Cleaning device, drain water processing system, and cleaning method

Abstract

To provide a cleaning device that efficiently and effectively cleans a filtration membrane provided in a drain water processing system while suppressing costs.SOLUTION: A cleaning device according to the present invention is a device that cleans a filtration membrane provided in a drain water processing device. The cleaning device includes: a bactericidal agent injection part that injects a bactericidal agent to a permeation side of the filtration membrane; a bactericidal agent collection part that collects the bactericidal agent from the filtration membrane; an inhibitor injection part that injects a quorum sensing inhibitor to the permeation side of the filtration membrane; and an inhibitor collection part that collects the quorum sensing inhibitor from the filtration membrane.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cleaning device for cleaning a filtration membrane provided in a wastewater treatment device, a wastewater treatment system including the same, and a cleaning method. [Background technology]

[0002] The membrane bioreactor (MBR) is a wastewater treatment method that uses a filtration membrane. Compared to the standard activated sludge process, which is one of the conventional treatment methods, it produces clear treated water and can be installed in a small space, so its introduction is progressing. The filtration membrane used in MBR has pores of about 0.1 to 0.3 μm, and the treated water (permeate) is sucked from the permeation side of the filtration membrane, that is, membrane filtration suction, to separate the treated water from sludge components and metabolites. However, membrane filtration suction causes sludge components to adhere to the membrane surface and inside the membrane pores, which causes clogging (fouling). Therefore, aeration cleaning, chemical cleaning, and sponge cleaning are used as operation and maintenance methods.

[0003] Aeration cleaning is always performed when the membrane filtration suction is in operation, and aeration from the bottom of the filtration membrane prevents the accumulation of metabolic products. However, after a certain period of time, metabolic products that are difficult to remove by aeration cleaning accumulate and a biofilm is formed.

[0004] When a biofilm is formed, a bactericidal agent (bactericide) is injected from the permeation side of the filtration membrane to perform chemical cleaning to remove the biofilm. Commonly used bactericides include sodium hypochlorite aqueous solution, oxalic acid, citric acid, hydrochloric acid, ozone water, etc. The use of bactericides is an effective method because it allows biofilm removal at a relatively low cost, but the effect of the chemical cleaning becomes less apparent as the number of cleanings increases.

[0005] When the chemical cleaning effect is no longer apparent, in order to maintain wastewater treatment operation, it is necessary to remove the biofilm by pulling the filtration membrane out of the reaction tank and scrubbing the filtration membrane surface with a sponge for sponge cleaning. Since sponge cleaning physically destroys the biofilm, it is effective in eliminating fouling, but the problem is that it requires a large amount of cleaning labor and costs.

[0006] In light of the above, it is important to improve the effectiveness of chemical cleaning and reduce the frequency of sponge cleaning in order to reduce the operational costs of membrane filtration. For this reason, efficient chemical cleaning methods have been investigated.

[0007] One of them is a method of preventing fouling by inactivating metabolites deposited on the membrane surface using a cleaning solution with high oxidizing and bactericidal power (Patent Document 1). In this method, cleaning with a sodium hypochlorite aqueous solution is performed in the first stage, and cleaning with a solution with a higher oxidizing power, such as ozone water, is performed in the second stage.

[0008] On the other hand, in recent years, it has been reported that washing with a bactericide releases homoserine derivatives, which are signal substances that promote metabolic accumulation (Non-Patent Document 1). It is said that metabolites in sludge sense the bacterial density and control production via signal substances. This is called a quorum sensing mechanism, and biofilm formation is also carried out by a similar mechanism for metabolites deposited on the membrane surface. Therefore, removing biofilms by utilizing the high oxidizing power of the washing solution can lead to the production of signal substances such as homoserine derivatives, which can be a factor in accelerating membrane clogging of the filtration membrane.

[0009] This suggests that, rather than using a drug with a higher oxidizing power to remove the signal substance released when using a disinfectant, it would be more effective to use a drug that has the effect of inhibiting the quorum sensing mechanism (hereinafter referred to as a quorum sensing inhibitor, or inhibitor).

[0010] Therefore, there is a method of suppressing the formation of biofilms on the surface of the filtration membrane by adding an inhibitor to the feed side of the filtration membrane in the reaction tank (Non-Patent Document 2). By adding vanillin, which is one of the inhibitors, to activated sludge, the metabolic properties are changed, and the frequency of membrane clogging has been successfully reduced.

