Reverse osmosis membrane operation monitoring method and operation monitoring system

Abstract

To provide an operation monitoring method and an operation monitoring system of a reverse osmosis membrane, for monitoring an operation of the reverse osmosis membrane which enables appropriate control of an operation of a reverse osmosis membrane treatment device.SOLUTION: An operation monitoring method of a reverse osmosis membrane, measures the electric power consumption of a water supply pump 12 that pressurizes water to be treated to supply the same to a reverse osmosis membrane treatment device 10 that separates the water to be treated into concentrated water and permeated water, to monitor the obtained electric power value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and system for monitoring the operation of a reverse osmosis membrane treatment device. [Background technology]

[0002] It is known that when reverse osmosis membrane treatment equipment continues treatment, so-called fouling occurs, in which microorganisms, organic matter, inorganic matter, etc. adhere to the reverse osmosis membrane. When fouling occurs, problems such as a decrease in treated water quality and treated water volume occur, so it is very important to detect and suppress the occurrence of fouling in order to obtain stable treated water. Conventional methods for suppressing fouling include controlling the addition of chemicals such as slime inhibitors according to the index of fouling. Indicators of fouling include water flow differential pressure, water supply pressure, permeation flow rate, permeation flow rate, and the rate of change thereof.

[0003] In Patent Document 1, the average rate of change in water flow differential pressure or water supply pressure is given as an index of reverse osmosis membrane fouling. However, even in cases where a change in water flow differential pressure has almost no effect on treatment, the addition of chemicals is controlled, resulting in more control than necessary. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Patent Application Publication No. 2020 / 158645 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method and system for monitoring the operation of a reverse osmosis membrane, which makes it possible to appropriately control the operation of a reverse osmosis membrane treatment device. [Means for solving the problem]

[0006] The present invention measures the power consumption of a pump that pressurizes and supplies water to a reverse osmosis membrane treatment device that separates the water into concentrated water and permeated water, and monitors the obtained power value. and calculating at least one of a supply flow rate corrected power value obtained by correcting the power value for a fluctuation between an actual supply flow rate and a target supply flow rate of the water to be treated to the reverse osmosis membrane treatment device, and a supply pressure corrected power value obtained by correcting the power value for a fluctuation between an actual supply pressure and a target supply pressure of the water to be treated to the reverse osmosis membrane treatment device, and monitoring at least one of the supply flow rate corrected power value and the supply pressure corrected power value. Fouling of the reverse osmosis membrane treatment device is determined based on at least one of the power value, the supply flow rate corrected power value, and the supply pressure corrected power value, and a water flow differential pressure and a transmembrane differential pressure in the reverse osmosis membrane treatment device, and when it is determined by the fouling determination that there is a tendency for fouling, controlling at least one of adding an agent to the water to be treated, changing the pH of the water to be treated, and changing the water temperature of the water to be treated. The present invention relates to a method for monitoring the operation of a reverse osmosis membrane.

[0010] In the method for monitoring the operation of a reverse osmosis membrane, it is preferable to calculate a water temperature corrected power value by correcting the power value for fluctuations in temperature of the water to be treated, and to monitor the water temperature corrected power value.

[0011] The present invention provides a power measuring device that measures the power consumption of a pump that pressurizes and supplies water to a reverse osmosis membrane treatment device that separates the water into concentrated water and permeated water, and a monitoring means that monitors the power value obtained by the power measuring device. a calculation means for calculating at least one of a supply flow rate corrected power value obtained by correcting the power value for a fluctuation between an actual supply flow rate of the water to be treated and a target supply flow rate to the reverse osmosis membrane treatment device, and a supply pressure corrected power value obtained by correcting the power value for a fluctuation between an actual supply pressure of the water to be treated and a target supply pressure to the reverse osmosis membrane treatment device, wherein the monitoring means monitors at least one of the supply flow rate corrected power value and the supply pressure corrected power value, and judges fouling of the reverse osmosis membrane treatment device based on at least one of the power value, the supply flow rate corrected power value, and the supply pressure corrected power value, and a water flow differential pressure and a transmembrane differential pressure in the reverse osmosis membrane treatment device; and a control means for controlling at least one of adding an agent to the water to be treated, changing the pH of the water to be treated, and changing the water temperature of the water to be treated when it is judged by the fouling judgment that there is a tendency for fouling. of moreover This is a reverse osmosis membrane operation monitoring system.

