Water treatment device

Abstract

To provide a water treatment device capable of performing high condensation even when applying an osmotic pressure assist membrane.SOLUTION: A water treatment device is assembled with a hardness removal part for removing a hardness component from a stock solution for water treatment, a carbonic acid removal part for removing a carbonic acid component from the hardness component-removed stock solution, and an osmotic pressure assist membrane part for condensation of the carbonic acid component-removed stock solution by using a permeable membrane. The osmotic pressure assist membrane part includes a permeable membrane and a first chamber and a second chamber separated by the permeable membrane, wherein the first chamber receives the carbonic acid component-removed stock solution, the second chamber receives the stock solution, a condensed stock solution obtained by condensation of the stock solution, or a solution comprising an ionic component having the same degree of concentration as the stock solution or the condensed stock solution and, by permeating water in the stock solution introduced to the first chamber to the second chamber via the permeable membrane, the stock solution introduced to the first chamber is condensed, and the stock solution, the condensed stock solution, or the solution introduced to the second chamber is diluted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a water treatment device suitable for a zero liquid discharge (hereinafter referred to as "ZLD") system. [Background technology]

[0002] In ZLD systems, it is important to concentrate total dissolved solids (hereafter referred to as "TDS") as highly as possible using the RO membrane, but organic and inorganic components (calcium, magnesium, silica, etc.) contained in the wastewater cause fouling / scaling and hinder concentration.

[0003] Furthermore, the higher the concentration, the higher the pressure supplied to the RO membrane must be, which inevitably increases the power consumption of the pump and requires the piping system to withstand higher pressures.

[0004] By using the osmotic pressure assisted membrane described in Patent Document 1, it is theoretically possible to concentrate the TDS to about 300,000 mg / l while keeping the supply pressure low. However, due to fouling / scaling issues, it is difficult to actually concentrate to that extent.

[0005] In addition, while the conventional high pH RO method has overcome the problems of fouling and scaling, the high regeneration cost of the high-performance ion exchange resin and the achievable TDS level of up to 130,000 mg / l are still bottlenecks. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-65114 A Summary of the Invention [Problem to be solved by the invention]

[0007] When concentrating liquids using an osmotic pressure assisted membrane, silica and organic matter (refractory COD) are usually removed in pretreatment as a measure against fouling / scaling. However, removing silica requires a large amount of inorganic chemicals such as dolomite, which not only increases the cost of these chemicals but also increases the amount of sludge, resulting in high sludge disposal costs.

[0008] In addition, activated carbon and advanced oxidation are necessary to remove persistent COD. Activated carbon needs to be replaced or regenerated after absorbing a certain amount of organic matter, and the cost of replacing the activated carbon is very high. Advanced oxidation also requires the installation of expensive equipment such as ozone and UV, and consumes a lot of electricity.

[0009] The problem to be solved by the present invention is to provide a water treatment device capable of high concentration even when an osmotic pressure assisted membrane is applied. [Means for solving the problem]

[0010] The water treatment device of the embodiment includes a hardness removal unit that removes hardness components from the stock solution to be treated, a carbonic acid removal unit that removes carbonic acid components from the stock solution from which the hardness components have been removed, and an osmotic pressure-assisted membrane unit that uses a osmotic membrane to concentrate the stock solution from which the carbonic acid components have been removed. The osmotic pressure-assisted membrane unit has a osmotic membrane and a first chamber and a second chamber separated by the osmotic membrane, the first chamber receives the stock solution from which the carbonic acid components have been removed, and the second chamber receives the stock solution, a concentrated stock solution obtained by concentrating the stock solution, or a solution containing ionic components having approximately the same concentration as the stock solution or the concentrated stock solution, and the water in the stock solution introduced into the first chamber is permeated into the second chamber via the osmotic membrane to concentrate the stock solution introduced into the first chamber and dilute the stock solution, concentrated stock solution, or solution introduced into the second chamber. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a water treatment device according to the first embodiment. [Diagram 2]FIG. 2 is a block diagram showing a configuration example of a modified example of the water treatment device of the first embodiment. [Diagram 3] FIG. 3 is a block diagram showing an example of the configuration of the water treatment device according to the second embodiment. [Figure 4] FIG. 4 is a block diagram showing a configuration example of a modified example of the water treatment device according to the second embodiment. [Diagram 5] FIG. 5 is a block diagram showing an example of the configuration of a water treatment device according to the third embodiment. [Figure 6] FIG. 6 is a block diagram showing a configuration example of a modified example of the water treatment device of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as the actual ones. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with respect to the previous drawings are given the same reference numerals, and detailed explanations and duplicated explanations are omitted as appropriate.

