JP2022124388A - Water purification method and water purification device - Google Patents

Abstract

To provide a water purification method and a water purification device that can safely and efficiently remove picophytoplankton, one factor of increased turbidity of filtered water, so that filtered water with low turbidity can be stably obtained.SOLUTION: A water purification method includes adding a flocculant to raw water containing picophytoplankton, filtering the flocculant-added water to make the filtered water, counting picophytoplankton in the raw water, treated water or filtered water, and controlling the amount of addition of the flocculant according to the results of counting picophytoplankton. As the flocculant to reduce the counts of picophytoplankton, polyaluminum chloride with a basicity of 60% or more is added.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a water purification method and a water purification apparatus for removing picoplankton contained in raw water such as river water and groundwater.

BACKGROUND ART In water treatment of raw water such as river water and groundwater, turbidity components, algae, and the like, which are insoluble components, are removed by solid-liquid separation techniques such as coagulation sedimentation treatment and sand filtration treatment. In the process of coagulating and filtering raw water, coagulation may be inhibited by various factors, and the presence of picoplankton has become a problem in recent years as one of the causes. Picoplankton is plankton having a size of 0.2 to 2 μm, and is reported to be a factor in increasing the turbidity of filtered water (Non-Patent Document 1).

Picoplankton are classified into two groups according to the mechanism of nutrient intake. One is heterotrophic picoplankton, which is mainly composed of bacteria that decompose organic matter and use it as a nutrient source, and the other is phytopicoplankton, which performs photosynthesis. Picoplankton has pigments such as chlorophyll, can be observed with a fluorescence microscope, and has been confirmed to exist in raw water or treated water for water purification.

In recent years, the Ministry of Health, Labor and Welfare has instructed management of filtered water turbidity of 0.1 degrees or less as a countermeasure against infections caused by Cryptosporidium generated through tap water (see Non-Patent Document 2). For this reason, water supply operators in various places regard it as one of the most important water quality management items to always manage filtered water turbidity at 0.1 degrees or less.

However, recent tap water sources all over the country are experiencing frequent outbreaks of picoplankton caused by eutrophication. Since picoplankton is as small as 0.2 to 2 μm in size, it leaks out from the filter basin and causes the turbidity of filtered water to rise to 0.1 degree or more. Water utilities are struggling to find a way to deal with it.

Since picoplankton is a biologically-derived turbidity, chlorine injection has been considered an effective means of treatment. However, trihalomethane generated as a by-product of chlorine injection poses a health problem as a carcinogenic substance. Therefore, a safer removal method is desired in place of chlorine injection.

For example, Japanese Patent Application Laid-Open No. 2014-240760 (Patent Document 1) describes a biological particle counting method and a biological particle counter for calculating the number of different types of algae contained in water. However, Patent Document 1 only describes a general method for removing turbidity, and does not describe picoplankton or its removal.

Japanese Patent Application Laid-Open No. 2011-110504 (Patent Document 2) discloses that the cause of poor water purification treatment is filtration failure due to microplankton, based on information on sedimentation water turbidity and filtered water turbidity obtained from a water purification treatment automatic continuous monitoring device. Disclosed is a continuous control system for a water purification process that determines whether or not there is a filtration failure due to microplankton, and automatically injects a coagulant in the coagulation treatment process. However, Patent Literature 2 only discloses a technique of automatically injecting a flocculant as a means of coping with filtration failure caused by microplankton.

In JP-A-2004-195304 (Patent Document 3), the turbidity of the water to be treated (filtered water) at the filter outlet is measured, and a coagulant is added to the filter inlet according to the detected turbidity. A flocculant injection control device is disclosed. However, it is a technique of injecting a flocculating agent into a filter based on turbidity detection results, and picoplankton and its removal means are not described.

Japanese Patent Application Laid-Open No. 2016-059867 (Patent Document 4) discloses a treatment method in a water purification plant that prevents picoplankton proliferation by irradiating with ultraviolet rays, and technology of equipment therefor. However, in this invention, there is a problem that the number of man-hours and costs increase because a process and an apparatus for irradiating ultraviolet rays are required.

Japanese Patent Application Laid-Open No. 2006-007086 (Patent Document 5) is an invention relating to a coagulation-sedimentation water treatment method and apparatus, and describes the properties of a coagulation improver (coagulation aid) and a treatment method. However, Patent Document 5 does not describe picoplankton or its removal means.

