WO2018198245A1

WO2018198245A1 - Reverse osmosis membrane plant and operation method for reverse osmosis membrane plant

Info

Publication number: WO2018198245A1
Application number: PCT/JP2017/016612
Authority: WO
Inventors: 嘉晃伊藤; 竹内　和久; 英夫鈴木; 岳近藤; みよ子田島
Original assignee: 三菱重工エンジニアリング株式会社
Priority date: 2017-04-26
Filing date: 2017-04-26
Publication date: 2018-11-01
Also published as: JPWO2018199093A1; WO2018199093A1

Abstract

A reverse osmosis membrane plant includes: a reverse osmosis membrane device 15 to which an inflow water line L1 for introducing influent water 11 is connected and which has a reverse osmosis membrane 14 for obtaining permeated water 12 obtained by removing a salt from the influent water 11 and concentrated water 13 in which the salt in the inflow water 11 is concentrated; a branch line L11 branching from the influent line L1 and branching a part of the influent water 11 as inspection water 21; an inspection container 22 to which the branch line L11 is connected and which causes the inspection water 21 to pass therethrough; at least one inspection carrier 23 which is accommodated in the inspection container 22, to which a biofilm derived from the inspection water 21 adheres, and which is made of a material having adhesiveness to the biofilm higher than that of the material of the reverse osmosis membrane 14; and a biofilm inspection device which stops the passage of the inspection water 21 to the inspection container 22 and which inspects the amount of the biofilm adhered to the inspection carrier 23.

Description

Reverse osmosis membrane plant and method of operating reverse osmosis membrane plant

The present invention relates to a reverse osmosis membrane plant and a method for operating a reverse osmosis membrane plant.

Conventionally, fresh water is obtained from seawater by evaporating the seawater and passing it through a kind of filtration membrane called reverse osmosis membrane (RO membrane: reverse osmosis membrane). There is a reverse osmosis method that throws away and throws out fresh water. The latter reverse osmosis method is more energy efficient than the evaporation method, but the RO membrane is clogged with microbial deposits (or biofilms) in seawater (or biofouling). It is necessary to pre-process carefully. As an example of this pretreatment, pretreatment such as sand filtration, UF membrane (ultrafiltration membrane) treatment or MF membrane (microfiltration membrane) treatment to remove turbidity in seawater as raw water, cleaning with chemicals Etc. have been proposed.

In addition, as a technique for judging whether this pretreatment is appropriate, a mode in which a reverse osmosis membrane used in a reverse osmosis membrane device is accommodated in an evaluation container, a part of the reverse osmosis membrane supply water is branched, and is not filtered. To the reverse osmosis membrane for evaluation, and the amount of biofilm attached to the reverse osmosis membrane is evaluated by ATP measurement, and the slope of the time-dependent change graph of the ATP amount per unit area is determined as a biofilm formation rate (Biofilm Formation Rate). : BFR), and it has been proposed to quantitatively monitor the amount of biofilm (see, for example, Patent Document 1).

Japanese Patent No. 5600864

However, in the technique of Patent Document 1, since the same material as the reverse osmosis membrane of the reverse osmosis membrane device is used as the evaluation reverse osmosis membrane, it is excellent from the viewpoint of grasping the same trend as the reverse osmosis membrane. In order to measure BFR, the lead time takes 15-20 days from the start of the evaluation until the biofilm adheres to the surface of the reverse osmosis membrane for use, and the biofilm adheres afterwards, and the inclination is determined. There is a problem that after this lead time has elapsed, another 15-30 days are required (a total of at least 30 days is required). As a result, when biofilm formation on the reverse osmosis membrane of the reverse osmosis membrane device of the actual plant progresses during the 30 days when the evaluation is made, for example, a problem such as chemical cleaning will be followed There is. That is, since the evaluation is made with the same material as the reverse osmosis membrane of the reverse osmosis membrane device of the actual plant, the trend of biofilm adhesion can be evaluated, but the biofilm to the reverse osmosis membrane precedes the actual plant. The trend of adhesion was not predictable.

Thus, when evaluating biofilm adhesion using the technique of Patent Document 1, even if biofilm adhesion is confirmed after measurement of at least about 30 days (1.5 months in the examples), the actual machine Since biofilm adhesion has already started on the reverse osmosis membrane of the plant, it can be used as an index for cleaning, but it is not an index for preventing biofilm from adhering to the reverse osmosis membrane of the actual plant. It was.

