PFAS removal system

Abstract

To provide a PFAS treatment system capable of efficiently removing PFAS, which is suitable for large quantities of treatment targets.SOLUTION: A PFAS treatment system includes ozone dissolution means 1 and PFAS adsorption means 2 arranged in the order from upstream in a flow path L through which liquid A to be treated for PFAS removal flows. The ozone dissolution means 1 dissolves ozone into the liquid A, and the PFAS adsorption means 2 brings the liquid A into contact with activated carbon. Multiple PFAS adsorption means 2 are arranged in parallel, enabling switching between the PFAS adsorption means 2 through which the liquid A flows.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a PFAS removal system suitable for use in removing PFOS (perfluorooctanesulfonic acid or perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid or perfluorooctanoate), which are organic fluorine compounds (PFAS), from liquids such as waste liquid and spring water.

Background Art

[0002] PFOS and PFOA are organic fluorine compounds excellent in heat resistance, chemical resistance, etc., and have been used in surfactants, chemicals for semiconductor manufacturing and metal plating, foam extinguishing agents, auxiliaries for fluororesin manufacturing, etc.

[0003] On the other hand, PFOS and PFOA are chemically extremely stable, water-soluble and non-volatile substances, and thus are likely to migrate into rivers etc. when released into the environment. Further, due to their low degradability and bioaccumulation properties, they are considered likely to remain in the environment, and there are concerns about their impact on the ecosystem.

[0004] PFOS and PFOA are chemically very stable and do not decompose in nature. Further, a high temperature of about 1000 °C or higher is required for thermal decomposition (Patent Document 1).

Prior Art Documents

Patent Documents

[0005] [

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Methods for removing PFAS such as PFOS and PFOA from liquids (raw water) include combustion treatment and high-pressure supercritical fluid treatment. However, these methods have the drawback of not being suitable when the amount of material to be treated is large.

[0007] The present invention has been made with the above-mentioned matters in mind, and its objective is to provide a PFAS treatment system that can efficiently perform PFAS removal and is suitable even when the amount of material to be treated is large. [Means for solving the problem]

[0008] To achieve the above objective, the PFAS treatment system according to the present invention provides an ozone dissolving means and a PFAS adsorption means in this order from the upstream side in a flow path through which the liquid to be subjected to PFAS removal treatment flows, the ozone dissolving means dissolves ozone in the liquid, and the PFAS adsorption means brings the liquid into contact with activated carbon. The PFAS removal system comprises a plurality of PFAS adsorption means arranged in parallel, the ability to switch between the PFAS adsorption means through which the liquid flows, and a measuring means for measuring the ozone concentration of the liquid provided downstream of the PFAS adsorption means, wherein a pressure switch is provided in the first flow path at the uppermost part of the flow path, the flow path branches into two second flow paths downstream of this pressure switch, each second flow path is equipped with a pump device for flowing the liquid, and downstream of the two second flow paths, the flow path is further divided into two After branching into a third channel, the two channels merge to form a fourth channel, and the two fourth channels further merge to form a fifth channel. Each third channel is equipped with an ozone dissolving means, which is a mixing device that dissolves ozone gas supplied from an ozonizer (where oxygen is supplied from an oxygen generator to form ozone gas) into the liquid. This mixing device moves the liquid flow up and down within the mixing tank, causing diffusion, collision, and convection to dissolve the ozone gas into the liquid, achieving an ozone concentration of 2.5 ppm or higher. The system is configured to achieve a certain ratio, with two sixth channels connected to the downstream side of the fifth channel via a three-way switching valve. Downstream of each sixth channel, the channel further branches into two seventh channels before merging to form an eighth channel, and the two eighth channels further merge to form a ninth channel. Switching the three-way switching valve switches the state from one of the two sixth channels through which the liquid flows to the other. Each of the seventh channels is provided with the PFAS adsorption means, and a bypass channel is provided downstream of the PFAS adsorption means in each seventh channel. This bypass channel is provided with an on-off valve and a measuring means for measuring the ozone concentration of the liquid. When the on-off valve is opened and the liquid flows into the bypass channel, the measuring means can measure the ozone concentration of the liquid. The pressure switch, pump device, oxygen generator, ozonizer, three-way switching valve, on-off valve, and measuring means are controlled by a control unit. (Claim 1).

