JP4517615B2 - Evaluation method and apparatus for reverse osmosis membrane feed water and operation management method for water treatment apparatus - Google Patents

Description

  The present invention relates to an evaluation method and apparatus for reverse osmosis membrane feed water and an operation management method for a water treatment apparatus including a reverse osmosis membrane. More specifically, the present invention relates to a method for evaluating reverse osmosis membrane feed water and reverse osmosis membrane feed water for stably operating a reverse osmosis membrane device over a long period of time without causing a decrease in the permeation flux of the reverse osmosis membrane. And a method for appropriately managing the operation of the water treatment apparatus based on the evaluation result.

  In the present invention, “reverse osmosis membrane” means “reverse osmosis membrane” in a broad sense including “reverse osmosis membrane” and “nanofiltration membrane”.

  A reverse osmosis membrane consisting of a dense surface layer and a porous support layer that allows solvent molecules to pass through but not solute molecules to allow one-stage desalination of seawater. Later, the field of use of reverse osmosis membranes expanded, and low-pressure reverse osmosis membranes that can be operated at low pressure were developed, which also reverses purification of sewage secondary treated water, factory effluent, river water, lake water, landfill leachate, etc. Osmotic membranes have been used.

  Since the reverse osmosis membrane has a high solute rejection rate, the permeated water obtained by the reverse osmosis membrane treatment has good water quality and can be effectively reused in various applications. However, on the other hand, the permeation flux of the membrane decreases with the continuation of the process and the operating pressure increases. In this case, the operation is stopped and the reverse osmosis membrane is washed to restore the membrane performance. It is necessary to perform processing.

  Conventionally, when water treatment is performed using a reverse osmosis membrane, the supply water to the reverse osmosis membrane module is defined in JIS K3802 in order to reduce the frequency of membrane washing and increase the treatment efficiency. Fouling index (FI), silt density index (SDI) defined in ASTM D4189, or MF value proposed by Taniguchi as a simpler evaluation method (Desalination, vol. 20, p.353-364) 1977), and pretreatment is performed as necessary so that the FI value or SDI value is 3 to 4 or less, for example, so that this value is not more than the predetermined value, and the reverse osmosis membrane supply By clarifying the water to some extent, avoiding obstacles such as reduced permeation flux and increased operating pressure in the reverse osmosis membrane module, stable A method of continuing operation has been implemented.

  The FI value, SDI value, and MF value are all determined when the reverse osmosis membrane feed water is filtered through a 0.45 μm microfiltration membrane (usually, a “Millipore filter” manufactured by Nihon Millipore Corporation is often used). The filtration time is measured and calculated based on this measured value. As the pretreatment, for example, in the case of factory wastewater, it is common to perform biological treatment by an activated sludge method or the like, or physicochemical treatment such as activated carbon adsorption or ultrafiltration.

  However, even if the reverse osmosis membrane supply water has a FI value, an SDI value, or an MF value equal to or lower than a predetermined value, a decrease in permeation flux and an increase in operating pressure may occur at an early stage in the reverse osmosis membrane. That is, the conventional evaluation of FI value, SDI value or MF value is based on SS because it can be reflected in filtration time by capturing SS (suspended solids) in reverse osmosis membrane feed water. Although effective for determining the quality of the reverse osmosis membrane supply water, the soluble soil component in the raw water is not reflected in the filtration time. For this reason, the quality as reverse osmosis membrane supply water based on the chemical interaction of dissolved substances cannot be accurately determined.

  Japanese Patent Application No. 2002-362543 discloses a method of passing reverse osmosis membrane feed water through a polyamide membrane filter and evaluating the quality of the reverse osmosis membrane feed water based on the magnitude of filtration resistance. With this method, by using a polyamide membrane filter made of the same material as the reverse osmosis membrane, it is also possible to detect a membrane contaminant that dissolves in the supply water and adsorbs on the reverse osmosis membrane. However, polyamide membrane filters are microfiltration membranes, and no matter how the reverse osmosis membrane and the material are the same, there is a limit to predicting a decrease in the permeation flux in the reverse osmosis membrane. Management of osmotic membrane feed water is not possible. In addition, the evaluation operation itself is complicated and troublesome.