Japanese Patent Application Laid-Open No. 2012-228673 (Patent Document 6) describes good fine floc formation by a cohesion improving agent (cohesion aid). However, picoplankton and its removal means are not described.

Japanese Patent No. 3225266 (Patent Document 7) describes a method for obtaining clear water such as industrial water from lakes and rivers containing algae, and a mixture of polyaluminum chloride and polydimethyldiallylammonium chloride is described. It is described to have a remarkable effect in removing algae together with general turbidity components. However, Patent Document 7 does not describe picoplankton, which leaks from the filter and causes an increase in filtered water turbidity. removal effect cannot be expected.

JP 2014-240760 A JP 2011-110504 A JP 2004-195304 A JP 2016-059867 A Japanese Patent Application Laid-Open No. 2006-007086 JP 2012-228673 A Japanese Patent No. 3225266

Japan Water Works Association, Guideline for Water Purification Treatment to Prevent Biological Disorders, March 2006, p.57 Ministry of Health, Labor and Welfare Notification, Pharmaceutical Water Notification No. 0529 No. 1, “Guidelines for Countermeasures against Cryptosporidium, etc. in Water Supply”, Attachment 2, Page 3, May 29, 2019

As described above, the current situation is that none of the conventional treatment technologies have been adequately studied as to countermeasures against the increase in turbidity due to the generation of picoplankton contained in the raw water.

In view of the above problems, the present invention can safely and efficiently remove picoplankton, which is one of the factors that increase the turbidity of filtered water, and can stably obtain filtered water with low turbidity. A water purification method and a water purification apparatus are provided.

As a result of intensive studies by the present inventors in order to solve the above problems, it is effective to add a predetermined flocculant for reducing the number of picoplankton according to the number of picoplankton in raw water or filtered water. I got some insight.

One aspect of the embodiment of the present invention completed based on the above findings is to add a coagulant to raw water containing picoplankton, and filter the treated water to obtain filtered water from the treated water after the addition of the coagulant. A flocculant for reducing the number of picoplankton, including treating and measuring the number of picoplankton in raw water, treated water, or filtered water, and controlling the amount of addition of the flocculant according to the measurement result of the number of picoplankton. It is a water purification method that adds polyaluminum chloride having a basicity of 60% or more.

In one embodiment, the water purification method according to the embodiment of the present invention includes adding two or more flocculants as flocculants, at least one flocculant contains polyaluminum chloride, and the number of picoplankton and controlling the type and supply of flocculant added.

In another embodiment, the water purification method according to the embodiment of the present invention includes adding a flocculating agent for reducing the number of picoplankton to the treated water flowing into the filtration process.

In still another embodiment of the water purification method according to the embodiment of the present invention, the relationship between the operating conditions of the filtration process, the filtered water quality information, and the picoplankton number measurement result is determined based on past performance. Predict the future measurement results of picoplankton numbers based on the analysis information analyzed by the method, and based on the prediction results, determine the amount of flocculant to be added so that the turbidity of the filtered water is maintained below the standard value. further includes

In another aspect of the embodiment of the present invention, flocculant addition means for adding a flocculant to raw water containing picoplankton, flocculation means for flocculating by forming flocs in raw water, and flocculation after flocculation treatment Filtration means for filtering treated water to obtain filtered water, measurement means capable of measuring the number of picoplankton in raw water, treated water or filtered water, and reducing the number of picoplankton according to the measurement result of the number of picoplankton The water purification apparatus includes a control means for adding polyaluminum chloride having a basicity of 60% or more as a flocculant for water purification and controlling the amount of addition.

In one embodiment of the water purification apparatus according to the embodiment of the present invention, the coagulant addition means includes a plurality of supply paths for adding two or more types of coagulants, one of the supply paths being polychlorinated It is a route for supplying aluminum, and the control means includes controlling switching of flocculant supply by a plurality of supply routes according to the measurement result of the number of picoplankton.

In another embodiment of the water purification apparatus according to the embodiment of the present invention, the path for supplying the polyaluminum chloride includes filtering means, and an inflow pipe for causing treated water after solid-liquid separation to flow into the filtering means. or connected to at least one of a sedimentation tank for sedimentation of flocs formed in the raw water.

In still another embodiment of the water purification apparatus according to the embodiment of the present invention, machine learning using the operating conditions of the filtering means, the filtered water quality information, and the measurement result of the number of picoplankton in the filtered water by the measuring means predicting the number of picoplankton in the future by performing, and based on the prediction result, further comprising a flocculant addition support means for determining the amount of flocculant to be added so that the turbidity of the filtered water is maintained below the reference value .

