JP2019018191A - Membrane filtration treatment apparatus and method therefor - Google Patents

Abstract

To provide an apparatus and method for membrane filtration treatment capable of controlling permeation flux of a membrane within an appropriate range according to a nature variation at the occurrence thereof, and of optimizing the operating conditions of the apparatus.SOLUTION: An apparatus for membrane filtration treatment includes control means 5 which controls at least one of the difference pressure between separation membranes and the membrane surface flow rate according to an estimated value of permeation flux of a membrane calculated by using actual measurement values which become controlling factors of nature variation of a water to be treated permeating through the separation membrane.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a membrane filtration treatment apparatus and a membrane filtration treatment method.

  The operating conditions of the membrane filtration treatment device are set in consideration of economy so that the membrane clogging is less likely to occur depending on the properties of the water to be treated and the membrane to be used. Operating conditions are often determined by preliminary tests and previous experience. For this reason, when the properties of the water to be treated fluctuate, the initial operating condition setting values are not necessarily optimum values even after the properties of the water to be treated have changed, and the operating conditions are set based on the property fluctuations. It is difficult to control the value.

  As a method for controlling operating conditions based on fluctuations in the properties of water to be treated, for example, Japanese Patent Laid-Open No. 2000-61466 (Patent Document 1) discloses that water to be treated is circulated through a membrane module and filtered. The method of preventing clogging of the membrane and improving the permeation flux is described by changing the membrane surface flow rate of the wastewater to be treated that passes through the membrane module according to the sludge concentration, that is, the size of the solute concentration. Yes.

JP 2000-61466 A

  However, in the method described in Patent Document 1, the basis for determining the optimum membrane surface flow velocity with respect to the sludge concentration in the wastewater to be treated is not clear, and the optimum method for setting the operating conditions of the membrane filtration device It cannot be said.

  For example, in the method described in Patent Document 1, it is described that the output of the circulation pump and the opening of the valve are adjusted so as to satisfy the conditions set in advance for the sludge concentration value. However, the control method is relatively simple, and only control that increases the membrane surface flow rate as the sludge concentration increases is described.

  In membrane treatment, the factor that determines the size of the permeation flux is not only the size of the solute concentration of the water to be treated. Therefore, in the method described in Patent Document 1, it is difficult to determine the optimum conditions for the membrane surface flow rate when the determinants of the membrane permeation flux other than the solute concentration of the water to be treated fluctuate.

  In view of the above problems, the present invention can control the permeation flux of the membrane to a more appropriate range following the property variation when the property variation of the water to be treated occurs. A membrane filtration apparatus and a membrane filtration method capable of optimizing operating conditions are provided.

  In order to achieve the above-mentioned object, the present inventor has intensively studied, and predicts the permeation flux of the separation membrane based on fluctuations of a plurality of actually measured values that are the characteristics variation factors of the water to be treated, and based on the prediction results. It was found that it is effective to control the operating conditions.

  The present invention completed on the basis of the above knowledge is based on the permeation flux predicted value of the separation membrane calculated using a plurality of actual measurement values that are the property variation factors of the treated water that permeates the separation membrane. There is provided a membrane filtration apparatus comprising a control means for controlling at least one of a transmembrane differential pressure and a membrane surface flow velocity of a separation membrane.

  In one embodiment of the membrane filtration apparatus according to the present invention, the plurality of actual measured values include actual measured values of the temperature of the water to be treated, the solute concentration, and the membrane surface flow velocity.