[0015] In the reverse osmosis membrane operation monitoring system, it is preferable that the system further includes a water temperature corrected power value calculation means for calculating a water temperature corrected power value by correcting the power value for fluctuations in the temperature of the water to be treated, and the monitoring means monitors the water temperature corrected power value.

[0016] The present invention is a water treatment method that includes a reverse osmosis membrane treatment process in which the water to be treated is separated into concentrated water and permeate water, and the power consumption of a pump that pressurizes the water to be treated and supplies it to the reverse osmosis membrane treatment process is measured, and the obtained power value is monitored.

[0017] The present invention is a water treatment device comprising a reverse osmosis membrane treatment device that separates water to be treated into concentrated water and permeate water, a pump that pressurizes the water to be treated and supplies it to the reverse osmosis membrane treatment device, a power measuring device that measures the power consumption of the pump, and a monitoring means that monitors the power value obtained by the power measuring device. Effect of the Invention

[0018] According to the present invention, it is possible to provide a method and system for monitoring the operation of a reverse osmosis membrane, which makes it possible to appropriately control the operation of a reverse osmosis membrane treatment device. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic configuration diagram showing an example of a water treatment device including an operation monitoring system according to an embodiment of the present invention. [Diagram 2] 13 is a graph showing the change over time in the corrected power value of the treated water supply pump in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention. The embodiment is merely an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0021] FIG. 1 shows an outline of an example of a water treatment device equipped with an operation monitoring system according to an embodiment of the present invention, and its configuration will be described.

[0022] The water treatment device 1 includes a reverse osmosis membrane treatment device 10 that separates the water to be treated into concentrated water and permeated water, and a water supply pump 12 that pressurizes and supplies the water to be treated to the reverse osmosis membrane treatment device 10. The water treatment device 1 includes a reverse osmosis membrane operation monitoring system 3 that includes a power measuring device 14 that measures the power consumption of the water supply pump 12 that pressurizes and supplies the water to be treated to the reverse osmosis membrane treatment device 10, and a control device 16 that serves as monitoring means for monitoring the power value obtained by the power measuring device 14.

[0023] The water treatment device 1 includes a permeate flow rate control device 18 as a permeate flow rate control means for controlling the flow rate of the permeate from the reverse osmosis membrane treatment device 10. The water treatment device 1 also includes a chemical tank 22 as a chemical supply means for supplying a chemical to the water to be treated, a pH adjuster tank 24 as a pH adjuster supply means for supplying a pH adjuster to the water to be treated, and a temperature adjustment device 26 as a water temperature adjustment means for adjusting the temperature of the water to be treated.

[0024] In the water treatment device 1 in Fig. 1, a pipe 52 is connected to the inlet of the reverse osmosis membrane treatment device 10 via a valve 36 and a water supply pump 12. A pipe 54 is connected to the permeate outlet of the reverse osmosis membrane treatment device 10 via a valve 38, and a pipe 56 is connected to the concentrated water outlet via a valve 40. A permeate flowmeter 20 is installed upstream of the valve 38 of the pipe 54 as a permeate flow rate measuring means for measuring the flow rate of the permeate. A pipe 58 branching off from the upstream side of the valve 40 of the pipe 56 is connected via a valve 42 to the downstream side of the valve 36 and the upstream side of the water supply pump 12 of the pipe 52.

[0025] The outlet of the chemical tank 22 and the downstream side of the valve 36 of the pipe 52 but upstream side of the pipe 58 are connected by a pipe 60 via a valve 44 and a pump 28. The outlet of the pH adjuster tank 24 and the downstream side of the valve 36 of the pipe 52 but upstream side of the pipe 58 are connected by a pipe 62 via a valve 46 and a pump 30. The downstream side of the valve 36 of the pipe 52 but upstream side of the pipe 58 and the inlet of the temperature adjustment device 26 are connected by a pipe 64 via a valve 48 and a pump 32, and the outlet of the temperature adjustment device 26 and the downstream side of the valve 36 of the pipe 52 but upstream side of the pipe 58 are connected by a pipe 66 via a valve 50 and a pump 34.