According to the present invention, picoplankton, which is one of the factors that increase the turbidity of filtered water, can be removed safely and efficiently, and water purification treatment that can stably obtain filtered water with low turbidity. A method and water treatment apparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic showing an example of the water-purifying-treatment method which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic showing an example of the water purification apparatus which concerns on embodiment of this invention. It is the schematic showing the water-purification apparatus which concerns on the modification of embodiment of this invention. It is a block diagram showing the structural example of the coagulant addition assistance means using the machine learning which concerns on embodiment of this invention. It is explanatory drawing showing the example of the data which the acquisition part of a coagulant addition assistance means acquires. 1 is a schematic diagram showing a processing flow of Example 1; FIG. FIG. 11 is a schematic diagram showing a processing flow of Example 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the embodiments shown below are examples of apparatuses and methods for embodying the technical idea of the present invention. It does not specify anything.

(Aggregation treatment method)
In the water purification method according to the first embodiment of the present invention, as shown in FIG. 1, a flocculant is added to raw water containing picoplankton, and the treated water after addition of the flocculant is treated to obtain filtered water. It involves filtering water, measuring the number of picoplankton in raw water, treated water or filtered water, and controlling the amount of coagulant to be added according to the measurement result of the number of picoplankton.

[Flocculant addition step]
In the flocculant addition step, a flocculant is added to the raw water. The raw water is not particularly limited as long as it can be used for water purification. For example, river water, lake water, reservoir water, rain water, subsoil water, ground water, well water, etc., which are used as raw water for tap water, can be suitably used as raw water according to the present embodiment. For example, raw water with a turbidity of 100 degrees or less, more typically 20 degrees or less, and still more typically about 2 to 10 degrees is used. Raw water typically passes through a settling basin or a receiving well and undergoes coagulation sedimentation treatment.

In this embodiment, a flocculant for reducing the number of picoplankton in the raw water is used as the flocculant added to the raw water. A polyaluminum chloride (PAC) solution with a basicity of 60% or more is used as a flocculant for reducing the number of picoplankton.

The higher the basicity of the PAC solution used for removing picoplankton, the higher the charge-neutralizing ability in the raw water, and the more effective the capture of fine particles. In addition, when maintaining the same processing capacity, the higher the basicity of the PAC solution, the lower the addition rate, so the processing efficiency is high and there is an economic advantage. In this embodiment, it is preferable to use a PAC solution with a basicity of 65% or more, more preferably 70% or more, and even more preferably 75% or more as a flocculant added to raw water. If the basicity of the PAC solution is too high, the flocculating property and the stability of the flocculant may be impaired. Although there is no upper limit for the basicity, the basicity of the PAC solution is preferably 90% or less, more preferably 85% or less, in order to perform more stable treatment.

Such a highly basic PAC solution (hereinafter also referred to as “high basicity PAC”) has, for example, an Al ₂ O ₃ concentration of 5 to 17% and a Cl/Al ₂ O ₃ (molar ratio) of 1.80 to 3 Prepare a basic aluminum chloride solution of 0.60, SO ₄ /Al ₂ O ₃ (molar ratio)=0-0.35 and a basicity of 40-63%. Then, an alkali metal and/or alkaline earth metal compound such as sodium carbonate or potassium carbonate is added to this basic aluminum chloride solution at a temperature of 85° C. or less at a molar ratio of M/Al ₂ O ₃ =0. .08 to 1.40 (where M represents the number of moles of the alkali metal and/or the number of moles twice the number of moles of the alkaline earth metal), and if necessary, the aluminum raw material is added. It can be produced by further adding and aging at 65 to 85° C. for 0.5 to 2 hours.

According to the present embodiment, by using a PAC solution with a basicity of 60% or more as a flocculating agent, compared to the case of using a general PAC solution with a basicity of about 50%, about 0.2 to 2 μm Fine picoplankton can be more effectively aggregated and removed from raw water.

As the flocculant, it is preferable to add two or more kinds of flocculants to the raw water. As a flocculating agent, in addition to the above-mentioned highly basic PAC solution (hereinafter also referred to as "high basicity PAC"), for example, general PAC having a basicity of about 50 to 55%, aluminum sulfate (aluminum sulfate) , polyiron sulfate, etc. can be used alone or in combination of two or more. These flocculants are agents that have cross-linking ability to neutralize the charge of suspended particles and colloidal substances in water and cause them to agglomerate and form flocs.