  In another aspect of the present invention, a separation membrane that receives supply of treated water to obtain membrane permeated water and discharged water, a pump provided on the treated water supply side of the separation membrane, and discharged water from the separation membrane A valve provided on the discharge side for obtaining water, pressure detection means for detecting the pressure of the water to be treated before permeating the separation membrane, the pressure of the membrane permeated water and the discharged water, and the water to be treated before permeating the separation membrane, Flow rate / flow rate detection means for detecting the flow rate or flow rate of the permeated water, temperature detection means for detecting the temperature of the water to be treated before permeating the separation membrane, and solute concentration of the water to be treated before permeating the separation membrane The concentration detection means for detecting the pressure difference, the pressure detection means, the flow velocity / flow rate detection means, the temperature detection means, and the permeation difference between the separation membranes based on the predicted permeation flux of the separation membrane calculated from the detection results of the concentration detection means Pump to control at least one of pressure and membrane surface flow velocity Driving and membrane filtration treatment apparatus and a control means for performing at least one control opening of the valve is provided.

  In one embodiment of the membrane filtration apparatus according to the present invention, the predicted permeation flux is the limiting permeation flux of the separation membrane.

  In another embodiment of the membrane filtration apparatus according to the present invention, the control means compares the permeation flux predicted value with the actual measurement value of the permeation flux of the separation membrane, and the permeation flux predicted value is smaller than the actual measurement value. If it is larger, control is performed to increase the transmembrane pressure difference, and if the permeation flux predicted value is equal to the actual measurement value, control is performed to decrease the transmembrane pressure difference.

  In yet another embodiment of the membrane filtration apparatus according to the present invention, the control means compares the permeation flux predicted value with the target value of the permeation flux of the separation membrane, and the permeation flux predicted value is equal to or greater than the target value. In this case, the membrane surface flow velocity is controlled to be lowered, and when the permeation flux prediction value is smaller than the target value, the membrane surface flow velocity is controlled to be increased.

In yet another embodiment of the membrane filtration apparatus according to the present invention, the control means calculates the permeation flux predicted value of the separation membrane based on the following relational expression (1).
_{J lim = J lim0 × ln (} C g / C) / ln (C g / C 0) × exp (E / T 0) × exp (E / T) × (v / v 0) n × exp (-Q / T) / exp (-Q / T ₀ ) (1)
(Where J _lim is the limit permeation flux, J _lim0 is the limit permeation flux of the separation membrane at the reference point, C _g is the solute concentration of the gel layer, C is the measured value of the solute concentration of the treated water, and C ₀ is the reference The solute concentration of the water to be treated at the point, E and Q are coefficients, T ₀ is the temperature of the water to be treated at the reference point, T is the measured value of the temperature of the treated water, v is the measured value of the membrane surface velocity, and v ₀ is (The actual measured value of the flow velocity at the reference point is shown.)

  In yet another embodiment of the membrane filtration apparatus according to the present invention, the water to be treated contains an oil-containing waste liquid.

  In yet another aspect of the present invention, the permeation flux prediction value of the separation membrane is calculated using a plurality of actual measurement values that are the property variation factors of the water to be treated that permeates the separation membrane, and the permeation flux prediction value is calculated. There is provided a membrane filtration treatment method including controlling at least one of a transmembrane differential pressure and a membrane surface flow velocity of a separation membrane based on a result.

  According to the present invention, when the property variation of the water to be treated occurs, the permeation flux of the membrane can be controlled to a more appropriate range following the property variation, and the operating conditions of the membrane filtration treatment device can be controlled. A membrane filtration apparatus and a membrane filtration method that can be optimized can be provided.