[0011] In addition, there is a method of two-stage membrane filtration treatment, for example, when performing treatment using an MBR membrane followed by treatment using an RO membrane, in which an inhibitor is added to the MBR membrane-treated water to reduce clogging of the RO membrane (Patent Document 2). [Prior art documents] [Patent documents]

[0012] [Patent Document 1] International Publication No. WO2016 / 031331 [Patent Document 2] JP 2016-117018 A [Non-patent literature]

[0013] [Non-Patent Document 1] WeiweiCai, et al., Journal of Membrane Science, (2016), 511, 84-91. [Non-Patent Document 2] Phuc-Nguon Hong, et al., Journal of Water Process Engineering, (2022), 47, 102644. Summary of the Invention [Problem to be solved by the invention]

[0014] As described above, various methods have been developed. In the method of Patent Document 1, it is expected that the effect of temporarily suppressing fouling can be expected, but there is a concern that repeated washing may result in the emergence of bacteria resistant to the washing solution. In addition, when the method of Non-Patent Document 2 is carried out, it is necessary to add a large amount of inhibitor to the reaction tank in which the filtration membrane is installed. In addition, in the method of Patent Document 2, the inhibitor is applied from the supply side of the filtration membrane, and it is considered that a large amount of inhibitor is required. Therefore, the cost increases and it is not practical.

[0015] Thus, there is a demand for an apparatus and method that can clean filtration membranes installed in wastewater treatment plants efficiently, effectively, and at reduced cost. [Means for solving the problem]

[0016] Therefore, the inventors of the present invention have studied diligently to solve the above problems, and have assumed that it is effective to contact the inhibitor from the permeation side of the filtration membrane, which is the side that contacts the treated water, rather than from the supply side, which is the side that contacts the wastewater of the filtration membrane. Furthermore, they thought that effective membrane cleaning would be possible by acting the inhibitor on the filtration membrane after cleaning the filtration membrane with a bactericide. As a result, they have finally completed the present invention.

[0017] It should be noted that there have been no reports of a method of injecting an inhibitor into the permeate side of a filtration membrane, nor of a cleaning method using a disinfectant and an inhibitor in combination.

[0018] The present invention is as follows. 1. A cleaning device for cleaning a filtration membrane provided in a wastewater treatment device, comprising: a disinfectant injection unit for injecting a disinfectant into the permeation side of the filtration membrane; a disinfectant recovery unit for recovering the disinfectant from the filtration membrane; an inhibitor injection unit for injecting a quorum sensing inhibitor into the permeation side of the filtration membrane; and an inhibitor recovery section that recovers the ram-sensing inhibitor from the filtration membrane. 2. A cleaning device as described in 1 above, wherein the quorum sensing inhibitor is a drug having an inhibitory effect on homoserine derivatives. 3. A cleaning device according to claim 1 or 2, wherein the quorum sensing inhibitor is a solution containing at least one of vanillin, cinnamic acid, caffeic acid, chlorogenic acid, and ferulic acid. 4. The cleaning device according to the above 1 or 2, wherein the quorum sensing inhibitor is a solution containing 0.01 to 20.00 wt % vanillin. 5. The cleaning device according to any one of 1 to 4 above, wherein the disinfectant is a solution containing at least one of sodium hypochlorite, oxalic acid, hydrochloric acid, citric acid, and ozone. 6. The cleaning device according to any one of the above items 1 to 5, wherein the wastewater treatment device is a device for performing wastewater treatment using a membrane separation activated sludge method. 7. A wastewater treatment system comprising the cleaning device according to any one of 1 to 6 above and the wastewater treatment device. 8. A cleaning method for cleaning a filtration membrane provided in a wastewater treatment device, comprising: a disinfectant injection step of injecting a disinfectant into the permeate side of the filtration membrane; a disinfectant recovery step of recovering the disinfectant from the filtration membrane; an inhibitor injection step of injecting a quorum sensing inhibitor into the permeate side of the filtration membrane after the disinfectant recovery step; and an inhibitor recovery step of recovering the quorum sensing inhibitor from the filtration membrane. 9. The cleaning method according to claim 8, further comprising a differential pressure measurement step of measuring a transmembrane pressure (TMP) value indicating the pressure difference between the permeate side and the supply side of the filtration membrane, and after detecting that the transmembrane pressure value has exceeded a predetermined value in the differential pressure measurement step, carrying out the disinfectant injection step, the disinfectant recovery step, the inhibitor injection step, and the inhibitor recovery step. Effect of the Invention