[0009] In the above PFAS processing system, The PFAS adsorption means is a forced adsorption device employing a cartridge filter that can be used with activated carbon, and the cartridge filter is a cassette type that can be replaced with a single touch. (Claim 2)

[0010] In the above PFAS processing system, A return channel is provided that extends from the 9th channel to the 1st channel and can return the liquid from the 9th channel to the 1st channel, and this return channel is provided with an on / off valve. This is also acceptable (Claim 3). [Effects of the Invention]

[0011] The present invention provides a PFAS treatment system that can efficiently remove PFAS and is suitable even when the amount of material to be treated is large.

[0012] In other words, the PFAS treatment system of the invention according to each claim of this application performs PFAS removal treatment by passing the liquid to be treated for PFAS removal through an ozone dissolving means and a PFAS adsorption means in that order, and since the treatment can be carried out efficiently with ozone and activated carbon, it is also suitable when the amount of liquid to be treated is large.

[0013] HonpatsuIn Akira's PFAS treatment system, multiple PFAS adsorption means are arranged in parallel, and it is possible to switch which PFAS adsorption means is used to process the liquid to be treated. For example, when replacing activated carbon, the liquid can be stopped from flowing through the PFAS adsorption means containing the activated carbon to be replaced, making the replacement work easier. Furthermore, by allowing the liquid to flow through other PFAS adsorption means during this process, the PFAS removal treatment can be continued without interruption.

[0014] Honpatsu In Akira's PFAS treatment system, when the activated carbon breaks through, it is assumed that the ozone concentration, along with the PFAS concentration downstream, will rise. By detecting this rise in ozone concentration using a measuring device, it is possible to evaluate that the activated carbon has broken through. If measures such as replacing the activated carbon are taken at the time this evaluation is obtained, it is possible to continue performing PFAS removal treatment using activated carbon at a high level, while also avoiding unnecessarily increasing the number of times the activated carbon needs to be replaced. [Brief explanation of the drawing]

[0015] [Figure 1] This is an explanatory diagram illustrating the schematic configuration of a PFAS removal system according to one embodiment of the present invention. [Modes for carrying out the invention]

[0016] Embodiments of the present invention are described below.

[0017] The PFAS removal system shown in Figure 1 has an ozone dissolving means 1 and a PFAS adsorption means 2 installed in the same order from upstream to downstream in a flow path L through which a liquid A (raw water such as spring water in the illustrated example) to be treated for PFAS (e.g., PFOS and / or PFOA) removal is carried out. The ozone dissolving means 1 dissolves ozone in liquid A, and the PFAS adsorption means 2 brings liquid A into contact with activated carbon. In Figure 1, 80A, 40A, and 20A indicate the sizes (nominal diameters) of the pipes that make up the flow path L.

[0018] Specifically, a pressure switch 3 (for example, turned on during PFAS removal treatment and turned off otherwise) is provided in the first flow path L1 (for example, with a nominal diameter of 80A) at the uppermost stream portion of the flow path L. Downstream of this pressure switch 3, the flow path L branches into two second flow paths L2, and a pump device (for example, a magnetic pump) 4 for flowing the liquid A is provided in each second flow path L2.

[0019] Also, downstream of the two second flow paths L2, the flow path L branches into two third flow paths L3 respectively and then merges into a fourth flow path L4, and the two fourth flow paths L4 further merge into one fifth flow path L5.

[0020] Here, an ozone dissolution means 1 is provided in each third flow path L3. In this example, ozone gas is formed in an ozonizer 6 to which oxygen is supplied from an oxygen generator 5, and the ozone dissolution means 1 is a mixing device that dissolves the ozone gas supplied from the ozonizer 6 into the liquid A. This mixing device can be configured to move the liquid flow up and down in, for example, a mixing tank, cause diffusion, collision, and convection, and dissolve the ozone gas into the liquid A to achieve a dissolution rate with an ozone concentration of 2.5 ppm or more.

[0021] Two sixth flow paths L6 are connected to the downstream side of the fifth flow path L5 via a three-way switching valve 7. Downstream of each sixth flow path L6, the flow path L branches into two seventh flow paths L7 respectively and then merges into an eighth flow path L8, and the two eighth flow paths L8 further merge into one ninth flow path L9. That is, by switching the three-way switching valve 7, the liquid A can be switched from flowing through one of the two sixth flow paths L6 to flowing through the other.

[0022] Here, PFAS adsorption means 2 is provided in each seventh flow path L7. This PFAS adsorption means 2 preferably adsorbs at least PFAS (at least PFOS and / or PFOA) and ozone in liquid A, and more preferably adsorbs other impurities as well. In this example, a forced adsorption device that employs a cartridge filter with granular filter media such as activated carbon (e.g., formed by compressing coconut shell powder), ion exchange resin, zeolite, etc. inside and can be used is used as the PFAS adsorption means 2. The cartridge filter is preferably in a cassette type that can be replaced with a single touch, which is preferable in terms of being able to be replaced quickly.