It is the schematic which shows an example of the membrane filtration processing apparatus which concerns on embodiment of this invention. 3 is a graph showing the relationship between transmembrane pressure difference ΔP and permeation flux J. It is a schematic diagram showing the change of the solute density | concentration of a separation membrane vicinity, and the gel layer deposited on a separation membrane. Shows a graph used to calculate the solute concentration C _g of the gel layer of the relation (1), the flux on the vertical axis for the historical data set, representing the relationship in the case of the natural logarithm of the solute concentration and the horizontal axis It is a graph. The membrane filtration processing apparatus which concerns on embodiment of this invention WHEREIN: It is a graph explaining the transmembrane differential pressure control method performed when theoretical value> actual measurement value, ie, permeation flux prediction value becomes larger than actual measurement value. is there. In the membrane filtration processing apparatus which concerns on embodiment of this invention, it is a graph explaining the transmembrane differential pressure control method performed when a theoretical value = actual measurement value, ie, permeation flux prediction value becomes equal to an actual measurement value. . It is a graph explaining the control method of the membrane surface flow rate based on a target value in the membrane filtration processing apparatus which concerns on embodiment of this invention. It is a flowchart explaining the control method of the transmembrane differential pressure using the membrane filtration processing apparatus which concerns on embodiment of this invention. It is a flowchart explaining the control method of the membrane surface flow velocity using the membrane filtration processing apparatus which concerns on embodiment of this invention. It is a graph showing the relationship between the measured value of a permeation flux, and the calculated value of the permeation flux calculated | required using the relational expression which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is to describe the structure, arrangement, etc. of components as follows. It is not something specific.

  As shown in FIG. 1, a membrane filtration apparatus according to an embodiment of the present invention includes a raw water tank 1 for storing treated water, a membrane filtration means 2 including a separation membrane for membrane-treating treated water, A pump 3 for supplying treated water from the raw water tank 1 to the membrane filtration means 2 and a circulation line L3 provided on the discharge side of the membrane filtration means 2 for circulating the drain water obtained by the filtration means 2 to the raw water tank 1 And a control means 5 capable of controlling at least one of the driving of the pump 3 and the opening degree of the valve 4.

  The kind of the to-be-processed water accommodated in the raw water tank 1 is not specifically limited. As the water to be treated, a fluid containing contaminants such as soluble organic matter, turbidity, and oil is used. For example, oil-containing wastewater discharged from factories related to secondary sewage treatment, marine products processing, automobile manufacturing, petroleum refining, dairy manufacturing, beverage manufacturing, metal processing, etc., groundwater, water, seawater The brackish water, leachate generated from the final disposal site for waste, and the like can be used as the water to be treated according to this embodiment.

  The membrane filtration means 2 includes a separation membrane that receives membrane water to obtain membrane permeated water and discharged water. The type of the separation membrane is not particularly limited, and various membranes such as an ultrafiltration membrane, a microfiltration membrane, and a nanofiltration membrane can be used. The membrane permeated water obtained by the membrane filtration means 2 is separated through a supply line L2 connected to the membrane filtration means 2. The discharged water obtained by the membrane filtration means 2 is discharged through the circulation line L3 and a part thereof is circulated to the raw water tank 1.

  The pump 3 is provided on the supply side of the treated water for supplying the treated water to the membrane filtration means 2, that is, on the supply line L 1 for supplying the treated water from the raw water tank 1 to the membrane filtration means 2. The supply line L1 has a concentration detection means 11 for detecting the solute concentration of the water to be treated before permeating the separation membrane, a temperature detection means 12 for detecting the temperature of the water to be treated before permeating the separation membrane, and a separation. A flow rate / flow rate detection means 13 for detecting the flow rate or flow rate of the water to be treated before permeating the membrane and a pressure detection means 14 for detecting the pressure of the water to be treated before permeating the separation membrane are provided.

  The supply line L2 is provided with a flow rate / flow rate detecting means 23 for detecting the flow rate or flow rate of the membrane permeated water and a pressure detecting means 24 for detecting the pressure of the membrane permeated water. The circulation line L3 is provided with pressure detecting means 34 for detecting the pressure of the discharged water. The detection results of the concentration detection means 11, the temperature detection means 12, the flow velocity / flow rate detection means 13, 23, and the pressure detection means 14, 24, 34 are output to the control means 5 as actual measured values of the membrane filtration apparatus.