[0019] In the present invention, a quorum sensing inhibitor having an inhibitory effect on the quorum sensing mechanism effectively acts on the metabolites after washing with a disinfectant, contributing to the reduction of fouling. In the present invention, the quorum sensing inhibitor is injected into the permeation side (the side in contact with the treated water) of the filtration membrane, so that a small amount of the inhibitor can be applied to the filtration membrane surface, unlike a method in which a large amount of the inhibitor is administered to the supply side (the side in contact with the wastewater). As a result, it is possible to reduce the frequency of sponge washing while suppressing chemical washing costs, and a significant reduction in membrane filtration operation costs can be expected. In addition, as described above, only a small amount of the quorum sensing inhibitor is used, and it is recovered, so the environmental load is also reduced.

[0020] In addition, if the clogging of the filtration membrane is not severe, it is expected that the fouling suppression effect can be achieved simply by injecting an inhibitor without injecting a bactericide and allowing the inhibitor to act on the metabolites accumulated on the surface of the filtration membrane. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic configuration diagram of a wastewater treatment device according to an embodiment of the present invention. [Diagram 2] 1 is a graph showing changes in TMP in Example 1 in which sodium hypochlorite washing and high-concentration vanillin washing were performed, and in Comparative Example 1 in which only sodium hypochlorite washing was performed. [Diagram 3] 1 is a graph showing changes in TMP in Example 2 in which sodium hypochlorite washing and low-concentration vanillin washing were performed, and in Comparative Example 2 in which only sodium hypochlorite washing was performed. [Figure 4] 1 is a graph showing changes in TMP in Example 3 in which only vanillin washing was performed, and in Comparative Example 3 in which only sodium hypochlorite washing was performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] A cleaning device and a wastewater treatment system according to an embodiment of the present invention will be described below with reference to FIG. The present invention is not limited to the following embodiments, and an optimum configuration can be selected for each application in accordance with the gist of the present invention.

[0023] FIG 1 is a schematic diagram of a wastewater treatment system 100 including a wastewater treatment device 1 equipped with a cleaning device 200 according to an embodiment of the present invention. In this embodiment, the wastewater treatment device 1 is a device that performs wastewater treatment using an MBR. The type of wastewater is not limited, and may be sewage, miscellaneous wastewater, special wastewater, etc. Also, pretreated wastewater may be used.

[0024] The wastewater treatment device 1 includes a reaction tank 10, a membrane unit 20, a wastewater supply section 30, a treated water circulation section 40, and a sludge return section 50. The cleaning device 200 includes a disinfectant tank 60 and an inhibitor tank 70.

[0025] The reaction tank 10 contains activated sludge and is a tank for treating wastewater. The membrane unit 20 includes a membrane element 21, a water collection pipe 22, and an aeration pipe 23. The wastewater supply section 30 includes a wastewater supply pump 31 and a wastewater supply pipe 32. The treated water circulation section 40 includes a treated water pipe 41 and a suction pump 42. The sludge return section 50 includes a sludge return pipe 51 and a sludge return pump 52. The disinfectant washing section 60 includes a disinfectant supply tank 61, a disinfectant supply tank pipe 62, a disinfectant supply pump 63, a disinfectant recovery tank 64, a disinfectant recovery tank pipe 65, and a disinfectant recovery pump 66. The inhibitor washing section 70 includes an inhibitor supply tank 71, an inhibitor supply pipe 72, an inhibitor pump 73, an inhibitor recovery tank 74, an inhibitor recovery pipe 75, and an inhibitor recovery pump 76.

[0026] A membrane unit 20 is installed in the reaction tank 10. A wastewater supply section 30 and a return sludge section 50 are also connected to the reaction tank 10. The membrane element 21 and treated water circulation section 40 are connected through a water collection pipe 22 and treated water piping 41. The membrane element 21 and disinfectant supply tank 61 are connected through a water collection pipe 22 and disinfectant supply tank piping 62. The membrane element 21 and disinfectant recovery tank 64 are connected through a water collection pipe 22 and disinfectant recovery tank piping 65. The membrane element 21 and inhibitor supply tank 71 are connected through a water collection pipe 22 and inhibitor supply tank 71. The membrane element 21 and inhibitor recovery tank 74 are connected through a water collection pipe 22 and inhibitor recovery piping 75.

