This scattered light intensity is used in a numerical analysis process described later. The average intensity of the scattered light may be used in the numerical analysis process.

  When the scattered light intensity is used as an optical measurement value, for example, the formation of flocs is determined by decreasing the intensity of scattered light (or the average intensity of scattered light) from the suspended substance. Therefore, the measurement of scattered light intensity is not suitable for a stock solution having a high concentration of suspended solids such as sludge and a relatively large suspended solid and a large floc formed. On the other hand, the scattered light intensity measurement is a stock solution containing a fine suspended substance, and the formed floc is also suitable for the measurement of a fine stock solution. Such a stock solution is, for example, raw water for water purification treatment.

  In the numerical analysis step, a numerical analysis value is obtained by numerical analysis of the optical measurement value obtained in the optical measurement step. Examples of numerical analysis values include an average value of optical measurement values, dispersion, standard deviation, peak area, peak height, and the like. The dispersion of the optical measurement values is a value obtained by statistically analyzing the optical measurement values, and is an amount indicating the degree of dispersion of the distribution of the optical measurement values obtained during a predetermined measurement time. Standard deviation is the positive value of the square root of the variance. The peak area is a graph drawn by plotting optical measurement values obtained during a predetermined measurement time on a graph in which the vertical axis represents the optical measurement value and the horizontal axis represents the measurement time, and the reference This is the area of a region surrounded by a line (for example, a base line). For example, the peak area corresponds to the area of the hatched region in FIG. The peak height is the peak of a curve drawn by plotting the optical measurement values obtained during a given measurement time on a graph where the vertical axis represents the optical measurement value and the horizontal axis represents the measurement time. The height from the horizontal axis.

  The number of optical measurement values above a certain threshold or the number of optical measurement values below a certain threshold may be used as the numerical analysis value. In the numerical analysis step, SS concentration, turbidity, chromaticity, floc particle size, etc. may be calculated from the optical measurement values, and these may be used as numerical analysis values. Here, the floc particle diameter means the diameter of the floc when the floc is spherical. When the floc is not spherical, the floc particle diameter means a Stokes diameter or a particle diameter measured by various measuring methods. The floc particle size may be the average particle size of the floc. Examples of the average particle diameter include an arithmetic average diameter, a maximum diameter, and a median diameter. The average particle diameter may be based on the number, may be based on mass, or may be based on volume.

  Known methods such as a transmitted light measurement method, a scattered light measurement method, a transmitted light / scattered light comparison method, and an integrating sphere measurement method can be used as methods for calculating the SS concentration and turbidity from the optical measurement values. As a method for calculating chromaticity from the optical measurement value, a known method such as a transmitted light measurement method can be used. As a method for calculating the floc particle diameter from the optical measurement value, a known method such as a laser diffraction / scattering method or a method of analyzing an image taken with a camera can be used. The floc particle size may be an average floc particle size or a particle size distribution of floc particle size. A commercially available measuring apparatus capable of calculating the SS concentration, turbidity, chromaticity, floc particle diameter and the like from the obtained optical measurement values can be used while performing optical measurement.

  The injection rate determination step is performed by using at least one numerical analysis value obtained by performing the stock solution supply step, the flocculant injection step, the stirring step, the optical measurement step, and the numerical analysis step at least once. This is a step of determining an appropriate injection rate. That is, in the present embodiment described so far, a stock solution containing a suspended substance is supplied to a stirring tank, a flocculant is injected into the stock solution, and the stock solution is stirred and stirred to form a suspended substance floc. The obtained stock solution is subjected to optical measurement, and the obtained optical measurement value is numerically analyzed to obtain a numerical analysis value. Based on the numerical analysis value obtained, it is determined whether or not the injection rate of the flocculant is appropriate. If the injection rate is not appropriate, the injection rate of the flocculant is changed, and the stirring step, the optical measurement step, Repeat the numerical analysis process to determine the proper injection rate. Depending on the injection rate of the flocculant, the suspended substance flocs may not be formed.

  The injection rate of the flocculant injected into the stock solution containing the suspended substance can be changed by changing the flow rate of the flocculant injected into the stock solution while the flow rate of the stock solution is controlled to be constant. Alternatively, the injection rate of the flocculant may be changed by changing the flow rate of the stock solution while the flow rate of the flocculant is controlled to be constant. Alternatively, both the flow rate of the stock solution and the flow rate of the flocculant may be changed in order to change the injection rate of the flocculant.

  FIG. 7 shows a flow chart showing a process for determining an appropriate injection rate. As shown in FIG. 7, in this embodiment, first, the injection rate a of the flocculant is set (step 1). The flocculant is injected into the stock solution containing the suspended solids supplied in the supply step at this injection rate a, and the stock solution is stirred together with the flocculant to form a floc (step 2). An optical measurement is performed on the stirred stock solution (step 3). Numerical analysis is performed on the optical measurement value obtained by the optical measurement, and thereby the numerical analysis value X is obtained (step 4). Based on this numerical analysis value X, it is determined whether or not the injection rate of the flocculant is appropriate (step 5).

  When the injection rate of the flocculant is not appropriate, the injection rate a of the flocculant is changed (step 6). In step 6, when the appropriate injection rate is determined by gradually decreasing the injection rate from the high injection rate, the predetermined change width b is subtracted from the injection rate a. When the appropriate injection rate is determined by gradually increasing the injection rate from the low injection rate a, a predetermined change width b is added to the injection rate a. At this changed injection rate a, Step 2, Step 3, Step 4, and Step 5 are repeated to obtain a new numerical analysis value X, and the flocculant injection is performed based on the new numerical analysis value X. It is determined whether the rate is appropriate. When the injection rate of the flocculant is appropriate, the determining step of the injection rate of the flocculant is completed.

  As a method of determining whether or not the injection rate of the flocculant is appropriate in Step 5, an absolute value of a difference between the numerical analysis value and a predetermined target value is obtained, and the absolute value of this difference is determined in advance. When the value is smaller than the value, there is a method of determining that the injection rate of the flocculant is appropriate. If the absolute value of the difference between the numerical analysis value and the target value is greater than or equal to the allowable value, the injection rate of the flocculant is changed, the stock solution supply step, the flocculant injection step, the stirring step, and the optical measurement step The numerical analysis process is performed again. Then, until the absolute value of the difference between the obtained numerical analysis value and the target value is smaller than the allowable value, the undiluted solution supply process, the flocculant injection process, the stirring process, the optical measurement process, and the numerical analysis process are aggregated. Repeat with different injection rates.

  An absolute value of the difference between the numerical analysis value described above and a predetermined target value is obtained, and a process for determining an appropriate injection rate of the flocculant by comparing the absolute value of this difference with an allowable value is shown. A flow chart is shown in FIG. As shown in FIG. 8, the injection rate a is set (step 1), and the flocculant is injected into the stock solution containing suspended solids supplied in the supply process at this injection rate a to form a floc. The stock solution is stirred with the flocculant (step 2). An optical measurement is performed on the stirred stock solution (step 3). Numerical analysis is performed on the optical measurement value obtained by the optical measurement, and a numerical analysis value X is obtained (step 4). Based on the numerical analysis value X obtained by numerical analysis, it is determined whether or not the injection rate of the flocculant is appropriate (step 5). In step 5, the absolute value of the difference between the predetermined target value Xt and the numerical analysis value X is calculated, and the absolute value of this difference is compared with a preset allowable value m.

  When the absolute value of the difference between the predetermined target value Xt and the numerical analysis value X is greater than or equal to the allowable value m, it is determined that the flocculant injection rate is not appropriate, and the flocculant injection rate a is changed. (Step 6). In step 6, when the appropriate injection rate is determined by gradually decreasing the injection rate from the high injection rate, the predetermined change width b is subtracted from the injection rate a. When the appropriate injection rate is determined by gradually increasing the injection rate from the low injection rate a, a predetermined change width b is added to the injection rate a. Step 2, Step 3, Step 4 and Step 5 are repeated with this changed injection rate a to obtain a new numerical analysis value X. Based on this new numerical analysis value X, the injection rate of the flocculant It is determined again whether or not is appropriate. When the absolute value of the difference between the predetermined target value Xt and the numerical analysis value X is smaller than the allowable value m, that is, when the injection rate of the flocculant is appropriate, the determination process of the flocculant injection rate ends. .

  Other methods for determining an appropriate flocculant injection rate include the methods described below. In this method, a plurality of injection rates are set in advance. At each of a plurality of preset injection rates, the flocculant is injected into the stock solution containing suspended solids supplied in the supply step, and the stock solution is stirred together with the flocculant to form a floc. Then, the stock solution stirred at each of the plurality of injection rates is subjected to optical measurement, and a plurality of numerical analysis values at each of the plurality of injection rates are acquired. The obtained numerical analysis values are compared, and, for example, the injection rate at which the maximum value or the minimum value is obtained is determined as an appropriate injection rate. A flowchart of this series of steps is shown in FIG. FIG. 9 is for setting a plurality of injection rates, acquiring a plurality of numerical analysis values at each of these injection rates, and determining the appropriate injection rate of the flocculant by comparing the acquired plurality of numerical analysis values. It is a flowchart showing a process.

  As shown in FIG. 9, in this method, a plurality (n) of injection rates ai = a1, a2,... An are set (step 1). i is set to 1 and the first injection rate ai (= a1) is selected (step 2). The flocculant is injected into the stock solution containing the suspended solids supplied in the supply step at an injection rate a1, and the stock solution is stirred together with the flocculant to form a floc (step 3). An optical measurement is performed on the stirred stock solution (step 4). Numerical analysis is performed on the optical measurement value obtained by the optical measurement, thereby obtaining a numerical analysis value Xi (= X1) (step 5). Thereafter, it is determined whether i = n (step 6). If i is not n, 1 is added to i (step 7). For example, when i is 1, i is changed to 2, and a2 is selected as the injection rate ai.

  The numerical analysis value Xi is acquired by repeating Step 3, Step 4 and Step 5 again with the changed injection rate ai. For example, when ai = a2, a numerical analysis value X2 is obtained, and when ai = a3, a numerical analysis value X3 is obtained. In order to obtain the numerical analysis value Xi, Step 3, Step 4, and Step 5 are repeated until i = n. Therefore, numerical analysis values X1, X2,... Xn are obtained. Based on the obtained numerical analysis values X1, X2,... Xn, an appropriate injection rate of the flocculant is determined (step 8). For example, the injection rate at which the maximum value or the minimum value of the numerical analysis values X1, X2,... Xn is obtained is determined as an appropriate injection rate.

  The average of the injection rate at which the largest numerical analysis value was obtained and the injection rate at which the second largest numerical analysis value was obtained may be used as the appropriate injection rate. Or it is good also considering the average value of the injection rate from which the smallest numerical analysis value was obtained, and the injection rate from which the 2nd smallest numerical analysis value was obtained as an appropriate injection rate.

  Moreover, you may employ | adopt the method described below as another method of determining the injection rate of an appropriate coagulant | flocculant based on the obtained numerical analysis value X1, X2, ... Xn. The numerical analysis values X1, X2,... Xn at the injection rates a1, a2,... An are plotted on the graph in which the vertical axis represents the numerical analysis values and the horizontal axis represents the injection rate of the flocculant. An approximate expression indicating the relationship between the injection rates a1, a2,... An and the numerical analysis values X1, X2,... Xn is calculated, and based on the obtained approximate expression, an appropriate injection rate of the flocculant Can be determined. For example, the injection rate at which the peak value of the numerical analysis value is obtained can be calculated from the approximate expression, and the obtained injection rate can be set as an appropriate injection rate of the flocculant.

