Neutralization treatment system and neutralization treatment method

Abstract

To provide a neutralization treatment system and a neutralization treatment method that, on addition of carbon dioxide as a neutralizer to strong alkaline raw water, can reduce supply amount of carbon dioxide, can perform efficient neutralization treatment, and can reduce environmental impact load.SOLUTION: A neutralization treatment system 100 includes a raw water tank 10 for accommodation of raw water, an intermediate tank 30, a discharge tank 40 for accommodation and discharging treatment water generated by the intermediate tank 30, a fine bubble generator 70 installed so as to be interposed into a channel connecting the raw water tank 10 and the intermediate tank 30, a pH meter 80 installed in the middle of the channel or either in the tank, a water supply means 50 and a carbon dioxide supply means 60 that respectively performs water supply and carbon dioxide supply to the fine bubble generator 70, a water supply control means 51 that controls water supply timing and water supply amount by the water supply means 50, and a carbon dioxide control means 61 that controls carbon dioxide supply timing and carbon dioxide supply amount by the carbon dioxide supply means 60.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a neutralization treatment system and a neutralization treatment method. [Background technology]

[0002] During construction work, highly alkaline construction wastewater containing suspended solids, such as concrete washwater, is generated. This construction wastewater undergoes coagulation and sedimentation treatment and neutralization in turbid water treatment facilities installed on-site, and is discharged off-site only after confirming that it meets the Water Pollution Control Act and the emission standards set by local governments.

[0003] Dilute sulfuric acid and carbon dioxide are typical chemicals used to neutralize construction wastewater, but carbon dioxide is used at many construction sites because it is easy to handle. When carbon dioxide gas is added as a neutralizing agent in this way, an aeration process is used in which gaseous carbon dioxide gas is injected into the wastewater. However, there is a large loss of carbon dioxide gas that is not used for neutralization, such as when carbon dioxide that does not dissolve is released into the atmosphere. This causes a significant environmental impact due to the carbon dioxide gas that is not used for neutralization being released into the atmosphere as carbon dioxide, which is an issue.

[0004] Here, Patent Document 1 proposes a water treatment device that treats treated water containing contaminants such as radioactive materials and organic materials, and purifies the water. This water treatment device has a nanobubble generation tank that generates nanobubbles and causes the nanobubbles to be contained in the water to be treated, and a treatment tank that stores or passes the treated water and is equipped with a plurality of electrodes whose tips are arranged at a predetermined interval between them. The gases that are converted into nanobubbles in the nanobubble generation tank and contained in the treated water include oxygen and carbon dioxide. The treated water is introduced into the treatment tank so that the tips of the electrodes are immersed, and a high voltage is applied between the electrodes to generate a plasma arc discharge and treat the treated water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-221436 Summary of the Invention [Problem to be solved by the invention]

[0006] The water treatment device described in Patent Document 1 is said to be able to perform water treatment using plasma discharge more economically and efficiently, but it does not disclose a means to solve the above-mentioned problem, that is, the problem that when carbon dioxide gas is added to construction wastewater as a neutralizing agent, a large amount of carbon dioxide gas is lost and not used for neutralization.

[0007] The present invention relates to a neutralization treatment system and a neutralization treatment method in which carbon dioxide gas is added as a neutralizing agent to strongly alkaline raw water, and aims to provide a neutralization treatment system and a neutralization treatment method that can reduce the amount of carbon dioxide gas supplied to perform efficient neutralization treatment and reduce the environmental impact. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the neutralization treatment system according to the present invention comprises: A neutralization treatment system that neutralizes alkaline raw water with a high pH value using carbon dioxide gas, a raw water tank that accommodates the alkaline raw water with a high pH value; An intermediate tank; a discharge tank for storing the treated water produced in the intermediate tank and discharging the treated water; a microbubble generator disposed in a flow path connecting the raw water tank and the intermediate tank among the flow paths connecting the respective tanks; a pH meter installed at a position along the flow path or in one of the tanks; a water supply means and a carbon dioxide gas supply means for supplying water and carbon dioxide gas, respectively, to the fine bubble generating device; a water supply control means for controlling the timing and amount of water supplied by the water supply means; The present invention is characterized by comprising a carbon dioxide gas control means for controlling the timing of supply of carbon dioxide gas by the carbon dioxide gas supply means and the amount of carbon dioxide gas supplied.

[0009] According to this embodiment, a fine-bubble generator is interposed in a flow path connecting a raw water tank containing alkaline raw water with a high pH value and an intermediate tank, and the timing of water supply by the water supply means to the fine-bubble generator and the amount of water supplied when water is supplied, and the timing of carbon dioxide supply by the carbon dioxide supply means and the amount of carbon dioxide supplied when carbon dioxide is supplied, are controlled by a water supply control means and a carbon dioxide control means, respectively.As a result, compared to conventional aeration treatment, loss of carbon dioxide gas added as a neutralizing agent that is not used for neutralization can be reduced, and the amount of carbon dioxide gas supplied can be reduced, allowing for efficient neutralization treatment. Furthermore, the addition of dilute sulfuric acid is not necessary, and raw water with a high alkaline (strongly alkaline) pH value of, for example, 11.0 or higher can be neutralized by adding carbon dioxide gas alone.

[0010] Here, the fine bubble generator is a device that generates, for example, microbubbles or nanobubbles (e.g., Ultra Fine Bubbles: a registered trademark), and in the process of mixing supplied carbon dioxide gas with water to produce carbonated water (saturated carbonated water), the device increases the specific surface area of ​​the carbon dioxide gas by ultra-fine-fine particle size, thereby efficiently dissolving the carbon dioxide gas and producing uniformly mixed carbonated water. The water supplied to the fine-bubble generator includes treated water produced in an intermediate tank and stored in a discharge tank, and tap water, but it is preferable to make effective use of treated water.