  The control means 5 uses at least a plurality of actually measured values that are characteristics variation factors of the treated water that permeates the separation membrane, that is, measured values of the temperature, solute concentration, and membrane surface flow velocity of the treated water in this embodiment. Then, the permeation flux predicted value of the separation membrane is calculated, and at least one of the transmembrane differential pressure and the membrane surface flow velocity of the separation membrane is controlled based on the calculation result of the permeation flux prediction value. As the control means 5, a general-purpose or dedicated computer that includes at least an arithmetic processing unit and a storage device (not shown) and sends a predetermined operation command based on a predetermined control algorithm can be used.

  Specifically, the control means 5 determines the permeation flux predicted value of the separation membrane from the detection results of the pressure detection means 14, 24, 34, the flow velocity / flow rate detection means 13, 23, the temperature detection means 12, and the concentration detection means 11. And at least one of the driving of the pump 3 and the opening of the valve 4 so as to control at least one of the transmembrane differential pressure and the membrane surface flow velocity of the separation membrane based on the calculation result of the permeation flux prediction value. Take control.

  In the membrane filtration process, as shown in FIG. 2, the permeation flux J gradually increases in proportion to the increase in the transmembrane pressure difference ΔP. The flux J converges to a certain value. This is because, as shown in FIG. 3, the solute in the water to be treated accumulates in the vicinity of the film surface, so that a gel layer having a concentration of several tens to several hundreds of the solute concentration in the water to be treated is generated on the film surface. This is because the resistance increases in proportion to the transmembrane pressure ΔP.

From the mass balance in the gel layer, the following equation (2) is established.
J * CD * dC / dx = JCp (2)
(Where J is the permeation flux, C is the solute concentration of the water to be treated, D is the solute diffusion coefficient, and Cp is the solute concentration of the permeated water.)

When the solute concentration of the gel layer is Cg, the solute concentration of membrane permeated water Cp = 0, and the equation (2) is integrated, the equation (3) is obtained for the permeation flux J.
J = k × ln (Cg / C) (3)
(Where k is the mass transfer coefficient (= solute diffusion coefficient D / boundary film thickness δ))

  That is, when the phenomenon that the above-described permeation flux J converges to a certain value occurs, Equation (3) is established, and the permeation flux at that time can be referred to as “limit permeation flux”. Operating the membrane filtration apparatus below the transmembrane differential pressure (hereinafter referred to as “limit transmembrane differential pressure”), which is the critical permeation flux, is important in considering the economics of membrane treatment.

According to this embodiment, the control means 5 calculates the limiting permeation flux _Jlim of the separation membrane as the permeation flux prediction value. Based on the calculation result of the limit permeation flux J _lim by the control means 5, the operating conditions are set in real time according to the change in the properties of the treated water so that the permeation flux J of the separation membrane approaches the limit permeation flux J _lim Therefore, the operating conditions of the membrane filtration means 2 can always be controlled within an appropriate range, and a more efficient membrane filtration process can be realized.

The permeation flux J can be expressed as in Equation (4) from Darcy's law.
J = ΔP / μR (4)
(Here, ΔP: transmembrane pressure difference, μ: viscosity of water to be treated, R: membrane filtration resistance.)

From the Andrade's equation, the viscosity μ of the water to be treated depends on the temperature T of the water to be treated and has the relationship of the equation (5).
μ = A × exp (E / T) (5)
(Here, A and E are coefficients, and T is the temperature of the water to be treated.)

On the other hand, from the Arrhenius equation, the diffusion coefficient D in the equation (2) depends on the temperature T of the water to be treated and has the relationship of the equation (6).
D = B × exp (−Q / T) (6)
(Here, B and Q are coefficients.)

The mass transfer coefficient k depends on the membrane surface flow velocity v, and has the relationship of equation (7) by the flow velocity change method.
k / k ₀ = (v / v ₀ ) ⁿ (7)
(Here, v _0: film surface velocity at the reference point, k _0: the reference mass transfer coefficient in the v _0, n: is a coefficient.)