Therefore, before the biofilm adheres to the reverse osmosis membrane of an actual plant, the emergence of a technology that can more quickly grasp the trend of biofilm adhesion to the reverse osmosis membrane is eagerly desired.

In view of the above problems, an object of the present invention is to provide a reverse osmosis membrane plant and a method of operating a reverse osmosis membrane plant that can more quickly grasp the trend of biofilm adhesion to a reverse osmosis membrane.

The first invention of the present invention for solving the above-mentioned problem is that an inflow water line for inflowing inflow water is connected, and the permeated water from which the salinity is removed from the inflow water and the salinity in the inflow water are concentrated. A reverse osmosis membrane device having a reverse osmosis membrane for obtaining concentrated water, a branch line branched from the inflow water line and branching a part of the inflow water as test water, the branch line is connected, and the inside At least one or more test containers for passing test water and the test container are attached, the biofilm derived from the test water adheres, and the biofilm adheres more than the material of the reverse osmosis membrane An inspection carrier made of a material, and a biofilm inspection device that stops the passage of the inspection water to the inspection container and inspects the amount of biofilm attached to the inspection carrier. In the reverse osmosis membrane plant to be.

The second invention is characterized in that, in the first invention, the biofilm adhesion of the test carrier is evaluated by comparing the amount of biofilm deposited with the material of the reverse osmosis membrane. Located in reverse osmosis membrane plant.

According to a third aspect of the present invention, in the first or second aspect of the invention, the biofilm inspection apparatus performs the inspection on the test carrier at a predetermined time or a predetermined number of times less than one day from the beginning of passing the inspection water. It exists in the reverse osmosis membrane plant characterized by evaluating the adhesion amount of a film.

A fourth invention is the reverse osmosis membrane plant according to any one of the first to third inventions, wherein the test carrier has flexibility.

The fifth invention is the reverse osmosis membrane plant according to any one of the first to fourth inventions, wherein the evaluation of the adhesion of the biofilm is evaluated by an ATP measurement method.

In a sixth aspect of the present invention, in any one of the first to fifth aspects, the flow of the inspection water is equivalent to the linear velocity of the inflow water on the membrane surface of the reverse osmosis membrane. Located in the osmosis membrane plant.

The seventh invention is the reverse osmosis membrane plant according to any one of the first to sixth inventions, further comprising a pretreatment unit for removing turbid components in the inflow water.

The eighth invention includes a reverse osmosis membrane step of separating by a reverse osmosis membrane to obtain permeated water from which salinity has been removed from inflow water and concentrated water in which the salinity in the inflow water is concentrated, and a part of the inflow water. A test water flow process for branching as test water and allowing the test water to flow inside the test container; and at least one of the test water is stored in the test container, and the biofilm adheres more than the material of the reverse osmosis membrane A biofilm adhering step for adhering the biofilm derived from the test water to the test carrier made of a high-quality material, and stopping the water flow of the test water to the test container and attaching the biofilm adhering to the test carrier In the biofilm adhesion amount measuring step for measuring the film adhesion amount, and in the biofilm adhesion amount measurement step, the biofilm adhesion amount is evaluated for a predetermined time or a predetermined number of times less than a day from the beginning of water flow. That has a biofilm adhered evaluation step, and based on the evaluation, in an operating method of the reverse osmosis membrane plant and controls the operation of the reverse osmosis membrane process.

According to a ninth invention, in the eighth invention, the biofilm adhesion of the test carrier is evaluated by comparing the amount of biofilm deposited with the material of the reverse osmosis membrane. The operation method of the osmosis membrane plant.

A tenth aspect of the invention is the reverse osmosis membrane plant according to the eighth or ninth aspect, wherein the water flow of the inspection water is equivalent to the linear velocity of the inflow water on the membrane surface of the reverse osmosis membrane. It is in the driving method.

According to the present invention, the material for the test carrier is a material having higher biofilm adhesion than the material of the reverse osmosis membrane used in the actual machine. The presence or absence of biofilm adhesion can be confirmed. As a result, it is possible to quickly predict the trend of adhesion of the reverse osmosis membrane device of the actual plant to the reverse osmosis membrane.