[0026] The feedwater pump 12 and the power measuring device 14, the power measuring device 14 and the control device 16, and the control device 16 and the pumps 28, 30, 32, and 34 are each connected by a wired or wireless electrical connection, etc. The permeate flow control device 18 and the feedwater pump 12, and the permeate flow meter 20 are each connected by a wired or wireless electrical connection, etc.

[0027] The water treatment method including the operation monitoring method according to the present embodiment and the operation of the water treatment device 1 equipped with the operation monitoring system will be described.

[0028] During normal operation, the valves 36, 38, 40, and 42 are open, the water supply pump 12 is operated, and the water to be treated is sent to the reverse osmosis membrane treatment device 10 through the pipe 52. In the reverse osmosis membrane treatment device 10, reverse osmosis treatment is performed by a reverse osmosis membrane, and the water is separated into concentrated water and permeated water (reverse osmosis membrane treatment step). The permeated water is discharged through the pipe 54, and the concentrated water is discharged through the pipe 56 or may be supplied to the pipe 52 through the pipe 58.

[0029] The feedwater pump 12 is provided with an inverter (not shown) for controlling the rotation speed of the pump, and the permeate flow rate control device 18 controls the rotation speed of the feedwater pump 12 so that the flow rate of the permeate detected by the permeate flow meter 20 is as constant as possible. For example, when the temperature of the water to be treated changes, the viscosity of the water changes, and the flow rate of the permeate separated by the reverse osmosis membrane treatment device 10 also changes. In response to this change, the permeate flow rate control device 18 controls the rotation speed of the feedwater pump 12. For example, when the temperature of the water to be treated decreases, the viscosity of the water increases, and as a result, the flow rate of the permeate separated by the reverse osmosis membrane treatment device 10 decreases. Therefore, the permeate flow rate control device 18 increases the rotation speed of the feedwater pump 12 to compensate for this decrease, thereby increasing the supply pressure of the water to be treated. Also, when the temperature of the water to be treated increases, the viscosity of the water decreases, and as a result, the flow rate of the permeate separated by the reverse osmosis membrane treatment device 10 increases. Therefore, the permeate flow rate control device 18 reduces the rotation speed of the feed water pump 12 so as to counteract this increase, thereby lowering the supply pressure of the water to be treated.

[0030] In the operation monitoring method and operation monitoring system according to the present embodiment, the power consumption of the water supply pump 12 that pressurizes and supplies the water to be treated to the reverse osmosis membrane treatment device 10 is measured, and the obtained power value is monitored. Then, based on the obtained power value, a determination is made as to whether or not there is fouling in the reverse osmosis membrane treatment device 10. If the determination of fouling indicates that there is a tendency for fouling, then at least one of the following may be controlled, for example: addition of a chemical to the water to be treated, change in the pH of the water to be treated, or change in the water temperature of the water to be treated.

[0031] For example, when the power value of the water supply pump 12 is measured by the power measuring device 14 and the power value is equal to or greater than a predetermined threshold value A and there is an increase in the water flow differential pressure in the reverse osmosis membrane treatment device 10, the pump 28 is operated by the control device 16, and with the valve 44 open, a chemical solution such as a slime inhibitor, a cleaning agent, or the like is added to the pipe 52 through the pipe 60 from the chemical tank 22 for adjustment. After the chemical solution is added, if the power value falls below a predetermined threshold value B, the pump 28 is stopped by the control device 16, and the addition of the chemical solution is stopped.