[0011] The pH value of the neutralized treated water is measured by a pH meter installed at a position along the flow path or in one of the tanks, and it is confirmed whether the measured value meets the specified control standard value. Although this control standard value may differ depending on the local government, for example, the control standard value of the Tokyo Metropolitan Government's Environment Bureau is a pH value in the range of 5.8 to 8.6.

[0012] Another aspect of the neutralization treatment system according to the present invention is The water supply control means controls the amount of water to be supplied and the carbon dioxide gas supply means controls the amount of carbon dioxide gas to be supplied, based on the value measured by the pH meter.

[0013] According to this embodiment, the amount of water supplied and the amount of carbon dioxide supplied are controlled based on the measurement value from the pH meter, so that the amount of carbon dioxide supplied can be appropriately controlled while neutralizing the raw water to a predetermined pH value to produce treated water.

[0014] Another aspect of the neutralization treatment system according to the present invention is The water supply means includes a water supply pump that is installed in the discharge tank, and the treated water in the discharge tank is supplied to the fine bubble generator by the water supply pump.

[0015] According to this embodiment, the treated water is supplied to the micro-bubble generator by a water supply pump included in the water supply means installed in the discharge tank, thereby making it possible to neutralize the raw water to a predetermined pH value while effectively utilizing the treated water.

[0016] In another embodiment of the neutralization treatment system according to the present invention, The intermediate tank includes a settling tank that precipitates flocs generated by supplying a coagulant to the raw water and generates treated water above the flocs. The pH meter is installed either inside the treated water in the settling tank, inside the treated water in the discharge tank, or in a flow path connecting the settling tank and the discharge tank.

[0017] According to this aspect, treated water can be efficiently produced by precipitating flocs generated by raw water and a coagulant in a settling tank (thickener) included in the intermediate tank to produce treated water for drinking water. In addition, by installing a pH meter in the settling tank, the discharge tank, or the flow path connecting them, the pH value of the treated water to be discharged can be determined with high accuracy.

[0018] In another embodiment of the neutralization treatment system according to the present invention, The volume ratio of water to carbon dioxide gas supplied to the microbubble generator is adjusted to a range of 1:1 to 1.5:1.

[0019] According to this embodiment, the volume ratio of water to carbon dioxide gas supplied to the fine-bubble generator is adjusted to a range of 1:1 to 1.5:1, thereby reducing the loss of carbon dioxide gas added as a neutralizing agent that is not utilized for neutralization and producing saturated carbonated water. When water and carbon dioxide gas are supplied to the fine-bubble generator at a volume ratio within this range, the pressure of the carbon dioxide gas is 0.05 to 0.1 MPa higher than the pressure of the water.

[0020] In another embodiment of the neutralization treatment system according to the present invention, a first electromagnetic valve is interposed in a flow path between the carbon dioxide gas supply means and the fine bubble generator; the water supply means is provided with an ON / OFF control mechanism including an ON control for supplying water and an OFF control for stopping water supply, or a second electromagnetic valve is interposed in a flow path between the water supply means and the fine bubble generator, The first electromagnetic valve and the ON / OFF control mechanism operate in conjunction with each other, or the first electromagnetic valve and the second electromagnetic valve operate in conjunction with each other.

[0021] According to this embodiment, the first electromagnetic valve located in the flow path between the carbon dioxide gas supply means and the micro-bubble generator and the ON / OFF control mechanism provided in the water supply means, or the second electromagnetic valve located in the flow path between the water supply means and the micro-bubble generator, operate in conjunction with each other, thereby efficiently neutralizing the raw water to a predetermined pH value and producing treated water.

[0022] In another embodiment of the neutralization treatment system according to the present invention, The treated water has upper and lower control standards based on the pH value, and When the measured value by the pH meter exceeds the upper control reference value, the first electromagnetic valve is controlled to be open and the ON / OFF control mechanism is controlled to be ON, or the first electromagnetic valve and the second electromagnetic valve are both controlled to be open, When the measurement value by the pH meter falls below the lower control reference value, The first electromagnetic valve is controlled to be closed and the ON / OFF control mechanism is controlled to be OFF, or the first electromagnetic valve and the second electromagnetic valve are both controlled to be closed.

[0023] According to this embodiment, when the measured value by the pH meter exceeds the upper control standard value, the first solenoid valve is opened and the ON / OFF control mechanism is turned ON, and when the measured value falls below the lower control standard value, the first solenoid valve is closed and the ON / OFF control mechanism is turned OFF, thereby enabling the pH value of the treated water to be controlled flexibly and with high precision between the upper and lower control standard values.

[0024] In another embodiment of the neutralization treatment system according to the present invention, The microbubble generator is characterized by being a powerless device that has a unit in which honeycomb-structured elements are connected in series, and inside the unit, shear force is applied to supplied water and supplied carbon dioxide gas, causing the two to mix and produce carbonated water.

[0025] According to this aspect, the fine bubble generator has a unit in which honeycomb-structured elements are connected in series, and generates carbonated water by applying shear force to water and carbon dioxide gas inside the unit to mix them, without using any power source. This, combined with the fact that carbon dioxide gas that is not used for neutralization can be prevented from being released into the atmosphere as carbon dioxide, can achieve a significant reduction in environmental impact. For example, a device that generates ultrafine bubbles using a micropore system can be cited as an example.