FIG. 1 is a schematic diagram of a reverse osmosis membrane plant according to a first embodiment. FIG. 2 is a configuration diagram of the test container and the test carrier according to the first embodiment. FIG. 3 is a configuration diagram of another test container and a test carrier according to the first embodiment. FIG. 4 is a configuration diagram of another test container and a test carrier according to the first embodiment. FIG. 5 is a schematic diagram of a material evaluation test apparatus for a test carrier. FIG. 6 is a schematic diagram of a simple material evaluation test apparatus for a test carrier. FIG. 7 is a graph of the material evaluation test result of the test carrier. FIG. 8 is a bar graph showing the result of the material evaluation test of the test carrier. FIG. 9 is a schematic diagram of a reverse osmosis membrane plant according to the second embodiment. FIG. 10 is a flowchart of evaluation. FIG. 11 is a schematic diagram of a reverse osmosis membrane plant according to a third embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

FIG. 1 is a schematic diagram of a reverse osmosis membrane plant according to a first embodiment. As shown in FIG. 1, a reverse osmosis membrane plant 100 </ b> A according to the present embodiment is connected to an inflow water line L ₁ for flowing in inflow water 11, and permeated water 12 and inflow water 11 from which salinity has been removed. A reverse osmosis membrane device 15 having a reverse osmosis membrane 14 for obtaining concentrated water 13 in which the salt content is concentrated, and a branch line branched from the inflow water line L ₁ and branching a part of the inflow water 11 as the inspection water 21. L ₁₁ is connected to the branch line L ₁₁ , and at least one or more inspection containers 22 for passing the inspection water 21 therein are accommodated in the inspection container 22, and a biofilm derived from the inspection water 21 adheres thereto. At the same time, the flow of the test carrier 23 made of a material having higher biofilm adhesion than the material of the reverse osmosis membrane 14 and the test water 21 to the test container 22 is stopped, and the bio adheres to the test carrier 23. Detect film adhesion And a biofilm inspection device to be inspected. Reference numeral 31 is the drug, 32 illustrates a drug supply unit for supplying a drug 31 by the drug supply line L _21. In addition, when filtering raw water, a pre-processing unit such as a sand filtration device, a UF membrane (ultrafiltration membrane) or an MF membrane (microfiltration membrane) for removing turbid components in seawater is used as in the conventional case. It may be preprocessed by using (omitted in the first embodiment).

As the reverse osmosis membrane 14 of the reverse osmosis membrane device 15, in addition to general reverse osmosis, an NF (Nano Filtration) membrane (hereinafter also referred to as “NF membrane”) or the like can be used. The reverse osmosis membrane is mostly made of aromatic polyamide.

Further, in this embodiment, the influent water 11 as raw water is processed by the reverse osmosis membrane device 15 to obtain the permeated water 12 which is fresh water and the concentrated water 13 in which the salinity is concentrated. As long as it contains salt, water other than seawater may be used as raw water. Moreover, as the inflow water 11, for example, pumped seawater, seawater once used in the plant as a refrigerant, or the like can be used, and it is not limited.

The inspection container 22 is interposed in a branch line L ₁₁ branched from the inflow water line L _1, and a part of the inflow water 11 is passed therethrough as inspection water 21. An inspection carrier 23 is accommodated in the inspection container 22. The test carrier 23 is made of a material having higher biofilm adhesion than the material of the reverse osmosis membrane 14 used in the reverse osmosis membrane device 15 (for example, a polyamide-based composite material).

FIG. 2 is a configuration diagram of the test container and the test carrier according to the first embodiment. As shown in FIG. 2, the outer surface 23 a of the test carrier 23 and the inner surface 22 a of the test container are arranged in the test container 22 so as to be in close contact with each other. Then, the inspection water 21 flowing into the inspection container 22 is passed through the inner surface 23b of the inspection carrier 23, and a biofilm is adhered to the inner surface 23b.

The inspection container 22 is sealed with a removable lid 24 after the inspection carrier 23 is accommodated therein. A connecting jig 25 connected to the branch line L ₁₁ is provided on the bottom side of the inspection container 22 and the upper side of the lid body 24. Further, a flow rate adjustment valve (not shown) for adjusting the inflow amount is provided on the inlet side of the inspection container 22. Here, it is preferable that the water flow of the inspection water 21 is equal to the linear velocity of the inflow water 11 on the membrane surface of the reverse osmosis membrane 14 installed in the reverse osmosis membrane device 15 of the actual machine. Thereby, it will be set as the conditions similar to the adhesion environment of the biofilm in an actual machine. Here, the typical linear velocity is preferably in the range of 50 to 350 mm / sec.