[0032] For example, when the power value is equal to or higher than a predetermined threshold value A, there is almost no increase in the water passing differential pressure in the reverse osmosis membrane treatment device 10, and there is an increase in the transmembrane pressure difference, the control device 16 operates the pump 28, and with the valve 44 open, a chemical solution such as a scale dispersant or a cleaning agent is added from the chemical tank 22 through the pipe 60 to the pipe 52 to adjust the pH of the water to be treated. Alternatively, the control device 16 operates the pump 30, and with the valve 46 open, a pH adjuster is added from the pH adjuster tank 24 through the pipe 62 to the pipe 52 to change the pH of the water to be treated. Alternatively, the control device 16 operates the pumps 32, 34, and with the valves 48, 50 open, the water to be treated is supplied from the pipe 52 to the temperature adjustment device 26 through the pipe 64, and after temperature adjustment, the water to be treated is discharged from the pipe 66 to the pipe 52, and the temperature of the water to be treated is changed. If the power value falls below a predetermined threshold value B after any of the operations of adding a chemical solution, adding a pH adjuster, or changing the temperature of the water to be treated by the temperature adjustment device 26, the control device 16 stops the operation.

[0033] In addition, since the power value of the feedwater pump 12 varies depending on the flow rate and water temperature of the water to be treated, it is preferable to calculate a supply flow rate corrected power value, a supply pressure corrected power value, and a water temperature corrected power value by multiplying the power value by a flow rate correction coefficient, a pressure correction coefficient, and a temperature correction coefficient calculated from the relationship between the water temperature and the power value during operation of the reverse osmosis membrane treatment device 10. When the power value is corrected, the power value of the feedwater pump 12 is measured by the power measuring device 14 and then corrected to calculate the corrected power value. Examples of correction methods for correcting the power value are shown below. However, the correction methods are not limited to these.

[0034] [Pattern 1: Supply flow rate correction] The actual supply flow rate of the water to be treated supplied to the reverse osmosis membrane treatment device 10 is measured, and the ratio to the target supply flow rate (target supply flow rate / supply flow rate) is calculated. This value is used as a supply flow rate correction coefficient and multiplied by the power value to obtain a supply flow rate corrected power value.

[0035] [Pattern 2: Supply pressure correction (derived from fluctuations in supply flow rate and concentrated flow rate)] The actual electrical conductivity of the water to be treated supplied to the reverse osmosis membrane treatment device 10 is measured, and the target concentrated water electrical conductivity is calculated from the target supply flow rate and the target concentrated flow rate. The actual supply water electrical conductivity and permeate water electrical conductivity are measured, and the target osmotic pressure is calculated from the osmotic pressure correction coefficient and the target concentrated water electrical conductivity. The actual supply pressure and osmotic pressure are measured, and the target supply pressure is calculated from the target osmotic pressure. The actual supply pressure is measured, and the supply pressure correction coefficient is calculated from the target supply pressure. The power value is multiplied by the supply pressure correction coefficient for correction to obtain a supply pressure corrected power value.

[0036] The calculation formula is shown below.

[0037] Target concentrated water electrical conductivity = feed water electrical conductivity x target feed flow rate / target concentrated flow rate Target osmotic pressure = ((Feed water electrical conductivity + Target concentrated water electrical conductivity) / 2-Permeate water electrical conductivity) x Correlation coefficient between osmotic pressure and electrical conductivity Target supply pressure = Supply pressure - Osmolality + Target osmolality Supply pressure correction coefficient = target supply pressure / supply pressure

[0038] [Pattern 3: Supply pressure correction (derived from fluctuations in supply flow rate, concentrated flow rate, and permeate flow rate)] The actual electrical conductivity of the water to be treated and the actual electrical conductivity of the permeated water supplied to the reverse osmosis membrane treatment device 10 are measured, and the target concentrated water electrical conductivity is calculated from the target supply flow rate, target concentrated flow rate, and target permeated flow rate. The actual supply water electrical conductivity and permeated water electrical conductivity are measured, and the target osmotic pressure is calculated from the osmotic pressure correction coefficient and the target concentrated water electrical conductivity. The actual supply pressure and osmotic pressure are measured, and the target supply pressure is calculated from the target osmotic pressure. The supply pressure is measured, and the supply pressure correction coefficient is calculated from the target supply pressure. The power value is multiplied by the supply pressure correction coefficient for correction to obtain a supply pressure corrected power value.

[0039] The calculation formula is shown below.