[0026] Furthermore, one aspect of the neutralization treatment method according to the present invention is to A neutralization method for neutralizing alkaline raw water with a high pH value using carbon dioxide, comprising: A step A of passing the raw water through an intermediate tank to produce treated water; A step B includes supplying water and carbon dioxide gas to the fine bubble generator to generate carbonated water, and supplying the generated carbonated water to the raw water for neutralization. In the step B, the pH value of the treated water is measured using a pH meter, and the timing and amount of water supply, and the timing and amount of carbon dioxide supply are controlled based on the value measured by the pH meter.

[0027] According to this embodiment, alkaline raw water with a high pH value is passed through an intermediate tank to generate treated water, feed water and carbon dioxide gas are supplied to a fine bubble generator to generate carbonated water, and the generated carbonated water is supplied to the raw water to perform neutralization treatment.By controlling the timing and amount of water supply, and the timing and amount of carbon dioxide gas supply, based on the pH value (measured value) of the treated water measured with a pH meter, it is possible to reduce the loss of carbon dioxide gas added as a neutralizing agent that is not used for neutralization, compared to conventional aeration treatment, and to reduce the amount of carbon dioxide gas supply, thereby enabling efficient neutralization treatment. [Effects of the Invention]

[0028] According to the neutralization treatment system and neutralization treatment method of the present invention, carbon dioxide gas is added as a neutralizing agent to strongly alkaline raw water, and the amount of carbon dioxide gas supplied can be reduced to perform efficient neutralization treatment, thereby reducing the environmental impact. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a configuration diagram of an example of a neutralization processing system according to an embodiment. [Figure 2] FIG. 10 is a diagram illustrating a state in which a micro-bubble generating device is incorporated into a flow channel. [Figure 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a water supply control means (carbon dioxide gas control means). [Figure 4A] FIG. 2 is a diagram illustrating an example of a functional configuration of a water supply control means. [Figure 4B] FIG. 2 is a diagram illustrating an example of a functional configuration of a carbon dioxide gas control means. [Figure 5] FIG. 1 is a diagram illustrating the relationship between the volume ratio of carbon dioxide gas to water, the pH value, and the degree of saturation. [Figure 6] FIG. 1 is a diagram illustrating the relationship between the volume ratio of carbon dioxide gas to water, the pH value, and excess gas. [Figure 7] FIG. 1 is a graph showing the change over time in pH values ​​of raw water and thickener. [Figure 8] FIG. 10 is a graph showing the change over time in the amount of carbonated water supplied. [Figure 9A] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the change in pH value over time during neutralization treatment using the neutralization treatment system of the embodiment. [Figure 9B] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the carbon dioxide addition history during neutralization treatment using the neutralization treatment system of the embodiment. [Figure 10A] FIG. 10 is a graph showing the results of an experiment to verify the carbon dioxide reduction effect, and is a graph showing the change in pH value over time during aeration treatment using a conventional aeration treatment system. [Figure 10B] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the carbon dioxide addition history during aeration treatment using a conventional aeration treatment system. [Figure 11A] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the amount of carbon dioxide added when washing concrete with washing water in the neutralization treatment system according to the embodiment and in a conventional aeration treatment system. [Figure 11B] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the amount of carbon dioxide added per unit processing volume in the neutralization treatment system according to the embodiment and a conventional aeration treatment system. [Figure 11C] FIG. 10 is a diagram showing the results of an experiment to verify the carbon dioxide reduction effect, and is a diagram showing the amount of carbon dioxide added per cycle in the neutralization treatment system according to the embodiment and a conventional aeration treatment system. [Figure 12A] FIG. 2 is a diagram showing the amount of water supply associated with the neutralization treatment using the neutralization treatment system according to the embodiment. [Figure 12B] FIG. 10 is a diagram showing the amount of carbon dioxide emitted with the operation of a water supply pump during neutralization treatment using the neutralization treatment system according to the embodiment. [Figure 12C] FIG. 10 is a diagram comparing the amount of carbon dioxide emissions in the neutralization treatment system according to the embodiment and a conventional aeration treatment system. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, a neutralization treatment system and a neutralization treatment method according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components are designated by the same reference numerals, and redundant description may be omitted.

[0031] [Neutralization treatment system and neutralization treatment method according to the embodiment] An example of a neutralization system and a neutralization method according to an embodiment will be described with reference to Figures 1 to 12. Here, Figure 1 is a configuration diagram of an example of a neutralization system according to an embodiment, and Figure 2 is a diagram illustrating a state in which a microbubble generator is incorporated into a flow path. Also, Figure 3 is a diagram showing an example of the hardware configuration of a water supply control means (carbon dioxide gas control means), and Figures 4A and 4B are diagrams showing examples of the functional configurations of the water supply control means and the carbon dioxide gas control means, respectively.

[0032] The neutralization treatment system 100 neutralizes highly alkaline raw water, for example, with a pH value of 11.0 or higher, using carbon dioxide gas (and carbonated water made from treated water) to produce treated water that meets specified discharge standards. Carbonated water that has been micro-bubbled by a micro-bubble generator 70 is supplied to the raw water, and is different from conventional systems that simply supply carbon dioxide gas to the raw water and perform an aeration treatment.