  In JP-A-10-286445, separation membrane feed water is passed through a main membrane module and a sub-membrane module having a smaller membrane area than the main membrane module, and the operation states of the main membrane module and the sub-membrane module are compared. Shows a method for discriminating whether the decrease in the amount of permeated water in the main membrane module and / or the sub-membrane module is due to the raw water of the membrane separation device or the device itself. However, this method is a method for discriminating whether the decrease in the amount of permeated water generated in the main membrane module or the sub-membrane module or both modules is due to deterioration in the quality of the water supplied to the membrane or due to inadequate equipment. It is not necessarily a method for judging the quality of the water supplied to the membrane.

  If this method is to be used for the evaluation of reverse osmosis membrane feed water, both the main membrane module and the sub membrane module continuously pass water for a long time. Even in the membrane module, the amount of permeated water is reduced. In a reverse osmosis membrane, once the permeated water amount is reduced, irreversible contamination that cannot be easily recovered by chemical cleaning or the like is generated, so this method is too late.

In addition, when water is continuously passed through the membrane module, if the quality of the feed water deteriorates at a certain point in time and the permeate flow rate decreases, the permeate flow rate of the membrane module remains low even if the subsequent feed water is normal. is there. Therefore, the supply water at the time of detecting a decrease in the amount of permeated water in the main membrane module and the sub membrane module is not necessarily deteriorated. On the other hand, when the reverse osmosis membrane supply water is, for example, drainage, the water quality is changing every moment, and an immediate evaluation of the water quality is required at that time, but the supply water is continuously passed through the membrane module. In the method disclosed in Japanese Patent Laid-Open No. 10-286445, it is impossible to determine at which time the amount of permeated water has decreased, and the quality of the supplied water at that time cannot be sufficiently evaluated.
Japanese Patent Application No. 2002-362543 Japanese Patent Laid-Open No. 10-286445 Desalination, vol. 20, p. 353-364, 1977

  The present invention relates to a reverse osmosis membrane feed water evaluation method and evaluation device capable of stably operating a reverse osmosis membrane device over a long period of time without causing a decrease in the permeation flux of the reverse osmosis membrane, and a reverse osmosis membrane It aims at providing the operation management method of the water treatment equipment containing a device.

  More specifically, by accurately evaluating the quality of the reverse osmosis membrane feed water supplied to the operating reverse osmosis membrane device in a short time, it is possible to avoid a decrease in the permeation flux of the reverse osmosis membrane in advance, It is an object of the present invention to provide a method for evaluating reverse osmosis membrane feed water that can stably operate a reverse osmosis membrane device over a period, and an operation management method for a water treatment device including the evaluation device and the reverse osmosis membrane device.

The method for evaluating the reverse osmosis membrane feed water of the present invention is based on whether the reverse osmosis membrane feed water supplied to a reverse osmosis membrane device (hereinafter referred to as “main reverse osmosis membrane device”) is good or bad. An evaluation method during operation of the apparatus , wherein the reverse osmosis membrane supply water is intermittently supplied to a reverse osmosis membrane device for evaluation different from the main reverse osmosis membrane device at a pressure higher than that of the main reverse osmosis membrane device. Measure the amount of permeated water in the reverse osmosis membrane feed water within a predetermined time within 1 hour from the start of water flow in the evaluation reverse osmosis membrane device, and compare this measured value with a preset reference value. The reverse osmosis membrane feed water is evaluated by the reverse osmosis membrane device for evaluation, and the reverse osmosis membrane device has an equivalent permeation flux at a lower pressure than the reverse osmosis membrane of the main reverse osmosis membrane device. It is a reverse osmosis membrane to be obtained, and is a good reverse osmosis membrane supply water when the measured value of the permeated water amount is larger than the reference value Evaluated, and evaluating the reverse osmosis membrane supply water is not good when less.