  Furthermore, the aggregation method mentioned above may include the dilution process which dilutes the stock solution stirred at the stirring process with a diluent as needed. The dilution step is performed between the stirring step and the optical measurement step. For example, in the flowchart shown in FIG. 7, the dilution process is performed between Step 2 and Step 3, and in the flowchart shown in FIG. 8, it is performed between Step 2 and Step 3. The dilution process is performed between Step 3 and Step 4 in the flowchart shown in FIG.

  The purpose of the dilution process is to reduce the concentration of suspended matter or floc by diluting the stirred stock solution with the diluent. In stock solutions with a high concentration of suspended solids, there is no difference between the optical measurement when floc is formed and the optical measurement when no floc is formed, and as a result, it is difficult to determine the injection rate of the flocculant. There are cases. For example, in the optical measurement process, when measuring the transmitted light intensity of a stock solution with a high concentration of suspended solids, there is almost no gap between the flocs even if flocs are formed with an appropriate injection rate of the flocculant, As shown in FIG. 4A, the transmitted light intensity may become substantially constant. On the other hand, when diluting the stirred stock solution with the diluent, the gap between the flocs can be increased, so that light is transmitted through the gap between the flocks, and transmitted as shown in FIG. Multiple light intensity peaks are measured. As a result, there is a difference between the transmitted light intensity when the floc is formed and the transmitted light intensity when the floc is not formed, and an appropriate injection rate can be determined. As the diluent, pure water, tap water, industrial water, ground water, treated water for various wastewater treatment, seawater, and the like can be used.

  The corrected injection rate may be determined by multiplying the obtained appropriate injection rate by a correction coefficient. When the corrected injection rate is determined, this corrected injection rate is used as the injection rate of the flocculant injected into the stock solution containing suspended solids. The step of determining the corrected injection rate is performed after an appropriate injection rate is determined in the injection rate determination step. For example, when it is desired to suppress the running cost of the flocculant, an appropriate injection rate obtained in the injection rate determination step may be multiplied by a correction coefficient of 0.9. When it is desired to increase the dewatering efficiency in the dewatering step performed after the aggregation step, the appropriate injection rate obtained in the injection rate determining step may be multiplied by a correction coefficient of 1.1.

According to the present embodiment, the control device described later determines that the floc is growing properly from the numerical analysis value obtained by numerical analysis of the optical measurement value. Thereby, the appropriate injection rate of the flocculant can be determined with high accuracy. As a result, the amount of the flocculant used can be reduced. Moreover, the injection rate of the flocculant can be appropriately controlled without the experience and intuition of the operator. Furthermore, even if the properties of the stock solution containing the suspended material (for example, the concentration of the suspended material in the stock solution) change, the injection rate of the flocculant can be controlled appropriately. In particular, in the present embodiment, the rotation speed of the stirring blade 8 that stirs the stock solution containing the suspended solid material into which the flocculant is injected is set to 400 min ⁻¹ or more. By this stirring, the flocculant is instantaneously dispersed in the stock solution, and the flocculant is efficiently and uniformly mixed with the stock solution. As a result, the suspended substance contained in the stock solution is efficiently aggregated. When such agitation is performed, a high stress is applied to the stock solution into which the flocculant is injected. Therefore, if the flocculant is not injected at an appropriate injection rate, the flocs are destroyed before they grow. According to this embodiment, it is possible to determine an appropriate injection rate of the flocculant capable of appropriately growing the floc.

Further, in the conventional flocculation method, the flocculant is dispersed in the stock solution by stirring in which the rotation speed of the stirring blade of the stirrer is set to about 10 to 300 min ⁻¹ , so that the flocculant can be uniformly dispersed in the stock solution. difficult. On the other hand, in the above-described embodiment, the flocculant can be uniformly dispersed in the stock solution by stirring with the rotation speed of the stirring blade 8 set to 400 min ⁻¹ or more. Therefore, the appropriate injection rate of the flocculant can be determined more accurately. Furthermore, in the above-described embodiment, since the flocculant can be instantaneously dispersed in the stock solution and flocs can be formed in a short time, the appropriate injection rate of the flocculant can be determined more quickly.

  Furthermore, according to this embodiment, the value of the ratio of the volume Va [L] of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. Even if the stock solution flow rate Fb is changed, the stirrer 1 is designed so that the value of the ratio of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2, or a plurality of stirrers 1 are connected. Optimal mixing conditions can be achieved. Alternatively, when the volume Va of the rotation region 15A is fixed, the optimum mixing condition can be achieved by changing the stock solution flow rate Fb.

  Furthermore, according to this embodiment, the value of the ratio of the volume Va to the stock solution flow rate Fb is in the range of 1.1 to 10.2, and the volume Va is in the range of 0.1L to 2.0L. If the stirrer 1 is designed under such conditions, the stirrer 1 of the optimum size can be manufactured, so that it is not necessary to manufacture an unnecessarily large stirrer 1, the manufacturing cost of the apparatus, the installation space of the apparatus, Electricity cost required for stirring can be reduced.

Next, an aggregating apparatus for carrying out the above-described aggregating method will be described.
FIG. 10 is a schematic view showing an embodiment of the aggregating apparatus of the present invention. The aggregating apparatus shown in FIG. 10 has a configuration in which a stock solution storage tank 10, a stirring device 1, and an optical measuring device 3 are connected in series in this order. The stock solution storage tank 10 stores a stock solution containing suspended solids. The stirring apparatus 1 shown in FIG. 10 has the same configuration as the stirring apparatus 1 described with reference to FIGS. 1, 2 (a), and 2 (b). The stirring device 1 includes a stirring tank 2 to which a stock solution containing a suspended substance is supplied, a stirring blade 8 for stirring the stock solution containing a suspended substance, a rotating shaft 17 to which the stirring blade 8 is connected, and a rotating shaft 17. A drive source 9 (for example, a motor) that rotates integrally with the stirring blade 8 is provided. The agitation tank 2 of the agitation apparatus 1 is connected to a stock solution supply pipe 18 for supplying the stock solution to the agitation tank 2, and the stock solution supply pipe 18 agitates the stock solution stored in the stock solution storage tank 10 at a predetermined flow rate. A supply device 7 for supplying the tank 2 is arranged. The supply device 7 is, for example, a pump, a valve, or a combination of a pump and a valve.

  Further, a discharge pipe 28 through which the stock solution discharged from the stirring tank 2 of the stirring device 1 flows is connected to the stirring tank 2, and the optical measuring device 3 is disposed in the discharge pipe 28. The optical measuring device 3 is, for example, a measuring device that measures the above-described transmitted light intensity or a measuring device that measures scattered light intensity. An optical measurement device that measures transmitted light intensity and an optical measurement device that measures scattered light intensity may be arranged in series. The optical measuring device 3 may be a measuring device capable of measuring transmittance, intensity of diffracted light, intensity of diffracted / scattered light, absorbance, intensity of reflected light, and the like.

  A flocculant storage tank 11 for storing the flocculant is provided, and a flocculant supply pipe 26 extending from the flocculant storage tank 11 is connected to the stirring tank 2. The flocculant supply pipe 26 is provided with the flocculant injection device 4. The flocculant injection device 4 is a device that injects the flocculant at a predetermined injection rate into the stock solution containing suspended solids. The flocculant injection device 4 is, for example, a pump, a valve, or a combination of a pump and a valve.

In this aggregating apparatus, the stock solution containing the suspended substance is supplied from the stock solution storage tank 10 to the stirring tank 2 by the supply device 7. The value of the ratio of the volume Va (see FIG. 2B) of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. The flocculant is supplied to the stirring tank 2 by the flocculant injection device 4. In the agitation tank 2, the agitation blade 8 is rotated at a rotational speed of 400 min ⁻¹ or more to mix the stock solution and the flocculant. This forms a floc of suspended material. Depending on the injection rate of the flocculant, the suspended substance flocs may not be formed. That is, in the stirring device 1, the stirring blade 8 is rotated at a rotational speed of 400 min ⁻¹ or more in order to form a suspended substance floc, but depending on the injection rate of the flocculant, the suspended substance floc is not formed. There is a case.

  A numerical analysis device 5 is electrically connected to the optical measuring device 3, and a control device 6 is electrically connected to the numerical analysis device 5. The numerical analysis device 5 may be incorporated in the control device 6. The control device 6 is electrically connected to the flocculant injection device 4.

  With such a configuration, the optical measurement value obtained from the optical measurement device 3 is sent to the numerical analysis device 5 as described above. The numerical analysis device 5 numerically analyzes the optical measurement value and acquires the numerical analysis value. The obtained numerical analysis value is sent to the control device 6. The control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value by the method as described above.

  FIG. 11 is a schematic view showing another embodiment of the aggregating apparatus of the present invention. In the coagulation apparatus shown in FIG. 11, the coagulant supply pipe 26 for supplying the coagulant is connected to the stock solution supply pipe 18 and is not connected to the stirring tank 2. Since the other configuration is the same as that of the embodiment shown in FIG. 10, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted. In this embodiment, the flocculant is injected into the stock solution supply pipe 18 disposed on the upstream side of the stirring tank 2. Thus, the flocculant injected into the stock solution containing the suspended solids may be injected into the stirring tank 2 as shown in FIG. 10, or upstream of the stirring tank 2 as shown in FIG. It may be injected into the undiluted solution supply pipe 18.

  FIG. 12 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 12, a line mixer is employed as the stirring apparatus 1. Since the other configuration is the same as that of the embodiment shown in FIG. 11, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted. The line mixer 1 is a mixer incorporated in a pipe. The advantage of the line mixer 1 is that the line mixer 1 is hermetically sealed. Therefore, if there are two pumps, that is, a supply device 7 disposed upstream of the line mixer 1 and a flocculant injection device 4, the line mixer 1 It is a point which can send undiluted | stock solution downstream.

FIG. 13 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 13, an aggregating tank agitation apparatus 12 different from the agitation apparatus 1 described so far is provided. The agglomeration tank agitation apparatus 12 is a conventionally used agitation apparatus, and the rotational speed of the agitation blade of the agglomeration tank agitation apparatus 12 is set to about 10 to 300 min ⁻¹ . A stock solution supply pipe (stock solution supply source pipe) 18 extending from the stock solution storage tank 10 includes a first stock solution supply pipe 19 connected to the stirring device 1, and a second stock solution supply pipe 25 connected to the aggregation tank stirring device 12. Branch to The stirrer 1, the supply device 7, the optical measurement device 3, the flocculant injection device 4, and the flocculant supply pipe 26 are the same as those in the embodiment shown in FIG. Therefore, the detailed description is abbreviate | omitted. Hereinafter, the supply device 7 is referred to as a first supply device 7, the flocculant injection device 4 is referred to as a first flocculant injection device, and the flocculant supply pipe 26 is referred to as a first flocculant supply pipe.

  The agglomeration tank agitation device 12 includes a coagulation agitation tank 37 to which a stock solution containing suspended substances is supplied, a coagulation tank agitation blade 38 for agitating the stock solution containing suspended substances, and a coagulation tank drive for rotating the agglomeration tank agitation blades 38. A source 39 (for example, a motor). A second stock solution supply pipe 25 is connected to the coagulation stirrer tank 37 of the coagulation tank stirrer 12, and the stock solution containing suspended solids is supplied to the coagulation stirrer tank 37 at a predetermined flow rate in the second stock solution supply pipe 25. A second supply device 35 for supplying is arranged. The second supply device 35 is, for example, a pump, a valve, or a combination of a pump and a valve.