[0033] For example, in conventional neutralization treatment systems that supply carbon dioxide to raw water through aeration, it is difficult to meet discharge standards (e.g., pH values ​​in the range of 5.8 to 8.6) by simply adding carbon dioxide to highly alkaline raw water (e.g., pH values ​​of 12.0 or higher) such as ready-mixed concrete wash water. Therefore, a neutralization treatment is carried out in which dilute sulfuric acid is added prior to the addition of carbon dioxide to lower the pH value of the raw water, and then carbon dioxide is supplied to the raw water through aeration treatment.

[0034] In contrast, the illustrated neutralization treatment system 100 does not require the addition of dilute sulfuric acid, and produces treated water with a pH value that meets the discharge standards simply by supplying carbonated water that has been micro-bubbled by the micro-bubble generator 70 to the raw water.

[0035] Here, the strongly alkaline raw water with a pH value of 11.0 or more is, for example, construction wastewater containing suspended solids such as cement, typified by concrete washing water generated in construction work.

[0036] In the neutralization treatment system 100, raw water is supplied to a settling basin 11 via flow path L1, the raw water from which suspended solids have been removed is supplied to a raw water tank 10 via flow path L2 by a pump 52 in the settling basin 11, and an inorganic coagulant is added to the raw water supplied to flow path L3 by a pump 53 in the raw water tank 10 from a PAC (polyaluminum chloride) tank 25 via flow path 15. The raw water to which the inorganic coagulant has been added passes through a line mixer 21 and flow path L4 to a reaction tank 22, and a polymer coagulant supplied from a polymer coagulant tank 23 is added to the reaction tank 22 via flow path 16.

[0037] Generally, the applicable range of pH values ​​for PAC is about 6 to 9, so coagulation and sedimentation is generally performed on raw water in the neutral range. For this reason, as mentioned above, conventional neutralization treatment systems neutralize highly alkaline turbid raw water (turbid water mixed with cement) with a pH adjuster such as dilute sulfuric acid, and then coagulate and sediment it. However, this neutralization treatment requires a large amount of dilute sulfuric acid, which is a factor in increasing treatment costs.

[0038] In contrast, in the illustrated neutralization treatment system 100, carbonated water (saturated carbonated water) that has been micro-bubbled by a micro-bubble generator 70 is supplied to raw water to which an inorganic coagulant has been added, thereby performing neutralization treatment, thereby enabling coagulation and precipitation without the need to add dilute sulfuric acid.

[0039] The inorganic flocculant is used to create flocculation seeds, and then a polymer flocculant is added, which produces coarse flocs through the cross-linking action of the polymer flocculant.

[0040] The raw water reacted with the polymer flocculant in the reaction tank 22 is supplied to the intermediate tank 30 via flow path L5. The intermediate tank 30 includes a granulation tank 31 and a settling tank 32 (thickener), and the raw water supplied to the granulation tank 31 produces flocs here, which are then settled, and treated water, which is clean water (post-treatment water), is produced after being separated from the flocs.

[0041] The flocs precipitated in the granulation tank 31 overflow into the settling tank 32 and further settle, and above this there is treated water, which is also drinking water, just like in the granulation tank 31.

[0042] In the illustrated example, a pH meter 80 is installed inside the treated water in the settling tank 32, and the installed pH meter 80 is configured to be able to freely transmit measurement data to the carbon dioxide gas control means 61. Here, the installation position of the pH meter can be set to various positions other than the illustrated example, and may be, for example, inside the treated water in the discharge tank 40, or in any of the flow paths including flow path L6.

[0043] The treated water in the settling tank 32 is supplied to and stored in the discharge tank 40 via flow path L6. The discharge tank 40 is equipped with a water supply pump 50 (an example of a water supply means) that supplies the treated water to the micro-bubble generator 70 via flow path 12, a pump 54 that operates when the treated water is discharged, and a pump 55 that operates when the treated water is returned to the raw water tank 10 via flow path L8 when the pH value of the treated water is outside the control standard value.

[0044] The settling tank 32 is connected to a slurry tank 91 via a flow path L9, and a pump 56 (extraction pump) disposed midway through the flow path L9 extracts flocs from the settling tank 32 and supplies them to the slurry tank 91, where the flocs are agitated and turned into a slurry.

[0045] The slurry tank 91 is connected to a dehydrator 92 via a flow path L10, and the slurried flocs are separated into a dehydrated cake 93 and filtered water 94 in the dehydrator 92. The dehydrated cake 93 is disposed of, and the filtered water 94 is supplied to a filtered water tank 95 and returned to the raw water tank 10 via a flow path L11 by a pump 58. The pH of the treated water is adjusted during the process of flowing from the raw water tank 10 to the intermediate tank 30 again, and this process is repeated until the treated water meets the control standard, after which the treated water that meets the control standard is discharged.

[0046] A flow path L14 leading to a fine-bubble generator 70 is fluidly connected to a flow path L3 connecting the raw water tank 10 and the line mixer 21. The fine-bubble generator 70 is connected to a carbon dioxide gas cylinder 60 (an example of a carbon dioxide gas supply means) via a flow path L13, and is further connected to the discharge tank 40 via a flow path L12.

[0047] A first electromagnetic valve 68 is installed in flow path L13, and carbon dioxide gas supply means 61 that controls the amount of carbon dioxide gas supplied is electrically connected to the first electromagnetic valve 68. Meanwhile, water supply control means 51 equipped with an ON / OFF control mechanism that controls the ON / OFF of water supply pump 50 is electrically connected to water supply pump 50, and water supply control means 51 and carbon dioxide gas control means 61 are electrically connected to each other.

