Water Treatment Systems

Abstract

The water treatment system purifies water to be treated by removing organic substances from the water, and includes a separation membrane device and an organic substance treatment device. The separation membrane device includes a separation membrane. The separation membrane separates the water to be treated into permeated water from which at least a portion of the organic substances have been removed and non-permeated water that did not pass through the separation membrane by passing the water through the separation membrane. The organic substance treatment device includes an adsorption element. The adsorption element contacts the non-permeated water and adsorbs the organic substances, thereby discharging the non-permeated water as adsorption-treated water. The adsorption element contacts a heated gas and desorbs the organic substances, thereby discharging a desorbed gas containing the heated gas and the organic substances.

Description

[Technical Field]

[0001] The present invention relates to a water treatment system. [Background technology]

[0002] Traditionally, organofluorine compounds such as polytetrafluoroethylene (hereinafter referred to as "PTFE") have been used to impart various functions, such as lubricity, to both industrial and consumer goods. Among these organofluorine compounds, perfluoroalkyl and polyfluoroalkyl compounds are collectively referred to as "PFAS." Among PFAS, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are particularly persistent, highly bioaccumulative, and highly mobile, and are known to persist widely on a global scale. Continued release of these PFAS into the environment raises concerns about their further accumulation, potentially posing adverse effects on human health, the habitats and growth of plants and animals, and other factors through the environment and food chain. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-150519 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned PFASs may also be contained in industrial wastewater and domestic wastewater (hereinafter simply referred to as "wastewater"). Japanese Patent Application Laid-Open Publication No. 2015-150519 (Patent Document 1) relates to a wastewater treatment system that purifies wastewater by removing organic substances from wastewater containing organic substances, and can remove organic substances such as the above-mentioned PFASs from a water system by incorporating them into wastewater. However, Patent Document 1 has the potential to generate large amounts of the above-mentioned wastewater, leaving room for improvement in the treatment of the above-mentioned wastewater.

[0005] In view of the above circumstances, an object of the present invention is to provide a water treatment system that can reduce the amount of waste liquid. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. The present inventors discovered that by appropriately combining elements capable of removing organic substances from liquids such as wastewater, it is possible to reduce the amount of wastewater discharged from a water treatment system. This discovery led to the completion of the present invention. The present invention relates to a water treatment system as described below.

[0007] [1] The present invention provides a water treatment system for purifying water to be treated by removing organic substances from the water, the system comprising: a separation membrane device; and an organic substance treatment device. The separation membrane device includes a separation membrane. The separation membrane separates the water to be treated into permeated water from which at least a portion of the organic substances have been removed and non-permeated water that has not passed through the separation membrane by passing the water through the separation membrane. The organic substance treatment device includes an adsorption element. The adsorption element contacts the non-permeated water and adsorbs the organic substances, thereby discharging the non-permeated water as adsorption-treated water. The adsorption element contacts a heated gas and desorbs the organic substances, thereby discharging a desorbed gas containing the heated gas and the organic substances. [2] The present invention provides a water treatment system for purifying water to be treated by removing organic substances from the water, the system comprising: a separation membrane device; and an organic substance treatment device. The organic substance treatment device comprises an adsorption element. The adsorption element comes into contact with the water to be treated and adsorbs the organic substances, thereby discharging the water to be treated as adsorption-treated water. The adsorption element comes into contact with a heated gas and desorbs the organic substances, thereby discharging a desorbed gas containing the heated gas and the organic substances. The separation membrane device comprises a separation membrane. The separation membrane is passed through the adsorption-treated water to separate the adsorption-treated water into permeate from which at least a portion of the organic substances have been removed, and non-permeate that has not passed through the separation membrane. [3] The water treatment system according to [1] or [2], further comprising a condenser for liquefying the desorbed gas. [4] The water treatment system according to [1], wherein the adsorption-treated water is returned to the water to be treated. [5] The water treatment system according to [2], wherein the non-permeated water is returned to the water to be treated. [6] The water treatment system according to any one of [1] to [5], further comprising an ion exchange device equipped with an ion exchange resin, through which the adsorption-treated water is passed. [7] The water treatment system according to any one of [1] to [6], further comprising an ion exchange device equipped with an ion exchange resin, through which the permeate is passed. [8] The water treatment system according to any one of [1] to [7], wherein the separation membrane comprises at least one member selected from the group consisting of a reverse osmosis membrane, a forward osmosis membrane, an ion exchange membrane, and a nanofiltration membrane. [9] The water treatment system according to any one of [1] to [8], wherein the adsorption element includes at least one member selected from the group consisting of activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina, and metal-organic frameworks.