  In the embodiment shown in FIG. 13, the first stock solution supply pipe 19 is branched from between the stock solution storage tank 10 and the second supply device 35, but the second supply device 35 and the coagulation agitation tank You may branch from between 37. Alternatively, the first stock solution supply pipe 19 may be directly connected to the stock solution storage tank 10. In this case, the stock solution supply pipe (stock solution supply source pipe) 18 is omitted.

  A second flocculant supply pipe 36 extending from the flocculant storage tank 11 that stores the flocculant is connected to the flocculant stirring tank 37. A second flocculant injection device 45 is disposed in the second flocculant supply pipe 36. The second flocculant injection device 45 is a device that injects the flocculant into the stock solution containing the suspended substance at a predetermined injection rate. The flocculant injection device 45 is, for example, a pump, a valve, or a combination of a pump and a valve. The flocculant storage tank 11 is also connected to the agitation tank 2 via the first flocculant supply pipe 26. In the embodiment shown in FIG. 13, the first flocculant supply pipe 26 is directly connected to the flocculant storage tank 11, but from between the flocculant storage tank 11 and the second flocculant injection device 45. It may branch off. Alternatively, the first flocculant supply pipe 26 may be branched from between the second flocculant injection device 45 and the flocculant stirring tank 37.

  A second discharge pipe 46 through which the stock solution discharged from the coagulation stirring tank 37 flows is connected to the coagulation stirring tank 37, and the dehydrator 14 is connected to the downstream side of the second discharge pipe 46. The dehydrator 14 dehydrates the stock solution in which flocks are formed, and separates it into a filtrate and a cake. The cake is recovered from the dehydrator 14.

  A numerical analysis device 5 is electrically connected to the optical measurement device 3 disposed on the downstream side of the stirring device 1, and a control device 6 is electrically connected to the numerical analysis device 5. The numerical analysis device 5 may be incorporated in the control device 6. The control device 6 is electrically connected to the first flocculant injection device 4 and the second flocculant injection device 45.

  In the aggregating device having such a configuration, first, the first supply device 7 is operated to supply the stock solution containing the suspended substance to the stirring device 1. The value of the ratio of the volume Va (see FIG. 2B) of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. The stock solution stirred by the stirring device 1 is sent to the optical measuring device 3. The optical measuring device 3 performs an optical measurement of the stirred stock solution and acquires an optical measurement value. The optical measurement value obtained from the optical measurement device 3 is sent to the numerical analysis device 5 as described above. The numerical analysis device 5 numerically analyzes the optical measurement value and acquires the numerical analysis value. The obtained numerical analysis value is sent to the control device 6. The control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value by the method as described above.

  The determined injection rate is sent to the second flocculant injection device 45. Then, the first supply device 7 is stopped and the second supply device 35 is operated. Thereby, the stock solution stored in the stock solution storage tank 10 is supplied to the agglomeration tank stirring device 12. The injection rate of the flocculant injected into the coagulation tank stirring device 12 is the injection rate determined previously. In this way, the flocculant is injected into the stock solution at an appropriate injection rate, and flocs are formed in the stock solution. The stock solution containing the flock is sent to the dehydrator 14 and dehydrated by the dehydrator 14.

  FIG. 14 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 14, a settling tank 20 is provided instead of the dehydrator 14. Since the other configuration is the same as that of the embodiment shown in FIG. 13, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted. The floc in the undiluted solution supplied to the settling tank 20 settles toward the bottom of the settling tank 20 due to its own weight, so that the undiluted solution containing the floc is a concentrated undiluted solution in which the floc exists at a high concentration (for example, concentrated sludge). And the processed liquid without floc. By providing the precipitation tank 20 in this way, it is possible to separate the floc and the processed liquid.

FIG. 15 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the flocculating apparatus shown in FIG. 15, a flocculating tank stirring apparatus 21 different from the flocculating tank stirring apparatus 12 is connected to the coagulating tank stirring apparatus 12 in series with the coagulating tank stirring apparatus 12. Hereinafter, the agglomeration tank agitation device 12 is referred to as a first agglomeration tank agitation device 12, and the agglomeration tank agitation device 21 is referred to as a second agglomeration tank agitation device 21. The second agglomeration tank agitation device 21 is a conventionally used agitation device, and the rotation speed of the agitation blade of the agglomeration tank agitation device 21 is set to a rotation speed of about 10 to 300 min ⁻¹ . Other configurations that are not particularly described are the same as those of the embodiment shown in FIG. 14, and thus the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  The second agglomeration tank agitation device 21 of the embodiment shown in FIG. 15 agitates this undiluted solution with a second agglomeration agitation tank 47 supplied with the stock solution in which the flocs are formed by the first agglomeration tank agitation device 12 A second agglomeration tank agitation blade 48 and a second agglomeration tank drive source 49 (for example, a motor) that rotates the second agglomeration tank agitation blade 48. The second aggregation stirring tank 47 is adjacent to the first aggregation stirring tank 37, and the second aggregation stirring tank 47 is directly connected to the first aggregation stirring tank 37. The second flocculating and stirring tank 47 is supplied with a second flocculating agent different from the first flocculating agent supplied to the stirring tank 2 and the first flocculating and stirring tank 37. The second flocculant is stored in the second flocculant storage tank 23. A third flocculant supply pipe 52 for supplying the second flocculant from the second flocculant reservoir 23 to the second flocculent agitation tank 47 is provided from the second flocculant reservoir 23 to the second flocculant agitation tank. 47. The third flocculant supply pipe 52 is provided with a third flocculant injecting device 53, and the third flocculant injecting device 53 causes the second flocculant to be injected into the second flocculent stirring tank at a predetermined injection rate. 47 is injected. The third flocculant injection device 53 is, for example, a pump, a valve, or a combination of a pump and a valve.

  As the first flocculant, for example, an inorganic flocculant is used. For example, a polymer flocculant is used as the second flocculant. When an inorganic flocculant is used, the surface charge of the suspended material is neutralized, thereby forming fine flocs. When the polymer flocculant is used, the surface charge of the suspended substance is neutralized, and a larger floc is formed by the adsorption action and the crosslinking action of the polymer flocculant. Therefore, by using these two different flocculants, a strong floc with good filterability can be formed.

  FIG. 16 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. Other configurations that are not particularly described are the same as those of the embodiment shown in FIG. 15, and therefore, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted. In the aggregating apparatus shown in FIG. 16, a second aggregating tank agitation apparatus 21 is connected in series with the first aggregating tank agitation apparatus 12. The first agglomeration tank agitation device 12 and the second agglomeration tank agitation device 21 are connected by a connection pipe 55, and a third stock solution supply pipe 57 extending to the agitation apparatus 1 is branched from the connection pipe 55. The second flocculant is supplied from the second flocculant storage tank 23 to the stirring device 1. Therefore, the stock solution measured by the optical measuring device 3 is a stock solution in which the first flocculant and the second flocculant are injected and stirred. The appropriate injection rate of the second flocculant is determined by the control device 6.

  The first flocculating tank stirring device 12 and the second flocculating tank stirring device 21 are connected by a connection pipe 55. A third undiluted solution supply pipe 57 extending to the stirring device 1 is branched from the connection pipe 55. A third supply device 56 is arranged on the downstream side of the connection pipe 55 where the third stock solution supply pipe 57 is branched. The third supply device 56 is, for example, a pump, a valve, or a combination of a pump and a valve. In the embodiment shown in FIG. 16, the third supply pipe 57 is branched from between the first aggregation stirring tank 37 and the third supply device 56. You may branch from between the 2nd aggregation stirring tank 47. Alternatively, the third supply pipe 57 may be directly connected to the first aggregation stirring tank 37.

  A fourth flocculant supply pipe 58 extends from the second flocculant storage tank 23 in which the second flocculant is stored, and the fourth flocculant supply pipe 58 is connected to the stirring device 1. . The fourth flocculant supply pipe 58 is provided with the first flocculant injection device 4. Further, the third flocculant supply pipe 52 for supplying the second flocculant from the second flocculant storage tank 23 to the second flocculant stirring tank 47 is provided from the second flocculant storage tank 23 to the second flocculant. It extends to the stirring tank 47. The third flocculant supply pipe 52 is provided with a third flocculant injecting device 53, and the third flocculant injecting device 53 causes the second flocculant to be injected into the second flocculent stirring tank at a predetermined injection rate. 47 is injected. In the embodiment shown in FIG. 16, the fourth flocculant supply pipe 58 is directly connected to the second flocculant reservoir 23, but the second flocculant reservoir 23 and the third flocculant injection You may branch from between the apparatuses 53. FIG. Alternatively, the fourth flocculant supply pipe 58 may be branched from between the third flocculant injection device 53 and the second flocculant stirring tank 47.

  A numerical analysis device 5 is electrically connected to the optical measurement device 3 disposed on the downstream side of the stirring device 1, and a control device 6 is electrically connected to the numerical analysis device 5. The numerical analysis device 5 may be incorporated in the control device 6. The control device 6 is electrically connected to the first flocculant injection device 4 and the third flocculant injection device 53.

  In the flocculation apparatus having such a configuration, first, the second supply device 35 and the first supply device 7 are operated, and the stock solution containing the suspended substance is transferred to the first flocculation tank stirring device 12 and the stirring device 1. Supply. The stock solution stirred to form a floc in the first flocculating tank stirring device 12 is supplied to the stirring device 1 and mixed with the second flocculant in the stirring device 1. The value of the ratio of the volume Va (see FIG. 2B) of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. The stock solution stirred by the stirring device 1 is sent to the optical measuring device 3. The optical measuring device 3 performs an optical measurement of the stirred stock solution and acquires an optical measurement value. The optical measurement value obtained from the optical measurement device 3 is sent to the numerical analysis device 5 as described above. The numerical analysis device 5 numerically analyzes the optical measurement value and acquires the numerical analysis value. The obtained numerical analysis value is sent to the control device 6. The control device 6 determines an appropriate injection rate of the second flocculant based on the numerical analysis value by the method as described above.

  The determined injection rate of the second flocculant is sent to the third flocculant injection device 53. Then, the first supply device 7 is stopped and the third supply device 56 is operated. That is, the supply devices that operate are the second supply device 35 and the third supply device 56. As a result, the stock solution stored in the stock solution storage tank 10 is supplied to the first coagulation tank agitation device 12 and the second coagulation tank agitation device 21. The injection rate of the second flocculant injected from the second flocculant storage tank 23 into the second flocculant agitation device 21 is the injection rate determined previously. Thereby, the injection rate of the second flocculant injected into the stock solution containing the suspended substance is automatically controlled. An appropriate floc is formed by injecting the second flocculant at an appropriate injection rate. The stock solution containing floc is sent to the precipitation tank 20 and separated into a processed solution and a concentrated stock solution.

  Note that the third supply device 56 can be omitted. In this case, a height difference is provided between the first flocculating tank stirring device 12 and the second flocculating tank stirring device 21. The stock solution is supplied from the first flocculating tank agitating device 12 to the second flocculating tank agitating device 21 by utilizing the position head difference resulting from the height difference (natural flow method).

  FIG. 17 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. The aggregating apparatus shown in FIG. 17 is an embodiment in which the aggregating apparatus shown in FIG. 15 is combined with the configuration of the aggregating apparatus shown in FIG. That is, the aggregating apparatus shown in FIG. 17 can determine an appropriate injection rate of the first flocculant and an appropriate injection rate of the second flocculant. Other configurations that are not particularly described are the same as those in the embodiment shown in FIGS. 15 and 16, and therefore, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  In order to determine the proper injection rate of the first flocculant, the flocculant comprises the stirrer 1 as described so far. In addition, the aggregating apparatus includes an agitation device 60 in order to determine an appropriate injection rate of the second aggregating agent. Hereinafter, the stirring device 1 is referred to as the first stirring device 1, and the stirring device 60 is referred to as the second stirring device 60. The 2nd stirring apparatus 60 has the structure similar to the stirring apparatus 1 demonstrated with reference to FIG.1, FIG.2 (a) and FIG.2 (b). That is, the second stirring device 60 includes a second stirring tank 61 to which a stock solution containing a suspended substance is supplied, a second stirring blade 62 for stirring the stock solution containing a suspended substance, and a second stirring blade. And a second drive shaft 63 (for example, a motor) that rotates the second rotation shaft 64 integrally with the second stirring blade 62. The ratio value R of the volume Va of the rotating region formed from the rotating body composed of the second stirring blade 62 and the rotating shaft 64 in the second stirring tank 61 to the flow rate Fb of the stock solution is 1. It is in the range of 1 to 10.2.