[0048] The measurement value (measurement data) of the pH value of the treated water measured by the pH meter 80 is sent to the carbon dioxide control means 61, and the carbon dioxide control means 61 determines whether the treated water meets the control standard value based on the received measurement value, and if it exceeds the upper control standard value, which is the upper limit of the control standard value, or falls below the lower control standard value, which is the lower limit of the control standard value, the carbon dioxide control means 61 performs linked open and close control of the first electromagnetic valve 68, and the water supply control means 51 performs linked ON control to supply water from the water supply pump 50 and OFF control to stop water supply. The linked control content of these two control means will be described in detail below.

[0049] As specifically shown in Figure 2, the micro-bubble generator 70 is a T-shaped cheese-type pipe with three connection ends, one end of which is connected to the end of flow path L12, through which treated water flows in the X1 direction, and the other end of which is connected to the end of flow path L13, through which carbon dioxide gas flows in the X2 direction.

[0050] Although the internal structure of the micro-bubble generator 70 is not shown in the drawings, the micro-bubble generator 70 has a unit in which honeycomb-structured elements are connected in series, and inside the unit, shear force is applied to the supplied water and supplied carbon dioxide gas to mix them and produce carbonated water, making it a micro-pore type device that does not use power.

[0051] As a specific example, a cheese-type piping system incorporating UFB DUAL (registered trademark) manufactured by Water Design Co., Ltd. can be applied. By applying a piping-type micro-bubble generator 70 as shown in the illustrated example, it becomes easy to incorporate it into turbid water treatment equipment.

[0052] Furthermore, as shown in Figures 1 and 2, the fine-bubble generator 70 is not installed directly in the flow path L3 through which the raw water flows, but is installed in a flow path separate from the flow path L3 to generate carbonated water, and the generated carbonated water is supplied in the X3 direction via flow path L14 to the raw water flowing in the X4 direction through flow path L3 to perform neutralization treatment, thereby eliminating concerns that suspended matter contained in the raw water will clog the fine-bubble generator 70 and impair the function of the fine-bubble generator 70.

[0053] In this way, the fine bubble generator 70 generates nanobubbles (e.g., ultrafine bubbles) without requiring any power source, and in the process of mixing supplied carbon dioxide gas with water to produce saturated carbonated water, the specific surface area of ​​the carbon dioxide gas is increased by ultra-fine atomization, allowing the carbon dioxide gas to be efficiently dissolved and producing homogenously mixed carbonated water. This increases the reaction efficiency of the carbon dioxide gas, eliminating the risk of undissolved carbon dioxide gas being released into the atmosphere and thus not being used for neutralization, and allows for a reduction in the amount of carbon dioxide gas supplied, enabling efficient production of treated water through the neutralization of raw water.

[0054] Next, an example of the hardware configuration of the water supply control means 51 and the carbon dioxide gas control means 61 will be described with reference to Fig. 3, and an example of the functional configuration of the water supply control means 51 and the carbon dioxide gas control means 61 will be described with reference to Figs. 4A and 4B. As shown in Fig. 3, the water supply control means 51 is configured by a control panel (information processing device) such as a PLC (Programmable Logic Controller). Note that the carbon dioxide gas control means 61 also has a similar hardware configuration, so the hardware configuration of the water supply control means 51 will be described below.

[0055] The control panel constituting the water supply control means 51 includes a CPU (Central Processing Unit) 101, a main memory device 102, an auxiliary memory device 103, a communication IF 105, and an input / output IF (interface) 105, which are interconnected by a connection bus 106. The main memory device 102 and the auxiliary memory device 103 are computer-readable recording media. Note that the above components may be provided separately, or some of the components may not be provided.

[0056] CPU 101 is also called an MPU (Microprocessor) or a processor, and may be a single processor or a multiprocessor. CPU 101 is a central processing unit that performs overall control of water supply control means 51, which is made up of a computer. CPU 101, for example, deploys programs stored in auxiliary storage device 103 in an executable manner in the working area of ​​main storage device 102, and controls peripheral devices through the execution of the programs, thereby providing functions that meet predetermined purposes.

[0057] The main memory device 102 stores computer programs executed by the CPU 101, data processed by the CPU 101, etc. The main memory device 102 includes, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory). The auxiliary memory device 103 stores various programs and various data on a readable and writable recording medium. The auxiliary memory device 103 stores, for example, an OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that exchanges data with external devices connected via the communication IF 104. External devices for the water supply control means 51 include the water supply pump 50, carbon dioxide gas control means 61, etc.

[0058] The auxiliary storage device 103 is used, for example, as a storage area that supports the main storage device 102, and stores computer programs executed by the CPU 101, data processed by the CPU 101, and the like.

[0059] The input / output IF 105 is an interface for inputting and outputting data between devices connected to the water supply control means 51. The water supply control means 51 receives operation instructions and the like from an operator who operates an input device via the input / output IF 105, and similarly receives open control commands and close control commands for the first electromagnetic valve 68 of the carbon dioxide gas control means 61.

[0060] The communication IF 104 is an interface with the network to which the water supply control means 51 is connected. The communication IF 104 receives open control commands and close control commands for the first electromagnetic valve 68 of the carbon dioxide gas control means 61 via various networks, such as a public network such as the Internet, a wireless network such as a mobile phone network, a dedicated network such as a VPN (Virtual Private Network), a LAN (Local Area Network), Bluetooth (registered trademark), infrared communication, etc., and transmits commands regarding ON control and OFF control to the ON / OFF control mechanism of the water supply pump 50 in conjunction with the carbon dioxide gas control means 61. Here, the water supply control means 51, the water supply pump 50, and the carbon dioxide gas control means 61 may be electrically connected by wire instead of wireless communication.