[0013] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[0014] (First embodiment) FIG. 1 is a block diagram showing an example of the configuration of a water treatment device according to the first embodiment.

[0015] The water treatment device 10A shown in FIG. 1 includes an original liquid supply tank 20, a hardness removal section 22, a carbon dioxide removal section 24A, an alkali injection section 28, and an osmotic pressure-assisted membrane section 30.

[0016] The raw liquid supply tank 20 stores the raw liquid a. The raw liquid a stored in the raw liquid supply tank 20 is supplied to the hardness removing unit 22.

[0017] The hardness removing unit 22 removes hardness components from the raw solution a supplied from the raw solution supply tank 20 by performing coagulation precipitation, high-precision ion exchange, etc. The raw solution b from which the hardness components have been removed in this manner is supplied to the carbon dioxide removing unit 24A.

[0018] The carbon dioxide removal unit 24A has a decarbonation tower, and removes carbon dioxide components from the raw solution b from which the hardness components have been removed, using the decarbonation tower.

[0019] The alkali injection unit 28 injects an alkali d into the raw solution c from which hardness components have been removed by the decarbonation tower, and increases the pH of the raw solution c to a value of 9 or higher. The raw solution e with a high pH in this manner is supplied to the osmotic pressure-assisted membrane unit 30.

[0020] The osmotic pressure-assisted membrane unit 30 has an osmotic pressure-assisted membrane 33, which is a semipermeable membrane, and a first chamber 31 and a second chamber 32 separated by the osmotic pressure-assisted membrane 33, and receives the raw solution e in both the first chamber 31 and the second chamber 32. This reduces the osmotic pressure. Then, by pressurizing the first chamber 31 with a relatively low pressure, the water in the raw solution e in the first chamber 31 is caused to permeate into the second chamber 32. In this way, the raw solution e in the first chamber 31 is concentrated, and the raw solution e in the second chamber 32 is diluted.

[0021] As a result, concentrated water f obtained by concentrating the stock solution e is discharged from the first chamber 31, and dilution water g obtained by diluting the stock solution e is discharged from the second chamber 32.

[0022] In addition, the second chamber 32 may not receive the original liquid e, but may receive a solution of the same concentration as the original liquid e but containing different ionic components, a concentrated original liquid obtained by concentrating the original liquid e, or a solution of the same concentration as the concentrated original liquid but containing different ionic components.

[0023] According to the water treatment device 10A of the first embodiment described above, by operating at a high pH (pH 9 or higher) rather than removing silica or organic matter, silica scaling and organic matter fouling can be prevented, and high concentration is possible even in a configuration using an osmotic pressure-assisted membrane.

[0024] At high pH, ​​the saturation solubility of silica becomes very high, so even if it is highly concentrated, it does not precipitate and does not cause scaling. In addition, at high pH, ​​organic matter does not easily adhere to the surface of the osmotic pressure assisted membrane 33, so fouling does not occur.

[0025] However, since hardness components such as calcium and magnesium are prone to precipitate under high pH conditions, these are removed by the hardness removal section 22.

[0026] Furthermore, since carbonate ions and bicarbonate ions cause the precipitation of carbonates, these components are removed by the carbonic acid removing section 24A.

[0027] Furthermore, for the osmotic pressure-assisted membrane 33, a material having high resistance to high pH, ​​such as a polyamide material, is selected since cellulose acetate-based materials have low resistance to high pH.