[10] The water treatment system according to any one of [1] to [9], wherein the organic substance treatment device has a means for repeatedly transferring the portion of the adsorption element where desorption treatment has been completed to the portion where adsorption treatment will be performed, and transferring the portion of the adsorption element where adsorption treatment has been completed to the portion where desorption treatment will be performed. [Effects of the Invention]

[0008] According to the present invention, there is provided a water treatment system that can reduce the amount of the waste liquid. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a system configuration diagram of a water treatment system according to a first embodiment. [Figure 2] FIG. 2 is a system configuration diagram of a water treatment system according to the second embodiment. [Figure 3] FIG. 3 is a system configuration diagram of a water treatment system according to the third embodiment. [Figure 4] FIG. 4 is a system configuration diagram of a water treatment system according to the fourth embodiment. [Figure 5] FIG. 5 is a system configuration diagram of a water treatment system according to the fifth embodiment. [Figure 6] FIG. 6 is a system configuration diagram of a water treatment system according to the sixth embodiment. [Figure 7] FIG. 7 is a system configuration diagram of a water treatment system according to the seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present invention will be described in more detail with reference to the drawings. The present invention is not limited to these embodiments. In the drawings, the same reference symbols represent the same or corresponding parts. In this specification, an expression in the form of "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and only a unit is specified for B, the unit of A and the unit of B are the same.

[0011] [Water treatment system] The water treatment system according to the present invention purifies water to be treated by removing organic substances from the water containing the organic substances. The water treatment system includes a separation membrane device and an organic substance treatment device. The separation membrane device includes a separation membrane. The separation membrane is passed through the water to separate the water into permeated water from which at least a portion of the organic substances have been removed and non-permeated water that did not pass through the separation membrane. The organic substance treatment device includes an adsorption element. The adsorption element contacts the non-permeated water and adsorbs the organic substances, thereby discharging the water to be treated or the non-permeated water as the adsorption-treated water. The adsorption element contacts a heated gas and desorbs the organic substances, thereby discharging a desorbed gas containing the heated gas and the organic substances.

[0012] Another water treatment system according to the present invention is a water treatment system that purifies water to be treated by removing organic substances from the water containing the organic substances. The water treatment system includes a separation membrane device and an organic substance treatment device. The organic substance treatment device includes an adsorption element. The adsorption element comes into contact with the water to be treated and adsorbs the organic substances, thereby discharging the water to be treated as adsorption-treated water. The adsorption element comes into contact with a heated gas and desorbs the organic substances, thereby discharging a desorbed gas containing the heated gas and the organic substances. The separation membrane device includes a separation membrane. The separation membrane is passed through the adsorption-treated water to separate the adsorption-treated water into permeate from which at least a portion of the organic substances have been removed and non-permeate that has not passed through the separation membrane.

[0013] In the water treatment system having such characteristics, when the desorbed gas discharged to the outside of the system is liquefied, the resulting liquid can contain high concentrations of organic substances. In other words, the amount of waste liquid discharged from the water treatment system can be reduced. The water treatment system preferably includes a condenser that liquefies the desorbed gas.

[0014] As used herein, the "organic substances" contained in the treated water are not limited to, but may include, for example, so-called PFAS. As used herein, "PFAS" refers collectively to perfluoroalkyl and polyfluoroalkyl compounds, as described above. In particular, the compounds listed on the "non-exhaustive list" published by the U.S. Environmental Protection Agency (EPA) on January 25, 2024, are defined as "PFAS." The "non-exhaustive list" refers to the list of compounds that meet the definition of "per / polyfluoroalkyl substances or PFAS" as defined in §705.3, "Definitions," of 40 CFR Part 705, which came into effect on November 13, 2023, pursuant to Section 8(a)(7) of the U.S. Toxic Substances Control Act (TSCA). Note that "PFAS" in this specification may also include perfluoroalkyl and polyfluoroalkyl compounds that become newly subject to regulation after the filing date of this patent application due to changes in definition or other reasons.

[0015] Alternatively, the "organic substances" contained in the water to be treated may be aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and acrolein; ketones such as methyl ethyl ketone, diacetyl, methyl isobutyl ketone, and acetone; esters such as 1,4-dioxane, 2-methyl-1,3-dioxolane, 1,3-dioxolane, tetrahydrofuran, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; alcohols such as ethanol, n-propyl alcohol, isopropyl alcohol, and butanol; glycols such as ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol; organic acids such as acetic acid and propionic acid; aromatic organic compounds such as phenols, toluene, xylene, and cyclohexane; ethers such as diethyl ether and allyl glycidyl ether; and diesters such as acrylonitrile. It may contain chlorinated organic substances such as tolyls, dichloromethane, 1,2-dichloroethane, trichloroethylene, and epichlorohydrin; organic substances such as N-methyl-2-pyrrolidone, dimethylacetamide, and N,N-dimethylformamide; dioxins such as polychlorinated dibenzoparadioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs); antibiotics such as tetracycline, oseltamivir, oseltamivir phosphate, bezafibrate, and triclosan; antilipidemic ingredients such as bezafibrate and fenofibrate; antipyretic and analgesic ingredients such as diclofenac, salicylic acid, and acetaminophen; antiepileptic ingredients such as carbamazepine; humic substances such as humic acid and fulvic acid; and hexamethylenetetramine, diosmin, and 2-methylisoborneol (2-MIB).