[0023] Also, a bypass flow path 8 is provided on the downstream side of the PFAS adsorption means 2 in each seventh flow path L7. An on-off valve 9 and a measuring means (e.g., an ozone concentration meter) 10 for measuring the ozone concentration of liquid A are provided in this bypass flow path 8. That is, when the on-off valve 9 is opened and liquid A flows through the bypass flow path 8, the measuring means 10 can measure the ozone concentration of liquid A.

[0024] In addition, in FIG. 1, reference numeral 11 is a control unit (e.g., a control panel), which is configured to control objects that require control in the PFAS removal system (e.g., the pressure switch 3, the pump device 4, the oxygen generator 5, the ozonizer 5, the three-way switching valve 7, the on-off valve 9, the measuring means 10).

[0025] The PFAS removal system configured as described above performs the PFAS removal treatment by flowing liquid A, which is the object of the PFAS removal treatment, through the ozone dissolution means 1 and the PFAS adsorption means 2 in this order. Since the treatment can be efficiently performed by the decomposition power of ozone and the adsorption power of activated carbon, etc., it is also suitable when there is a large amount of the target liquid A.

[0026] Furthermore, in the PFAS treatment system of this example, multiple PFAS adsorption means 2 are arranged in parallel, and the switching of the PFAS adsorption means 2 through which the liquid A to be treated flows is made possible by a three-way switching valve 7. For example, when replacing activated carbon (cartridge filter), the liquid A can be prevented from flowing through the PFAS adsorption means 2 containing the activated carbon (cartridge filter) to be replaced, making the replacement work easier. Also, by allowing liquid A to flow through another PFAS adsorption means 2 during this work, the PFAS removal treatment can be continued without interruption.

[0027] Furthermore, in the PFAS treatment system of this example, when the activated carbon breaks through, the ozone concentration in liquid A downstream is expected to rise along with the PFAS concentration. By detecting this rise in ozone concentration with the measuring means 10, it is possible to evaluate that the activated carbon has broken through. If measures such as replacing the activated carbon (cartridge filter) are taken at the time such evaluation is obtained, it is possible to continue performing PFAS removal treatment with activated carbon at a high level, and it is also possible to avoid unnecessarily increasing the number of times the activated carbon (cartridge filter) needs to be replaced.

[0028] Furthermore, in this example of a PFAS removal system, general bacteria in liquid A can also be removed by ozone and activated carbon, thus producing high-quality recycled water that can be used as drinking water (sterile water).

[0029] The following are specific examples of the processing capacity and equipment configuration of the PFAS removal system in this example.

[0030] The processing capacity of the PFAS removal system can be such that the treatment volume of liquid A is 120 L / min, the PFAS concentration of liquid A to be treated is 1000 ng or less, and the temperature is between 10°C and 35°C.

[0031] It is preferable that at least the parts in contact with the liquid in the ozone dissolution means 1 (mixing device) are made of a material that does not corrode, such as stainless steel.

[0032] Each PFAS adsorption means 2 can accommodate (install) for, for example, 12 filter cartridges, and each filter cartridge is thought to have a diameter of 90 mm and a length of 286 mm.

[0033] For example, the pump device 4 can employ a magnetic pump (water transfer pump) with a maximum pumping capacity of 300 L / min.

[0034] The oxygen generator 5 is preferably equipped with an oxygen concentration of 90% or higher, a discharge pressure of 0.1 ± 0.01 MPa, an oxygen flow rate of 6 L / min, an alarm function (device malfunction, pressure abnormality, power outage alarm), and a check valve function.

[0035] The Ozonizer 6 can utilize a silent discharge method with a cooling fan.

[0036] The control unit 11 could potentially utilize an electrical control panel equipped with sequence control and an emergency stop function in case of abnormalities.

[0037] It should be noted that the present invention is not limited in any way to the embodiments described above, and can be implemented in various ways without departing from the spirit of the invention. For example, the following modifications can be given.

[0038] In the example shown in Figure 1, there are four third channels L3 each containing an ozone dissolving means 1. However, the system is not limited to this configuration; the number of third channels L3 (ozone dissolving means 1) may be one to three, or five or more. Furthermore, multiple ozone dissolving means 1 may be provided in a single third channel L3.

[0039] In the example shown in Figure 1, the downstream side of the fifth flow path L5 is divided into two systems, the first system S1 and the second system S2, and a three-way switching valve 7 is used to ensure that liquid A flows only through one of the systems S1 or S2. However, the number of systems is not limited to two; for example, there may be three or more systems. In this case, a three-way switching valve or on-off valve can be appropriately provided to allow switching between which system liquid A flows through.