The apparatus for evaluating reverse osmosis membrane supply water of the present invention is an apparatus for evaluating the quality of reverse osmosis membrane supply water supplied to a reverse osmosis membrane device (hereinafter referred to as “main reverse osmosis membrane device”). Thus, the reverse osmosis membrane supply water is intermittently passed at a pressure higher than that of the main reverse osmosis membrane device , and the evaluation reverse osmosis membrane device is one hour from the start of water passage in the evaluation reverse osmosis membrane device. Means for measuring the amount of permeated water in the reverse osmosis membrane feed water within a predetermined time within , and comparing the measured value of the measuring means with a preset reference value, when the measured value of the permeated water amount is greater than the reference value It was evaluated to be a good reverse osmosis membrane supply water, Ri na an arithmetic means for assessing the reverse osmosis membrane supply water is not good if less, the reverse osmosis membrane of the evaluation reverse osmosis membrane device, the main reverse reverse osmosis membrane der Rukoto the equivalent flux can be obtained at a pressure lower than the reverse osmosis membrane of osmosis unit And features.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the permeability of reverse osmosis membrane feed water at the initial stage of water flow when reverse osmosis membrane feed water is passed through a reverse osmosis membrane device for evaluation. In particular, it has been found that there is a close relationship between the amount of permeated water and the permeation flux of the main reverse osmosis membrane device that continues to operate with the supplied water, and the present invention has been completed based on this finding. .

  According to the present invention, the reverse osmosis membrane supply water is intermittently passed through the evaluation reverse osmosis membrane device, and the permeability of the reverse osmosis membrane supply water within a predetermined time at the initial stage of the water flow, in particular, the permeated water amount is a reference value. As a result, it is possible to simply and accurately evaluate the quality of the reverse osmosis membrane supply water in a short time.

The operation management method of the water treatment apparatus of the present invention evaluates the quality of the reverse osmosis membrane supply water by the evaluation method or the evaluation apparatus of the reverse osmosis membrane supply water of the present invention, and performs the operation management based on the result. When the measured amount of permeated water is larger than the reference value, it is evaluated that the reverse osmosis membrane supply water is good, and the reverse osmosis membrane treatment is continued under the same conditions, and when it is small, it is not good. Evaluate it as reverse osmosis membrane feed water and control the pretreatment conditions of reverse osmosis membrane feed water and / or the operating conditions of the main reverse osmosis membrane device to prevent a decrease in permeation flux. Therefore, stable operation can be continued for a long time without causing problems such as a decrease in permeation flux and an increase in operating pressure in the reverse osmosis membrane device.

  According to the evaluation method and apparatus for reverse osmosis membrane supply water of the present invention, the reverse osmosis membrane supply water is intermittently passed through the evaluation reverse osmosis membrane device, and the amount of permeated water within a predetermined time at the initial stage of the water flow, etc. The quality of the reverse osmosis membrane feed water can be easily and accurately evaluated in a short time by comparing the permeability of the water with the reference value. And according to the operation management method of the water treatment apparatus of the present invention for performing operation management based on the evaluation result using the permeability such as the amount of permeated water at the initial stage of water passing through such an evaluation reverse osmosis membrane apparatus, A high permeation flux can be maintained in the membrane device, and stable operation can be continued for a long time.

  Embodiments of a reverse osmosis membrane feed water evaluation method and evaluation apparatus according to the present invention and an operation management method for a water treatment apparatus will be described in detail below.

  In the present invention, a part of the reverse osmosis membrane supply water supplied to the main reverse osmosis membrane device is intermittently passed through the evaluation reverse osmosis membrane device, and after the start of water passage in the evaluation reverse osmosis membrane device, a predetermined amount is passed. The reverse osmosis membrane feed water is evaluated by measuring the permeability of the reverse osmosis membrane feed water in time and comparing this measured value with a preset reference value.

  The permeability of the reverse osmosis membrane feed water is preferably the amount of permeated water, but generally represents the permeability of the membrane, such as operating pressure, permeation flux, or processing time required to obtain a certain amount of permeated water. Things are used.

  The material of the reverse osmosis membrane (hereinafter referred to as “main reverse osmosis membrane”) of the main reverse osmosis membrane device to which the method for evaluating the reverse osmosis membrane feed water of the present invention is applied is not particularly limited, and for example, a polyamide-based reverse osmosis membrane , Cellulose ester reverse osmosis membrane, polysulfone reverse osmosis membrane, polyimide reverse osmosis membrane and the like. The form of the main reverse osmosis membrane is not particularly limited, and it can be used for either a phase change membrane or a composite membrane. Among these, a polyamide-based reverse osmosis membrane using polysulfone as an ultrafiltration membrane serving as a membrane support and using a crosslinked polyamide, linear polyamide, polypiperazine amide or the like as a dense layer can be suitably used.