[0016] Additionally, the term "water to be treated" in this specification means, for example, wastewater from factories or homes, river water, seawater, drinking water, industrial water, etc. Hereinafter, details of several embodiments illustrating the present invention will be described with reference to the drawings.

[0017] First Embodiment FIG. 1 is a system configuration diagram of a water treatment system according to a first embodiment. The water treatment system according to the first embodiment purifies water A to be treated by removing organic substances from the water A. As shown in FIG. 1, the water treatment system includes a separation membrane device 10 and an organic substance treatment device 20. The separation membrane device 10 includes a separation membrane 110. The separation membrane 110 is passed through the water A to be treated, separating the water A into a permeate B from which at least some or all of the organic substances have been removed and a non-permeate B that did not pass through the separation membrane 110. The organic substance treatment device 20 includes adsorption elements 211 and 221. The adsorption elements 211 and 221 come into contact with the non-permeate and adsorb the organic substances, thereby discharging the non-permeate as adsorption-treated water. The adsorption elements 211 and 221 come into contact with a heated gas C and desorb the organic substances, thereby discharging a desorbed gas containing the heated gas C and the organic substances. That is, in the wastewater treatment system according to the first embodiment, water to be treated A is passed through the separation membrane 110. The adsorption elements 211, 221 come into contact with non-permeated water. The adsorption-treated water is returned to the water to be treated A. The water treatment system according to the first embodiment includes a condenser 24 that liquefies the desorbed gas. The desorbed gas is liquefied into condensed water D by the condenser 24. The condensed water D is discharged outside the water treatment system.

[0018] The water treatment system includes a supply tank T1 for supplying water A to be treated introduced from outside the system to the separation membrane device 10, and an intermediate tank T2 for receiving non-permeated water separated by the separation membrane device 10 and supplying the non-permeated water to the organic substance treatment device 20. The supply tank T1 and the separation membrane device 10, the separation membrane device 10 and the intermediate tank T2, the intermediate tank T2 and the organic substance treatment device 20, and the organic substance treatment device 20 and the supply tank T1 are each connected by piping. A more specific structure of the water treatment system will be described below.

[0019] (Separation membrane device) As described above, the separation membrane device 10 includes the separation membrane 110. The separation membrane 110 is provided in a separation membrane module 11 that forms the separation membrane device 10. The separation membrane module 11 includes the separation membrane 110 and a first chamber 111 and a second chamber 112 that are separated by the separation membrane 110. The separation membrane device 10 includes, as a component thereof, a liquid feed pump 12 for supplying the water to be treated A in the supply tank T1 to the separation membrane module 11.

[0020] The separation membrane 110 preferably includes at least one member selected from the group consisting of a reverse osmosis membrane (RO membrane), a forward osmosis membrane (FO membrane), an ion exchange membrane (IE membrane), and a nanofiltration membrane (NF membrane). In particular, the separation membrane 110 is preferably an RO membrane or an NF membrane. For example, RO membranes are known for their high efficiency in separating substances that undergo ionization in water, such as NaCl. On the other hand, for organic substances that do not undergo ionization, RO membranes allow the membrane material to be selected according to the properties of the organic substances to be separated, in terms of molecular diameter and affinity with the membrane material. Generally, organic substances with larger molecular diameters and lower affinity with the membrane material tend to be less permeable through RO membranes and tend to be concentrated (contained in the non-permeated water).

[0021] The material of the separation membrane 110 is preferably at least one selected from the group consisting of a polymer membrane, a carbon membrane, a ceramic membrane, a zeolite membrane, and an alumina membrane. For example, the material of the RO membrane is not particularly limited, but examples include polymer membranes made of aromatic polyamide, cellulose acetate, and polyvinyl alcohol. The separation performance of the RO membrane is not particularly limited, but preferably has an NaCl rejection of 99 mass% or more. This makes it possible to significantly reduce the possibility of organic substances being contained in the permeate B.

[0022] The pressure of the liquid feed pump 12 is not particularly limited, but when the separation membrane 110 is an RO membrane, it is preferably set to a pressure of 50% or more of the pressure limit value. This makes it possible to ensure the amount of water passing through the separation membrane 110 while significantly reducing the possibility of organic substances being contained in the permeate B. A conventionally known pump can be used as the liquid feed pump 12.