[0028] It should be noted that modifications of the water treatment device 10A are possible.

[0029] FIG. 2 is a block diagram showing a configuration example of a modified example of the water treatment device of the first embodiment.

[0030] 2, the water treatment device 10B is obtained by replacing the carbonate removal unit 24A of the water treatment device 10A with a carbonate removal unit 24B. The carbonate removal unit 24B has a degassing membrane, and removes carbonate components from the raw solution b from which the hardness components have been removed, using the degassing membrane.

[0031] The alkali injecting unit 28 injects an alkali d into the raw solution c from which hardness components have been removed by the degassing membrane, thereby increasing the pH of the raw solution c. The raw solution e having a high pH in this manner is supplied to the osmotic pressure-assisted membrane unit 30.

[0032] In addition, in the hardness removing section 22, not only coagulation sedimentation or high-precision ion exchange but also an NF membrane may be used to remove hardness.

[0033] The other configurations are the same as those of the water treatment device 10A, so a duplicated description will be avoided.

[0034] Even in a modification in which the carbon dioxide removing unit 24A of the water treatment device 10A is replaced with a carbon dioxide removing unit 24B, like the water treatment device 10B, the same effects as those of the water treatment device 10A can be achieved.

[0035] Second embodiment FIG. 3 is a block diagram showing an example of the configuration of the water treatment device according to the second embodiment.

[0036] The water treatment device 10C shown in FIG. 3 includes an RO membrane unit 40 between the carbon dioxide removing unit 24A and the osmotic pressure-assisted membrane unit 30 of the water treatment device 10A, downstream of the alkali injection unit .

[0037] The RO membrane section 40 has an RO membrane 43, and a first chamber 41 and a second chamber 42 separated by the RO membrane 43. The first chamber 41 receives the raw solution e to which the alkali d has been added by the alkali injection section 28, and the water in the raw solution e permeates from the first chamber 41 to the second chamber 42 through the RO membrane 43, whereby the raw solution e in the first chamber 41 is concentrated and concentrated water f is discharged from the first chamber 41. Meanwhile, permeated water h is discharged from the second chamber 42.

[0038] The concentrated water f discharged from the first chamber 41 is received in both the first chamber 31 and the second chamber 32 of the osmotic pressure-assisted membrane unit 30.

[0039] In the osmotic pressure-assisted membrane unit 30, the water in the concentrated water f introduced into the first chamber 31 permeates into the second chamber 32 through the osmotic pressure-assisted membrane 33, thereby further concentrating the concentrated water f in the first chamber 31. As a result, the concentrated water f introduced into the second chamber 32 is diluted by the permeated water from the first chamber 31. As a result, concentrated water F, which is the further concentrated concentrated water f, is discharged from the first chamber 31, and diluted water g, which is the diluted concentrated water f, is discharged from the second chamber 32.

[0040] In this way, by providing an RO membrane section 40 between the carbon dioxide removal section 24A and the osmotic pressure-assisted membrane section 30, downstream of the alkali injection section 28, it is possible to discharge concentrated water F, which is even more concentrated than concentrated water f, from the first chamber 31 of the osmotic pressure-assisted membrane section 30.

[0041] It should be noted that modifications of the water treatment device 10C are possible.

[0042] FIG. 4 is a block diagram showing a configuration example of a modified example of the water treatment device according to the second embodiment.

[0043] 4 shows a water treatment device 10D in which the carbonate removal unit 24A of the water treatment device 10C is replaced with a carbonate removal unit 24B. The carbonate removal unit 24B has a degassing membrane, and removes carbonate components from the raw solution b from which the hardness components have been removed, using the degassing membrane.

[0044] The alkali injection unit 28 injects an alkali d into the raw solution c from which hardness components have been removed by the degassing membrane, thereby increasing the pH of the raw solution c. The raw solution e having a high pH in this manner is supplied to the RO membrane unit 40.

[0045] In addition, in the hardness removing section 22, not only coagulation sedimentation or high-precision ion exchange but also an NF membrane may be used to remove hardness.