  Moreover, there is no restriction | limiting in particular also in the kind of membrane module of a main reverse osmosis membrane apparatus, For example, a spiral module, a hollow fiber module, a plane membrane module, a tubular module etc. can be mentioned.

  On the other hand, the material of the reverse osmosis membrane of the evaluation reverse osmosis membrane device (hereinafter referred to as “reverse osmosis membrane for evaluation”) is not particularly limited. For example, polyamide reverse osmosis membrane, cellulose ester reverse osmosis membrane, polysulfone A reverse osmosis membrane, a polyimide-type reverse osmosis membrane, etc. can be mentioned. There is no restriction | limiting in particular also in the form of the reverse osmosis membrane for evaluation, It can use for any of a phase change membrane and a composite membrane. Moreover, there is no restriction | limiting in particular also in the kind of membrane module of the reverse osmosis membrane apparatus for evaluation, For example, a spiral module, a hollow fiber module, a plane membrane module, a tubular module etc. can be mentioned. Among these, the same reverse osmosis membrane as the main reverse osmosis membrane, or the same material as the main reverse osmosis membrane, but capable of passing water at a lower pressure, that is, equivalent permeation flux at a lower pressure than the main reverse osmosis membrane A low-pressure, ultra-low pressure reverse osmosis membrane capable of obtaining the above can be suitably used. For example, when a low pressure reverse osmosis membrane is used as the main reverse osmosis membrane, it is a preferable combination to use an ultra-low pressure reverse osmosis membrane as the evaluation reverse osmosis membrane.

  That is, in the present invention, it is a preferable aspect to measure the amount of permeated water within a predetermined time from the start of water passage of the evaluation reverse osmosis membrane device, but this amount of permeated water is as much as possible in a short time from the start of water passage. Obtaining the amount of water is important for reducing measurement errors and increasing measurement accuracy. For this purpose, use an evaluation reverse osmosis membrane that can obtain an equivalent permeation flux at a pressure lower than that of the main reverse osmosis membrane, and pass water at the same pressure as the main reverse osmosis membrane device, or for evaluation. It is preferable to pass the reverse osmosis membrane device at a higher pressure than the main reverse osmosis membrane device to increase the amount of permeated water.

  In the present invention, if the predetermined time for measuring the amount of permeated water from the start of water passage of the evaluation reverse osmosis membrane device is excessively short, a sufficient amount of permeated water cannot be obtained, which causes measurement errors. However, if the predetermined time is excessively long, the frequency of evaluation becomes low, and it becomes impossible to follow the change in water quality over time of the reverse osmosis membrane feed water.

  Therefore, the evaluation interval (intermittent water flow to the evaluation reverse osmosis membrane device) and the predetermined time from the start of water flow for measuring the amount of permeated water are the performance of the reverse osmosis membrane for evaluation and the reverse osmosis membrane feed water used. Although it depends on the quality of the water and its fluctuations, in general, evaluation is performed by passing water through the evaluation reverse osmosis membrane device at a frequency of about three times a day in the morning, day and night, and the amount of permeated water is measured. The predetermined time from the start of water is within 1 hour, for example, 5 minutes to 40 minutes, preferably about 10 to 30 minutes.

  In the present invention, the evaluation reverse osmosis membrane is replaced with a new membrane every time the amount of permeated water is measured, that is, every time the reverse osmosis membrane supply water is intermittently passed to the evaluation reverse osmosis membrane device. By doing in this way, based on the amount of permeated water of the evaluation reverse osmosis membrane device, the quality of the reverse osmosis membrane feed water can be accurately evaluated. However, the new membrane is not necessarily limited to an unused reverse osmosis membrane, and a membrane whose performance has been restored to the same level as the new membrane by washing the used reverse osmosis membrane may be used.

  There is no particular limitation on the method of setting a reference value for comparison with the permeated water amount within a predetermined time from the start of water flow measured by intermittently passing reverse osmosis membrane supply water to the evaluation reverse osmosis membrane device, for example, , Create a calibration curve by determining the relationship between the amount of permeated water in the initial reverse osmosis membrane for the evaluation reverse osmosis membrane using the simulated drainage and the stable permeated water amount or permeation flux in the main reverse osmosis membrane. And a reference value set from the necessary permeate amount or permeate flux, or a daily value stored in an actual water treatment apparatus, and a reference value set based on the stored data can be used.