  In order to determine the appropriate injection rate of the first flocculant, the flocculant has the first stirring device 1, the first optical measuring device 3, and the first numerical value as described above. An analysis device 5 and a first control device 6 are provided. A first stock solution supply pipe 19 for supplying a stock solution to the first stirring tank 2 of the first stirrer 1 is branched from the stock solution supply pipe (stock solution supply source pipe) 18 and extends. The first supply device 7 is disposed in the stock solution supply pipe 19. A stock solution containing suspended solids is supplied to the first stirring tank 2 by the first supply device 7.

  A first discharge pipe 28 through which the stock solution discharged from the stirring tank 2 flows is connected to the stirring tank 2, and the first optical measuring device 3 is arranged in the first discharge pipe 28. The first optical measurement device 3 is, for example, the above-described measurement device that measures the transmitted light intensity or the measurement device that measures the scattered light intensity. An optical measurement device that measures transmitted light intensity and an optical measurement device that measures scattered light intensity may be arranged in series. The optical measuring device 3 may be a measuring device capable of measuring transmittance, intensity of diffracted light, intensity of diffracted / scattered light, absorbance, intensity of reflected light, and the like.

  A first flocculant storage tank 11 for storing the first flocculant is provided, and a first flocculant supply pipe 26 extending from the first flocculant storage tank 11 is connected to the first agitation tank 2. A first flocculant injection device 4 is disposed in the first flocculant supply pipe 26. The first flocculant injection device 4 is a device that injects the first flocculant at a predetermined injection rate into a stock solution containing suspended solids. The first flocculant injection device 4 is, for example, a pump, a valve, or a combination of a pump and a valve.

  A second coagulant supply pipe 36 extending from the first coagulant storage tank 11 is connected to the first coagulation agitation tank 37 of the first coagulation tank agitation device 12. A second flocculant injection device 45 is disposed in the second flocculant supply pipe 36. The second flocculant injection device 45 is a device for injecting the first flocculant at a predetermined injection rate into the stock solution containing suspended solids. The second flocculant injection device 45 is, for example, a pump, a valve, or a combination of a pump and a valve. In the embodiment shown in FIG. 17, the first flocculant supply pipe 26 is directly connected to the first flocculant reservoir 11, but the first flocculant reservoir 11 and the second flocculant injection You may branch from between the apparatuses 45. Alternatively, the first flocculant supply pipe 26 may be branched from between the second flocculant injection device 45 and the first flocculant stirring tank 37.

  A first numerical analysis device 5 is electrically connected to the first optical measurement device 3, and a first control device 6 is electrically connected to the first numerical analysis device 5. The first numerical analysis device 5 may be incorporated in the first control device 6. The first controller 6 is electrically connected to the first flocculant injection device 4 and the second flocculant injection device 45.

  In the aggregating apparatus shown in FIG. 17, a second aggregating tank agitation apparatus 21 is connected in series with the first aggregating tank agitation apparatus 12. The first agglomeration tank agitation device 12 and the second agglomeration tank agitation device 21 are connected by a connection pipe 55, and a third stock solution supply pipe 57 extending to the second agitation apparatus 60 is branched from the connection pipe 55. . The second stirring device 60 is connected to a second stirring tank 61 to which a stock solution containing a suspended substance is supplied, a second stirring blade 62 for stirring the stock solution containing a suspended substance, and a stirring blade 62. A second rotation shaft 64 and a drive source 63 (for example, a motor) that rotates the second rotation shaft 64 integrally with the second stirring blade 62 are provided. A second stock solution supply pipe 57 is connected to the second stirring tank 61 of the second stirrer 60, and the third stock solution supply pipe 57 contains a second stock solution containing suspended substances at a predetermined flow rate. The 4th supply apparatus 65 supplied to the stirring tank 61 of this is arrange | positioned. The fourth supply device 65 is, for example, a pump, a valve, or a combination of a pump and a valve. In the embodiment shown in FIG. 17, the third stock solution supply pipe 57 is branched from between the first agglomeration stirring tank 37 and the third supply device 56. And the second agglomeration stirring tank 47 may be branched. Alternatively, the third supply pipe 57 may be directly connected to the first aggregation stirring tank 37.

  A second flocculant different from the first flocculant supplied to the first agitation tank 2 and the first agglomeration agitation tank 37 is supplied to the second aggregation agitation tank 47. The second flocculant is stored in the second flocculant storage tank 23. A third flocculant supply pipe 52 for supplying the second flocculant from the second flocculant reservoir 23 to the second flocculant agitation tank 47 is provided from the second flocculant reservoir 23 to the third agitation tank 47. It extends to. The third flocculant supply pipe 52 is provided with a third flocculant injecting device 53, and the third flocculant injecting device 53 causes the second flocculant to be injected into the second flocculent stirring tank at a predetermined injection rate. 47 is injected. The third flocculant injection device 53 is, for example, a pump, a valve, or a combination of a pump and a valve.

  A fourth flocculant supply pipe 58 extends from the second flocculant reservoir 23 to the second agitation tank 61 of the second agitator 60. A fourth flocculant injection device 66 is disposed in the fourth flocculant supply pipe 58. The fourth flocculant injection device 66 injects the second flocculant into the second stirring tank 61 at a predetermined injection rate. The fourth flocculant injection device 66 is, for example, a pump, a valve, or a combination of a pump and a valve. In the embodiment shown in FIG. 17, the fourth flocculant supply pipe 58 is directly connected to the second flocculant reservoir 23, but the second flocculant reservoir 23 and the third flocculant injection are used. You may branch from between the apparatuses 53. FIG. Alternatively, the fourth flocculant supply pipe 58 may be branched from between the third flocculant injection device 53 and the second flocculant stirring tank 47.

  A third discharge pipe 69 through which the undiluted solution discharged from the second stirring tank 61 flows is connected to the second stirring tank 61, and the second optical measuring device 68 is connected to the third discharge pipe 69. Is arranged. The second optical measuring device 68 disposed on the downstream side of the second stirring device 60 has the same configuration as the first optical measuring device 3, and for example, measures the above-described transmitted light intensity. Or a measuring device for measuring scattered light intensity can be used.

  A second numerical analysis device 70 is electrically connected to the second optical measurement device 68, and a second control device 71 is electrically connected to the second numerical analysis device 70. The second numerical analysis device 70 may be incorporated in the second control device 71. The second control device 71 is electrically connected to the third flocculant injection device 53 and the fourth flocculant injection device 66.

In the aggregating apparatus having such a configuration, first, the first supply device 7 is operated, and the stock solution containing suspended substances in the stock solution storage tank 10 is supplied to the first stirring device 1. The value of the ratio of the volume Va (see FIG. 2B) of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. The first flocculant is supplied to the first stirring tank 2 of the first stirring device 1 by the first flocculant injection device 4. In the 1st stirring tank 2, the 1st stirring blade 8 is rotated with the rotational speed which is 400 min < ^-1 > or more, and mixes a stock solution and a flocculant.

  The stock solution stirred by the first stirring device 1 is sent to the first optical measuring device 3. The first optical measurement device 3 performs an optical measurement of the stirred stock solution and obtains an optical measurement value. The optical measurement value obtained from the first optical measurement device 3 is sent to the first numerical analysis device 5 as described above. The first numerical analysis device 5 performs numerical analysis on the optical measurement value and acquires a numerical analysis value. The obtained numerical analysis value is sent to the first control device 6. The first control device 6 determines an appropriate injection rate of the first flocculant based on the numerical analysis value by the method as described above.

  The determined injection rate of the first flocculant is sent from the first controller 6 to the second flocculant injection device 45. Then, the first supply device 7 is stopped, and the second supply device 35 and the fourth supply device 65 are operated. The stock solution in the stock solution storage tank 10 is sent to the first aggregating tank stirring device 12. A first flocculant is injected into the first aggregating tank agitating device 12 at the injection rate determined as described above, and the flocculant is mixed with the stock solution, whereby flocs are primarily formed.

The stock solution containing flocs primarily formed using the first flocculant is supplied to the second stirring device 60 by the fourth supply device 65. Similar to the first stirring device 1, the value of the ratio of the volume Va of the rotating region of the rotating body to the flow rate Fb of the stock solution is in the range of 1.1 to 10.2. The second flocculant is supplied to the second stirring tank 61 of the second stirring device 60 by the fourth flocculant injection device 66. In the second agitation tank 61, the second agitation blade 62 is rotated at a rotational speed of 400 min ⁻¹ or more to mix the stock solution and the second aggregating agent.

  The stock solution stirred by the second stirring device 60 is sent to the second optical measuring device 68. The second optical measurement device 68 performs an optical measurement of the stock solution stirred by the second stirring device 60 and acquires an optical measurement value. The optical measurement value obtained from the second optical measurement device 68 is sent to the second numerical analysis device 70 as described above. The second numerical analysis device 70 performs numerical analysis on the optical measurement value and acquires a numerical analysis value. The obtained numerical analysis value is sent to the second control device 71. The second control device 71 determines an appropriate injection rate of the second flocculant based on the numerical analysis value by the method as described above.

  The determined injection rate of the second flocculant is sent from the second control device 71 to the third flocculant injection device 53. Then, the fourth supply device 65 is stopped and the third supply device 56 is operated. In other words, the supply devices that operate are the second supply device 35 and the third supply device 56. As a result, the stock solution stored in the stock solution storage tank 10 is supplied to the first coagulation tank agitation device 12 and the second coagulation tank agitation device 21.

  The injection rate of the first flocculant injected into the first coagulation tank agitator 12 is the injection rate determined previously. Similarly, the injection rate of the second flocculant injected into the second coagulation tank agitating device 21 is the injection rate determined previously. Thereby, the injection rates of the first flocculant and the second flocculant injected into the stock solution containing the suspended substance are automatically controlled. By injecting the first flocculant and the second flocculant at an appropriate flocculant injection rate, an appropriate floc is formed in the stock solution. The stock solution containing the flock is sent to the precipitation tank 20 and separated into a treated solution and a concentrated stock solution.

  In the embodiment shown in FIG. 17, the third supply device 56 can be omitted. In this case, a height difference is provided between the first flocculating tank stirring device 12 and the second flocculating tank stirring device 21. The stock solution is supplied from the first flocculating tank agitating device 12 to the second flocculating tank agitating device 21 by utilizing the position head difference resulting from the height difference (natural flow method).

  FIG. 18 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. The aggregating apparatus shown in FIG. 18 has a configuration in which a stock solution storage tank 10, an agitation apparatus 1, an optical measurement apparatus 3, an agglomeration tank agitation apparatus 12, and a dehydrator 14 are connected in this order. The stock solution storage tank 10 stores a stock solution containing suspended solids. The stirring device 1 shown in FIG. 18 has the same configuration as the stirring device 1 shown in FIGS. 1, 2 (a), and 2 (b). A stock solution supply pipe 18 extending from the stock solution storage tank 10 is connected to the stirring tank 2 of the stirrer 1, and the stock solution supplied to the stock solution supply pipe 18 is supplied to the stirring tank 2 at a predetermined flow rate. A device 7 is arranged.