In addition, as shown in FIG. 3, a plurality of test carriers 23 are accommodated in the test container 22, and the test carriers 23 are taken out every predetermined time or every predetermined number of times in a day. You may make it confirm adhesion of a film.

Further, as shown in FIG. 4, the plurality of inspection carriers 23 are not limited to cylindrical ones. For example, a flexible film-like one is rolled and stored in the inspection container 22. You may make it do.

The biofilm inspection apparatus performs the amount of biofilm adhering to the inspection carrier 23 using an inspection apparatus that measures the amount of ATP per unit area. This inspection device collects an attached biofilm and reacts with a coloring reagent to indirectly determine the ATP amount from the coloring amount of the reagent, and a commercially available measuring instrument can be used. For example, “Lushipac® II (manufactured by Kikkoman Biochemifa)”, “ATP wiping inspection kit (manufactured by Nitta)” and the like can be exemplified. Here, ATP (Adenosine tri-phosphate: adenosine triphosphate) is an energy molecule present in the cells of all plants, animals and microorganisms. In this ATP test, the bioluminescence principle is applied. ATP is reacted with a coloring reagent, and the amount of ATP is determined by a fluorescence measuring instrument.

In addition, the amount of biofilm adhered to the inner surface 23b of the test carrier 23 is evaluated by the ATP measurement method, and the slope of the time-dependent graph of the amount of ATP per unit area is determined as a biofilm formation rate (BFR). You may make it ask as.

The material of the test carrier 23 used in this evaluation is a material (for example, PP, polyvinyl chloride, or the like) that has higher biofilm adhesion than the material of the reverse osmosis membrane 14 (for example, polyamide-based composite material), as shown in the following test examples. Silicone) is used, so every predetermined time (for example, 1, 2, 3 hours) less than one day from the beginning (0 hour) of the start of the test water 21 or every predetermined number of times (at least every 1 to 6 hours) The amount of biofilm attached to the test carrier 23 is evaluated in one unit.

According to the present invention, since the presence or absence of biofilm adhesion can be confirmed within a few hours (for example, 2 to 8 hours) less than a day from the start of evaluation, the reverse osmosis of the reverse osmosis membrane device 15 of the actual plant. The trend of adhesion to the film 14 can be predicted quickly.

This is because the measurement of SDI and FI, which is currently used as an inspection index when making water using a reverse osmosis membrane device, is generally measured once a day. The accuracy of fouling countermeasures can be dramatically improved by evaluating the amount of biofilm deposited in less than a day.

Here, SDI (Silt Density Index) is one of the indicators of the amount of turbid components contained in water, and how much inflow water that is going to perform reverse osmosis membrane treatment fouls into the reverse osmosis membrane. Is one of the semi-quantitative indicators that indicate whether or not the SDI is caused, and usually requires pre-processing so that the SDI is 3 to 4 or less (see ASTM D4189). Also, the fouling index (FI value) is defined in JISK3802, and is a semi-quantitative index indicating how much fouling occurs in the reverse osmosis membrane by the inflowing water to be subjected to the reverse osmosis membrane treatment. In general, preprocessing is required so that the FI value is 3 to 4 or less.

That is, as shown in the above-mentioned Patent Document 1, when the material of the reverse osmosis membrane 14 used in the actual reverse osmosis membrane device 15 is used as an evaluation carrier, the increase in biofilm adhesion is measured after a lead time of one month. Therefore, when the adhesion is measured, the microorganism is already adhered to the reverse osmosis membrane 14 of the reverse osmosis membrane device 15 of the actual machine. As a result, it becomes an index for immediate cleaning, but it does not adhere to the actual plant. It is not an indicator for

On the other hand, according to the present invention, the evaluation can be completed in less than one day, and an operation that does not cause biofilm adhesion can be performed in accordance with the evaluation result. Specifically, when adhesion is expected, measures such as changing the pretreatment mode, changing the type and amount of the sterilizing agent, and adjusting the frequency of the agent treatment are performed to form a biofilm. Can be blocked.

That is, according to the present invention, when an adhesion carrier having a better adhesion property than a reverse osmosis membrane is selected and a water passage test is performed using the selected inspection carrier, the trend of adhesion is less than a day. It can be evaluated quickly in an extremely short time. And according to the degree of adhesion of this biofilm, measures such as pretreatment and sterilization treatment can be taken. As a result, the RO membrane plant can be operated stably.