  Therefore, if the amount of permeated water measured is small compared to the reference value set in this way, the reverse osmosis membrane supply water cannot be said to have an appropriate water quality in the reverse osmosis membrane treatment, It is judged that there is a risk of reducing the permeation flux of the reverse osmosis membrane device at an early stage by continuing the processing. Conversely, if the measured amount of permeated water seems to be larger than this reference value, it is good reverse osmosis membrane feed water, and the reverse osmosis membrane treatment can be continued under the same conditions.

  Such an evaluation method of the reverse osmosis membrane supply water of the present invention includes, for example, means for intermittently separating a part of the reverse osmosis membrane supply water supplied to the main reverse osmosis membrane device, and the reverse osmosis membrane supply Reverse osmosis membrane device for evaluation in which water is intermittently passed, means for measuring the amount of permeated water within a predetermined time after the start of water passage in the reverse osmosis membrane device for evaluation, and a reference value in which this measured value is set in advance Compared to the above, it can be easily carried out by an evaluation device comprising a calculation means for evaluating the quality of the reverse osmosis membrane supply water.

  In the operation management method of the water treatment apparatus of the present invention, the reverse osmosis membrane supply water is intermittently passed through the evaluation reverse osmosis membrane apparatus by the reverse osmosis membrane supply water evaluation method or evaluation apparatus of the present invention. Then, the quality of the reverse osmosis membrane supply water is evaluated, and the operation of the water treatment device including the main reverse osmosis membrane device is managed based on the result. There is no restriction | limiting in particular in this operation management method, For example, control of the pretreatment conditions of reverse osmosis membrane feed water, and / or control of the operation conditions of the main reverse osmosis membrane apparatus are mentioned.

  There is no particular restriction on the pretreatment method of reverse osmosis membrane feed water, for example, activated sludge method, photo-oxidation method, wet contact oxidation method, coagulation sedimentation method, pressurized flotation method, activated carbon adsorption method, microfiltration method, ultrafiltration Law. These pretreatment methods can be used alone or in combination of two or more. The preprocessing conditions are controlled by a method of newly adding, rearranging, or reducing these preprocessing devices, or changing the processing conditions of each preprocessing device.

  As for the operating conditions of the reverse osmosis membrane device, the operating pressure of the reverse osmosis membrane device, the water recovery rate, the frequency of backwashing, adjustment of the washing frequency, etc. can be mentioned. By controlling these conditions, it is possible to prevent the permeation flux from decreasing with time, maintain a high permeation flux, and perform stable operation of the reverse osmosis membrane device over a long period of time.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

Example 1
Prepare an aqueous solution in which 0.1, 1.0, 5.0, 10.0 mg / L of the nonionic surfactant polyoxyethylene nonylphenyl ether [NS208.5, Nippon Oil & Fat Co., Ltd.] was dissolved in pure water, respectively. These were used as reverse osmosis membrane feed water. That is, a nonionic surfactant is an example of a reverse osmosis membrane contaminant that lowers the permeation flux in a reverse osmosis membrane, and reverse osmosis membrane supply water having different degrees of reverse osmosis membrane contamination by using aqueous solutions of various concentrations. Was simulated.

  As the reverse osmosis membrane supply water, a low pressure polyamide reverse osmosis membrane [NTR759HR, Nitto Denko Corporation] was used as the main reverse osmosis membrane, and constant pressure water flow at 25 ° C. and an operating pressure of 1.5 MPa was continuously performed.

  For evaluation of reverse osmosis membrane feed water, a flat membrane was prepared by cutting a low pressure polyamide reverse osmosis membrane [NTR759HR, Nitto Denko Corp.] into φ35mm as an evaluation reverse osmosis membrane, and this flat membrane was made into a dedicated pressure cell. Filling was performed by intermittently performing constant-pressure water passage at 25 ° C. and an operating pressure of 1.5 MPa in the same manner as the main reverse osmosis membrane. The reverse osmosis membrane for evaluation was replaced with a new membrane for each evaluation. Moreover, at the time of evaluation of reverse osmosis membrane feed water, the total amount of permeated water of the evaluation reverse osmosis membrane was received by an electronic balance, and the indicated value of the electronic balance was measured 30 minutes after the start of water flow.