An agent called a flocculation aid for improving floc sedimentation separation in flocculation treatment and trapping in a rapid filtration basin and forming dense and strong flocs with a large diameter is further used as a flocculating agent according to the present embodiment. It can also be added. As such a flocculation aid, a flocculation aid, an alkali agent, active silicic acid, alginic acid, an organic flocculation aid, a polymer flocculant, a flocculation improver, and the like can be used. For the polymer flocculant, one or more of cationic polymer flocculants, anionic polymer flocculants, and nonionic polymer flocculants are appropriately selected in consideration of the surface charge of particles in the heavy liquid. It is preferred to use

The amount of the flocculant to be added is appropriately selected according to the basicity of the selected flocculant. Usually, the amount of flocculant added is 1 to 50 mg/L. In the later-described control step, the amount and type of flocculant to be added can be controlled within this range.

[Aggregation treatment step]
The raw water to which the flocculant has been added is subjected to flocculation treatment. For example, a flocculant is added to raw water, stirred and mixed in a mixing tank to form flocs, and then the flocs formed in the raw water are coarsened in a floc forming tank. The treated water obtained by the flocculation treatment is sent to the filtration process after solid-liquid separation of flocs in a sedimentation basin as necessary.

[Filtration process]
In the filtering step, the treated water to which the coagulant has been added is filtered. A conventional method can be used for the filtration treatment, and sand filtration is generally used.

[Particle measurement process]
In the fine particle measurement step, the number of picoplankton contained in the fine particles is measured by measuring the number of fine particles contained in raw water and filtered water. In the present embodiment, fine particles refer to particles having a particle size of 0.1 μm to several hundred μm. In the fine particle measurement step, the number of picoplankton with a particle size of 0.2 μm to 2.0 μm is measured among the fine particles. Picoplankton is a generic term for microplankton, phytoplankton, microplankton, microalgae, algae bioparticles, and the like.

In this embodiment, the particle size of picoplankton refers to the minimum length of picoplankton. In addition, as a method for extracting only picoplankton of 0.2 μm to 2.0 μm from fine particles of all sizes, a filter with an opening size of 0.2 μm and a filter with an opening size of 2.0 μm are used, This can be done by passing raw or filtered water through the

As a method used for measuring the number of picoplankton in the fine particle measurement step, for example, fluorescence measurement using a fluorescence microscope can be used. In fluorescence measurement, the presence of picoplankton is confirmed by measuring fluorescence emitted by chlorophyll contained in picoplankton, and the number of picoplankton present is counted by a counter. In the fine particle measurement step, it is more preferable to measure the turbidity of raw water and filtered water at the same timing as the number of picoplankton. Turbidity can be measured with a conventionally used turbidity meter.

[Control process]
In the control step, based on the number of picoplankton measured in the fine particle measurement step, control is performed to adjust the addition amount of the flocculant. For example, when the number of picoplankton in raw water, treated water, or filtered water is equal to or greater than a predetermined value within the range of 10 ⁷ to 10 ³ cells/mL, the amount of coagulant added is controlled to increase. is preferred. When the measurement result of picoplankton number decreases as a result of increasing the amount of flocculant added, it is also preferable to perform control such as decreasing the amount of flocculant added. In this embodiment, the unit "cells/mL" refers to the number of picoplankton per 1 mL of raw or filtered water.

More specifically, the number of picoplankton in the raw water, treated water, or filtered water is within the range of 10 ⁷ to 2×10 ³ cells/mL, and the picoplankton that provides filtered water with a turbidity of 0.1 degree or less. A number is set as a threshold value, and when the measurement result of the picoplankton number is equal to or higher than the threshold value, control is preferably performed to increase the addition amount of the flocculant to reduce the picoplankton number.

The picoplankton count threshold can be set according to the relationship with the turbidity of filtered water obtained at a water purification plant. For example, at a water purification plant, it is known that when the number of picoplankton in filtered water is 2×10 ⁵ cells/mL, the turbidity is 0.1 degree or less. In such a case, the picoplankton threshold for adding the flocculant is set to 2 × 10 ⁵ cells / mL, and when the measured number of picoplankton is above the threshold, control is performed to increase the amount of flocculant added. By doing so, it becomes easy to manage the turbidity of the filtered water at 0.1 degree or less.