Critical flux J _lim does not depend on the transmembrane pressure [Delta] P, by the equation (3) to (7), the limit flux J _lim at present in the membrane filtration treatment, as in equation (8) Can express.
_{J lim = J lim0 × R 0} / R × In (C g / C) / ln (C g / C 0) × exp (E / T 0) / exp (E / T) × (v / v 0) n × exp (-Q / T) / exp (-Q / T 0) ··· (8)
(Where C ₀ is the solute concentration of the treated water at the reference point, C _g is the solute concentration of the gel layer, C is the solute concentration of the treated water at the present time, T ₀ is the temperature of the treated water at the reference point, J _lim0 indicates the limit permeation flux of the separation membrane at the reference point, and the reference point indicates a value obtained by appropriately setting an actual measurement value at a certain point in time in the past.

Assuming that the membrane occlusion at the current point of time, i.e. the measurement, is negligible from the reference point, i.e.
R ₀ / R≈1 (9)
It becomes.

When Expression (8) is transformed using Expression (9), the limiting permeation flux J _lim of the separation membrane can be calculated based on the following relational expression (1).
_{J lim = J lim0 × ln (} C g / C) / ln (C g / C 0) × exp (E / T 0) × exp (E / T) × (v / v 0) n × exp (-Q / T) / exp (-Q / T ₀ ) (1)
(Where J _lim is the critical permeation flux, J _lim0 is the critical permeation flux of the separation membrane at the reference point, C _g is the solute concentration of the gel layer, C is the measured value of the solute concentration of the treated water, and C ₀ is The solute concentration of the water to be treated at the reference point, E and Q are coefficients, T ₀ is the temperature of the water to be treated at the reference point, T is the measured value of the temperature of the treated water, v is the measured value of the membrane surface velocity, and v _0. Indicates the measured value of the membrane surface flow velocity at the reference point.) As shown in FIG. 4, the solute concentration C _g of the gel layer is the natural flux of solute concentration with the permeation flux for the past data group as the vertical axis. It is obtained as the intercept of the horizontal axis in the graph with the logarithmic horizontal axis.

The control means 5 calculates the limit permeation flux J _lim at the time of measurement as the permeation flux predicted value of the separation membrane based on the relational expression (1). That is, the control means 5 includes the temperature T ₀ , the solute concentration C ₀ , the membrane surface flow velocity v ₀ , the limit permeation flux J _lim0 , the pressure detection means 14, 24, 34, the flow velocity / Using the values of the temperature T, the solute concentration C, and the membrane surface flow velocity v detected by the flow rate detection means 13 and 23, the temperature detection means 12 and the concentration detection means 11 as the predicted permeation flux of the separation membrane. The critical permeation flux J _lim is calculated.

Furthermore, the control means 5 compares the calculation result (calculated value) of the limit permeation flux _Jlim with the actual measurement value J of the permeation flux of the separation membrane. As a result of the comparison, if the critical permeation flux J _lim is larger than the actual measurement value J, the control means 5 determines the critical permeation flux J _lim = the actual measurement value J according to the comparison result, that is, the difference in permeation flux. Until at least one of the driving of the pump 3 and the opening of the valve 4 is controlled so as to increase the transmembrane pressure difference ΔP (see FIG. 5).

Even if the limit permeation flux J _lim = actual value J, the permeation flux may converge to a predetermined value (see FIG. 6). This is because the solute in the water to be treated remains in the vicinity of the film surface, so that a gel layer is formed on the film surface, and the resistance of the gel layer increases in proportion to the transmembrane pressure difference ΔP. In this case, it can be said that the transmembrane pressure difference ΔP is in an excess state. Therefore, when the limiting permeation flux J _lim = actual value J, the control means 5 performs control for once adjusting the driving of the pump 3 and the opening of the valve so that the transmembrane pressure difference ΔP decreases. Specifically, when the critical permeation flux J _lim = actual value J, the transmembrane pressure difference ΔP is once lowered until the critical permeation flux J _lim > the actual measurement value J, and then the critical permeation flux J _lim = The transmembrane pressure difference ΔP is increased so that the measured value J is obtained. As a result, it is possible to set and control more appropriate operating conditions according to fluctuations in the properties of the water to be treated.