[0023] In the separation membrane device 10, first, water to be treated A introduced into a supply tank T1 from outside the system is supplied to the first chamber 111 of the separation membrane module 11 by the action of the liquid feed pump 12. Next, the water to be treated A in the first chamber 111 is passed through the separation membrane 110 by the pressure of the liquid feed pump 12. As described above, the separation membrane 110 separates the water to be treated A into permeated water B, from which at least some or all of the organic substances have been removed, and non-permeated water, which did not pass through the separation membrane 110. As a result, the permeated water B moves to the second chamber 112 and is then discharged from the separation membrane device 10. The non-permeated water is discharged from the separation membrane device 10 from the first chamber 111 by the pressure of the liquid feed pump 12 and sent to the intermediate tank T2.

[0024] (organic substance treatment equipment) As described above, the organic substance treatment device 20 includes the adsorption elements 211 and 221. The adsorption elements 211 and 221 are provided in the first treatment tank 21 and the second treatment tank 22 that form the organic substance treatment device 20. The organic substance treatment device 20 includes, as one of its components, a liquid feed pump 23 for supplying the non-permeated water in the intermediate tank T2 to the first treatment tank 21 and the second treatment tank 22.

[0025] As will be described later, the organic substance treatment device 20 is provided with valves V201 to V210 that adjust the flow of non-permeated water or heated gas C toward the first treatment tank 21 and the second treatment tank 22, so that the first treatment tank 21 and the second treatment tank 22 alternately function as adsorption tanks and desorption tanks for organic substances.

[0026] As described above, the adsorption elements 211, 221 come into contact with the non-permeated water and adsorb the organic substances, thereby discharging the non-permeated water as adsorbed-treated water from which at least some or all of the organic substances have been removed from the organic substance treatment device 20. The adsorption elements 211, 221 come into contact with the heated gas C and desorb the organic substances from the adsorption elements 211, 221, thereby discharging a desorbed gas containing the heated gas C and the organic substances from the organic substance treatment device 20.

[0027] Adsorption elements 211 and 221 preferably contain at least one member selected from the group consisting of activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina, and metal-organic frameworks. Adsorption elements 211 and 221 may use one of these materials alone or a combination of two or more. For example, adsorption elements 211 and 221 may be formed by packing the upstream adsorption side with activated carbon (crushed carbon) and the downstream adsorption side with a material made of activated carbon fiber. The "metal-organic framework" refers to, for example, MOF (metal-organic framework) or PCP (porous coordination polymyer).

[0028] For example, granular, particulate, honeycomb-shaped activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina, and metal-organic frameworks can be used for the adsorption elements 211 and 221. Activated carbon fiber is more preferably used for the adsorption elements 211 and 221. Activated carbon fiber has a fibrous structure with micropores on the surface, which allows for high contact efficiency with water and a particularly fast adsorption rate of organic substances in water, making it possible to achieve extremely high adsorption efficiency compared to other adsorption materials.

[0029] For example, the physical properties of the activated carbon fiber used as the adsorption elements 211 and 221 are not particularly limited, but the BET specific surface area is preferably 700 to 3000 m 2 / g, pore volume 0.4 to 1.35 cm 3 / g and an average pore diameter of 14 to 27 Å (angstroms). By providing these physical properties, the cost of the adsorption elements 211 and 221 can be reduced, while the amount of organic substances adsorbed can be increased efficiently.

[0030] The heated gas C is not particularly limited, but examples thereof include water vapor, heated air, and heated nitrogen. It is preferable that the heated gas C is water vapor at, for example, 100°C or higher, since this facilitates liquefaction by the condenser 24 described below. Examples of heating methods for raising the heated gas C to a predetermined temperature (for example, 100°C or higher) include, but are not particularly limited to, indirect heating, heating by an electric heater, and heating by microwaves.

[0031] The organic substance treatment apparatus 20 may have a means for repeatedly transferring the portions of the adsorption elements 211, 221 for which desorption treatment has been completed to the portion for adsorption treatment, and transferring the portions of the adsorption elements 211, 221 for which adsorption treatment has been completed to the portion for desorption treatment. Specifically, the first treatment tank 21 and the second treatment tank 22 containing the adsorption elements 211, 221 alternately function as an adsorption tank and a desorption tank by opening and closing the valves V201 to V208. By opening and closing the valves V201 to V208, for example, when the first treatment tank 21 functions as an adsorption tank, the second treatment tank 22 functions as a desorption tank. When the first treatment tank 21 functions as a desorption tank, the second treatment tank 22 functions as an adsorption tank.

[0032] When functioning as desorption tanks, the first treatment tank 21 and the second treatment tank 22 are preferably purged. Purging refers to passing a purge gas through the adsorption elements 211, 221 before passing the heated gas C through them to purge and remove non-permeated water adhering to the adsorption elements 211, 221. This increases the desorption efficiency of the adsorption elements 211, 221. The purged non-permeated water is preferably returned to the intermediate tank T2 by opening and closing V209 and V210, for example. This is because the non-permeated water adhering to the adsorption elements 211, 221 may simply be water from which organic substances have not been sufficiently removed.