The number of picoplankton may be measured at one or more locations in raw water, treated water, or filtered water, but it is particularly preferable to measure the number of fine particles in filtered water. By directly measuring the number of picoplankton in the filtered water, which can directly influence changes in the turbidity of the filtered water, the goal of maintaining a stable low value of turbidity in the filtered water can be reliably achieved.

In the control step, in addition to controlling the addition amount of the flocculant, it is more preferable to control the type and supply of the flocculant according to the measurement result of the number of picoplankton. For example, in combination with the above-mentioned high basicity PAC, a normal basicity PAC, a flocculation aid, an alkali agent, active silicic acid, alginic acid, an organic flocculation aid, a polymer flocculant, a flocculation modifier, etc. are added. In addition, these flocculants can be used in appropriate combination according to the properties of raw water, treated water, or filtered water.

For example, during normal operation, 1 to 50 mg/L of PAC with normal basicity is used, and when the turbidity of the filtered water is high, more is added. If it is found in the fine particle measurement step that the concentration of picoplankton, which is difficult to agglomerate, tends to increase, a high basicity PAC with a basicity of 60% or more is further added to a predetermined amount. Alternatively, the flocculant feed is switched and high basicity PAC is added at similar loadings instead of normal basicity PAC.

In the control step, the addition position of the flocculant can also be controlled. For example, depending on the increase or decrease in the number of picoplankton, the flocculant is controlled to be added not only before the flocculation treatment but also at any position such as the inflow pipe of the filter after the flocculation treatment, the upper part of the filter, or the sedimentation tank. can do. This makes it possible to reduce picoplankton more effectively.

According to the water purification method according to the embodiment of the present invention, polyaluminum chloride having a basicity of 60% or more is added as a flocculant for reducing the number of picoplankton according to the measurement result of the number of picoplankton. . Therefore, even if a sudden change in the properties of raw water causes a large outbreak of picoplankton due to eutrophication, picoplankton can be removed safely and efficiently, and stable, low-turbidity filtered water can be obtained. can be obtained.

(Water purification equipment)
The water purification apparatus according to the embodiment of the present invention, as shown in FIG. Aggregation means 2, filtration means 3 for obtaining filtered water by filtering treated water after aggregation treatment, measuring means 4 capable of measuring the number of picoplankton in raw water, treated water or filtered water, and control means 5 Prepare.

The coagulant addition means 1 is a device capable of adding a coagulant to raw water, treated water after coagulation treatment, or filtered water. The flocculant addition means 1 preferably has a plurality of supply paths 11 and 12 for adding two or more types of flocculants to the raw water. The number of supply paths 11 and 12 can be appropriately changed according to the type of flocculant. However, it is preferred that one of the supply paths 11, 12, the supply path 12, is the path for supplying the high basicity PAC.

The supply path 12 for supplying the high basicity PAC is preferably connected to the filtering means 3 or to an inflow pipe 31 for allowing the treated water from the flocculating means 2 to flow into the filtering means 3 . By connecting the supply route 12 to the filtration means 3 or the inflow pipe 31, treatment for effectively reducing picoplankton is focused on treated water with lower turbidity than raw water after flocculation. Since it can carry out, the turbidity of filtered water can be reduced more effectively. The feed line 12 may be connected to a sedimentation tank 22 .

The flocculation means 2 typically includes a flocculation tank 21 composed of a mixing tank, a flocculation tank, etc., and a sedimentation tank 22 composed of a sedimentation tank, etc. for sedimentation separation of flocs formed in the raw water. but not limited to the configuration described above. For example, the coagulation treatment may be performed in a single coagulation tank instead of being divided into a plurality of tanks. If solid-liquid separation is not required, the sedimentation tank 22 can be omitted. As the filtering means 3, a sand filter can typically be used, but other known filtering devices such as a membrane filtration device can be used.

The measuring means 4 is not particularly limited as long as it can measure the number of picoplankton with a particle size of 0.2 μm to 2.0 μm. For example, it is possible to more easily and accurately measure the number of picoplankton by using a fluorescence microscope or the like that utilizes fluorescence measurement. For example, a counter capable of measuring bioparticles containing phytopicoplankton can be used for raw water, treated water, or filtered water to be measured. Although not shown, as the measuring means 4, a measuring device for measuring water quality such as turbidity, water temperature, and pH of raw water, treated water, and filtered water is provided, and the raw water, treated water, and filtered water are measured. Preferably, the results are output to the control means 5 .