[0061] As shown in Fig. 4A, the water supply control means 51 provides various functions of at least an acquisition unit 201, an ON / OFF control unit 203, a display unit 204, and a memory unit 205 through execution of a program by the CPU 101. Also, as shown in Fig. 4B, the carbon dioxide gas control means 61 provides various functions of at least an acquisition unit 301, a determination unit 302, a first electromagnetic valve control unit 303, a display unit 304, and a memory unit 305 through execution of a program by the CPU 101.

[0062] The acquisition unit 301 of the carbon dioxide gas control means 61 acquires measurement data relating to the pH value of the treatment water in the settling tank 32 measured by the pH meter 80 and stores it in the memory unit 305.

[0063] The storage units 305 and 205 also store upper control reference value data and lower control reference value data, which are upper and lower control reference values ​​for the treated water.

[0064] The determination unit 302 compares the acquired measurement data regarding the pH value of the treated water with the upper control reference value data and the lower control reference value data. If the comparison shows that the measurement data exceeds the upper control reference value, it is necessary to supply more carbonated water to the raw water to promote neutralization treatment and lower the pH value of the treated water. Therefore, an open control command is sent to the first electromagnetic valve control unit 303, and the first electromagnetic valve 68 is controlled to open to supply carbon dioxide gas to the fine bubble generator 70.

[0065] At this time, the acquisition unit 201 of the water supply control means 51 also receives an open control command from the first electromagnetic valve control unit 303, and the ON / OFF control unit 203 sends an ON control command to the ON / OFF control mechanism provided in the water supply pump 50 to execute water supply, thereby operating the water supply pump 50 and supplying treated water to the micro-bubble generator 70.

[0066] Here, the preferred volume ratio of carbon dioxide gas to water (here, treated water) when carbonated water is produced by the fine bubble generator will be described with reference to Figures 5 and 6. Figure 5 is a diagram illustrating the relationship between the volume ratio of carbon dioxide gas to water, the pH value, and the degree of saturation, and Figure 6 is a diagram illustrating the relationship between the volume ratio of carbon dioxide gas to water, the pH value, and excess gas.

[0067] The results shown in the figures are the results of verification by the inventors, and show the relationship between the volume ratio of carbon dioxide to water, the degree of saturation of carbonated water supplied to raw water, the pH value of the raw water, and the relationship with excess gas. Here, in this verification, the volume ratio of carbon dioxide to water is assumed to be at 20°C and 1 atmosphere.

[0068] As can be seen from FIG. 5, the pH value of the raw water converges to about 4.5 when the degree of saturation is about 100%, and the volume ratio at which the degree of saturation of carbonated water becomes about 100% is in the range of about 1.0 to 1.5.

[0069] On the other hand, as shown in Figure 6, when the volume ratio of carbon dioxide to water is in the range of approximately 1.0 to 1.5, the pH value converges to approximately 4.8, and the proportion of excess gas, which increases with increasing volume ratio, can be suppressed to less than 50% (approximately 25% to 45%).

[0070] From the results of this verification, it is desirable to adjust the volume ratio of treated water to carbon dioxide gas supplied to the fine-bubble generator 70 within the range of 1:1 to 1.5:1. When treating water and carbon dioxide gas are supplied to the fine-bubble generator 70 at a volume ratio within this range, both are supplied such that the carbon dioxide gas pressure exceeds the treated water pressure by 0.05 to 0.1 MPa.

[0071] The micro-bubble generator 70 mixes the supplied treated water with the supplied carbon dioxide gas to generate saturated carbonated water, which is then supplied to the flow path L3 to neutralize the raw water.

[0072] On the other hand, when the result of judgment by the judgment unit 302 is that the measurement data falls below the lower control standard value, it is necessary to stop the supply of carbonated water to the raw water, stop the neutralization process, and increase the pH value of the treated water. Therefore, a close control command is sent to the first solenoid valve control unit 303, and the first solenoid valve 68 is controlled to close, stopping the supply of carbon dioxide gas to the fine bubble generator 70.

[0073] At this time, the acquisition unit 201 of the water supply control means 51 also receives a close control command from the first solenoid valve control unit 303, and the ON / OFF control unit 203 sends an OFF control command to the ON / OFF control mechanism equipped in the water supply pump 50 to stop the water supply, thereby stopping the operation of the water supply pump 50 and stopping the supply of treated water to the micro-bubble generator 70.

[0074] In this way, the carbon dioxide gas control means 61 and the water supply control means 51 operate in conjunction with each other based on measurement data regarding the pH value of the treated water to perform the generation of saturated carbonated water by the micro-bubble generator 70, supply of the saturated carbonated water to the raw water, and stop the generation of saturated carbonated water, thereby adjusting the pH value of the treated water to fall within the upper and lower control standard values.

[0075] Figure 7 shows an example of control content for strongly alkaline raw water with a time-series fluctuation in which the pH value rises from 9.0 to 11.0, remains at 11.0 for a certain period of time, and then drops back to 9.0. The control content is a set of opening control of the first solenoid valve 68 and turning on control of the feedwater pump 50, and a set of closing control of the first solenoid valve 68 and turning off control of the feedwater pump 50, and each set of control is repeatedly executed as shown in Figure 8, thereby fluctuating the pH value of the treated water in the thickener 32 between the upper and lower control standard values ​​as needed, thereby adjusting the pH value of the treated water within the control standard value.

[0076] As shown in the example, when the pH value of the treated water is within the upper and lower control standard values, the pH value of the treated water can be adjusted within the control standard values ​​by repeatedly executing each set of opening control of the first solenoid valve 68 and turning on control of the water supply pump 50, and closing control of the first solenoid valve 68 and turning off control of the water supply pump 50.