Next, a test for selecting a material having higher biofilm adhesion than the material of the reverse osmosis membrane 14 (for example, a polyamide-based composite material) will be described.
FIG. 5 is a schematic diagram of a material evaluation test apparatus for a test carrier. As shown in FIG. 5, a plurality of inspection carriers 23-1 to 23-4 of the same type (four in this test) are stored in the inspection container 22. Here, the test apparatus 50 includes a seawater tank 52 for storing the sea water 51, through the supply pump 53 from the seawater tank 52, a circulation line L ₅₁ that circulates the seawater 51 is interposed the circulation line L ₅₁ And an inspection container 22. A flow rate adjusting valve 54 is installed on the downstream side of the supply pump 53, thereby adjusting the flow rate of the seawater 51 to the inspection container 22, and part of the seawater whose flow rate has been adjusted is contained in the seawater tank 52. It is returning.

In this test, (1) polypropylene (PP), (2) polyvinyl chloride (PVC), and (3) silicone are selected for the test carrier 23, and (4) reverse osmosis membrane (RO A polyamide-based composite material as the material of the film 14 was used. The shape of the test carrier 23 was a cylindrical tube having an outer diameter of 15 mm, an inner diameter of 12 mm, and a length of 20 mm.

The seawater 51 for testing was pH 8.0 and EC 4.5 S / m. In the test, filtered water obtained by filtering seawater through a filter having a pore diameter of 0.75 μm was used. The linear velocity of the flowing seawater 51 in the inspection container 22 was set to 250 mm / sec.

1 hour after the start of water flow, the water flow of the seawater 51 was stopped, the lid body 24 was opened, and the first inspection carrier 23-1 was taken out. Next, the lid body 24 was closed, and after another 1 hour (2 hours in total), the second test carrier 23-2 was taken out in the same manner. Next, the lid 24 was closed, and after a further 2 hours (4 hours in total), the third test carrier 23-3 was taken out in the same manner. Next, the lid 24 was closed, and after a further 2 hours (6 hours in total), the fourth test carrier 23-4 was taken out in the same manner. The same test operation was performed three times for each material. For taking out the test carrier 23, for example, a take-out jig such as tweezers was used.

The measurement of the test carrier 23 was performed using a biomass measurement kit “Lucipak II (trade name: manufactured by Kikkoman Biochemifa)”. Specifically, the inner peripheral surface 23b of the test carrier 23 was wiped off with an attached cotton swab, and then the cotton swab was returned to the measuring device main body, mixed with the reagent, the measurement tube was removed, and the amount of luminescence was measured. That is, the amount of biofilm adhered to the test carrier 23 was periodically evaluated by the ATP measurement method. Then, the attached ATP amount was divided by the wiped area, the ATP amount per unit area was calculated, and the change with time of the ATP amount per unit area was confirmed. The slope of this time course graph was defined as BFR (ATP (pg) / cm ² / d). This ATP (adenosine triphosphate) is a chemical substance that exists as an energy source for all living organisms, and by measuring the amount of ATP, the amount of “existence of organisms or traces of organisms” can be measured.

The average of the results of measurement at n = 3 is obtained and shown in FIGS. Table 1 below shows the BFR results for the carrier material. Here, FIG. 7 is a graph of the material evaluation test result of the test carrier, and FIG. 8 is a bar graph of the material evaluation test result of the test carrier (FIG. 8 shows an error range of three times. )

As shown in FIG. 7 and FIG. 8, the adhesion of each material of polypropylene (PP) and polyvinyl chloride (PVC) becomes remarkable after 2 hours from the start of evaluation, and further after 4 hours and after 6 hours. Became prominent. It has been found that each material of polypropylene (PP), polyvinyl chloride (PVC), and silicone has higher adhesive properties than the material of the RO membrane.

Also, as shown in Table 1, it was found that all of polypropylene (PP), polyvinyl chloride (PVC), and silicone had a BFR (inclination) larger than the material of the RO membrane.

Further, the evaluation of the material of the test carrier 23 is performed by simple evaluation using a beaker in addition to storing the test carrier 23 in a test container 22 as shown in FIG. be able to.

FIG. 6 is a schematic diagram of a simple material evaluation test apparatus for a test carrier. As shown in FIG. 6, the simple test is performed by putting seawater 51 into a beaker container 61 and placing the test carrier 23 to be evaluated on an indicator member 62 such as a wire mesh. Then, the seawater is gently stirred at a predetermined rotation using the stirring blades 63 of the stirrer, and the adhesion of the biofilm to the test carrier 23 is confirmed.