[0046] The other configurations are the same as those of the water treatment device 10C, so a duplicated description will be avoided.

[0047] A modification such as the water treatment device 10D in which the carbon dioxide remover 24A of the water treatment device 10C is replaced with a carbon dioxide remover 24B can also achieve the same effects as the water treatment device 10C.

[0048] (Third embodiment) FIG. 5 is a block diagram showing an example of the configuration of a water treatment device according to the third embodiment.

[0049] A water treatment device 10E shown in FIG. 5 includes an RO membrane unit 40 between the raw liquid supply tank 20 and the hardness removal unit 22 of the water treatment device 10A.

[0050] As described in the second embodiment, the RO membrane unit 40 has an RO membrane 43, and a first chamber 41 and a second chamber 42 separated by the RO membrane 43. The first chamber 41 receives the raw liquid a supplied from the raw liquid supply tank 20, and the water in the raw liquid a permeates from the first chamber 41 to the second chamber 42 through the RO membrane 43, thereby concentrating the raw liquid a in the first chamber 41, and the concentrated raw liquid A is discharged from the first chamber 41. On the other hand, permeated water h is discharged from the second chamber 42.

[0051] The concentrated stock solution A is supplied to the hardness removing section 22.

[0052] The hardness removing section 22 removes hardness components from the concentrated stock solution A by performing coagulation precipitation, high-precision ion exchange, etc. Concentrated stock solution B from which the hardness components have been removed in this manner is supplied to the carbon dioxide removing section 24A.

[0053] The carbon dioxide removal unit 24A has a decarbonation tower, and uses the decarbonation tower to remove carbon dioxide components from the concentrated stock solution B from which the hardness components have been removed.

[0054] The alkali injection unit 28 injects an alkali d into the concentrated stock solution C from which hardness components have been removed by the decarbonation tower, thereby increasing the pH of the stock solution C. The stock solution E having a high pH in this manner is supplied to the osmotic pressure-assisted membrane unit 30.

[0055] The osmotic pressure-assisted membrane unit 30 has an osmotic pressure-assisted membrane 33 and a first chamber 31 and a second chamber 32 separated by the osmotic pressure-assisted membrane 33, and receives the stock solution E in both the first chamber 31 and the second chamber 32. As described above, the osmotic pressure-assisted membrane 33 is used to concentrate the stock solution E in the first chamber 31 and to dilute the stock solution E in the second chamber 32. As a result, concentrated water F in which the stock solution E is concentrated is discharged from the first chamber 31, and diluted water g in which the stock solution E is diluted is discharged from the second chamber 32.

[0056] In this way, even if the RO membrane section 40 is configured to be located upstream of the hardness removal section 22, it is possible to discharge concentrated water F, which is even more concentrated than the concentrated water f, from the first chamber 31 of the osmotic pressure-assisted membrane section 30.

[0057] Modifications of the water treatment device 10E are also possible.

[0058] FIG. 6 is a block diagram showing a configuration example of a modified example of the water treatment device of the third embodiment.

[0059] 6 shows a water treatment device 10F in which the carbonate removal unit 24A of the water treatment device 10E is replaced with a carbonate removal unit 24B. The carbonate removal unit 24B has a degassing membrane, and removes carbonate components from the raw solution B from which the hardness components have been removed, using the degassing membrane.

[0060] The alkali injecting unit 28 injects an alkali d into the raw solution C from which hardness components have been removed by the degassing membrane, thereby increasing the pH of the raw solution C. The raw solution E having a high pH in this manner is supplied to the osmotic pressure-assisted membrane unit 30.

[0061] In addition, in the hardness removing section 22, not only coagulation sedimentation or high-precision ion exchange but also an NF membrane may be used to remove hardness.

[0062] The other configurations are the same as those of the water treatment device 10E, so a duplicated description will be avoided.

[0063] Even in a modified example in which the carbon dioxide remover 24A is replaced with the carbon dioxide remover 24B, such as the water treatment device 10F, the same effects as those of the water treatment device 10E can be achieved.