  Water flow through the main reverse osmosis membrane was first started with a nonionic surfactant polyoxyethylene nonylphenyl ether 0.1 mg / L aqueous solution. Immediately after the start of water flow to the main reverse osmosis membrane, the first feed water evaluation using the evaluation reverse osmosis membrane was performed, and the balance indicated value was 17.53 g. The water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and the water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane was almost stable at 1.00 m / d 50 hours after the start of water flow.

  The reverse osmosis membrane feed water was changed to an aqueous solution having a nonionic surfactant concentration of 1 mg / L, and water flow to the main reverse osmosis membrane was continued as it was. Immediately after the change of the feed water, the second feed water evaluation using the evaluation reverse osmosis membrane was performed, and the balance indicated value was 14.86 g. Water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane showed a tendency to decrease after the supply water change, but was almost stable at 0.90 m / d after 50 hours of the supply water change.

  Based on this result, as a reference value for obtaining a permeation flux slightly inferior to the permeation flux of pure water, the permeated water amount (balance indication value) until 30 minutes after the start of water passage in the evaluation reverse osmosis membrane. Set as 00 g.

  Thereafter, the reverse osmosis membrane feed water was changed to an aqueous solution having a nonionic surfactant concentration of 5 mg / L, and water flow to the main reverse osmosis membrane was continued. Immediately after the change of the feed water, the third feed water evaluation using the evaluation reverse osmosis membrane was carried out, and the indicated value of the balance was 11.21 g.

  Since the balance indicated value was lower than the standard value, water was passed through a column packed with granular activated carbon [Crycol WG160, Kurita Kogyo Co., Ltd.] as a pretreatment with an aqueous solution having a nonionic surfactant concentration of 5 mg / L. Adsorption treated water was supplied to the main reverse osmosis membrane as reverse osmosis membrane feed water. After the start of the adsorption treatment, the fourth feed water evaluation using the evaluation reverse osmosis membrane was performed on the adsorption treated water. As a result, the balance indicated value was 18.22 g.

  Since the balance indicated value exceeded the reference value, water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane was almost stable at 0.90 m / d 50 hours after the start of the adsorption treatment.

  Thereafter, the reverse osmosis membrane feed water was changed to an aqueous solution having a nonionic surfactant concentration of 10 mg / L, and water flow to the main reverse osmosis membrane was continued. At this time, the activated carbon adsorption treatment that was carried out as a pretreatment was also continued. Immediately after the change of the feed water, the fifth feed water evaluation using the reverse osmosis membrane for evaluation was performed on the adsorption treated water, and the balance indicated value was 18.05 g.

  Since the balance indicated value exceeded the reference value, water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane was almost stable at 0.89 m / d after 50 hours of supply water change.

Example 2
Except that the management of the reverse osmosis membrane supply water was not performed based on the evaluation result in the evaluation reverse osmosis membrane, the water flow to the main reverse osmosis membrane and the evaluation of the supply water by the evaluation reverse osmosis membrane were the same as in Example 1. Carried out.

  Water flow through the main reverse osmosis membrane was first started with a nonionic surfactant polyoxyethylene nonylphenyl ether 0.1 mg / L aqueous solution. Immediately after the start of water flow to the main reverse osmosis membrane, the first feed water evaluation using the evaluation reverse osmosis membrane was performed, and the balance indicated value was 17.53 g. The water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and the water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane was almost stable at 1.00 m / d 50 hours after the start of water flow.

  The reverse osmosis membrane feed water was changed to an aqueous solution having a nonionic surfactant concentration of 1 mg / L, and water flow to the main reverse osmosis membrane was continued as it was. Immediately after the change of the feed water, the second feed water evaluation using the evaluation reverse osmosis membrane was performed, and the balance indicated value was 14.86 g. Water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane showed a tendency to decrease after the supply water change, but was almost stable at 0.90 m / d after 50 hours of the supply water change.

  Thereafter, the reverse osmosis membrane feed water was changed to an aqueous solution having a nonionic surfactant concentration of 5 mg / L, and water flow to the main reverse osmosis membrane was continued. Immediately after the change of the feed water, the third feed water evaluation using the evaluation reverse osmosis membrane was carried out, and the indicated value of the balance was 11.21 g. Water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane showed a decreasing tendency after the supply water change, and decreased to 0.45 m / d 50 hours after the supply water change.