Here, the evaluation of the material is performed by measuring the amount of biofilm attached at regular intervals (for example: at least once every 1, 2, 3 hours) from the beginning of the evaluation (0 hours). Then, it is evaluated in comparison with the amount of biofilm deposited on the reverse osmosis membrane material. By using an evaluation material having an amount of adhesion earlier than the material of the reverse osmosis membrane of the reverse osmosis membrane device, it is possible to confirm the biofilm adhesion earlier than the adhesion to the reverse osmosis membrane. In particular, by using the same material as the reverse osmosis membrane 14 used in the actual reverse osmosis membrane device 15 as a basis for comparison, further objective evaluation can be performed. In addition, since it is comparative evaluation of a material, it is not limited to less than one day, You may make it confirm by performing evaluation more than one day.

In this example, a method for confirming the trend of biofilm adhesion using the test container will be described. FIG. 9 is a schematic diagram of a reverse osmosis membrane plant according to the second embodiment. In addition, about the member which overlaps with the reverse osmosis membrane plant of Example 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. As shown in FIG. 9, the worker stores the inspection carrier 23 in the inspection container 22. As described above, the number of inspection carriers 23 in the storage container 22 may be one or plural. Here, when one is stored, it is confirmed once a day. When storing two or more bottles, confirmation is made several times a day (once every predetermined time (for example, 2 to 3 hours)). In addition, a plurality of test carriers may be accommodated, and a plurality of test carriers may be extracted at the same time, and the ATP amount and the like may be confirmed by a plurality, and the average value may be calculated.

Then, the extracted test carrier 23 is brought into the biofilm evaluation apparatus 35, where biofilm adhesion is confirmed. As confirmation of biofilm adhesion, the amount of ATP itself may be confirmed using the above-described commercially available test kit, or the slope by BFR may be obtained. In any case, the determination is made by comparing the threshold value of the ATP amount or the threshold value of BFR set in advance with the measurement data.

An example of the determination process will be described below. The actual plant uses the reverse osmosis membrane device 15 to continuously produce water except for the maintenance period.

In this evaluation process example, the case of measurement twice a day will be described. The evaluation starts from a specific time (for example, 10 o'clock) within one day operation (S10). When the evaluation is performed every 2 hours, the first evaluation is performed at 12:00 after 2 hours.

FIG. 10 is a flowchart of evaluation. As shown in FIG. 10, it is determined whether or not the first measurement data exceeds the threshold in advance by comparing with the threshold for the ATP amount and the threshold for BFR (S11). When the threshold value is not exceeded (No), it is determined that the reverse osmosis membrane 14 of the actual machine has no biofilm attached and is in a healthy operating state. Then, after the next 2 hours, the second measurement data is compared with the threshold of ATP amount or the threshold of BFR in advance to determine whether or not it exceeds the threshold (S12). If the threshold is not exceeded (No), the inspection for that day ends (S13). Note that the same evaluation operation is repeated at the same time on and after the next day.

In the second evaluation (S12), if the threshold value is exceeded (Yes), it is determined that there is a risk of biofilm adhering to the actual reverse osmosis membrane 14.

In this case, the biofilm adhesion prevention measures are taken (S20). Here, as an example of a biofilm adhesion prevention measure, a treatment for increasing the supply amount of the drug 31 from the drug supply unit 32 is performed. After a predetermined time has elapsed after this drug increase, evaluation after the drug mode change is started (S21).

This evaluation is the first re-evaluation after 2 hours from the start of the re-evaluation (S22). In this evaluation (S22), when the threshold value is exceeded (Yes), it is determined that the measures for preventing the biofilm from adhering to the reverse osmosis membrane 14 of the actual machine are not good, and another measure (change of the type of drug) Etc.).

On the other hand, when the threshold value is not exceeded (No), it is determined that the reverse osmosis membrane 14 of the actual machine has no biofilm attached and is in a healthy operating state. The measurement data of the second time is compared with the threshold value of the ATP amount or the threshold value of BFR in advance, and it is determined whether or not it exceeds the threshold value (S23). In the evaluation of this step S23, when the threshold value is not exceeded (No), the inspection for that day ends (S24). Repeat the same evaluation operation at the same time on the next day.

In this process example, the first evaluation (S11) and the second evaluation (S23) after the medicine mode (S20) are described as cases where the threshold is not exceeded (No). If it exceeds (Yes), the medicine mode (S20) may be performed.