[0033] The pressure of the liquid feed pump 23 is not particularly limited, but is preferably set so as to ensure the amount of non-permeated water that contacts the adsorption elements 211, 221 in accordance with the physical properties of the adsorption elements 211, 221. This allows the adsorption elements 211, 221 to efficiently adsorb organic substances, thereby reducing the concentration of organic substances in the adsorption-treated water discharged from the organic substance treatment apparatus 20. A conventionally known pump may be used as the liquid feed pump 23.

[0034] In the organic substance treatment device 20, the non-permeated water introduced into the intermediate tank T2 is first supplied to the first treatment tank 21 or the second treatment tank 22, which functions as an adsorption tank, by the action of the liquid feed pump 23 and the opening and closing of the valves V201 to V208. The non-permeated water supplied to the first treatment tank 21 or the second treatment tank 22 then comes into contact with the adsorption elements 211 and 221. The adsorption elements 211 and 221 adsorb organic substances in the non-permeated water by contacting the non-permeated water as described above. The non-permeated water from which the organic substances have been removed is then discharged from the organic substance treatment device 20 as adsorption-treated water. The adsorption-treated water is then returned to the water to be treated A in the supply tank T1 by the pressure of the liquid feed pump 23. In this way, in the water treatment system according to the first embodiment, the adsorption-treated water can be passed through the separation membrane 110 when the adsorption-treated water is supplied from the supply tank T1 by the pressure of the liquid feed pump 12. Therefore, a greater amount of organic substances can be removed from the water to be treated A.

[0035] (condenser) The water treatment system according to the first embodiment includes a condenser 24 that liquefies the desorbed gas as described above. The condenser 24 liquefies the desorbed gas discharged from the first treatment tank 21 and the second treatment tank 22, which have functioned as desorption tanks, and discharges the desorbed gas as condensed water D containing concentrated organic substances to the outside of the system. A known heat exchanger may be used as the condenser 24. The desorbed gas is introduced into the condenser 24 and heat-exchanged to liquefy the desorbed gas, forming condensed water D containing concentrated organic substances. The condensed water D is then discharged outside the water treatment system. Because the condensed water D contains concentrated organic substances, its volume is significantly smaller than that of the water to be treated A containing the same amount of organic substances. This reduces the amount of waste liquid discharged from the water treatment system. The cooling method for the desorbed gas in the condenser includes, but is not limited to, indirect cooling using cooling water or groundwater, cooling using a chiller (cold water), and the like.

[0036] (effect) According to the wastewater treatment system of the first embodiment, permeate B is obtained from water to be treated A, from which organic substances have been removed through the separation membrane 110 of the separation membrane device 10. Meanwhile, the organic substances in the non-permeate water that did not pass through the separation membrane 110 are adsorbed by the adsorption elements 211, 221 of the organic substance treatment device 20, then desorbed from the adsorption elements 211, 221 by the desorption gas, and subsequently liquefied by the desorption gas to form condensed water D in which the organic substances are concentrated, which is then discharged outside the system. As a result, the amount of waste liquid discharged from the water treatment system can be reduced.

[0037] Second Embodiment FIG. 2 is a system configuration diagram of a water treatment system according to a second embodiment. The water treatment system according to the second embodiment has the same structure as the water treatment system according to the first embodiment, except that it includes an ion exchange device 30 into which adsorption-treated water is introduced. In other words, the water treatment system according to the second embodiment has an aspect in which the water treatment system according to the first embodiment further includes an ion exchange device 30 equipped with ion exchange resin 311. Specifically, the ion exchange device 30 is disposed midway through the piping connecting the organic substance treatment device 20 and the supply tank T1. Therefore, the adsorption-treated water is passed through the ion exchange resin 311. The ion exchange device 30 includes an ion exchange column 31 and ion exchange resin 311 packed in the ion exchange column 31.

[0038] In the water treatment system according to the second embodiment, the adsorption-treated water discharged from the organic substance treatment device 20 is introduced into the ion exchange device 30 and passes through the ion exchange resin 311. As described above, the adsorption-treated water may contain the organic substances. In this case, the organic substances are adsorbed by the ion exchange resin 311, thereby further reducing the concentration of the organic substances in the adsorption-treated water. A known ion exchange resin may be used as the ion exchange resin 311. The ion exchange resin 311 may be in any of the following forms: granular, particulate, fibrous, and membrane-like. Other than the ion exchange device 30, the aspects of the water treatment system according to the second embodiment are the same as those of the first embodiment, and therefore, redundant description will not be repeated.