  A flocculant storage tank 11 for storing the flocculant is provided, and a first flocculant supply pipe 26 extending from the flocculant storage tank 11 is connected to the stock solution supply pipe 18. The flocculant injection device 4 is disposed in the first flocculant supply pipe 26. The flocculant injection device 4 is a device that injects the flocculant at a predetermined injection rate into the stock solution containing suspended solids.

  A second flocculant supply pipe 36 extending from the flocculant storage tank 11 is connected to the flocculant agitation tank 37. A second flocculant injection device 45 is disposed in the second flocculant supply pipe 36. The second flocculant injection device 45 is a device that injects the flocculant into the stock solution containing the suspended substance at a predetermined injection rate. In the embodiment shown in FIG. 18, the second flocculant supply pipe 36 is directly connected to the flocculant storage tank 11, but from between the flocculant storage tank 11 and the first flocculant injection device 4. It may branch off. Alternatively, the second flocculant supply pipe 36 may be branched from between the first flocculant injection device 4 and the stock solution supply pipe 18.

  The agitation device 1 and the agglomeration tank agitation device 12 are connected in series by a connection pipe 55, and the optical measuring device 3 is disposed in the connection pipe 55. Therefore, the stock solution measured by the optical measuring device 3 is a stock solution stirred by the stirring device 1. The stock solution stirred by the stirring device 1 is supplied to the coagulation tank stirring device 12. The stock solution supplied to the aggregation stirring tank 37 of the aggregation tank stirring device 12 is mixed with the flocculant supplied from the coagulant storage tank 11 in the aggregation stirring tank 37.

  A second discharge pipe 46 through which the stock solution discharged from the coagulation stirring tank 37 flows is connected to the coagulation stirring tank 37, and the dehydrator 14 is connected to the downstream side of the second discharge pipe 46. The dehydrator 14 dehydrates the stock solution in which flocks are formed, and separates it into a filtrate and a cake. The cake is recovered from the dehydrator 14.

  A numerical analysis device 5 is electrically connected to the optical measuring device 3, and a control device 6 is electrically connected to the numerical analysis device 5. The numerical analysis device 5 may be incorporated in the control device 6. The control device 6 is electrically connected to the first flocculant injection device 4 and the second flocculant injection device 45.

  With such a configuration, the optical measurement value obtained from the optical measurement device 3 is sent to the numerical analysis device 5 as described above. The numerical analysis device 5 numerically analyzes the optical measurement value and acquires the numerical analysis value. The obtained numerical analysis value is sent to the control device 6. The control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value by the method as described above. The injection rate determined by the control device 6 is sent to the first coagulant injection device 4 and the second coagulant injection device 45. The first flocculant injection device 4 and the second flocculant injection device 45 inject the flocculant into the stock solution containing the suspended substance at the determined injection rate. Thereby, the injection | pouring rate of the coagulant | flocculant inject | poured into the stock solution containing a suspended solid is controlled automatically. The injection rate determined by the control device 6 may be the injection rate of the flocculant injected by the first flocculant injection device 4 or the flocculant injected by the second flocculant injection device 45. It is good also as an injection rate. Further, the injection rate determined by the control device 6 is the sum of the injection rate of the flocculant injected by the first flocculant injection device and the injection rate of the flocculant injected by the second flocculant injection device 45. It is good also as an injection rate.

  FIG. 19 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 19, a settling tank 20 is provided instead of the dehydrator 14. Since the other configuration is the same as that of the embodiment shown in FIG. 18, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted. The floc in the undiluted solution supplied to the settling tank 20 settles toward the bottom of the settling tank 20 due to its own weight, so that the undiluted solution containing the floc is a concentrated undiluted solution in which the floc exists at a high concentration (for example, concentrated sludge). And the processed liquid without floc. By providing the precipitation tank 20 in this way, it is possible to separate the floc and the processed liquid.

  FIG. 20 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 20, the fifth stock solution supply pipe 80 is branched from the connection pipe 55 to supply the optical measurement apparatus 3 to the fifth stock solution supply pipe 80 and the stock solution to the optical measurement apparatus 3. The fifth supply device 81 is arranged. The fifth supply device 81 is, for example, a pump, a valve, or a combination of a pump and a valve. Since the other configuration is the same as that of the embodiment shown in FIG. 18, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, first, the first supply device 7 and the fifth supply device 81 are operated, and the stock solution mixed with the flocculant by the stirring device 1 is supplied to the optical measuring device 3. The value of the ratio of the volume Va (see FIG. 2B) of the rotating region 15A of the rotating body 15 to the flow rate Fb [L / sec] of the stock solution is in the range of 1.1 to 10.2. The optical measurement value obtained from the optical measurement device 3 is sent to the numerical analysis device 5 as described above. The numerical analysis device 5 numerically analyzes the optical measurement value and acquires the numerical analysis value. The obtained numerical analysis value is sent to the control device 6. The control device 6 determines an appropriate injection rate of the flocculant based on the numerical analysis value by the method as described above. The injection rate determined by the control device 6 is sent to the first coagulant injection device 4 and the second coagulant injection device 45. The first flocculant injection device 4 and the second flocculant injection device 45 inject the flocculant into the stock solution containing the suspended substance at the determined injection rate. Thereby, the injection | pouring rate of the coagulant | flocculant inject | poured into the stock solution containing a suspended solid is controlled automatically.

  In the present embodiment, the fifth supply device 81 boosts the pressure of the stock solution stirred with the flocculant by the stirring device 2 and supplies it to the optical measuring device 3. Therefore, the stock solution inlet 3 </ b> A of the optical measuring device 3 can be disposed at a position higher than the stock solution outlet 2 </ b> A of the stirring device 2. The stock solution outlet 3 </ b> B of the optical measuring device 3 may be arranged at a position higher than the stock solution inlet 3 </ b> A of the optical measuring device 3.

  Next, the fifth supply device 81 is stopped, and the stock solution that has passed through the stirring device 1 is supplied to the coagulation tank stirring device 12. The stock solution discharged from the aggregating tank stirring device 12 is supplied to the dehydrator 14 through the second discharge pipe 46, and is separated into filtrate and cake by the dehydrator 14.

  FIG. 21 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the flocculating device shown in FIG. 21, the flocculating agent supplied from the first flocculating agent injection device 4 to the stock solution is supplied to the stirring tank 2 of the stirring device 1 instead of being supplied to the stock solution supply pipe 18. Since the other configuration is the same as that of the embodiment shown in FIG. 20, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 22 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the flocculating apparatus shown in FIG. 22, instead of the flocculating agent supplied to the stock solution from the second flocculating agent injection device 45 being supplied to the flocculating stirring tank 37 of the flocculating tank stirring device 12, It is supplied to the connection pipe 55 arranged on the upstream side. Since the other configuration is the same as that of the embodiment shown in FIG. 20, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 23 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. In the aggregating apparatus shown in FIG. 23, the aggregating tank agitation apparatus 12 is omitted, and the connection pipe 55 extending from the agitation apparatus 1 is directly connected to the dehydrator 14. Further, the flocculant supplied from the second flocculant injection device 45 to the stock solution is supplied to the connection pipe 55. The dehydrator 14 of this embodiment is a dehydrator having a coagulation tank function for forming a flock. An example of the dehydrator 14 having a coagulation tank function is a centrifugal dehydrator.

  FIG. 24 is a schematic view showing still another embodiment of the aggregating apparatus of the present invention. The aggregating apparatus shown in FIG. 24 includes a diluent storage tank 85 that stores a diluent, and a diluent supply apparatus 86 that supplies the diluent stored in the diluent storage tank 85 to the stock solution stirred by the stirring device 1 at a predetermined flow rate. And comprising. A diluent supply pipe 87 extends from the diluent storage tank 85, and this diluent supply pipe 87 is connected to the discharge pipe 28 between the stirring device 1 and the optical measuring device 3. The diluent supply device 86 is disposed in the diluent supply pipe 87. Since the other configuration is the same as that of the embodiment shown in FIG. 10, the corresponding components are denoted by the same reference numerals, and detailed description thereof is omitted.

  The diluent supply device 86 is a device that supplies the diluent to the stock solution at a predetermined flow rate before the stock solution stirred by the stirring device 1 is supplied to the optical measuring device 3. The diluent supply device 86 is, for example, a pump, a valve, or a combination of a pump and a valve. In this aggregating apparatus, the diluent is supplied from the diluent storage tank 85 to the stock solution stirred by the stirring device 1 by the diluent supply device 86. The stock solution diluted with the diluent is supplied to the optical measurement device 3, and optical measurement is performed by the optical measurement device 3.

  By diluting the stirred stock solution with a diluent, the concentration of suspended solids or flocs can be reduced. In stock solutions with a high concentration of suspended solids, there is no difference between the optical measurement when floc is formed and the optical measurement when no floc is formed, and as a result, it is difficult to determine the injection rate of the flocculant. There are cases. For example, when measuring the transmitted light intensity of a stock solution having a high concentration of suspended solids with the optical measuring device 3, even if flocs are formed with an appropriate injection rate of the flocculant, there are almost no gaps between the flocs. As shown in FIG. 4A, the transmitted light intensity may become substantially constant. On the other hand, when diluting the stock solution stirred by the stirrer 1 with the diluent, the gap between the flocks can be increased, so that light is transmitted through the gap between the flocks, as shown in FIG. Thus, a plurality of transmitted light intensity peaks are measured. As a result, there is a difference between the transmitted light intensity when the floc is formed and the transmitted light intensity when the floc is not formed, and an appropriate injection rate can be determined. As the diluent, pure water, tap water, industrial water, ground water, treated water for various wastewater treatment, seawater, and the like can be used.

  The diluting liquid storage tank 85 and the diluting liquid supply device 86 shown in FIG. 24 may be arranged in the aggregating apparatus according to the embodiment described with reference to FIGS. 10 to 23. In this case, the diluent supply pipe 87 that extends from the diluent storage tank 85 and in which the diluent supply apparatus 86 is disposed is the discharge pipe 28 between the stirrer 1 and the optical measuring device 3 and / or the stirrer 60. Connected to a discharge pipe 69 between the optical measuring devices 68.

  The embodiment of the aggregating apparatus has been described with reference to FIGS. 10 to 24. In these embodiments, the following method can be used to change the injection rate of the flocculant injected into the stock solution containing suspended solids supplied to the agitation tanks 2 and 61.

  Supplying to the agitation tanks 2, 61 by changing the flow rate of the flocculant injected into the stock solution from the flocculant injection devices 4, 66 while the flow rate of the stock solution supplied by the supply devices 7, 65 is kept constant. It is possible to change the injection rate of the flocculant injected into the stock solution containing the suspended substance. Alternatively, in a state where the flow rate of the flocculant injected from the flocculant injection devices 4 and 66 is controlled to be constant, the flow rate of the stock solution supplied by the supply devices 7 and 65 is changed to supply the stirring tanks 2 and 61. You may change the injection | pouring rate of the coagulant | flocculant inject | poured into the stock solution containing the suspended solids. Alternatively, in order to change the injection rate of the flocculant injected into the stock solution containing suspended solids supplied to the stirring tanks 2 and 61, the flow rate of the stock solution supplied by the supply devices 7 and 65, and the flocculant injection device Both the flow rate of the flocculant injected into the stock solution from 4, 66 may be changed.

  Hereinafter, the present invention will be described in more detail based on the following experimental results.