[0027] The membrane filtration operation in the wastewater treatment device 1 will be described. The wastewater supply pump 31 is driven to supply wastewater to the reaction tank 10 through the wastewater supply pipe 32. The activated sludge in the reaction tank 10 decomposes the organic components of the wastewater. When an increase in the activated sludge volume value (MLSS: mixed liquor suspended solids) in the reaction tank 10 is confirmed, the return sludge pump 52 is driven to discharge excess sludge outside the reaction tank 10 through the return sludge pipe 51.

[0028] The treated water circulation section 40 and the water collection pipe 22 are connected, and by operating the suction pump 42, the pressure on the permeate side of the membrane of the membrane element 21 is reduced, making it possible to separate the activated sludge and the treated water.

[0029] The membrane element 21 includes a filtration membrane and a frame material surrounding the filtration membrane. Examples of the material of the filtration membrane of the membrane element 21 include, but are not limited to, chlorinated polyvinyl chloride (CPVC), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), cellulose acetate, ceramics, and the like. Among them, materials with excellent chemical resistance are preferable. The type of the filtration membrane is not particularly limited, and any known filtration membrane in the relevant technical field, such as a microfiltration membrane or an ultrafiltration membrane, can be used. The permeation side of the membrane element 21 is the side that comes into contact with the treated water (permeate), and the supply side is the side that comes into contact with the wastewater.

[0030] Next, cleaning of the membrane element 21 using the cleaning device 200, i.e., membrane cleaning, will be described. In the cleaning device 200, disinfectant cleaning and inhibition cleaning are performed. First, regarding disinfectant cleaning, A sufficient amount of disinfectant is prepared in a disinfectant supply tank 61. Then, a disinfectant supply pump 63 is operated to inject the disinfectant into the permeate side of the membrane element 21 through the supply tank piping 62 and the water collection pipe 22. In other words, the inhibitor acts in the opposite direction to the flow of the permeate.

[0031] If the disinfectant supply tank 61 is located at a position sufficiently higher than the membrane unit 20, it is also possible to adopt a gravity injection method without using the disinfectant supply pump 63. After the disinfectant is injected into the membrane element 21, it is left to stand for a certain period of time to remove the activated sludge components and metabolites attached to the filtration membrane surface. Thereafter, the washed disinfectant is recovered into the disinfectant recovery tank 74 through the disinfectant recovery pipe 65 and the water collection pipe 22 by operating the disinfectant recovery pump 66. It is also possible to recover the washed disinfectant through the water collection pipe 22 and the treated water pipe 42 by driving the suction pump 42 used in the membrane filtration operation without using the disinfectant recovery tank 64, the disinfectant recovery pipe 65, and the disinfectant recovery pump 66. When performing the series of operations, the operation is performed in a state in which aeration is performed from the aeration pipe 23, or in a state in which aeration from the aeration pipe 23 is stopped. The aeration flow rate from the aeration pipe 23 is not limited.

[0032] The disinfectant used in disinfectant cleaning includes, for example, a solution containing sodium hypochlorite, oxalic acid, hydrochloric acid, citric acid, and ozone. When using sodium hypochlorite, it is preferable to use an aqueous solution of 0.1 to 1.0 vol%, but this is not limited thereto.

[0033] The time for which the disinfectant is allowed to stand after being injected into the permeation side of the membrane element 21 is preferably about 10 minutes to 2 hours, but may be outside this range.

[0034] Next, inhibitor washing will be described. Inhibitors are agents that can inhibit the quorum sensing mechanism. A sufficient amount of inhibitor is prepared in an inhibitor supply tank 71. After washing with a disinfectant, an inhibitor supply pump 73 is operated to inject the inhibitor into the permeate side of the membrane element 21 through an inhibitor supply pipe 72 and a water collection pipe 22. In other words, the inhibitor acts in the opposite direction to the flow of the permeate.

[0035] If the inhibitor supply tank 71 is located at a position sufficiently higher than the membrane unit 20, a gravity injection method can be adopted without using the inhibitor supply pump 73. After the inhibitor is injected into the membrane element 21, it is left to stand for a certain period of time to act on the remaining metabolites on the membrane surface. The inhibitor after acting on the membrane element 21 is recovered in the inhibitor recovery tank 74 through the inhibitor recovery pipe 75 and the water collection pipe 22 by operating the inhibitor recovery pump 76. The inhibitor after acting may be recovered through the water collection pipe 22 and the treated water pipe 42 by operating the suction pump 42 used in the membrane filtration operation without using the inhibitor recovery tank 74, the inhibitor recovery pipe 75, and the inhibitor recovery pump 76. The series of operations are performed in a state in which aeration is performed from the aeration pipe 23, or in a state in which aeration from the aeration pipe 23 is stopped. The aeration flow rate from the aeration pipe 23 is not limited.