[0040] Furthermore, in the example shown in Figure 1, two seventh channel L7s, each having a PFAS adsorption means 2, are installed in parallel for each system S1 and S2, but they may also be installed one or three or more in parallel for each system.

[0041] In the example shown in Figure 1, the fifth flow path L5 is connected to two sixth flow paths L6 via a three-way switching valve 7. However, the design is not limited to this configuration. For example, instead of providing the three-way switching valve 7, each of the two sixth flow paths L6 could be fitted with an on / off valve.

[0042] In the example shown in Figure 1, a bypass channel 8, an on-off valve 9, and a measuring means 10 are provided in each of the seventh channels L7. However, instead of providing the bypass channel 8, on-off valve 9, and measuring means 10 in each of the eighth channels L8 or ninth channels L9, they may also be provided in each of the seventh channels L7.

[0043] Alternatively, the on-off valve 9 and measuring means 10 may be directly installed in the 7th flow path L7, the 8th flow path L8, or the 9th flow path L9 without providing the bypass flow path 8, in which case the on-off valve 9 may be omitted.

[0044] If the measuring means 10 detects an increase in ozone concentration, for example, a return channel extending from the ninth channel L9 to the first channel L1 may be provided so that liquid A can be returned to the first channel L1 without being drained from the ninth channel L9. In this case, it is conceivable that an on / off valve or the like may be provided in the return channel.

[0045] Needless to say, the above variations can be combined as appropriate. [Explanation of symbols]

[0046] 1. Ozone dissolution method 2 PFAS adsorption means 3. Pressure switch 4. Pumping device 5. Oxygen generator 6 Ozonizer 7. Three-way switching valve 8 Bypass channel 9. Shut-off valves 10 Measurement means 11 Control Unit A liquid L channel L1~L9 Channel 1~Channel 9

Claims

1. In the flow path through which the liquid to be subjected to PFAS removal treatment flows, an ozone dissolving means and a PFAS adsorption means are provided in this order from the upstream side. The ozone dissolving means dissolves ozone in the liquid, The PFAS adsorption means brings the liquid into contact with activated carbon. Multiple PFAS adsorption means are arranged in parallel, and the PFAS adsorption means through which the liquid flows can be switched. A PFAS removal system comprising a measuring means for measuring the ozone concentration of the liquid, located downstream of the PFAS adsorption means, A pressure switch is provided in the first channel at the uppermost part of the aforementioned channel, and downstream of this pressure switch, the channel branches into two second channels, each of which is equipped with a pump device for flowing the liquid. Downstream of the two second channels, each channel further branches into two third channels before merging to form a fourth channel, and the two fourth channels further merge to form a single fifth channel. Each third flow path is provided with an ozone dissolution means, which is a mixing device that dissolves ozone gas supplied from an ozonizer (where oxygen is supplied from an oxygen generator to form ozone gas) into the liquid. This mixing device is configured to move the liquid flow up and down within the mixing tank, causing diffusion, collision, and convection to dissolve the ozone gas into the liquid, thereby achieving a dissolution rate of ozone concentration of 2.5 ppm or higher. Downstream of the fifth flow path, two sixth flow paths are connected via a three-way switching valve. Downstream of each sixth flow path, the flow path further branches into two seventh flow paths before merging to form an eighth flow path. The two eighth flow paths then merge again to form a ninth flow path. By switching the three-way switching valve, the flow of the liquid from one of the two sixth flow paths to the other is switched. Each of the seven channels is provided with the PFAS adsorption means. A bypass channel is provided downstream of the PFAS adsorption means in each of the seven channels, and this bypass channel is equipped with an on / off valve and a measuring means for measuring the ozone concentration of the liquid. When the on / off valve is opened and the liquid flows through the bypass channel, the measuring means can measure the ozone concentration of the liquid. A PFAS removal system configured to control the pressure switch, the pump device, the oxygen generator, the ozonizer, the three-way switching valve, the on / off valve, and the measuring means by a control unit.

2. The PFAS removal system according to Claim 1, wherein the PFAS adsorption means is a forced adsorption device employing a cartridge filter that can be used with activated carbon, and the cartridge filter is a cassette type that can be replaced with a single touch.

3. The PFAS removal system according to claim 1 or 2, wherein a return channel is provided that extends from the ninth channel to the first channel and can return the liquid from the ninth channel to the first channel, and an on / off valve is provided in the return channel.

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