[0039] <Third embodiment> FIG. 3 is a system configuration diagram of a water treatment system according to a third embodiment. The water treatment system according to the third embodiment has the same structure as the water treatment system according to the first embodiment, except that it includes an ion exchange device 30 into which permeate B is introduced. In other words, the water treatment system according to the third embodiment has an aspect in which the water treatment system according to the first embodiment further includes an ion exchange device 30 equipped with an ion exchange resin 311. Specifically, the ion exchange device 30 is disposed midway through a pipe through which permeate B discharged from the separation membrane device 10 flows toward the outside of the system. Therefore, permeate B is passed through the ion exchange resin 311. The structure of the ion exchange device 30 may be the same as the ion exchange device 30 described in the second embodiment.

[0040] According to the water treatment system of the third embodiment, permeate B separated by the separation membrane 110 of the separation membrane device 10 is introduced into the ion exchange device 30 and passes through the ion exchange resin 311. In this case, organic substances in the permeate B can be further removed. Since aspects of the water treatment system of the third embodiment other than the ion exchange device 30 are the same as those of the first embodiment, redundant explanations will not be repeated.

[0041] <Fourth embodiment> 4 is a system configuration diagram of a water treatment system according to a fourth embodiment. The water treatment system according to the fourth embodiment has the same configuration as the water treatment system according to the first embodiment, except that it does not include an intermediate tank into which non-permeated water separated by the separation membrane device 10 is introduced, and a liquid feed pump that generates pressure to supply the non-permeated water to the organic substance treatment device 20. In this case, in the water treatment system, the non-permeated water discharged from the separation membrane device 10 is supplied to the first treatment tank 21 and the second treatment tank 22 of the organic substance treatment device 20 by the pressure of the liquid feed pump 12. The water treatment system may be provided with a pressure regulating valve NV201 for the purpose of regulating the amount of non-permeated water supplied to the first treatment tank 21 and the second treatment tank 22.

[0042] The manner in which the water to be treated A in the water treatment system according to the fourth embodiment is treated is the same as that in the first embodiment, except that the non-permeated water is supplied directly to the organic substance treatment device 20 without passing through an intermediate tank, and therefore redundant explanations will not be repeated. The water treatment system according to the fourth embodiment can omit the intermediate tank and the liquid feed pump, which may reduce installation costs, etc.

[0043] Fifth Embodiment FIG. 5 is a system configuration diagram of a water treatment system according to a fifth embodiment. The water treatment system according to the fifth embodiment differs from the water treatment system according to the first embodiment, in that the water to be treated A is supplied to an organic substance treatment device 20. That is, the water treatment system according to the fifth embodiment is a water treatment system that purifies the water to be treated A by removing organic substances from the water to be treated A containing organic substances. As shown in FIG. 5, the water treatment system includes a separation membrane device 10 and an organic substance treatment device 20. The organic substance treatment device 20 includes adsorption elements 211 and 221. The adsorption elements 211 and 221 contact the water to be treated A and adsorb the organic substances, thereby discharging the water to be treated A as adsorption-treated water. The adsorption elements 211 and 221 contact the heated gas C and desorb the organic substances, thereby discharging a desorbed gas containing the heated gas C and the organic substances. The separation membrane device 10 includes a separation membrane 110. The separation membrane 110 separates the adsorption-treated water into permeated water B, from which at least some or all of the organic substances have been removed, and non-permeated water that has not passed through the separation membrane 110, by passing the adsorption-treated water through it. That is, in the wastewater treatment system according to the fifth embodiment, the separation membrane 110 passes the adsorption-treated water through it. The adsorption elements 211, 221 come into contact with the water to be treated A. The non-permeated water is returned to the water to be treated A. The water treatment system according to the fifth embodiment includes a condenser 24 that liquefies the desorbed gas. The desorbed gas is liquefied into condensed water D by the condenser 24. The condensed water D is discharged outside the water treatment system.

[0044] The water treatment system includes a supply tank T1 for supplying water to be treated A introduced from outside the system to the organic substance treatment device 20, and an intermediate tank T2 for receiving adsorption-treated water separated in the organic substance treatment device 20 and supplying the adsorption-treated water to the separation membrane device 10. The supply tank T1 and the organic substance treatment device 20, the organic substance treatment device 20 and the intermediate tank T2, the intermediate tank T2 and the separation membrane device 10, and the separation membrane device 10 and the supply tank T1 are each connected by piping.

[0045] The structures of the separation membrane device 10 itself and the organic substance treatment device 20 itself in the water treatment system according to the fifth embodiment are the same as those in the water treatment systems according to the first to fourth embodiments, respectively, and therefore redundant descriptions will not be repeated. Furthermore, the water treatment system according to the fifth embodiment includes a condenser 24 that liquefies the desorbed gas as described above, but the structure of the condenser 24 is also the same as those in the water treatment systems according to the first to fourth embodiments, and therefore redundant descriptions will not be repeated.