[0077] When the pH value of the treated water exceeds the upper control standard value due to factors such as an increase in the pH value of the raw water supplied to the raw water tank 10, instead of repeating the control of each set described above, the control of opening the first solenoid valve 68 and the control of turning on the water supply pump 50 are continued for a certain period of time, and when the pH value of the treated water falls below the upper control standard value, the control content is shifted to repeating the control of each set described above.

[0078] Conversely, when the pH value of the treated water falls below the lower control standard value due to factors such as a decrease in the pH value of the raw water supplied to the raw water tank 10, instead of repeating the control of each set described above, the control of closing the first solenoid valve 68 and the control of turning off the water supply pump 50 are continued for a certain period of time, and when the pH value of the treated water exceeds the lower control standard value, the control content is shifted to repeating the control of each set described above.

[0079] Here, the display unit 304 of the carbon dioxide gas control means 61 displays the open / close status of the first solenoid valve 68 and the current pH value of the treated water, and the display unit 204 of the water supply control means 51 displays the operating status of the water supply pump 50, etc.

[0080] In the illustrated example, the ON / OFF control mechanism provided in the water supply pump 50 performs ON control and OFF control, but it may also be configured, for example, such that a separate second electromagnetic valve is interposed in the flow path L12 and the opening and closing control of the second electromagnetic valve is performed.

[0081] As described above, in the illustrated neutralization treatment system 100, a fine-bubble generator 70 is interposed in the flow path connecting the raw water tank 10, which stores alkaline raw water with a high pH value, and the intermediate tank 30, and the timing and amount of water supplied by the water supply means 50 to the fine-bubble generator 70, and the timing and amount of carbon dioxide supplied by the carbon dioxide supply means 60, are controlled by the water supply control means 51 and the carbon dioxide control means 61, respectively. As a result, compared to conventional aeration treatment, loss of carbon dioxide gas added as a neutralizing agent that is not used for neutralization can be reduced, and the amount of carbon dioxide gas supplied can be reduced, allowing for efficient neutralization treatment. This leads to a reduction in the environmental impact.

[0082] Furthermore, the addition of dilute sulfuric acid is not necessary, and raw water with a high alkaline (strongly alkaline) pH value of, for example, 11.0 or higher can be neutralized by adding carbon dioxide gas alone.

[0083] In addition, the neutralization treatment method according to the embodiment using the illustrated neutralization treatment system 100 includes, in step A, passing raw water through an intermediate tank 30 to produce treated water, and in step B, supplying water and carbon dioxide gas to a fine bubble generator 70 to produce carbonated water, and supplying the produced carbonated water to the raw water for neutralization treatment. In step B, the pH value of the treated water is measured with a pH meter 80, and the timing and amount of water supply, and the timing and amount of carbon dioxide supply are controlled based on the value measured by the pH meter 80.

[0084] [Experiments to verify the carbon dioxide reduction effect and their results] Next, with reference to FIGS. 9 to 12, an experiment carried out by the present inventors to verify the carbon dioxide gas reduction effect and the results thereof will be described. 9A and 9B are graphs showing the change in pH value over time during neutralization treatment using the neutralization system according to the embodiment and a graph showing the carbon dioxide gas addition history during neutralization treatment. Also, FIGS. 10A and 10B are graphs showing the change in pH value over time during aeration treatment using a conventional aeration system and a graph showing the carbon dioxide gas addition history during aeration treatment. Also, FIGS. 11A, 11B, and 11C are graphs showing the results of an experiment verifying the carbon dioxide gas reduction effect, respectively, showing the amount of carbon dioxide gas added during concrete washing water cleaning in the neutralization system according to the embodiment and in a conventional aeration system, the amount of carbon dioxide gas added per unit treatment volume, and the amount of carbon dioxide gas added per cycle. Furthermore, FIG. 12A is a graph showing the amount of water supply during neutralization treatment using the neutralization system according to the embodiment. FIG. 12B is a graph showing the amount of carbon dioxide emitted by the operation of the feedwater pump during neutralization treatment using the neutralization system according to the embodiment. FIG. 12C is a graph comparing the amount of carbon dioxide emitted in the neutralization system according to the embodiment and in a conventional aeration system.

[0085] The inventors conducted a test on a turbid water treatment facility (treatment capacity 50 m) for mountain tunnel construction to confirm the operation of the neutralization treatment system according to the embodiment and to verify the carbon dioxide reduction effect of the neutralization treatment system. 3 / h). In mountain tunnel construction, concrete washing water is generated mainly after the sprayed concrete is applied, so the treatment flow rate and carbon dioxide gas addition amount were adjusted for each washing. In addition, the treatment method for the neutralization treatment system according to the embodiment and the conventional aeration treatment system can be switched using a valve, and the treatment results for each were recorded.

[0086] Comparing Figures 9 and 10, it can be seen that the neutralization treatment system according to the embodiment is able to quickly reduce the pH value of the thickener during wastewater treatment, suggesting that carbon dioxide acts more effectively as a neutralizing agent.

[0087] In addition, the amount of carbon dioxide added at this time was 580 L / min in the aeration treatment system, while it was 180 L / min in the neutralization treatment system of the embodiment, and it has been confirmed that the neutralization treatment system can quickly carry out neutralization treatment with a relatively small amount of carbon dioxide added.