[0040] Target concentrated water electrical conductivity = (target supply flow rate x supply water electrical conductivity - target permeate flow rate x permeate electrical conductivity) / target concentrated flow rate Target osmotic pressure = ((Feed water electrical conductivity + Target concentrated water electrical conductivity) / 2-Permeate water electrical conductivity) x Correlation coefficient between osmotic pressure and electrical conductivity Target supply pressure = Supply pressure - Osmolality + Target osmolality Supply pressure correction coefficient = target supply pressure / supply pressure

[0041] [Pattern 4: Water temperature correction] The temperature of the water to be treated supplied to the reverse osmosis membrane treatment device 10 is measured, and the power value is corrected by multiplying it by a temperature correction coefficient obtained from the relationship between the water temperature and the power value. As the water temperature drops, it becomes more difficult to obtain permeated water, so the rotation speed is increased. As the water temperature rises, it becomes easier to obtain permeated water, so the rotation speed is decreased. If the water temperature fluctuates significantly or if the water temperature has not been adjusted in the previous stage, it is recommended to perform water temperature correction.

[0042] The water to be treated is not particularly limited, but examples thereof include seawater, brackish water, industrial water, and recycled water.

[0043] There are no particular limitations on the power measurement device 14 that measures the power consumption value of the feedwater pump for the water to be treated, as long as it can measure the power value of the feedwater pump. The power of the feedwater pump may be measured continuously or intermittently, and it is preferable to measure, for example, once every 1 to 60 minutes, or once every 10 minutes.

[0044] It is desirable to constantly monitor the power consumption data of the water supply pump, and it is preferable to provide a remote monitoring system.

[0045] For example, if the power value exceeds a predetermined threshold A, it is determined that there is a tendency for fouling, and chemical feeding to the water to be treated or the water temperature or pH of the water to be treated may be started. Also, for example, if the power value falls below a predetermined threshold B due to chemical feeding or a change in water temperature or pH, it is determined that fouling has been suppressed, and chemical feeding or the change in water temperature or pH may be stopped.

[0046] The control device 16 is composed of, for example, a microcomputer and electronic circuits including a calculation means such as a CPU that calculates a program, and a storage means such as a ROM and a RAM that store the program and the calculation results. The control device 16 can function as a monitoring means for monitoring the power value obtained by the power measurement device 14, a calculation means for calculating at least one of a supply flow rate corrected power value and a supply pressure corrected power value, a water temperature corrected power value calculation means for calculating a water temperature corrected power value, a determination means for determining fouling of the reverse osmosis membrane treatment device 10 based on at least one of the power value, the supply flow rate corrected power value, the supply pressure corrected power value, and the water temperature corrected power value, and a control means for controlling at least one of adding a chemical to the water to be treated, changing the pH of the treated water, and changing the water temperature of the treated water when it is determined that there is a tendency for fouling by the determination of fouling.

[0047] The operation monitoring system 3 may include an output unit as an output means for performing a predetermined output. As the output from the output unit, in addition to an audiovisually perceptible alarm such as a display or sound indicating the fouling state in the reverse osmosis membrane treatment device 10, a response method for responding to the fouling state, an improvement proposal, etc. may be displayed. The output unit may be, for example, anything that can display and output information, and is not particularly limited. Examples of the output unit include a display device that is a display means such as a liquid crystal display or an organic EL display, and an audio output device that is an audio output means such as a speaker. For example, examples of the method of issuing an alarm include displaying on a touch panel of a control panel, notifying an operator via Internet communication, notifying a monitoring room, etc.

[0048] The permeate flow rate control device 18 is composed of, for example, a microcomputer and electronic circuitry, which includes a computing means, such as a CPU, that operates a program, and storage means, such as a ROM and RAM, that store the program and the results of the calculation. The permeate flow rate control device 18 can function as a permeate flow rate control means that controls the rotation speed of the feed water pump 12 based on the flow rate of the permeate detected by the permeate flow meter 20. The control device 16 and the permeate flow rate control device 18 may be configured as a single control device.

[0049] There are no particular limitations on the permeate flow meter 20 as long as it can measure the flow rate of the permeate. The operation monitoring system 3 may further include a treated water flow meter as treated water flow rate measuring means for measuring the flow rate of the treated water, a concentrated water flow meter as concentrated water flow rate measuring means for measuring the flow rate of the concentrated water, a thermometer as treated water temperature measuring means for measuring the temperature of the treated water, etc.