Alternatively, the control means 5 may be compared with the target value J _T of flux limit flux J _lim and the separation membrane. The target value J _T can be set in advance in accordance with the properties of the water to be treated and the characteristics of the separation membrane. Result of the comparison, if the limit flux J _lim is greater than the target value J _T, in order to limit flux J _lim = target value J _T, the drive and the pump 3 to lower the film surface velocity v At least one of the opening degrees of the valve 4 may be controlled. When the limit permeation flux J _lim is smaller than the target value J _T , the control means 5 drives the pump 3 to increase the membrane surface flow velocity v so that the control limit permeation flux J _lim = the target value J _T. In addition, at least one of the opening degrees of the valve 4 may be controlled (see FIG. 7).

According to the membrane filtration apparatus according to the embodiment of the present invention, the control unit 5 can predict the critical permeation flux J _lim of the separation membrane using the relational expression (1), and the critical permeation flux J By adjusting at least one of the driving of the pump 3 and the opening degree of the valve 4 so as to approach _lim , useless power can be reduced and a high permeation flux can always be obtained.

In the membrane filtration apparatus shown in FIG. 1, a heating unit (not shown) is separately provided in, for example, an arbitrary flow path of the water to be treated or the raw water tank 1 to control the heated temperature. 5 so as to detect, as the actual measurement value J of flux approaches the limit flux J _lim, or limit the permeation flux J _lim is to approach the target value J _T, the temperature of the water to be treated It is also possible to control to adjust. Thereby, the permeation flux of the membrane can be controlled in a more appropriate range following the temperature variation of the water to be treated.

Furthermore, in the membrane filtration apparatus shown in FIG. 1, the control unit 5 calculates the limit permeation flux J _lim , but the control unit 5 is an independent unit for calculating the limit permeation flux J _lim . Of course, a calculation means (not shown) may be arranged.

  An example of the operation method of the membrane filtration apparatus according to the embodiment of the present invention will be described with reference to FIGS. The example shown in FIG. 8 shows an example of a flow for adjusting the transmembrane pressure difference ΔP of the separation membrane based on the fluctuation of the treated water, and the example shown in FIG. 9 shows the separation membrane based on the fluctuation of the treated water. The example of the flow which adjusts the membrane surface flow velocity v is shown.

In step S11 of FIG. 8, the pressure detection means 14, 24, 34, flow velocity / flow rate detection means 13, 23, temperature detection means 12, and concentration detection means 11 of FIG. Measured values of circulating water flow rate (membrane flow velocity), permeated water flow rate (permeation flux), circulating water inlet side pressure / outlet side pressure and permeated water side pressure are detected. In step S12, the control means 5 calculates the current limit permeation flux J _lim as a permeation flux predicted value (calculation value) using each actual measurement value measured in step S11.

In step S13, the control means 5 compares the measured value J of the permeation flux measured in step S11 with the current permeation flux J _lim calculated in step S12, and the limit permeation flux J _lim > It is determined whether or not the measured value J is obtained. If the limit permeation flux J _lim > measured value J, the process proceeds to step S15. If the limit permeation flux J _lim > measured value J is not satisfied, the process proceeds to step S14.

In step S14, the control means 5 decreases the output of the pump 3, increases the opening of the valve 4 or increases the output of the pump 3 and the opening of the valve 4 until the limit permeation flux J _lim > the actual measurement value J. Both of these are adjusted, and the process proceeds to step S15.

In step S15, the control means 5 increases the difference between the limit permeation flux J _lim and the actual measurement value J so as to increase the transmembrane pressure difference ΔP of the separation membrane until the limit permeation flux J _lim = the actual measurement value J. Accordingly, the output of the pump 3 is increased, the opening of the valve 4 is decreased, or both the output of the pump 3 and the opening of the valve 4 are adjusted.