  Furthermore, the reverse osmosis membrane feed water was changed to a nonionic surfactant concentration 10 mg / L aqueous solution, and water flow to the main reverse osmosis membrane was continued. Immediately after the change of the feed water, the fourth feed water evaluation using the evaluation reverse osmosis membrane was performed, and the balance indicated value was 9.10 g. Water flow to the evaluation reverse osmosis membrane was stopped in 30 minutes, and water flow to the main reverse osmosis membrane was continued thereafter. The permeation flux in the main reverse osmosis membrane showed a decreasing tendency after the supply water change, and decreased to 0.29 m / d 50 hours after the supply water change.

  Changes in the permeation flux in the main reverse osmosis membranes of Example 1 and Example 2 are shown in FIG.

  From the results of Example 1 and Example 2, the reverse osmosis membrane supply water is intermittently passed through the evaluation reverse osmosis membrane, and the quality of the reverse osmosis membrane supply water is determined in a short time from the initial permeate flow rate. It can be seen that high permeation flux can be maintained in the main reverse osmosis membrane by performing operation management based on this result.

  Table 1 and FIG. 2 summarize the measurement results of four times in the evaluation reverse osmosis membrane of Example 2 and the stable permeation flux of the main reverse osmosis membrane.

  From Table 1, the balance indicated value (permeated water amount at the initial stage of water flow in the evaluation reverse osmosis membrane) is changed with the change of the feed water, and when the permeated water amount decreases, the permeation flux of the main reverse osmosis membrane decreases. I understand that

  In addition, as shown in FIG. 2, there is a close relationship between the amount of permeated water (balance indication value) until 30 minutes after the start of water passage in the evaluation reverse osmosis membrane and the stable permeation flux in the main reverse osmosis membrane. I understand.

Example 3
In parallel with the implementation of Example 2, as a reverse osmosis membrane for evaluation, the main reverse osmosis membrane and the raw material are the same, and an ultra-low pressure capable of obtaining an equivalent permeation flux at a lower operating pressure than the main reverse osmosis membrane Using reverse osmosis membrane [ES10, Nitto Denko Corporation], the reverse osmosis membrane feed water was similarly evaluated except that the amount of permeated water in the evaluation reverse osmosis membrane was evaluated with the balance indicated value 10 minutes after the start of water flow. Evaluation was performed.

  When the reverse osmosis membrane feed water was an aqueous solution having a nonionic surfactant concentration of 0.1 mg / L, the balance indicated value after 10 minutes was 12.12 g.

  When the reverse osmosis membrane feed water was an aqueous solution having a nonionic surfactant concentration of 1 mg / L, the balance indicated value after 10 minutes was 10.92 g.

  When the reverse osmosis membrane feed water was an aqueous solution having a nonionic surfactant concentration of 5 mg / L, the balance indicated value after 10 minutes was 7.9 g.

  When the reverse osmosis membrane feed water was an aqueous solution having a nonionic surfactant concentration of 10 mg / L, the balance indicated value after 10 minutes was 6.57 g.

  From this result and the result of Example 1, by managing the reference value to be 11 g or more after 10 minutes in the evaluation reverse osmosis membrane, a decrease in the permeation flux in the main reverse osmosis membrane is avoided. It can be seen that a high permeation flux can be obtained stably for a long time.

  When an ultra-low pressure reverse osmosis membrane is used for the evaluation reverse osmosis membrane, the amount of permeated water (balance indication value) up to 10 minutes after water flow in the evaluation reverse osmosis membrane, and the low pressure reverse osmosis membrane is used for the main reverse osmosis membrane FIG. 3 shows the relationship with the stable permeation flux.

  FIG. 3 shows that there is a close relationship between the two. Furthermore, by passing the water through the ultra-low pressure reverse osmosis membrane, which is a reverse osmosis membrane for evaluation, at an operation pressure twice as high as the standard operation pressure (0.75 MPa), the quality of the reverse osmosis membrane supply water can be improved in a shorter time. I understand that I can judge.

  The present invention is effective for long-term stable operation of a reverse osmosis membrane device.

It is a graph which shows a time-dependent change of the permeation | transmission flux of the main reverse osmosis membrane in Example 1 and Example 2. FIG. It is a graph which shows the relationship between the permeation flux at the time of the stability of the main reverse osmosis membrane in Example 2, and the balance instruction | indication value after 30 minutes in the reverse osmosis membrane for evaluation. It is a graph which shows the relationship between the permeation | transmission flux at the time of the stability of the main reverse osmosis membrane in Example 3, and the balance instruction | indication value after 10 minutes in the reverse osmosis membrane for evaluation.