[0036] Examples of inhibitors used for washing the inhibitor include solutions containing vanillin, cinnamic acid, caffeic acid, chlorogenic acid, and ferulic acid, which have an inhibitory effect on homoserine derivatives. The inhibitor is not limited to the above, as long as it can inhibit the quorum sensing mechanism. When using an aqueous vanillin solution as the inhibitor, the aqueous solution preferably contains 0.01 to 1.0 wt% vanillin.

[0037] The time for which the inhibitor is allowed to stand after being injected into the membrane element 21 is preferably about 10 minutes to 2 hours, but may be outside this range.

[0038] In the inhibitor washing, the inhibitor is injected into the permeation side of the membrane element 21, so that a small amount of the inhibitor can act on the filtration membrane surface, unlike the method of administering a large amount of the inhibitor to the supply side. As a result, it is possible to reduce the frequency of sponge cleaning while suppressing chemical cleaning costs, and a significant reduction in membrane filtration operation costs can be expected. In addition, there is little impact on the water environment inside the reaction tank. In this way, by using the cleaning device 200 of this embodiment, it is possible to perform membrane cleaning efficiently and effectively while suppressing costs.

[0039] After the disinfectant cleaning and the inhibitor cleaning are performed, the membrane filtration operation is resumed. If the membrane clogging is minor, only the inhibitor cleaning may be performed without performing the disinfectant cleaning.

[0040] In this embodiment, the disinfectant washing section 60 is provided with two tanks and the inhibitor washing section 70 is provided with two tanks, but one tank A may be provided. In this case, a disinfectant is placed in tank A and injected into the permeate side of the membrane element 21, the disinfectant after cleaning is recovered in tank A, and then the disinfectant is removed from tank A. Next, an inhibitor is placed in tank A and injected into the permeate side of the membrane element 21, and the inhibitor after cleaning is recovered in tank A. Alternatively, one tank B may be provided in the disinfectant washing section 60, and one tank C may be provided in the inhibitor washing section 70. In this case, a disinfectant is placed in tank B, the disinfectant is injected into the permeate side of the membrane element 21, and the disinfectant after washing is recovered in tank B. An inhibitor is placed in tank C, the inhibitor is injected into the permeate side of the membrane element 21, and the inhibitor after washing is recovered in tank C.

[0041] The MLSS value of the reaction tank 10 when cleaning is carried out is preferably controlled at 3000 to 10000 mg / L, but is not limited to this range.

[0042] By performing the membrane filtration operation, a biofilm is formed on the membrane surface of the membrane element 21, and membrane clogging progresses. As an index for checking the membrane clogging state, it is possible to use a transmembrane pressure (TMP), which is a value indicating the pressure difference between the permeation side and the supply side of the filtration membrane. Therefore, the wastewater treatment system 100 may be equipped with a measuring device for measuring the TMP. It is preferable to measure the TMP, which is an index of membrane clogging, and perform cleaning using the cleaning device 200 when the TMP rises to about 10 to 20 kPa. However, in order to suppress the formation of a strong biofilm that causes membrane clogging, cleaning using the cleaning device 200 may be performed even in a state of 10 kPa or less. Also, cleaning may be performed at 20 kPa or more, where a strong biofilm has already been formed. There is no particular limitation on the frequency of cleaning.

[0043] Although the above describes the cleaning of a wastewater treatment device that performs wastewater treatment using an MBR, the cleaning device, cleaning system, and cleaning method of the present invention can also be applied to wastewater treatment devices, systems, and methods that use other filtration membranes (e.g., wastewater UF membranes, wastewater MF membranes, etc.). EXAMPLES

[0044] The effects of the present invention will be specifically shown below by way of examples. The following examples are not intended to limit the present invention, and any design modifications made in accordance with the spirit described above and below are within the technical scope of the present invention.