As measures to prevent biofilm adhesion, depending on the degree of increase in the amount of ATP, for example, change of pretreatment conditions, addition mode of drugs (including fungicides) (change of drug type, change of drug concentration, Change of the number of times the drug is added), change of the recovery rate of the actual reverse osmosis membrane device, supply of the inflow water 11 to the reverse osmosis membrane device 15 is stopped, and the reverse osmosis membrane 14 of the reverse osmosis membrane device 15 is reversely washed. Change the pre-processing mode, such as changing to a mode. After taking this measure, the inspection mode is resumed.

For these operations, the operator can visually check the inspection data and change the operation mode. However, the operation data is processed by the control device and the operation mode is changed by automatic control. Good.

In this example, a method for confirming the trend of biofilm adhesion in a pretreatment apparatus using this inspection container will be described. FIG. 11 is a schematic diagram of a reverse osmosis membrane plant according to a third embodiment. In addition, about the member which overlaps with the reverse osmosis membrane plant of Example 1, 2, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. As shown in FIG. 11, the reverse osmosis membrane plant 100 </ b> C according to the present embodiment includes, as the pretreatment unit 41 illustrated in FIG. 9, a first pretreatment unit 41 </ b> A that is a sand filtration unit in the influent water line L ₁ , A second pretreatment unit 41B, which is a UF (or MF) membrane treatment unit, is installed on the downstream side of the first pretreatment unit 41A. The inflow water line L ₁ between the first pretreatment unit 41A and the second pretreatment unit 41B is connected to the inflow water line L ₁ downstream of the second pretreatment unit 41B. A bypass line L ₄ that bypasses the processing unit 41B is provided.

Then, a part of the sand filtration treated water subjected to the sand filtration of the first pretreatment unit 41A from a portion between the first pretreatment unit 41A and the second pretreatment unit 41B is used as the inspection water 21-1 and the branch line L _11. The biofilm is attached to the test carrier 23 in the test container 22-1.

The evaluation biofilm is inspected in the inspection container 22-1 every predetermined time (or a predetermined number of times), and the inspection water 21-1 partially branched from the sand filtrate is evaluated. As a result of the evaluation of the test water 21-1, when it is determined that no biofilm adheres to the sand filtrate, pretreatment in the second pretreatment unit 41B of the UF (or MF) membrane treatment unit is unnecessary. to decide. Then, in order to bypass the processing of the second pre-processing unit 41B, as sand filtered water flows into the bypass line L ₄ to bypass the second pre-processing section 41B, it switches the flow channel switching valve 42, the second pre-processing Bypass to the downstream side of the portion 41B.

As a result, by bypassing the second pretreatment unit 41B of the UF (or MF) membrane treatment unit, the processing load of the UF (or MF) membrane treatment unit is reduced, and the running cost of the desalination plant is reduced. be able to.

The biofilm installed between the second pretreatment unit 41B and the reverse osmosis membrane device 15 is evaluated at least once a day using the test container 22-2. This evaluation is performed by branching a part of the inflow water by the sand filtrate after bypassing the second pretreatment part 41B as the inspection water 21-2. As a result of the evaluation of the test water 21-2 using the sand filtrate as the influent water 11, when it is determined that there is no biofilm attached to the test water 21-2, the bypass of the second pretreatment unit 41B is continued. to decide.

On the other hand, as a result of the evaluation of the test water 21-2, when it is determined that the adhesion of the biofilm in the sand filtrate is equal to or greater than the threshold, the second pretreatment unit 41B of the UF (or MF) membrane treatment unit It is determined that the processing in is necessary. And in order to perform the pre-processing in the second pre-processing section 41B, it switches the channel switching valve 42 to stop the bypass of the bypass line L _4, passed through a sand filter water to the second pre-processing section 41B Then, pre-processing is performed. Thereafter, evaluation is performed and the same judgment is made. According to this embodiment, when the first pretreatment part 41A of the sand filtration part and the second pretreatment part 41B of the UF (or MF) membrane treatment part are installed, the biofilm adhesion factor of the raw water 40 is very small. In this case, since it is determined that only the first pretreatment part 41A of the sand filtration part can be used, a material having higher biofilm adhesion than a reverse osmosis membrane used in an actual machine is used. The presence or absence of the biofilm can be confirmed at a predetermined time or a predetermined number of days less than one day. As a result of the confirmation, when it is determined that the processing in the second pretreatment unit 41B is unnecessary, the load in the second pretreatment unit 41B is reduced by bypassing the second pretreatment unit 41B, and the desalination plant The running cost can be reduced.