[0064] In addition, in all of the above-mentioned embodiments of the water treatment device 10 (water treatment devices 10A, 10B, 10C, 10D, 10E, and 10F are collectively referred to as water treatment device 10), the installation locations of the hardness removal unit 22 and the carbon dioxide removal units 24A and 24B may be interchanged.

[0065] According to the water treatment device 10 of each of the embodiments described above, it is possible to realize many advantages, such as being able to concentrate to a very high concentration, being able to operate at a relatively low supply pressure, thereby reducing power consumption, and being able to keep the pressure resistance of the piping system low, compared to the high pH RO method.

[0066] Furthermore, the water treatment device 10 of each embodiment can be applied not only to highly concentrating wastewater, but also to highly concentrating beverages, seasonings, and the like, and highly concentrating valuable inorganic ions.

[0067] Furthermore, in the conventional high pH RO method, it was necessary to remove calcium components to a very low concentration in ion exchange, but in particular, by using the carbonate removal unit 24B with a degassing membrane as in the water treatment devices 10B, 10D, and 10F, carbonate ions can be removed with high accuracy, so it is possible to operate with a lower accuracy of calcium removal. This makes it possible to use a low-accuracy ion exchange resin in the hardness removal unit 22 in the water treatment devices 10B, 10D, and 10F. Since the regeneration cost of a low-accuracy ion exchange resin is lower than the regeneration cost of a high-accuracy ion exchange resin, it is possible to reduce operating costs.

[0068] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0069] 10 Water treatment equipment 20 Stock solution supply tank 22 Hardness removal part 24A Carbon dioxide removal section (decarbonation tower) 24B Carbon dioxide removal section (degassing membrane) 28 Alkaline injection section 30 Osmotic pressure assist membrane section 31 Room 1 32 Room 2 33 Osmotic pressure assisted membrane 40 RO membrane section 41 Room 1 42 Room 2 43 RO Membrane

Claims

1. a hardness removal unit that removes hardness components from the raw water to be treated; a carbon dioxide removal unit that removes carbon dioxide components from the raw liquid from which the hardness components have been removed; The raw liquid from which the carbon dioxide components have been removed is concentrated using an osmotic pressure-assisted membrane unit, The osmotic pressure-assisted membrane unit has the osmotic membrane and a first chamber and a second chamber separated by the osmotic membrane, The first chamber receives the concentrate from which the carbon dioxide components have been removed, The second chamber receives the stock solution, a concentrated stock solution obtained by concentrating the stock solution, or a solution containing ion components having a concentration similar to that of the stock solution or the concentrated stock solution, A water treatment device that concentrates the stock solution introduced into the first chamber by permeating the water in the stock solution introduced into the first chamber into the second chamber through the permeation membrane, and dilutes the stock solution, concentrated stock solution, or solution introduced into the second chamber.

2. An RO membrane unit is provided between the carbon dioxide removal unit and the osmotic pressure-assisted membrane unit, which uses an RO membrane to concentrate the stock solution from which the carbon dioxide components have been removed, The water treatment device according to claim 1 , wherein the raw liquid received by the osmotic pressure-assisted membrane unit is a raw liquid concentrated by the RO membrane unit.

3. The apparatus includes an RO membrane unit that uses an RO membrane to concentrate the stock solution before the hardness components are removed, The water treatment device according to claim 1 , wherein the hardness removing unit removes the hardness components from the raw liquid concentrated by the RO membrane unit.

4. The water treatment device according to claim 1 , wherein the carbon dioxide removal unit has a decarbonation tower.

5. The water treatment device according to claim 4 , further comprising an alkali injection section that injects an alkali into the raw liquid from which the hardness components have been removed by the decarbonation tower.

6. The water treatment device according to claim 1 , wherein the carbon dioxide removing section has a deaeration membrane.

7. The water treatment device according to claim 6 , further comprising an alkali injection section that injects an alkali into the raw liquid from which the hardness components have been removed by the degassing membrane.

Images