[0046] In the water treatment system according to the fifth embodiment, the water to be treated A is treated as follows. First, the water to be treated A is introduced into the supply tank T1 and supplied to the first treatment tank 21 or the second treatment tank 22, which functions as an adsorption tank of the organic substance treatment device 20, by the action of the liquid feed pump 23 and the opening and closing of the valves V201 to V208. Next, the water to be treated A supplied to the first treatment tank 21 or the second treatment tank 22 comes into contact with the adsorption elements 211 and 221. The adsorption elements 211 and 221 adsorb organic substances in the water to be treated A by contacting the water to be treated A. The water to be treated A from which the organic substances have been removed is discharged from the organic substance treatment device 20 as adsorption-treated water. The adsorption-treated water is then sent to the intermediate tank T2 by the pressure of the liquid feed pump 23.

[0047] The adsorption-treated water introduced into the intermediate tank T2 is then supplied to the first chamber 111 of the separation membrane module 11 in the separation membrane device 10 by the action of the liquid feed pump 12. The adsorption-treated water in the first chamber 111 is then passed through the separation membrane 110 by the pressure of the liquid feed pump 12. The separation membrane 110 separates the adsorption-treated water into permeated water B, from which at least a portion of the organic substances have been removed, and non-permeated water that did not pass through the separation membrane 110. The permeated water B moves to the second chamber 112 and is then discharged from the separation membrane device 10. The non-permeated water is discharged from the separation membrane device 10 from the first chamber 111 by the pressure of the liquid feed pump 12 and returned to the water to be treated A in the supply tank T1. As a result, in the water treatment system according to the fifth embodiment, the adsorption elements 211 and 22 come into contact with the non-permeated water as it is supplied from the supply tank T1 by the pressure of the liquid feed pump 23. Therefore, a larger amount of organic matter in the water to be treated A can be removed.

[0048] Sixth Embodiment FIG. 6 is a system configuration diagram of a water treatment system according to a sixth embodiment. The water treatment system according to the sixth embodiment has the same structure as the water treatment system according to the fifth embodiment, except that it includes an ion exchange device 30 into which adsorption-treated water is introduced. In other words, the water treatment system according to the sixth embodiment has an aspect in which the water treatment system according to the fifth embodiment further includes an ion exchange device 30 equipped with ion exchange resin 311. Specifically, the ion exchange device 30 is disposed midway through the piping connecting the organic substance treatment device 20 and the intermediate tank T2. Therefore, the adsorption-treated water is passed through the ion exchange resin 311. The structure of the ion exchange device 30 may be the same as the ion exchange device 30 described in the second and third embodiments.

[0049] According to the water treatment system of the sixth embodiment, the adsorption-treated water discharged from the organic substance treatment device 20 is introduced into the ion exchange device 30 and passes through the ion exchange resin 311. In this case, the concentration of organic substances in the adsorption-treated water can be further reduced. Since the aspects of the water treatment system of the sixth embodiment other than the ion exchange device 30 are the same as those of the fifth embodiment, redundant explanations will not be repeated.

[0050] Seventh Embodiment FIG. 7 is a system configuration diagram of a water treatment system according to a seventh embodiment. The water treatment system according to the seventh embodiment has the same structure as the water treatment system according to the fifth embodiment, except that it includes an ion exchange device 30 into which permeate B is introduced. In other words, the water treatment system according to the seventh embodiment has an aspect in which the water treatment system according to the fifth embodiment further includes an ion exchange device 30 equipped with an ion exchange resin 311. Specifically, the ion exchange device 30 is disposed midway through a pipe through which permeate B discharged from the separation membrane device 10 flows toward the outside of the system. Therefore, permeate B is passed through the ion exchange resin 311. The structure of the ion exchange device 30 may be the same as the ion exchange device 30 described in the sixth embodiment.

[0051] According to the water treatment system of the seventh embodiment, permeate B separated by the separation membrane 110 of the separation membrane device 10 is introduced into the ion exchange device 30 and passes through the ion exchange resin 311. In this case, organic substances in the permeate B can be further removed. Since aspects of the water treatment system of the seventh embodiment other than the ion exchange device 30 are the same as those of the fifth embodiment, redundant explanations will not be repeated.

[0052] <Other embodiments> The water treatment system according to the present invention may include not only the aspects illustrated in the drawings as the first to seventh embodiments, but also other aspects. For example, the water treatment system according to the first or fifth embodiment may include an ion exchange device equipped with an ion exchange resin, and the non-permeated water may be passed through the ion exchange resin. That is, in the water treatment system according to this aspect, when described with reference to FIG. 1, the ion exchange device may be disposed midway in the piping connecting the separation membrane device 10 and the intermediate tank T2. Even in this aspect, the water treatment system can remove a greater amount of organic matter from the water to be treated.