Claims (6)

A method for evaluating the quality of water supplied to a reverse osmosis membrane device (hereinafter referred to as "main reverse osmosis membrane device") as reverse osmosis membrane supply water during operation of the reverse osmosis membrane device,
The reverse osmosis membrane device for evaluation is passed through a reverse osmosis membrane device for evaluation different from the main reverse osmosis membrane device at a pressure higher than that of the main reverse osmosis membrane device. how the permeate flow of the reverse osmosis membrane supply water within one hour within a predetermined time after passing the start of water was measured by comparing the reference value set this measurement in advance, to assess the reverse osmosis membrane supply water in Because
The reverse osmosis membrane of the reverse osmosis membrane device for evaluation is a reverse osmosis membrane that can obtain an equivalent permeation flux at a lower pressure than the reverse osmosis membrane of the main reverse osmosis membrane device,
The reverse osmosis membrane supply water is evaluated as a good reverse osmosis membrane supply water when the measured value of the permeated water amount is larger than a reference value, and is evaluated as an unfavorable reverse osmosis membrane supply water when the measured value of the permeated water amount is larger than a reference value. Evaluation method. Oite to claim 1, the evaluation method of the reverse osmosis membrane supply water, characterized in that to replace the reverse osmosis membrane a reverse osmosis membrane supply water permeability measurements every new film of the evaluation for reverse osmosis unit. A device for evaluating the quality of water supplied to a reverse osmosis membrane device (hereinafter referred to as “main reverse osmosis membrane device”) as reverse osmosis membrane supply water , wherein the reverse osmosis membrane supply water is the main reverse osmosis membrane supply water. Reverse osmosis membrane device for evaluation that is intermittently passed at a pressure higher than that of the osmosis membrane device, and permeation of reverse osmosis membrane feed water within a predetermined time within one hour from the start of water passage in the reverse osmosis membrane device for evaluation A means for measuring the amount of water , comparing the measured value of the measuring means with a preset reference value, and evaluating that the reverse osmosis membrane feed water is good when the measured value of the permeated water amount is larger than the reference value, Ri Na an arithmetic means for assessing the reverse osmosis membrane supply water is less not good, reverse osmosis membrane of the evaluation reverse osmosis membrane device, comparable at a pressure lower than the reverse osmosis membrane of the main reverse osmosis unit reverse osmosis membrane supply water of the evaluation device, characterized in reverse osmosis membrane der Rukoto the permeation flux can be obtained 4. The reverse osmosis membrane feed water evaluation device according to claim 3 , further comprising means for intermittently separating a part of the reverse osmosis membrane feed water supplied to the main reverse osmosis membrane device. In the method of managing the operation of a water treatment apparatus including a reverse osmosis membrane device, the quality of water supplied to the reverse osmosis membrane device is evaluated by the reverse osmosis membrane feed water evaluation method according to claim 1 or 2. , A method for performing operation management based on the evaluation results, and evaluating that the reverse osmosis membrane feed water is good when the measured permeated water amount is larger than the reference value, and performing reverse osmosis under the same conditions. Continue the membrane treatment and evaluate the reverse osmosis membrane feed water as poor when there is little, and control the pretreatment conditions of the reverse osmosis membrane feed water and / or the operating conditions of the main reverse osmosis membrane device to lower the permeation flux The operation management method of the water treatment apparatus characterized by preventing . In the method of managing the operation of a water treatment apparatus including a reverse osmosis membrane device, the quality of water supplied to the reverse osmosis membrane device is evaluated by the reverse osmosis membrane feed water evaluation device according to claim 3 or 4. , A method for performing operation management based on the evaluation results, and evaluating that the reverse osmosis membrane feed water is good when the measured permeated water amount is larger than the reference value, and performing reverse osmosis under the same conditions. Continue the membrane treatment and evaluate the reverse osmosis membrane feed water as poor when there is little, and control the pretreatment conditions of the reverse osmosis membrane feed water and / or the operating conditions of the main reverse osmosis membrane device to lower the permeation flux The operation management method of the water treatment apparatus characterized by preventing .

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