[0045] [Example 1 and Comparative Example 1] Using actual activated sludge liquid A, fouling characteristics were measured for a case in which bactericidal cleaning and inhibitor cleaning were performed (Example 1) and a case in which only bactericide cleaning was performed (Comparative Example 1). Hereinafter, cleaning using a sodium hypochlorite aqueous solution as the bactericide is referred to as sodium hypochlorite cleaning. Cleaning using a vanillin aqueous solution as the inhibitor is referred to as vanillin cleaning.

[0046] A submerged membrane separation activated sludge test device (Model IMF-5) manufactured by Miyamoto Seisakusho was used. Activated sludge liquid A was adjusted so that the MLSS concentration in the device was about 2000 mg / L. The membrane area of ​​the membrane element was 1 m 2 Percentage: 0.3m 3 / day filtration rate with tube pump Suction filtration was performed by the suction filter. Intermittent operation was performed by repeating 8-minute suction filtration operation followed by 2-minute stop. The aeration rate was adjusted to 3 L / min per membrane element. To carry out a comparative verification, two systems, a system of Example 1 in which sodium hypochlorite washing and vanillin washing are performed, and a system of Comparative Example 1 in which only sodium hypochlorite washing is performed, were placed in parallel and membrane filtration operation was carried out for approximately three days.

[0047] 20 hours and 40 hours after the start of operation, membrane cleaning was performed as follows. For the system of Example 1, 300 mL of 0.5 vol% sodium hypochlorite aqueous solution was injected per membrane element, and left to stand for 5 minutes. Thereafter, the sodium hypochlorite aqueous solution remaining inside the membrane was removed by suction with a suction pump. Next, 300 mL of 0.5 wt% vanillin aqueous solution was injected per membrane element, left to stand for 5 minutes, and then removed by suction. For the system of Comparative Example 1, 300 mL of 0.5 vol% sodium hypochlorite aqueous solution was injected per membrane element, left to stand for 10 minutes, and then removed by suction. The TMP was measured over time to determine the state of membrane clogging for the system of Example 1 and the system of Comparative Example 1. A graph of the TMP measurement results is shown in FIG.

[0048] [Example 2 and Comparative Example 2] Using actual activated sludge liquid B, operation was carried out at the same filtration rate and aeration volume using the same equipment as in Example 1. Activated sludge liquid B was adjusted so that the MLSS concentration in the equipment was about 2000 mg / L. In order to carry out comparative verification, membrane filtration operation was carried out in parallel for about 3 days using two systems, a system of Example 2 in which sodium hypochlorite washing and vanillin washing were carried out, and a system of Comparative Example 2 in which only sodium hypochlorite washing was carried out.

[0049] After 1, 20, and 40 hours from the start of operation, membrane cleaning was performed as follows. For the system of Example 2, 300 mL of 0.5 vol% sodium hypochlorite aqueous solution was injected per membrane element, and left to stand for 30 minutes. After that, the sodium hypochlorite aqueous solution remaining inside the membrane was removed by suction with a suction pump. Next, 300 mL of 0.1 wt% vanillin aqueous solution was injected per membrane element, left to stand for 30 minutes, and then removed by suction. For the system of Comparative Example 2, 300 mL of 0.5 vol% sodium hypochlorite aqueous solution was injected per membrane element, left to stand for 60 minutes, and then removed by suction. The trans-membrane pressure (TMP) change was measured over time to determine the state of membrane clogging for the system of Example 2 and the system of Comparative Example 2. A graph of the TMP measurement results is shown in FIG.

[0050] [Example 3 and Comparative Example 3] Using actual activated sludge liquid C, the same equipment as in Example 1 was used to carry out operation at the same filtration rate and aeration volume. The activated sludge liquid C was adjusted so that the MLSS concentration in the equipment was about 5000 mg / L. In order to carry out comparative verification, membrane filtration operation was carried out in parallel in two systems, the system of Example 3 in which only vanillin washing was carried out, and the system of Comparative Example 3 in which only sodium hypochlorite washing was carried out.

[0051] Membrane cleaning was performed 1, 2, 3, 4, and 5 hours after the start of operation, as follows. For the system of Example 3, 300 mL of 0.5 wt% vanillin was injected per membrane element, left to stand for 10 minutes, and then removed by suction. For the system of Comparative Example 3, 300 mL of 0.5 vol% aqueous sodium hypochlorite solution was injected per membrane element, left to stand for 10 minutes, and then removed by suction. The TMP was measured over time to determine the state of membrane clogging for the system of Example 3 and the system of Comparative Example 3. A graph of the TMP measurement results is shown in FIG.