[0053] Furthermore, the water treatment system may include a plurality of ion exchange devices. That is, the ion exchange devices may be disposed in the pipe through which the adsorption-treated water flows, the pipe through which the permeated water flows, and the pipe through which the non-permeated water flows, in order to remove organic substances from the adsorption-treated water, the permeated water, and the non-permeated water, respectively. In the water treatment system, the ion exchange devices may be disposed in the pipe through which the adsorption-treated water flows and the pipe through which the permeated water flows, or in the pipe through which the adsorption-treated water flows and the pipe through which the non-permeated water flows, or in the pipe through which the non-permeated water flows and the pipe through which the permeated water flows.

[0054] The water treatment system may be provided with an aeration tank capable of blowing air or other gas into the water to be treated or the non-permeated water, which is located before the separation membrane device or between the separation membrane device and the organic substance treatment device. In this case, it may be possible to reduce the treatment load of the separation membrane device and the organic substance treatment device.

[0055] The water treatment system may include a pretreatment facility in front of the separation membrane device or organic substance treatment device to remove impurities that may cause deterioration of the separation membrane or adsorption element. The specific pretreatment facility may be selected appropriately depending on the properties of the impurities to be removed.

[0056] Furthermore, in the water treatment system, a fluid transport means such as a pump can be disposed at an appropriate position as required.

[0057] Although the embodiments of the present invention have been described above, it is also planned from the beginning to combine the configurations of the above-described embodiments as appropriate.

[0058] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0059] A: Water to be treated, B: Permeate water, C: Heated gas, D: Condensed water, 10: Separation membrane device, 11: Separation membrane module, 110: Separation membrane, 111: First chamber, 112: Second chamber, 12: Liquid feed pump, 20: Organic substance treatment device, 21: First treatment tank, 211: Adsorption element, 22: Second treatment tank, 221: Adsorption element, 23: Liquid feed pump, 24: Condenser, 30: Ion exchange device, 31: Ion exchange column, 311: Ion exchange resin, T1: Supply tank, T2: Intermediate tank, V201-V210: Valves, NV201: Pressure regulating valve.

Claims

1. A water treatment system that purifies water to be treated by removing organic substances from water to be treated that contains organic substances, It includes a separation membrane device and an organic substance processing device, The separation membrane apparatus includes a separation membrane, The separation membrane, by passing water through it, separates the water to be treated into permeate from which at least a portion of the organic matter has been removed and non-permeate water that did not pass through the separation membrane. The aforementioned organic substance processing apparatus includes an adsorption element, The adsorption element comes into contact with the impermeable water and adsorbs the organic substance, thereby discharging the impermeable water as adsorbed treated water. A water treatment system in which the adsorption element comes into contact with a heated gas and desorbs the organic substance, thereby discharging a desorbed gas containing the heated gas and the organic substance.

2. A water treatment system that purifies water to be treated by removing organic substances from water to be treated that contains organic substances, It includes a separation membrane device and an organic substance processing device, The aforementioned organic substance processing apparatus includes an adsorption element, The adsorption element comes into contact with the water to be treated and adsorbs the organic substance, thereby discharging the water to be treated as adsorbed water. The adsorption element comes into contact with the heated gas and desorbs the organic substance, thereby discharging a desorbed gas containing the heated gas and the organic substance. The separation membrane apparatus includes a separation membrane, A water treatment system in which the separation membrane is passed through the adsorption-treated water to separate the adsorption-treated water into permeate water from which at least a portion of the organic substance has been removed and impermeate water that has not passed through the separation membrane.

3. The water treatment system according to claim 1 or claim 2, further comprising a condenser for liquefying the desorption gas.

4. The water treatment system according to claim 1, wherein the adsorbed water is returned to the water to be treated.

5. The water treatment system according to claim 2, wherein the non-permeable water is returned to the water to be treated.

6. Includes an ion exchange device equipped with an ion exchange resin, The water treatment system according to claim 1 or claim 2, wherein the ion exchange resin is passed through the adsorption-treated water.

7. Includes an ion exchange device equipped with an ion exchange resin, The water treatment system according to claim 1 or claim 2, wherein the ion exchange resin is passed through the permeate water.

8. The water treatment system according to claim 1 or claim 2, wherein the separation membrane includes at least one component selected from the group consisting of a reverse osmosis membrane, a forward osmosis membrane, an ion exchange membrane, and a nanofiltration membrane.

9. The water treatment system according to claim 1 or claim 2, wherein the adsorption element includes at least one member selected from the group consisting of activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina, and organometallic structure.

10. The water treatment system according to claim 1 or 2, wherein the organic substance treatment apparatus has means for repeatedly performing the operation of moving the portion of the adsorption element in which the desorption process has been completed to the portion in which the adsorption process is performed, and moving the portion of the adsorption element in which the adsorption process has been completed to the portion in which the desorption process is performed.

Images