In the present embodiment, the first preprocessing unit 41A and the second preprocessing unit 41B are different types of preprocessing devices, but the present invention is not limited to this, and the first preprocessing unit 41A and The same type of pre-processing apparatus may be used for the second pre-processing unit 41B. For example, the first pretreatment unit 41A may be a front-stage sand filtration unit, and the second pretreatment unit 41B may be a two-stage process of the rear-stage sand filtration unit. As a result, if the BFR value is sufficiently small in the first stage sand filtration unit of the first pretreatment unit 41A, the second pretreatment unit 41B is bypassed to bypass the processing in the second stage sand filtration unit. The flow path switching valve 42 is switched so that the sand filtered water flows into the bypass line L ₄ to be bypassed to the downstream side of the second pretreatment unit 41B. Thereby, reduction of the running cost by bypassing the 2nd pre-processing part 41B can be aimed at.

100A to 100C Reverse Osmosis Membrane Plant 11 Inflow Water 12 Permeated Water 13 Concentrated Water 14 Reverse Osmosis Membrane 15 Reverse Osmosis Membrane Device 21 Test Water 22 Test Container 23 Test Carrier 24 Lid L ₁ Inflow Water Line L ₁₁ Branch Line

Claims

A reverse osmosis membrane device having a reverse osmosis membrane connected to an inflow water line for inflowing inflow water to obtain permeated water from which salt content has been removed from the inflow water and concentrated water in which salt content in the inflow water is concentrated;
A branch line branched from the inflow water line and branching a part of the inflow water as inspection water;
An inspection container to which the branch line is connected and through which the inspection water is passed;
At least one or more contained in the test container, the biofilm derived from the test water adheres, and a test carrier made of a material having higher biofilm adhesion than the material of the reverse osmosis membrane,
A reverse osmosis membrane plant, comprising: a biofilm inspection device that stops water flow of the inspection water to the inspection container and inspects the amount of biofilm attached to the inspection carrier.
In claim 1,
The biofilm adhesion of the test carrier is evaluated by comparing the amount of biofilm deposited with the material of the reverse osmosis membrane.
In claim 1 or 2,
The test of the biofilm test apparatus is characterized by evaluating the amount of biofilm attached to the test carrier at a predetermined time or a predetermined number of times less than a day from the beginning of water flow of the test water. Membrane plant.
In any one of Claims 1 thru | or 3,
The reverse osmosis membrane plant, wherein the test carrier is flexible.
In any one of Claims 1 thru | or 4,
The bio-film adhesiveness is evaluated by an ATP measurement method, a reverse osmosis membrane plant.
In any one of Claims 1 thru | or 5,
The reverse osmosis membrane plant characterized in that the flow of the inspection water is equivalent to the linear velocity of the inflow water on the membrane surface of the reverse osmosis membrane.
In any one of Claims 1 thru | or 6,
A reverse osmosis membrane plant comprising a pretreatment unit for removing turbid components in the inflowing water.
A reverse osmosis membrane step of separating by a reverse osmosis membrane to obtain permeated water from which salinity has been removed from the inflow water and concentrated water in which the salinity in the inflow water is concentrated;
A test water flow process for branching a part of the inflow water as test water and passing the test water into a test container;
A biofilm attachment step of attaching a biofilm derived from the test water to a test carrier made of a material having a biofilm adhesion higher than that of the reverse osmosis membrane; ,
Stopping the flow of the inspection water to the inspection container, and measuring a biofilm adhesion amount measuring step for measuring the amount of biofilm adhered to the inspection carrier;
In the biofilm adhesion amount measuring step, a biofilm adhesion evaluation step for evaluating the amount of biofilm adhesion in a predetermined time or a predetermined number of times less than a day from the beginning of water flow,
An operation method of a reverse osmosis membrane plant, wherein the operation of the reverse osmosis membrane process is controlled based on the evaluation.
In claim 8,
The biofilm adhesion of the test carrier is evaluated by comparing the amount of biofilm deposited with the material of the reverse osmosis membrane.
In claim 8 or 9,
The method of operating a reverse osmosis membrane plant, wherein the flow of the inspection water is equivalent to the linear velocity of the inflow water on the membrane surface of the reverse osmosis membrane.