The control means 5 is connected to the measuring means 4 and the coagulant adding means 1 and configured to output a control signal for controlling the measuring means 4 and the coagulant adding means 1 . Control means 5 controls the addition amount of high basicity PAC added as a flocculant for reducing the number of picoplankton and other flocculants, controls the addition position, and Controls switching of the coagulant to be added.

According to the water purification apparatus according to the embodiment of the present invention, the measurement means 4 capable of measuring the number of picoplankton in raw water, treated water or filtered water, and the amount of coagulant added according to the measurement result of the number of picoplankton By providing a control means 5 that controls, picoplankton, which is one of the factors that increase the turbidity of filtered water, can be detected more appropriately. processing can be performed. As a result, filtered water with low turbidity can be stably obtained.

(Modification)
As shown in FIG. 3, the water purification apparatus according to the modification of the embodiment of the present invention predicts the number of picoplankton in future raw water, treated water, or filtered water, and based on the prediction result, the amount of coagulant added It is different from the water purification treatment apparatus shown in FIG.

The coagulant addition support means 6 is connected to the measurement means 4 and the control means 5 . The coagulant addition support means 6 does not necessarily need to be arranged adjacent to the control means 5, and may be installed in a place different from the water purification treatment apparatus of FIG. may be stored in the form of a program or the like.

The coagulant addition support means 6 is based on the analysis information obtained by analyzing the relationship between the operating conditions of the filtration process, the water quality information of the filtered water, and the measurement result of the number of picoplankton based on the past performance. Determine the amount of flocculant to be added so that the turbidity of the liquid remains below the standard value.

Filtration operation information includes water quality information (temperature, conductivity, pH, concentration of organic matter, turbidity, etc.) of raw water or influent (aggregated water), operating conditions of filtration equipment (filter material, particle size, filter bed height, pressure, flow rate, filtration time, filtration resistance, etc.). It is preferable that the operation information of the filtration process includes maintenance information such as cleaning timing of the filtering device.

The filtered water quality information includes water temperature, pH, concentration of metals such as aluminum, information on organic substances such as COD and BOD, conductivity of permeated water, number of picoplankton, and the like. In addition to the operation status of the filtration process and the water quality condition of the filtered water, it is preferable that the injection control data of the coagulant be included in the operation information of the filtration process.

It is said that the average removal rate of picoplankton in a sedimentation pond is about 70%, and depending on the number of picoplankton generated, it may not be completely removed by filtration. For example, when the water temperature exceeds 20°C, the turbidity is less than 10 degrees, and the raw water pH exceeds 7.5, the picoplankton concentration in the raw water may be high. Therefore, picoplankton in filtered water cannot be completely removed in general water purification treatment, and the increase in picoplankton may increase the possibility of increased turbidity in filtered water. For example, the operator uses past raw water turbidity, water temperature, organic matter concentration, picoplankton number, and filtered water turbidity, water temperature, and picoplankton number data to determine the relationship between the type of flocculant and the injection rate. Based on this, prepare analysis information for predicting the number of picoplankton in filtered water, and prepare in advance a relational expression for determining the addition rate of the flocculant according to the measurement result of the number of picoplankton in filtered water. . For example, under conditions where an increase in picoplankton is expected in the future, for example, when at least one of the above-mentioned temperature, turbidity, and raw water pH continues for a certain period of time or longer, the addition rate of the flocculant is increased step by step. Create a relational expression such as Then, the coagulant addition support means 6 uses the relational expression and the measurement result of the number of picoplankton in the filtered water, so that the turbidity of the filtered water is stably maintained below the reference value. can be determined.

Prediction of the number of picoplankton can be more accurately predicted by using a machine learning function using artificial intelligence (AI). For example, the flocculant addition support means 6 is composed of a computer system including a storage device capable of storing information necessary for operation control of the water purification treatment device, an input device, an output device, and a communication means. may be communicatively connected to another water treatment device or server. Then, it may be configured such that the learned model created by the flocculant addition support means 6 or various information recorded in a server or another water purification treatment apparatus can be shared with each other.