[0050] Regarding the chemicals contained in the added chemical solution, if there is an increase in the water flow differential pressure, it is preferable to add a slime inhibitor or a cleaning agent. There are no particular limitations on the type of slime inhibitor, but examples include organic or inorganic slime inhibitors.

[0051] The organic slime inhibitor is not particularly limited, but examples thereof include halocyanoacetamide compounds such as DBNPA (2,2-dibromo-3-nitrilopropionamide), isothiazolone compounds, and organic bromine compounds such as Bronopol (2-bromo-2-nitropropane-1,3-diol). The amount of the organic slime inhibitor added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg / L.

[0052] The inorganic slime inhibitor is not particularly limited, but includes free halogen compounds such as hypochlorous acid and hypobromous acid, combined chlorine slime inhibitors, combined bromine slime inhibitors, iodine oxidizing agents, etc. In particular, a stabilized hypobromous acid composition containing a bromine oxidizing agent and a sulfamic acid compound, and a stabilized hypochlorous acid composition containing a chlorine oxidizing agent and a sulfamic acid compound are more preferable because they have a slight effect on the reverse osmosis membrane and have sufficient bactericidal power. The amount of the inorganic slime inhibitor added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg / L.

[0053] The type of detergent is not particularly limited, but examples include alkaline agents, acids, surfactants, chelating agents, etc. The amount of detergent added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg / L.

[0054] When there is almost no increase in the water flow differential pressure but an increase in the transmembrane pressure differential, it is preferable to add a scale dispersant or cleaning agent. There are no particular limitations on the type of scale dispersant, but examples include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of scale dispersant added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg / L as the concentration in the reverse osmosis membrane concentrated water.

[0055] The type of detergent is not particularly limited, but examples include alkaline agents, acids, surfactants, chelating agents, etc. The amount of detergent added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg / L.

[0056] In addition, in order to suppress fouling due to scale formation without using a dispersant, the operating conditions of the water to be treated, such as the pH and water temperature, may be adjusted, for example, so that the silica concentration in the reverse osmosis membrane concentrated water is below its solubility and the Langelier index, which is an index of calcium scale, is below 0.

[0057] Examples of pH adjusters for adjusting the pH of the water to be treated include acids such as hydrochloric acid and sulfuric acid, and alkaline agents such as an aqueous solution of sodium hydroxide.

[0058] The temperature adjustment device 26 for adjusting the temperature of the water to be treated is not particularly limited as long as it can adjust the temperature of the water to be treated, and examples thereof include a heater, a heat exchanger, and a chiller. EXAMPLES

[0059] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0060] [Test Method] The power consumption of the water supply pump of the seawater desalination reverse osmosis membrane treatment device for the treated water was measured every 10 minutes, and the power consumption was compared between the system without the addition of chemicals and the system with the addition of chemicals. In the system with the addition of chemicals, a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound was used as a slime inhibitor. The stabilized hypobromous acid composition was prepared by mixing liquid bromine: 16.9% by weight (wt%), sulfamic acid: 10.7% by weight, sodium hydroxide: 12.9% by weight, potassium hydroxide: 3.94% by weight, and water: the remainder under a nitrogen atmosphere (pH of the stabilized hypobromous acid composition: 14, total chlorine concentration: 7.5% by weight).

[0061] [Test conditions] Water to be treated: Seawater Electrical conductivity of treated water: 50000±2000μS / cm pH of treated water: 7 Flow rate (per line): Feed water: 600L / h, concentrated water: 500L / h, permeate: 100L / h Power meter: Clamp-on power logger PW3360 (HIOKI EE Corporation)

[0062] <Example 1 and Example 2> The power consumption value of each feed water pump was measured while adding a stabilized hypobromous acid composition as a slime inhibitor to the water to be treated in Example 1, and adding no slime inhibitor to the water to be treated in Example 2. The change over time (h) of the corrected power value obtained by multiplying the power value by both a supply flow rate correction coefficient calculated from the ratio between the target supply flow rate and the supply flow rate (target supply flow rate / supply flow rate) and a supply pressure correction coefficient calculated from the ratio between the target supply pressure and the supply pressure (target supply pressure / supply pressure) is shown in Figure 2.