  First, the first experiment will be described. The procedure of the first experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmitted light intensity of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As a numerical analysis value of the obtained transmitted light intensity, an average value, dispersion, standard deviation, and peak area of the transmitted light intensity are calculated (numerical analysis step). Appropriate coagulant injection rate according to the present invention using the obtained numerical analysis values as an index, repeating the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the coagulant (Injection rate determining step).

  The stock solution containing suspended solids used in the first experiment is sludge A. Sludge A is a mixed raw sludge (a mixture of primary sludge and excess sludge) in a sewage treatment plant. The TS (Total Solids) of sludge A was 30.3 g / L. TS is an evaporation residue and is a concentration of a substance remaining when the sludge A is evaporated to dryness at 105 to 110 ° C. The measurement method conformed to the sewage test method.

  The flocculant used in the first experiment is a cationic polymer flocculant a (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the first experiment, the ratio R of the volume Va in the rotation region to the sludge flow rate Fb was changed by changing the flow rate Fb of the sludge A between 0.015 L / sec and 0.240 L / sec. That is, the solution of the cationic polymer flocculant a was injected into the sludge A at a plurality of different ratios R, and the flocculant injection rates at the plurality of different ratios R were determined. Sludge A into which the cationic polymer flocculant a was injected was mixed using a stirring device in which the rotation speed of the stirring blade was set to 600 min ⁻¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 0.8 to 13.5. Next, the transmitted light intensity of the stirred sludge A was measured for a certain time. Next, the average value, dispersion, standard deviation, and peak area of the obtained transmitted light intensity data were calculated. These operations were performed at a plurality of flocculant injection rates. The injection rate of the cationic polymer flocculant a at which these numerical analysis values become the maximum value was determined as an appropriate flocculant injection rate according to the present invention.

On the other hand, a beaker test was performed to determine an appropriate injection rate of the flocculant. 250 mL of sludge A was collected in a beaker, and a predetermined amount of the cationic polymer flocculant a solution was injected (step 1). Next, the sludge A into which the cationic polymer flocculant a was injected was stirred using a stirring device in which the rotation speed of the stirring blade was set to 100 min ⁻¹ (step 2). Next, the size of the floc and the clarity of the supernatant liquid were visually determined, and the results were recorded. Change the injection rate of the cationic polymer flocculant a, repeat Step 1 to Step 3, and use the floc size and the clarity of the supernatant as an index to determine the appropriate injection rate of the cationic polymer flocculant a. Were determined. The experimental results are shown in Table 1.

  As can be seen from Table 1, when the ratio R of the volume Va in the rotating region to the sludge flow rate Fb is in the range of 1.1 to 10.2, the appropriateness of the cationic polymer flocculant a determined by the present invention. The correct injection rate was consistent with the proper injection rate of the cationic polymer flocculant a determined by the beaker test. Therefore, when the ratio R of the volume Va in the rotation region to the sludge flow rate Fb is in the range of 1.1 to 10.2, an appropriate injection rate of the cationic polymer flocculant a can be determined.

  Next, the second experiment will be described. The procedure of the second experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmittance of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As the numerical analysis value of the obtained transmitted light rate, the number of data larger than a predetermined threshold among the obtained transmitted light rate data was calculated (numerical analysis step). Appropriate injection rate of the flocculant according to the present invention using the obtained numerical analysis values as an index by repeating the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant (Injection rate determining step).

  The stock solution containing suspended solids used in the second experiment is sludge B. Sludge B is a sludge (mixture of raw urine and septic tank sludge) of a human waste treatment plant. The TS (Total Solids) of sludge B was 9.2 g / L. TS is an evaporation residue and is a concentration of a substance remaining when the sludge A is evaporated to dryness at 105 to 110 ° C. The measurement method conformed to the sewage test method.

  The flocculant used in the second experiment is a cationic polymer flocculant b (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the second experiment, the ratio R of the volume Va in the rotating region to the sludge flow rate Fb was changed by changing the flow rate Fb of the sludge B between 0.015 L / sec and 0.270 L / sec. That is, the solution of the cationic polymer flocculant b was injected into the sludge B at a plurality of different ratios R, and the flocculant injection rate at the plurality of different ratios R was determined. Sludge B into which the cationic polymer flocculant b was injected was mixed using a stirring device in which the rotation speed of the stirring blade was set to 600 min ⁻¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 0.8 to 13.7. Next, the transmittance of the stirred sludge B was measured for a certain time. Next, among the obtained transmission light rate data, the number of data having a transmission light rate larger than 4% was calculated. These operations were performed at a plurality of flocculant injection rates. The injection rate of the cationic polymer flocculant a at which these numerical analysis values become the maximum value was determined as an appropriate flocculant injection rate according to the present invention.

On the other hand, a beaker test was performed to determine an appropriate injection rate of the flocculant. 250 mL of sludge B was collected in a beaker, and a predetermined amount of the cationic polymer flocculent b solution was injected (step 1). The sludge B into which the cationic polymer flocculant b was injected was stirred using a stirring device in which the rotation speed of the stirring blade was set to 100 min ⁻¹ (step 2). The size of the floc and the clarity of the supernatant were visually determined and the results were recorded (step 3). Change the injection rate of the cationic polymer flocculant b and repeat Steps 1 to 3 to determine the appropriate injection rate of the cationic polymer flocculant b using the size of the flock and the clarity of the supernatant as indicators. did. The experimental results are shown in Table 2.

  As can be seen from Table 2, the injection of the cationic polymer flocculant b determined according to the present invention when the ratio R of the volume Va of the rotating region to the sludge flow rate Fb is in the range of 1.1 to 10.3. The rate was consistent with the proper injection rate of cationic polymeric flocculant b determined by the beaker test. Therefore, when the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is in the range of 1.1 to 10.2, an appropriate injection rate of the cationic polymer flocculant b can be determined.

  Next, a third experiment will be described. The procedure of the third experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmitted light intensity of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As a numerical analysis value of the obtained transmitted light intensity, an average value, dispersion, standard deviation, and peak area of the transmitted light intensity are calculated (numerical analysis step). Appropriate injection rate of the flocculant according to the present invention using the obtained numerical analysis values as an index by repeating the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant (Injection rate determining step).

  The stock solution containing suspended solids used in the third experiment is sludge C. Sludge C is a mixed raw sludge (mixture of primary sludge and excess sludge) at a sewage treatment plant. The TS (Total Solids) of sludge C was 26.6 g / L. TS is an evaporation residue and is a concentration of a substance remaining when the sludge C is evaporated to dryness at 105 to 110 ° C. The measurement method conformed to the sewage test method.

  The flocculant used in the third experiment is a cationic polymer flocculant c (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the third experiment, a solution of the cationic polymer flocculant c was injected into the sludge C (sludge flow rate Fb: 0.030 L / sec). Sludge C into which the cationic polymer flocculant c was injected was mixed using a stirring device in which the rotation speed of the stirring blade was set to 300 min ⁻¹ , 400 min ⁻¹ , and 500 min ⁻¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 6.8. Next, the transmitted light intensity of the stirred sludge C was measured for a certain time. Subsequently, the average value, dispersion, standard deviation, and peak area of the obtained transmitted light intensity data were calculated. These operations were performed at a plurality of flocculant injection rates. The flocculant injection rate at which these numerical analysis values become the maximum value was determined as the appropriate injection rate according to the present invention.

On the other hand, a beaker test was performed to determine an appropriate injection rate of the flocculant. 250 mL of sludge C was collected in a beaker, and a predetermined amount of the cationic polymer flocculant c solution was injected (step 1). Next, the sludge C into which the cationic polymer flocculant c was injected was stirred using a stirring device in which the rotation speed of the stirring blade was set to 100 min ⁻¹ (step 2). Next, the size of the floc and the clarity of the supernatant were visually determined, and the results were recorded (step 3). Change the injection rate of the cationic polymer flocculant c, repeat Step 1 to Step 3, and determine the appropriate injection rate of the cationic polymer flocculant c using the floc size and the clarity of the supernatant as indicators. did. The experimental results are shown in Table 3.

As is clear from Table 3, according to the present invention, even when the rotational speed of the stirring blade is 300 min ⁻¹ , the injection rate of the cationic polymer flocculant c that can aggregate the sludge C so that it can be dehydrated, That is, an appropriate injection rate of the cationic polymer flocculant c can be determined. Furthermore, when the rotation speed of the stirring blade is 400 min ⁻¹ or more, the injection rate of the cationic polymer flocculant c determined by the present invention is more appropriate for the cationic polymer flocculant c determined by the beaker test. Consistent with the correct injection rate. Therefore, when the rotation speed of the stirring blade is 400 min ⁻¹ or more, a more appropriate injection rate of the cationic polymer flocculant c can be accurately determined.

  Next, a fourth experiment will be described. The procedure of the fourth experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmittance of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As the numerical analysis value of the obtained transmitted light rate, the number of data larger than a predetermined threshold among the obtained transmitted light rate data is calculated (numerical analysis step). Appropriate injection rate of the flocculant according to the present invention using the obtained numerical analysis values as an index by repeating the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant (Injection rate determining step).

  The stock solution containing suspended solids used in the fourth experiment is sludge D. Sludge D is sludge (mixture of raw urine and septic tank sludge) of human waste treatment plant. The TS (Total Solids) of sludge D was 9.6 g / L. TS is an evaporation residue and is a concentration of a substance remaining when the sludge D is evaporated to dryness at 105 to 110 ° C. The measurement method conformed to the sewage test method.

  The flocculant used in the fourth experiment is a cationic polymer flocculant d (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the fourth experiment, a solution of the cationic polymer flocculant d was injected into the sludge D (sludge flow rate Fb: 0.045 L / sec). The sludge D cationic polymer flocculants d is injected, rotational speed of the stirring blade is ^{200 min -1,} 400 min -1, 600 min ^-1, and mixed using a set stirrer 800 min ^-1. At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 4.6. Next, the transmittance of the stirred sludge D was measured for a certain time. Next, among the obtained transmission light transmittance data, the number of data having a transmittance greater than 2% was calculated. These operations were performed at a plurality of flocculant injection rates. The flocculant injection rate at which these numerical analysis values become the maximum value was determined as the appropriate injection rate according to the present invention.

On the other hand, a beaker test was performed to determine an appropriate injection rate of the flocculant. 250 mL of sludge D was collected in a beaker, and a predetermined amount of the cationic polymer flocculant d solution was injected (step 1). Next, the sludge D into which the cationic polymer flocculant b was injected was stirred using a stirring device in which the rotation speed of the stirring blade was set to 100 min ⁻¹ (step 2). Next, the size of the floc and the clarity of the supernatant were visually determined, and the results were recorded (step 3). Change the injection rate of the cationic polymer flocculant d and repeat Steps 1 to 3 to determine the appropriate injection rate of the cationic polymer flocculant d using the size of the flock and the clarity of the supernatant as indicators. did. The experimental results are shown in Table 4.

As is clear from Table 4, according to the present invention, even when the rotational speed of the stirring blade is 200 min ⁻¹ , the injection rate of the cationic polymer flocculant d that can aggregate the sludge D so that it can be dehydrated, That is, an appropriate injection rate of the cationic polymer flocculant d can be determined. Furthermore, when the rotational speed of the stirring blade is 400 min ⁻¹ or more, the injection rate of the cationic polymer flocculant d determined by the present invention is more appropriate for the cationic polymer flocculant c determined by the beaker test. Consistent with the correct injection rate. Therefore, when the rotation speed of the stirring blade is 400 min ⁻¹ or more, a more appropriate injection rate of the cationic polymer flocculant d can be accurately determined.