[0052] [Consideration] From the graph in Figure 2, it can be seen that compared to the case of sodium hypochlorite cleaning only, by performing vanillin cleaning after sodium hypochlorite cleaning, the increase in TMP is suppressed. In other words, clogging is suppressed. Furthermore, from the graph in Figure 3, it was confirmed that the increase in TMP is suppressed by extending the immersion time, even if the vanillin aqueous solution used in the vanillin cleaning is low in concentration, and it became clear that the clogging suppression effect is realized.

[0053] In addition, the graph in Figure 4 confirms that vanillin washing alone suppresses the increase in TMP compared to sodium hypochlorite washing alone. Therefore, it was confirmed that vanillin washing alone has a certain clogging suppression effect. [Industrial Applicability]

[0054] According to the cleaning device and cleaning method of the present invention, when the filtration membrane becomes clogged with activated sludge, metabolites, etc., it can be efficiently and effectively cleaned, contributing to long-term stable membrane filtration operation. Since the inhibitor is injected into the permeate side of the filtration membrane and then recovered, costs can be reduced and there is little impact on the water environment inside the reaction tank. Therefore, it can greatly contribute to the field of wastewater treatment using filtration membranes. [Explanation of symbols]

[0055] 1 wastewater treatment device, 10 reaction tank, 20 membrane unit, 21 filtration membrane, 22 collection pipe, 23 aeration pipe, 30 drainage supply section, 31 drainage supply pump, 32 drainage supply piping, 40 treated water flow section, 41 treated water piping, 42 suction pump, 50 sludge return section, 51 sludge return piping, 52 sludge return pump, 60 disinfectant cleaning section, 61 disinfectant supply tank, 62 disinfectant supply piping, 63 disinfectant supply pump, 64 disinfectant recovery tank, 65 disinfectant recovery piping, 66 disinfectant recovery pump, 70 inhibitor washing section, 71 inhibitor supply tank, 72 inhibitor supply piping, 73 inhibitor supply pump, 74 inhibitor recovery tank, 75 inhibitor recovery piping, 76 inhibitor recovery pump, 100 Wastewater treatment system, 200 Cleaning device

Claims

1. A cleaning device for cleaning a filtration membrane provided in a wastewater treatment device, A disinfectant injection section that injects a disinfectant into the permeation side of the filtration membrane; A disinfectant recovery section that recovers the disinfectant from the filtration membrane; An inhibitor injection unit that injects a quorum sensing inhibitor into the permeation side of the filtration membrane; A cleaning device comprising: an inhibitor recovery section that recovers the quorum sensing inhibitor from the filtration membrane.

2. The cleaning device according to claim 1 , wherein the quorum sensing inhibitor is a drug having an inhibitory effect on homoserine derivatives.

3. The cleaning device according to claim 1 , wherein the quorum sensing inhibitor is a solution containing at least one of vanillin, cinnamic acid, caffeic acid, chlorogenic acid, and ferulic acid.

4. 2. The cleaning device according to claim 1, wherein the quorum sensing inhibitor is a solution containing 0.01 to 20.00 wt % vanillin.

5. 2. The cleaning device according to claim 1, wherein the disinfectant is a solution containing at least one of sodium hypochlorite, oxalic acid, hydrochloric acid, citric acid, and ozone.

6. 2. The cleaning apparatus according to claim 1, wherein the wastewater treatment apparatus is an apparatus for treating wastewater by a membrane separation activated sludge method.

7. A wastewater treatment system comprising the cleaning device according to any one of claims 1 to 6 and the wastewater treatment device.

8. A cleaning method for cleaning a filtration membrane provided in a wastewater treatment device, A disinfectant injection step of injecting a disinfectant into the permeate side of the filtration membrane; a disinfectant recovery step of recovering the disinfectant from the filtration membrane; After the disinfectant recovery step, an inhibitor injection step of injecting a quorum sensing inhibitor into the permeation side of the filtration membrane; and an inhibitor recovery step of recovering the quorum sensing inhibitor from the filtration membrane.

9. A differential pressure measurement step of measuring a transmembrane pressure (TMP) value indicating a pressure difference between the permeation side and the supply side of the filtration membrane, The cleaning method according to claim 8 , wherein the disinfectant injection step, the disinfectant recovery step, the inhibitor injection step, and the inhibitor recovery step are carried out after it is detected in the differential pressure measurement step that the transmembrane pressure difference value has exceeded a predetermined value.

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