  In step S16, the control means 5 determines whether or not a target total permeated water amount or a target concentration rate that is arbitrarily set in advance has been achieved. When the target total permeated water amount or the target concentration ratio is achieved, the operation is terminated. When the target permeated water amount or the target concentration ratio is not achieved, the process returns to step S11 and steps S12 to S16 are repeated.

When controlling the membrane surface flow velocity of the separation membrane, in step S21 of FIG. 9, the pressure detection means 14, 24, 34, flow velocity / flow rate detection means 13, 23, temperature detection means 12, concentration detection means 11 of FIG. Measured values of treated water temperature, solute concentration, circulating water flow rate (membrane flow velocity), permeated water flow rate (permeation flux), circulating water inlet side pressure / outlet side pressure and permeated water side pressure Measure. In step S22, the control means 5 calculates the current limit permeation flux J _lim as the permeation flux prediction value using each actual measurement value measured in step S21.

In step S23, the control unit 5 compares the target value J _T of flux J of a predetermined separation membrane, the critical flux J _lim at present, which is calculated in step S22, the limit flux It is determined whether or not J _lim <target value J _T. If the limit permeation flux J _lim <the target value J _T , the process proceeds to step S25. If the limit permeation flux J _lim <target value J _T is not satisfied, the process proceeds to step S24.

In step S24, the control means 5 decreases the output of the pump 3, increases the opening of the valve 4 or opens the output of the pump 3 and the valve 4 until the limit permeation flux J _lim = the target value J _T. Both degrees are adjusted, and the process proceeds to step S25.

In step S25, the control means 5 increases the output of the pump 3 or increases the opening of the valve 4 so as to increase the transmembrane pressure difference ΔP of the separation membrane until the limit permeation flux J _lim = target value J _T. Or adjust both the output of the pump 3 and the opening of the valve 4.

  In step S26, the control means 5 determines whether or not the target permeated water amount or the target concentration rate is achieved. If the target permeated water amount or the target concentration rate is achieved, the operation is terminated. When the target permeated water amount or the target concentration rate is not achieved, the process returns to step S21 and steps S22 to S26 are repeated.

  Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the calculation means (not shown) is included in the control means 5, and the example of calculating the permeation flux predicted value by the calculation means (not shown) is shown. It is also included in the present invention that a calculation process is executed by a provided calculation means (not shown), and the control means 5 performs predetermined control based on the calculation result. As described above, the present invention is expressed by the invention specifying matters in the scope of claims appropriate from the above disclosure, and can be modified and embodied based on the common general technical knowledge of those skilled in the art without departing from the gist thereof. It is.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

  The water-soluble cutting fluid waste liquid discharged from the factory was used as test raw water and concentrated using an ultrafiltration membrane (fractionated molecular weight of 300,000). When the concentration of the normal hexane extractable substance (= solute concentration C) in the concentrate is 16000, 33000, 54000 mg / L, the limit permeation flow in the combination of the conditions of the temperature T of the concentrate and the membrane surface flow velocity v shown in Table 1 The bundle was measured.

The critical permeation flux J _{lim for} each condition was determined using the above relational expression (1). Each coefficient in the equation (1) was obtained by conducting a separate preliminary experiment. FIG. 10 shows a comparison between the measured value of the critical permeation flux and the calculated value (predicted value) using the relational expression (1). In addition, each permeation flux is shown by the ratio with respect to the permeation flux defined arbitrarily.

  As shown in FIG. 10, it can be seen that the actually measured value of the critical permeation flux and the calculated value (predicted value) according to the equation (1) are almost the same.