  Next, a fifth experiment will be described. The procedure of the fifth experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmitted light intensity of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As a numerical analysis value of the obtained transmitted light intensity, an average value, dispersion, standard deviation, and peak area of the transmitted light intensity are calculated (numerical analysis step). Repeat the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant, and examine the relationship between the obtained numerical analysis values and the appropriate injection ratio (injection rate) Decision process). In order to determine an appropriate injection rate, a stock solution containing suspended solids aggregated with a flocculant was dehydrated with a dehydrator, and the moisture content of the obtained dehydrated cake was used as an index.

  The stock solution containing suspended solids used in the fifth experiment is sludge E. Sludge E is anaerobic digested sludge from a sewage treatment plant. The TS (Total Solids) of sludge E was 13.2 g / L. TS is an evaporation residue, and is a concentration of a substance remaining when the sludge E is evaporated to dryness at 105 to 110 ° C. The measurement method conformed to the sewage test method.

  The flocculant used in the fifth experiment is a cationic polymer flocculant e (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the fifth experiment, a solution of the cationic polymer flocculant e was injected into sludge E (sludge flow rate Fb: 0.28 L / sec). Sludge E into which the cationic polymer flocculant e was injected was mixed using a stirring device (stirring unit volume 0.8 L) in which the rotation speed of the stirring blade was set to 1000 min- ¹ . At this time, the ratio R of the volume Va in the rotation region to the sludge flow rate Fb is 1.7. Next, the transmitted light intensity of the stirred sludge E was measured for a certain time. Next, the average value, dispersion, standard deviation, and peak area of the obtained transmitted light intensity data were calculated. These operations were performed at multiple injection rates of flocculant.

On the other hand, in order to determine an appropriate injection rate of the flocculant, a solution of the cationic polymer flocculant e was injected into the sludge E (sludge flow rate Fb: 0.28 L / sec). Sludge E into which the cationic polymer flocculant e was injected was mixed using a stirrer (stirring tank volume 300 L) in which the rotation speed of the stirring blade was set to 33 min ⁻¹ to form floc. Finally, the sludge E containing floc was dehydrated with a screw press dehydrator, and the water content (%) of the obtained dehydrated cake was measured. These operations were performed at multiple injection rates. The results of the fifth experiment are shown in Table 5.

  It can be seen that the average value, the dispersion, the standard deviation, and the peak area of the transmitted light intensity all take the maximum value when the injection rate of the flocculant is 1.1% (vs. TS). On the other hand, from the results of the screw press dehydrator, it can be seen that the proper injection rate is 1.1% (vs. TS). From these results, it was found that the injection rate of the flocculant that can most reduce the moisture content of the cake can be determined based on the average value, the dispersion, the standard deviation, and the maximum peak area of the transmitted light intensity. More specifically, it has been found that the injection rate of the flocculant that can reduce the moisture content of the cake can be determined based on the flocculant injection rate at which the average value, dispersion, standard deviation, and peak area values of the transmitted light intensity are maximized.

  Next, a sixth experiment will be described. The procedure of the second experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The transmitted light intensity of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). As a numerical analysis value of the obtained transmitted light intensity, an average value, dispersion, standard deviation, and peak area of the transmitted light intensity are calculated (numerical analysis step). Repeat the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant, and examine the relationship between the obtained numerical analysis values and the appropriate injection ratio (injection rate) Decision process). In order to determine an appropriate injection rate, a stock solution containing suspended solids aggregated with a flocculant was dehydrated with a dehydrator, and the moisture content of the obtained dehydrated cake was used as an index.

  The stock solution containing suspended solids used in the sixth experiment is sludge F, which is different from the sludge E used in the fifth experiment. Sludge F is mixed raw sludge (mixture of primary sludge and surplus sludge) at a sewage treatment plant. The TS of the sludge F is 14.2 g / L. The measurement method conformed to the sewage test method.

  The flocculant used in the sixth experiment is a cationic polymer flocculant f (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the sixth experiment, a solution of the cationic polymer flocculant f was injected into the sludge F (sludge flow rate Fb: 0.42 L / sec). Sludge F into which the cationic polymer flocculant f was injected was mixed using a stirring device (stirring unit volume 0.8 L) in which the rotation speed of the stirring blade was set to 500 min ⁻¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 1.1. Subsequently, the transmitted light intensity of the stirred sludge F was measured for a certain time. Next, the average value, dispersion, standard deviation, and peak area of the obtained transmitted light intensity data were calculated. These operations were performed at multiple injection rates of flocculant.

On the other hand, in order to determine an appropriate injection rate of the flocculant, a solution of the cationic polymer flocculant f was injected into the sludge F (sludge flow rate Fb: 0.42 L / sec). Sludge F into which the cationic polymer flocculant f was injected was mixed using a stirrer (stirring tank volume 300 L) in which the rotation speed of the stirring blade was set to 33 min ⁻¹ to form floc. Finally, the sludge F containing floc was dehydrated with a screw press dehydrator, and the moisture content (%) of the obtained dehydrated cake was measured. The above operation was carried out at a plurality of flocculant injection rates. The results of the sixth experiment are shown in Table 6.

  It can be seen that the average value of transmitted light intensity, dispersion, standard deviation, and peak area all take the maximum value when the injection rate of the flocculant is 0.70% (vs. TS). On the other hand, from the results of the screw press dehydrator, it can be seen that when the flocculant injection rate is 0.70% (vs. TS) or less, the moisture content of the cake is greatly reduced every time the injection rate is increased by about 0.1%. . In contrast, when the injection rate of the flocculant is 0.70% (vs. TS) or more, even if the injection rate increases by about 0.1%, the moisture content of the cake is reduced, but it is almost the same. I understand. From these results, it was found that the coagulant injection rate enabling the most efficient dehydration can be determined based on the average value, the dispersion, the standard deviation, and the peak area of the transmitted light intensity. More specifically, it was found that the injection rate of the flocculant capable of performing the most efficient dehydration can be determined based on the average value, the dispersion, the standard deviation, and the maximum peak area of the transmitted light intensity.

  Next, a seventh experiment will be described. The procedure of the seventh experiment is as follows. First, a stock solution (raw water for purified water treatment) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The laser diffraction / scattered light of the stirred stock solution is measured to obtain an optical measurement value (optical measurement step). The obtained laser diffraction / scattered light data is numerically analyzed to calculate the average floc particle diameter of the floc (numerical analysis step). Repeat the supply process, injection process, stirring process, optical measurement process, and numerical analysis process at different injection rates of the flocculant, and examine the relationship between the obtained numerical analysis values and the appropriate injection ratio (injection rate) Decision process). In order to determine an appropriate injection rate, a stock solution containing suspended solids aggregated with a coagulant was coagulated and precipitated, and the quality of the obtained treated water was used as an index.

  The stock solution containing suspended solids used in the seventh experiment is raw water G for water purification treatment. The turbidity and chromaticity of the raw water G are 50 degrees and 80 degrees, respectively. The measuring method was based on the water test method.

  The flocculant used in the seventh experiment was polyaluminum chloride, and a 10 wt% polyaluminum chloride aqueous solution (in terms of aluminum oxide) was used as the flocculant solution. The flocculant concentration means the concentration of the flocculant in the aqueous solution.

In the seventh experiment, an aqueous solution of polyaluminum chloride was injected into the raw water G (raw water flow rate Fb: 0.28 L / sec) for water purification treatment. The raw water G into which an aqueous solution of polyaluminum chloride was poured was mixed using a stirring device (stirring unit volume 0.8 L) in which the rotation speed of the stirring blade was set to 500 min ⁻¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 1.1. Next, the laser diffraction / scattered light of the stirred raw water G was measured for a certain time. Next, the average floc particle diameter was calculated from the obtained laser diffraction / scattered light data. These operations were performed at multiple injection rates of flocculant.

On the other hand, a jar test was performed to determine an appropriate injection rate of the flocculant. In the jar test, an aqueous solution of polyaluminum chloride was poured into 500 mL of raw water G, the rotation speed at the time of stirring was set to 130 min ⁻¹ , and the raw water G and the aqueous solution of polyaluminum chloride were mixed for 3 minutes. Furthermore, the rotation speed at the time of stirring was set to 30 min ⁻¹ , and raw water G and an aqueous solution of polyaluminum chloride were mixed for 10 minutes to form a floc. Finally, it was left to stand for 5 minutes, and a supernatant was collected as treated water, and turbidity and chromaticity were measured. The above operation was carried out at a plurality of flocculant injection rates.

  The results of the seventh experiment are shown in Table 7 and FIG. FIG. 25 is a graph plotting the results of the seventh experiment. In FIG. 25, the horizontal axis represents the injection rate of the flocculant, and the vertical axis represents the average floc particle size. FIG. 25 shows an approximate curve (cubic curve) obtained from the experimental results.

  From the approximate curve in FIG. 25, it can be seen that the average floc particle diameter takes a maximum value when the injection rate of the flocculant is 50 to 60 mg / L (in terms of 10 wt% aqueous solution). On the other hand, it can be seen from the results of the jar test that the proper injection rate is 60 mg / L (in terms of 10 wt% aqueous solution). From these results, it was found that the injection rate of the flocculant that can obtain the best treated water can be determined based on the average floc particle size. More specifically, it has been found that the injection rate at which the best treated water quality can be obtained can be determined based on the injection rate of the flocculant having the maximum average floc particle size.

  Next, an eighth experiment will be described. The procedure of the eighth experiment is as follows. First, a stock solution (sludge) containing suspended solids is supplied to a stirring tank (supply process). The flocculant is supplied from the stock solution supply pipe to the stirring tank, and the flocculant is injected into the stock solution (injection step). In the injection step, the flocculant may be supplied to the stirring tank. The stock solution and the flocculant are mixed by stirring the stock solution into which the flocculant has been injected (stirring step). The stirred sludge is diluted with a diluent (dilution step). The transmitted light intensity of the diluted stock solution is measured to obtain an optical measurement value (optical measurement step). As a numerical analysis value of the obtained transmitted light intensity, dispersion, standard deviation, and peak area of the transmitted light intensity were calculated (numerical analysis step). Repeat the supply process, injection process, stirring process, dilution process, optical measurement process, and numerical analysis process at different injection rates of the flocculant, and examine the relationship between the obtained numerical analysis values and the appropriate injection rate (Injection rate determination step). In order to determine an appropriate injection rate, a stock solution containing suspended solids aggregated with a flocculant was dehydrated with a dehydrator, and the moisture content of the obtained dehydrated cake was used as an index.

  The stock solution containing suspended solids used in the eighth experiment is sludge H. Sludge H is mixed raw sludge (mixture of primary sludge and surplus sludge) in a sewage treatment plant. The sludge H TS is 25.4. g / L. The measurement method conformed to the sewage test method.

  The flocculant used in the eighth experiment is a cationic polymer flocculant h (DAA polymer flocculant). The solution of the flocculant is an aqueous solution obtained by dissolving the flocculant in water, and the concentration of the flocculant means the concentration of the flocculant in the aqueous solution.

In the eighth experiment, a solution of the cationic polymer flocculant h was injected into the sludge H (sludge flow rate Fb: 0.3 L / sec). The sludge H into which the cationic polymer flocculant h was injected was mixed using a stirrer (stirring unit volume 0.5 L) in which the rotation speed of the stirring blade was set to 600 min- ¹ . At this time, the ratio R of the volume Va of the rotation region to the sludge flow rate Fb is 6.8. Next, the stirred sludge H was diluted with a diluent (diluent flow rate: 0.04 L / sec). As the diluting liquid, sand filtered water of sewage treated water was used. Next, the transmitted light intensity of the diluted sludge H was measured for a certain time. Next, the dispersion, standard deviation, and peak area of the obtained transmitted light intensity data were calculated. These operations were performed at multiple injection rates of flocculant.