For example, as shown in FIG. 4, the coagulant addition support means 6 includes an acquisition unit 61, a learning unit 62, a model storage unit 63, a prediction unit 64, a determination unit 65, and an output unit 66. can be done. For example, as shown in FIG. 5, the acquisition unit 61 acquires raw water quality data indicating past raw water quality information, coagulant injection data indicating the type of coagulant and its injection rate, filtration time, filtration resistance, flow rate, conductivity, , operating data including temperature, etc., and filtered water data including filtered water quality information such as pH, turbidity, COD, and picoplankton count. The acquisition unit 61 further acquires the measurement results of each measurement device (time, thermometer, pH meter, filtration resistance pressure gauge, flow meter, conductivity meter, etc.) obtained during operation of the water treatment device, thereby performing water purification treatment. Get the operating information of the equipment.

Based on the information acquired by the acquisition unit 61, the learning unit 62 creates a learned model of the water purification apparatus by machine learning using a predetermined machine learning algorithm. Machine learning algorithms include, for example, PCR method (principal component regression method), PLS method (partial least squares method), SVR method (support vector regression method), ARIMA, LSTM, neural network (ANN and RNN) method, random forest An analysis tool using a method, a decision tree method, or the like can be appropriately selected and used.

The parameters of the machine learning model, such as the number of layers and the number of neurons in each layer in the neural network method, are not particularly limited, but for example, the number of neurons in each layer can be 1 to 50, further 1 to 30, The number of layers can be 1 or more, or even 1 to 4 layers. The trained model thus created is configured to receive predetermined explanatory variables and output predetermined objective variables.

For example, when using the neural network method, raw water quality data indicating past raw water quality information, coagulant injection data indicating the type and injection rate of coagulant, filtration time, filtration resistance, flow rate, conductivity, temperature etc., filtered water data including filtered water quality information such as pH, turbidity, COD, picoplankton number, meteorological condition data including past temperature, and past measurement results of picoplankton number in the input layer. input, and configured to output from the output layer the particulate count including picoplankton count of future filtered water after a predetermined time (eg, several minutes to several hours). The weighting coefficients between neurons of the neural network are optimized by supervised learning using data in which the data input to the input layer and the data output from the output layer are linked. A trained model is stored in the model storage unit 63 .

The prediction unit 64 uses the learned model created by the learning unit 62 to at least predict the future number of picoplankton in the raw water, treated water, or filtered water of the water purification system. For example, the prediction unit 64 inputs the measurement results of each measurement device obtained during operation of the water treatment device acquired by the acquisition unit 61 into the input layer of the learning model, and the number of picoplankton in the filtered water after a predetermined time is output layer Output from

The determining unit 65 determines the optimum addition amount of the coagulant based on the past data according to the prediction result of the predicting unit 64 so that the turbidity of the filtered water is maintained at a reference value or less. The output unit 66 outputs control information on the optimal combination of flocculants determined by the determination unit 65 and the addition amount thereof to the control unit 5 .

According to the water purification method according to the modification of the embodiment of the present invention, by measuring the number of picoplankton in raw water, treated water, or filtered water, and predicting the number of picoplankton after the elapse of a predetermined time, the prediction result Based on, if the picoplankton number increases, a suitable flocculant can be added to reduce the picoplankton number. As a result, picoplankton, which is one of the factors that increase the turbidity of filtered water, can be removed safely and efficiently, and filtered water with low turbidity can be stably obtained.

Although the present invention has been described by the above embodiments, the statements and drawings forming part of this disclosure should not be understood to limit the present invention. That is, the present disclosure is not limited to the above-described embodiments, and it goes without saying that the constituent elements can be combined with each other, modified, and embodied without departing from the scope of the present disclosure.

Examples of the present invention are presented below along with comparative examples, which are provided for a better understanding of the invention and its advantages and are not intended to be limiting of the invention.

(Example 1)
Water purification treatment was performed along the treatment flow shown in FIG. A PAC having a normal basicity was added to the flocculation tank, and the treated water obtained by solid-liquid separation in the sedimentation tank was subjected to a sand filtration treatment to obtain filtered water. When the addition amount of PAC with normal basicity in the flocculation tank was 30 mg / L, the turbidity of the filter was 0.08 degrees, and the picoplankton concentration increased to 10 ⁶ cells / mL, so the basicity was 65 in the front stage of the filter. % or more and 85% or less of a polyaluminum chloride (PAC) solution of ⁵ mg/L was added. Decreased.

(Reference example 1)
The treatment was performed under the same conditions as in Example 1, except that the addition of a polyaluminum chloride (PAC) solution having a basicity of 65% or more and 85% or less in the front stage of the filter was not performed. When the amount of normal basicity PAC added to the flocculation tank was 30 mg/L, the turbidity of the filter increased to 0.08 degrees and the picoplankton concentration increased to 10 ⁶ cells/mL. When this state was continued, the turbidity after 24 hours increased to 0.20 degrees and the picoplankton concentration increased to 10 ⁷ cells/mL.