DESCRIPTION OF SYMBOLS 1 ... Raw water tank 2 ... Membrane filtration means 3 ... Pump 4 ... Valve 5 ... Control means 11 ... Concentration detection means 12 ... Temperature detection means 13, 23 ... Flow velocity / flow rate detection means 14, 24, 34 ... Pressure detection means

Claims (9)

  Based on the predicted permeation flux of the separation membrane calculated using a plurality of actual measurement values that are the property variation factors of the treated water that permeates the separation membrane, the transmembrane differential pressure and the membrane surface flow velocity of the separation membrane are calculated. A membrane filtration apparatus comprising control means for controlling at least one.   The membrane filtration processing apparatus according to claim 1, wherein the plurality of actually measured values include measured values of the temperature, solute concentration, and membrane surface flow rate of the water to be treated. A separation membrane that receives supply of water to be treated to obtain permeated water and discharged water;
A pump provided on the supply side of the water to be treated of the separation membrane;
A valve provided on the discharge side for obtaining drain water of the separation membrane;
Pressure detecting means for detecting pressures of the water to be treated, the membrane permeated water and the discharged water before passing through the separation membrane;
A flow rate / flow rate detection means for detecting the water to be treated before passing through the separation membrane, the flow rate or flow rate of the permeate, respectively;
Temperature detecting means for detecting the temperature of the water to be treated before passing through the separation membrane;
Concentration detecting means for detecting the solute concentration of the water to be treated before passing through the separation membrane;
Based on the permeation flux predicted value of the separation membrane calculated from the detection results of the pressure detection means, the flow velocity / flow rate detection means, the temperature detection means, and the concentration detection means, the transmembrane differential pressure of the separation membrane and A membrane filtration apparatus comprising control means for controlling at least one of driving of the pump and opening of the valve so as to control at least one of the membrane surface flow velocity.   The membrane permeation processing apparatus according to any one of claims 1 to 3, wherein the permeation flux predicted value is a limit permeation flux of the separation membrane.   The control means compares the predicted value of the permeation flux with an actual value of the permeation flux of the separation membrane, and if the predicted value of the permeation flux is larger than the actual value, the transmembrane pressure difference is calculated. It controls to raise, and when the said permeation | transmission flux estimated value is equal to the said actual value, it controls so that the said transmembrane differential pressure may be lowered | hung. Membrane filtration equipment.   The control means compares the predicted value of the permeation flux with a target value of the permeation flux of the separation membrane, and controls to decrease the membrane surface flow velocity if the permeate flux predicted value is equal to or greater than the target value. And when the said permeation | transmission flux estimated value is smaller than the said target value, it controls to raise a membrane surface flow velocity, The membrane filtration processing apparatus of any one of Claims 1-4 characterized by the above-mentioned. The membrane filtration apparatus according to any one of claims 1 to 6, wherein the control means calculates a permeation flux predicted value of the separation membrane based on the following relational expression (1). .
_{J lim = J lim0 × ln (} C g / C) / ln (C g / C 0) × exp (E / T 0) × exp (E / T) × (v / v 0) n × exp (-Q / T) / exp (-Q / T ₀ ) (1)
(Where J _lim is the limit permeation flux, J _lim0 is the limit permeation flux of the separation membrane at the reference point, C _g is the solute concentration of the gel layer, C is the measured value of the solute concentration of the treated water, and C ₀ is the reference The solute concentration of the water to be treated at the point, E and Q are coefficients, T ₀ is the temperature of the water to be treated at the reference point, T is the measured value of the temperature of the treated water, v is the measured value of the membrane surface velocity, and v ₀ is (The actual measured value of the flow velocity at the reference point is shown.)   The membrane filtration apparatus according to any one of claims 1 to 7, wherein the water to be treated contains an oil-containing waste liquid.   A predicted permeation flux value of the separation membrane is calculated using a plurality of actual measurement values that are characteristics variation factors of the water to be treated that permeates the separation membrane, and the separation membrane based on the calculation result of the predicted permeation flux value is calculated. A membrane filtration treatment method comprising controlling at least one of a transmembrane pressure difference and a membrane surface flow velocity.