On the other hand, in order to determine an appropriate injection rate of the flocculant, a solution of the cationic polymer flocculant h was injected into 250 mL of sludge H. The sludge H into which the cationic polymer flocculant h was injected was mixed using a stirrer (stirring tank volume 300 L) in which the rotation speed of the stirring blade was set to 33 min ⁻¹ to form floc. Finally, the sludge H containing floc was dehydrated with a belt press dehydrator, and the water content (%) of the obtained dehydrated cake was measured. These operations were performed at multiple injection rates of flocculant. The results of the eighth experiment are shown in Table 8.

  It can be seen that the dispersion, standard deviation, and peak area of the transmitted light intensity all take a maximum value when the injection rate of the flocculant is 0.58% (vs. TS). On the other hand, from the results of the belt press dehydrator, it is understood that when the flocculant injection rate is 0.58% (vs. TS) or less, the moisture content of the cake is greatly reduced as the injection rate is increased. In contrast, it can be seen that when the flocculant injection rate is 0.58% (vs. TS) or more, the moisture content of the cake hardly changes even if the injection rate increases. From these results, it was found that the coagulant injection rate enabling the most efficient dehydration can be determined based on the dispersion of the transmitted light intensity, the standard deviation, and the maximum value of the peak area. More specifically, it has been found that the injection rate of the flocculant capable of the most efficient dehydration can be determined based on the flocculant injection rate at which the values of transmitted light intensity dispersion, standard deviation, and peak area are maximized.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible.

DESCRIPTION OF SYMBOLS 1 1st stirring apparatus 2 1st stirring tank 3 1st optical measuring apparatus 4 1st flocculant injection apparatus 5 1st numerical analysis apparatus 6 1st control apparatus 7 1st supply apparatus 8 1st Stirring blades 9 First drive source 10 Stock solution storage tank 11 First flocculant storage tank 12 First coagulation tank stirring device 14 Dehydrator 15 Rotating body 17 Rotating shaft 18 Stock solution supply pipe (stock solution supply source pipe)
DESCRIPTION OF SYMBOLS 19 1st undiluted | stock solution supply piping 20 Precipitation tank 21 2nd flocculent tank stirring apparatus 23 2nd flocculant storage tank 25 2nd stock solution supply piping 26 1st flocculant supply piping 28 1st discharge piping 35 2nd Supply device 36 Second coagulant supply pipe 37 First coagulation agitation tank 38 First coagulation tank agitation blade 39 First coagulation tank drive source 40 Transparent window 41 Light source 42 Photo detector 43 Light source 44 Photo detector 45 No. 2 coagulant injection device 46 Second discharge pipe 47 Second coagulation agitation tank 48 Second coagulation tank agitation blade 49 Second coagulation tank driving source 50 Data logger 52 Third coagulant supply pipe 53 Third Flocculant injection device 55 Connection pipe 56 Third supply device 57 Third stock solution supply pipe 58 Fourth flocculant supply pipe 60 Second agitation device 61 Second agitation tank 62 Second agitation blade 63 Second Drive source 64 second rotation Axis 65 Fourth supply device 66 Fourth flocculant injection device 68 Second optical measurement device 69 Third discharge piping 70 Second numerical analysis device 71 Second control device 80 Fifth supply piping 81 First 5 Supply device 85 Diluent storage tank 86 Diluent supply device 87 Diluent supply piping

Claims (35)

An agitation apparatus comprising an agitation tank, a rotating shaft rotated by a driving source, an agitation blade connected to the rotating shaft and disposed in the agitation tank, and a stock solution supply pipe connected to the agitation tank. In a flocculation method that agglomerates a stock solution containing suspended matter,
A supply step of supplying the stock solution from the stock solution supply pipe to the stirring tank;
An injecting step of supplying a flocculant to the stirring tank or the stock solution supply pipe and injecting the flocculant into the stock solution;
A stirring step of rotating the stirring blade to stir the stock solution into which the flocculant has been injected;
An optical measurement step of irradiating the stirred stock solution with light to obtain an optical measurement value;
Numerical analysis of the optical measurement value to obtain a numerical analysis value; and
An injection rate determination step of determining an appropriate injection rate of the flocculant based on the numerical analysis value,
The volume of the rotation region formed by the rotation of the rotating blade composed of the stirring blade and the rotating shaft in the stirring tank is Va [L], and the flow rate of the stock solution passing through the stirring tank is Fb [L / Second], the ratio value of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2. The aggregation method according to claim 1, wherein the rotation speed of the stirring blade is set to 400 min ⁻¹ or more.   The aggregation method according to claim 1 or 2, wherein the volume Va of the rotation region is in a range of 0.1L to 2.0L. The injection rate determination step includes
Based on the numerical analysis value, determine whether the injection rate of the flocculant is appropriate,
Until the proper injection rate of the flocculant is determined, the supply step, the injection step, the agitation step, the optical measurement step, and the numerical analysis step are repeated steps while changing the injection rate. The aggregation method according to any one of claims 1 to 3, wherein   5. The change in the injection rate is to change one or both of a flow rate of the stock solution flowing into the stirring device and a flow rate of the flocculant injected into the stock solution. The aggregating method described in 1.   The aggregation method according to claim 1, wherein the optical measurement step is a step of measuring the transmitted light intensity by irradiating the stirred stock solution with light.   The aggregation method according to claim 1, wherein the optical measurement step is a step of measuring the scattered light intensity by irradiating the stirred stock solution with light.   6. The optical measurement step is a step of measuring both transmitted light intensity and scattered light intensity by irradiating the stirred stock solution with light. Aggregation method.   The aggregation method according to claim 1, wherein the dispersion of the optical measurement values is used as the numerical analysis value.   The aggregation method according to claim 1, wherein a peak area of the optical measurement value is used as the numerical analysis value.   The aggregation method according to any one of claims 1 to 8, wherein a standard deviation of the optical measurement value is used as the numerical analysis value.   The aggregation method according to any one of claims 1 to 3, wherein the numerical analysis value is a particle size of a floc of the suspended substance. The injection rate determination step includes
Obtaining a plurality of numerical analysis values by repeating the supplying step, the injection step, the stirring step, the optical measurement step, and the numerical analysis step a plurality of times while changing the injection rate,
The aggregation method according to any one of claims 1 to 3, wherein the aggregation method is a step of determining an appropriate injection rate of the flocculant based on the plurality of numerical analysis values.   The aggregation method according to claim 13, wherein an injection rate at which a maximum value or a minimum value is obtained among the plurality of numerical analysis values is determined as the appropriate injection rate.   The average value of the injection rate at which the maximum value is obtained among the plurality of numerical analysis values and the injection rate at which the second largest value is obtained, or the injection rate at which the minimum value is obtained among the plurality of numerical analysis values The aggregation method according to claim 13, wherein an average value of the injection rate at which the second smallest value is obtained is determined as the appropriate injection rate.   4. The correction injection rate determination step of determining a correction injection rate by multiplying an appropriate injection rate determined in the injection rate determination step by a correction coefficient. The aggregation method according to item. Further comprising a dilution step of diluting the stirred stock solution with a diluent,
The aggregation method according to any one of claims 1 to 3, wherein the dilution step is performed between the stirring step and the optical measurement step. A stirring tank, a rotating shaft rotated by a driving source, a stirring blade connected to the rotating shaft and disposed in the stirring tank, and a stock solution supply pipe connected to the stirring tank; An agitation device for agitating the stock solution containing the injected suspended material;
A supply device for supplying the stock solution to the stirring tank;
An injection device for supplying the flocculant to the stirring tank or the stock solution supply pipe and injecting the flocculant into the stock solution;
An optical measurement device for obtaining optical measurement values by irradiating the stirred stock solution with light;
Numerical analysis of the optical measurement value to obtain a numerical analysis value, and a numerical analysis device,
A controller for determining an appropriate injection rate of the flocculant based on the numerical analysis value,
The volume of the rotation region formed by the rotation of the rotating blade composed of the stirring blade and the rotating shaft in the stirring tank is Va [L], and the flow rate of the stock solution passing through the stirring tank is Fb [L / Second], the ratio of the volume Va to the flow rate Fb is in the range of 1.1 to 10.2. The aggregating apparatus according to claim 18, wherein a rotation speed of the stirring blade is set to 400 min ^-1 or more.   The aggregation apparatus according to claim 18 or 19, wherein the stock solution inlet of the optical measuring device is located higher than the stock solution outlet of the stirring device.   21. The aggregating apparatus according to claim 18, wherein a stock solution outlet of the optical measuring device is located higher than a stock solution inlet of the optical measuring device. The controller is
Based on the numerical analysis value, determine whether the injection rate of the flocculant is appropriate,
Operate one or both of the flocculant injection device and the supply device, the stirring device, the optical measuring device, and the numerical analysis device until an appropriate injection rate of the flocculant is determined. Then, supply of the stock solution to the stirring tank, injection of the flocculant into the stock solution, stirring of the stock solution, acquisition of the optical measurement value, and acquisition of the numerical analysis value are repeated while changing the injection rate. The aggregating apparatus according to any one of claims 18 to 21, wherein the aggregating apparatus is characterized in that   The aggregating apparatus according to any one of claims 18 to 22, wherein the optical measuring device measures the transmitted light intensity by irradiating the stirred stock solution with light.   The aggregating apparatus according to any one of claims 18 to 22, wherein the optical measuring device irradiates the stirred stock solution with light and measures scattered light intensity.   The aggregating apparatus according to any one of claims 18 to 22, wherein the optical measuring device is both a measuring device that measures transmitted light intensity and a measuring device that measures scattered light intensity.   The aggregation device according to any one of claims 18 to 25, wherein the numerical analysis device acquires a dispersion of the optical measurement value as the numerical analysis value.   The aggregation device according to any one of claims 18 to 25, wherein the numerical analysis device acquires a peak area of the optical measurement value as the numerical analysis value.   The aggregation device according to any one of claims 18 to 25, wherein the numerical analysis device acquires a standard deviation of the optical measurement value as the numerical analysis value.   The aggregating apparatus according to any one of claims 18 to 21, wherein the numerical analysis device acquires a floc particle size of the suspended solids as the numerical analysis value. The controller is
By operating one or both of the flocculant injection device and the supply device, the stirring device, the optical measuring device, and the numerical analysis device, supply of the stock solution to the stirring tank, the stock solution To obtain a plurality of numerical analysis values by repeating the injection of the flocculant, stirring the stock solution, obtaining the optical measurement values, and obtaining the numerical analysis values a plurality of times while changing the injection rate,
The aggregating apparatus according to any one of claims 18 to 21, wherein an appropriate injection rate of the aggregating agent is determined based on the plurality of numerical analysis values.   The aggregating apparatus according to claim 30, wherein the control device determines an injection rate at which a maximum value or a minimum value is obtained from the plurality of numerical analysis values as the appropriate injection rate.   The control device has an average value of an injection rate at which a maximum value is obtained among the plurality of numerical analysis values and an injection rate at which a second largest value is obtained, or a minimum value among the plurality of numerical analysis values is The aggregation device according to claim 30, wherein an average value of the obtained injection rate and the injection rate at which the second smallest value is obtained is determined as the appropriate injection rate.   The aggregating apparatus according to any one of claims 18 to 21, wherein the control device multiplies the determined appropriate injection rate by a correction coefficient to determine a correction injection rate.   The aggregating device according to any one of claims 18 to 21, wherein the numerical analysis device is incorporated in the control device.   The aggregating apparatus according to any one of claims 18 to 21, further comprising a diluent supply device that supplies a diluent to the stirred stock solution.

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