(Example 2)
Water purification treatment was performed along the treatment flow shown in FIG. Trends in the number of fine particles and picoplankton counts in filtered water for the past two years, trends in turbidity data in filtered water, pH, water volume data, operating conditions for filtration equipment, filtration time, filtration resistance, flow rate, conductivity Operation data including rate, temperature, etc. are used as explanatory variables for learning. The prediction unit incorporates a model that predicts the number of picoplankton in the filtered water created by the learning data. By sensing the learning data and entering the data, the prediction unit predicts the turbidity in the filtered water after one hour. Configure.

When the amount of normal basicity PAC added to the flocculation tank was 30 mg/L, the turbidity of the filter increased to 0.08 degrees and the picoplankton concentration increased to 10 ⁶ cells/mL. As a result of AI prediction, the turbidity of filtered water after one hour was 0.12 degrees. Therefore, when control was performed by adding 5 mg / L of polyaluminum chloride (PAC) solution with a basicity of 65% or more and 85% or less in the front stage of the filter, the turbidity after 1 hour decreased to 0.06 degrees. , the turbidity did not exceed 0.1 degrees.

Thus, according to the present disclosure, picoplankton, which is one of the factors that increase the turbidity of filtered water, can be removed safely and efficiently, and filtered water with low turbidity can be stably obtained. .

1 coagulant addition means 2 coagulation means 3 filtration means 4 measurement means 5 control means 6 coagulant addition support means 11, 12 supply route 21 coagulation tank 22 sedimentation tank 31 inflow pipe 61 acquisition Part 62...Learning part 63...Model storage part 64...Prediction part 65...Determination part 66...Output part

Claims (8)

Add a flocculant to raw water containing picoplankton,
Filtering the treated water to obtain filtered water from the treated water after the addition of the coagulant,
Measuring the picoplankton number of the raw water, the treated water or the filtered water,
Controlling the addition amount of the flocculant according to the measurement result of the number of picoplankton,
A water purification method, wherein polyaluminum chloride having a basicity of 60% or more is added as a flocculant for reducing the number of picoplankton. As the flocculant, adding two or more flocculants,
at least one flocculant comprises the polyaluminum chloride;
The water purification method according to claim 1, further comprising controlling the type and supply of said flocculant to be added according to said picoplankton number. The water purification method according to claim 1 or 2, comprising adding the flocculant for reducing the number of picoplankton to the treated water flowing into the filtration treatment. Future measurement results of the number of picoplankton based on analysis information obtained by analyzing the relationship between the operating conditions of the filtration process, the water quality information of the filtered water, and the measurement results of the number of picoplankton based on past performance and determining the addition amount of the flocculant so that the turbidity of the filtered water is maintained at a reference value or less based on the prediction result. water treatment method. a flocculant addition means for adding a flocculant to raw water containing picoplankton;
flocculation means for forming flocs in the raw water to perform flocculation;
Filtration means for obtaining filtered water by filtering the treated water after the flocculation treatment;
a measuring means capable of measuring the number of picoplankton in the raw water, the treated water, or the filtered water;
Control to control the amount of polyaluminum chloride added so that polyaluminum chloride having a basicity of 60% or more is added as a flocculant for reducing the number of picoplankton according to the measurement result of the number of picoplankton. means and
A water purification device comprising: The flocculant addition means includes a plurality of supply paths for adding two or more types of the flocculants, one of the supply paths is a path for supplying the polyaluminum chloride, and the control means is a water purification apparatus according to claim 5, including controlling switching of the supply of the coagulant through the plurality of supply routes according to the measurement result of the number of picoplankton. The route for supplying the polyaluminum chloride is the filtering means, an inflow pipe for flowing the treated water after the solid-liquid separation into the filtering means, or sedimentation separation of flocs formed in the raw water. 7. The water purification apparatus according to claim 6, including being connected to at least one of the sedimentation tanks. Predicting and predicting the number of picoplankton in the future by performing machine learning using the operating conditions of the filtering means, the water quality information of the filtered water, and the measurement result of the number of picoplankton in the filtered water by the measuring means The coagulant addition support means for determining the amount of the coagulant to be added based on the result so that the turbidity of the filtered water is maintained at a reference value or less. water treatment equipment.

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