[0063] The injection conditions are as follows:

[0064] [Drug injection conditions] Additive: Stabilized hypobromous acid composition Additive concentration: 13.3 mg / L (concentration in concentrated water) Addition time: 1h / day

[0065] As shown in Figure 2, after approximately 5,800 hours, in Example 2, the power value increased by approximately 20% compared to the start of measurement, whereas in Example 1 the increase was only approximately 9%. This shows that by monitoring the power value of the water supply pump and adding a slime inhibitor, fouling could be further suppressed.

[0066] In this way, the method of the embodiment makes it possible to appropriately control the operation of the reverse osmosis membrane treatment device. [Explanation of symbols]

[0067] 1 water treatment device, 3 operation monitoring system, 10 reverse osmosis membrane treatment device, 12 feed water pump, 14 power measuring device, 16 control device, 18 permeate flow control device, 20 permeate flow meter, 22 chemical tank, 24 pH adjuster tank, 26 temperature control device, 28, 30, 32, 34 pump, 36, 38, 40, 42, 44, 46, 48, 50 valve, 52, 54, 56, 58, 60, 62, 64, 66 piping.

Claims

1. Measure the power consumption of a pump that pressurizes and supplies the water to be treated to a reverse osmosis membrane treatment device that separates the water to be treated into concentrated water and permeated water, and monitor the obtained power value; calculating at least one of a supply flow rate corrected power value obtained by correcting the power value for a fluctuation between an actual supply flow rate of the water to be treated and a target supply flow rate to the reverse osmosis membrane treatment device, and a supply pressure corrected power value obtained by correcting the power value for a fluctuation between an actual supply pressure of the water to be treated and a target supply pressure to the reverse osmosis membrane treatment device, and monitoring at least one of the supply flow rate corrected power value and the supply pressure corrected power value; determining fouling of the reverse osmosis membrane treatment device based on at least one of the power value, the supply flow rate corrected power value, and the supply pressure corrected power value, and a water flow differential pressure and a transmembrane pressure differential in the reverse osmosis membrane treatment device; A method for monitoring the operation of a reverse osmosis membrane, characterized in that when the fouling assessment determines that there is a tendency for fouling, at least one of the following is controlled: adding a chemical to the water to be treated, changing the pH of the water to be treated, or changing the water temperature of the water to be treated.

2. 2. The method for monitoring operation of a reverse osmosis membrane according to claim 1, A method for monitoring an operation of a reverse osmosis membrane, comprising the steps of: calculating a water temperature corrected power value by correcting the power value for fluctuations in temperature of the water to be treated; and monitoring the water temperature corrected power value.

3. a power measuring device for measuring the power consumption of a pump that pressurizes and supplies the water to be treated to a reverse osmosis membrane treatment device that separates the water to be treated into concentrated water and permeated water; a monitoring means for monitoring the power value obtained by the power measuring device; a calculation means for calculating at least one of a supply flow rate corrected power value obtained by correcting the power value for a fluctuation between an actual supply flow rate of the water to be treated and a target supply flow rate to the reverse osmosis membrane treatment device, and a supply pressure corrected power value obtained by correcting the power value for a fluctuation between an actual supply pressure of the water to be treated and a target supply pressure to the reverse osmosis membrane treatment device; Equipped with The monitoring means monitors at least one of the supply flow rate corrected power value and the supply pressure corrected power value, a determination means for determining fouling of the reverse osmosis membrane treatment device based on at least one of the power value, the supply flow rate corrected power value, and the supply pressure corrected power value, and a water flow differential pressure and a transmembrane pressure differential in the reverse osmosis membrane treatment device; A control means for controlling at least one of adding a chemical to the water to be treated, changing the pH of the water to be treated, and changing the water temperature of the water to be treated when the fouling judgment determines that there is a tendency for fouling; The reverse osmosis membrane operation monitoring system further comprises:

4. The reverse osmosis membrane operation monitoring system according to claim 3, The water temperature correction power value calculation means calculates a water temperature correction power value by correcting the power value for fluctuations in the water temperature of the water to be treated, The reverse osmosis membrane operation monitoring system is characterized in that the monitoring means monitors the water temperature corrected power value.

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