[0088] On the other hand, Figure 11 shows a comparison of the amount of carbon dioxide used by the neutralization treatment system (carbonated water treatment) and the aeration treatment system (aeration treatment) of the embodiment, using data extracted from raw water with a peak pH value of 11.2. The aeration treatment uses an average of 27.9 kg per treatment, while the carbonated water treatment uses an average of 8.2 kg per treatment, confirming that the amount of carbon dioxide added can be reduced by approximately 70%.

[0089] In addition, in the case of carbonated water treatment, there were concerns about the impact on treatment capacity due to the pumping of discharged water for carbonated water production. However, as shown in Figure 12A, the amount of water supplied for carbonated water treatment was an average of 0.5 m 3 It has been confirmed that the amount is extremely small, at 1 / time.

[0090] Furthermore, as shown in Figure 12B, CO emissions from the water supply pump during carbonated water treatment 2 CO emissions (power consumption) 2 Emissions intensity (0.451 kg-CO 2 / kw) multiplied by CO 2 The CO emissions are 0.2 kg. 2 Taking into account emissions, CO per treatment of cleaning water 2 When comparing emissions between aeration treatment and carbonated water treatment, it has been confirmed that a reduction of 19.5 kg can be achieved, which is a 70% reduction.

[0091] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0092] 10: Raw water tank 11: Settling pond 21: Line mixer 22: Reactor 23: Polymer flocculant tank 25:PAC tank 30: Intermediate tank 31: Granulation tank 32: Settling tank (thickener) 40: Outlet tank 50: Water supply means (water supply pump) 51: Water supply control means (control panel) 52~58: Pump 60: Carbon dioxide gas supply means (carbon dioxide gas cylinder) 61: Carbon dioxide control means (control panel) 70: Microbubble generator 80:pH meter 91: Slurry tank 92: Dehydrator 93: Dehydrated cake 94: Filtrate 95: Filter tank 100: Neutralization treatment system L1 to L16: Flow path

Claims

1. A neutralization treatment system that neutralizes alkaline raw water with a high pH value using carbon dioxide gas, a raw water tank that accommodates the alkaline raw water with a high pH value; An intermediate tank; a discharge tank for storing the treated water produced in the intermediate tank and discharging the treated water; a microbubble generator disposed in a flow path connecting the raw water tank and the intermediate tank among the flow paths connecting the respective tanks; a pH meter installed at a position along the flow path or in one of the tanks; a water supply means and a carbon dioxide gas supply means for supplying water and carbon dioxide gas, respectively, to the fine bubble generating device; a water supply control means for controlling the timing and amount of water supplied by the water supply means; A neutralization treatment system characterized by comprising a carbon dioxide gas control means for controlling the timing and amount of carbon dioxide gas supplied by the carbon dioxide gas supply means.

2. 2. The neutralization treatment system according to claim 1, wherein the water supply control means controls the amount of water supplied and the carbon dioxide gas supply means controls the amount of carbon dioxide gas supplied based on the measured value of the pH meter.

3. 3. The neutralization treatment system according to claim 2, wherein a water supply pump included in the water supply means is installed in the discharge tank, and the treated water in the discharge tank is supplied to the micro-bubble generator by the water supply pump.

4. The intermediate tank includes a settling tank that precipitates flocs generated by supplying a coagulant to the raw water and generates treated water above the flocs. The neutralization treatment system according to claim 3, characterized in that the pH meter is installed either inside the treated water in the settling tank, inside the treated water in the discharge tank, or in a flow path connecting the settling tank and the discharge tank.

5. 5. The neutralization treatment system according to claim 4, wherein the volume ratio of water to carbon dioxide gas supplied to the microbubble generator is adjusted within the range of 1:1 to 1.5:

1.

6. a first electromagnetic valve is interposed in a flow path between the carbon dioxide gas supply means and the fine bubble generator; the water supply means is provided with an ON / OFF control mechanism including an ON control for executing water supply and an OFF control for stopping water supply, or a second electromagnetic valve is interposed in a flow path between the water supply means and the fine bubble generator, The neutralization treatment system according to claim 5, wherein the first electromagnetic valve and the ON / OFF control mechanism operate in conjunction with each other, or the first electromagnetic valve and the second electromagnetic valve operate in conjunction with each other.

7. The treated water has upper and lower control reference values ​​based on the pH value, and When the measurement value by the pH meter exceeds the upper control reference value, the first electromagnetic valve is controlled to be open and the ON / OFF control mechanism is controlled to be ON, or the first electromagnetic valve and the second electromagnetic valve are both controlled to be open; When the measurement value by the pH meter falls below the lower control reference value, The neutralization processing system described in claim 6, characterized in that the first electromagnetic valve is controlled to be closed and the ON / OFF control mechanism is controlled to be OFF, or the first electromagnetic valve and the second electromagnetic valve are both controlled to be closed.

8. The neutralization treatment system according to any one of claims 5 to 7, characterized in that the micro-bubble generator has a unit in which honeycomb-structured elements are connected in series, and inside the unit, shear force is applied to the supplied water and supplied carbon dioxide gas, and the two are mixed to produce carbonated water, making it a non-powered device.

9. A neutralization method for neutralizing alkaline raw water with a high pH value using carbon dioxide, comprising: A step A of passing the raw water through an intermediate tank to produce treated water; A step B includes supplying water and carbon dioxide gas to the fine bubble generator to generate carbonated water, and supplying the generated carbonated water to the raw water for neutralization. In the step B, the pH value of the treated water is measured with a pH meter, and the timing and amount of water supply, and the timing and amount of carbon dioxide supply are controlled based on the measured value by the pH meter.

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