Method for real-time monitoring of membrane fouling potential

Abstract

The present invention relates to a method for real-time monitoring of membrane fouling potential, which includes the following steps: irradiating flowing sewage with excitation light to generate emitted light, and collecting the fluorescence signal of the emitted light; processing the fluorescence signal and calculating to obtain the fluorescence parameter of the sewage; according to the exponential equation y = ke<supgt;ax< / supgt> between the fluorescence parameter and the membrane fouling potential, obtaining the membrane fouling potential of the irradiated sewage, where y is the membrane fouling potential, x is the fluorescence parameter, and k and a are both constants.

Description

Technical Field

[0001] The present invention belongs to the field of water treatment, and particularly relates to a method for real-time monitoring of membrane fouling potential. Background Art

[0002] As an effective water treatment technology, compared with the traditional activated sludge process, the membrane technology has the advantages of small floor area, good effluent quality, high pollutant removal efficiency, etc., and has been widely used in the fields of sewage treatment, drinking water and reclaimed water reuse in recent years. However, membrane fouling is still an urgent problem to be solved in the development of membrane technology. Membrane fouling will lead to a decrease in membrane filtration flux and an increase in filtration pressure, thereby resulting in a reduction in the treatment capacity of the membrane filtration device and an increase in energy consumption. Organic matter in sewage is an important factor causing membrane fouling. Therefore, monitoring the content of organic matter in water is an important means to reflect the membrane fouling potential.

[0003] The membrane fouling potential of the water sample to be filtered is generally evaluated by an off-line ultrafiltration cup dead-end filtration device. However, this method is cumbersome and time-consuming, and is not conducive to the water plant to timely monitor the fouling potential of the membrane inlet water. Although the traditional methods for measuring organic matter are significantly correlated with the membrane fouling potential to a certain extent, such as chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total organic carbon (TOC), these methods are cumbersome, time-consuming in the test process and difficult to achieve real-time on-line monitoring. In addition, the development process of membrane fouling can also be reflected by the change of transmembrane pressure difference (TMP). However, when the TMP rises, the formation of membrane fouling has become an established fact and it is impossible to give an early warning. When the content of organic matter in the water plant suddenly increases, resulting in an increase in the membrane fouling potential, the above methods cannot give an early warning of the sudden situation in time, which will cause the water plant to miss the opportunity to take timely measures to control the occurrence of serious membrane fouling conditions. Summary of the Invention

[0004] In view of this, it is necessary to provide a method for real-time on-line monitoring of membrane fouling potential.

[0005] A method for real-time monitoring of membrane fouling potential, which includes the following steps: irradiating flowing sewage with excitation light to generate emitted light, and collecting the fluorescence signal of the emitted light; processing the fluorescence signal and calculating to obtain the fluorescence parameter of the sewage; according to the exponential equation y =ke ax , obtaining the membrane fouling potential of the irradiated sewage, where y is the membrane fouling potential, x is the fluorescence parameter, and k and a are both constants.

[0006] A method for real-time monitoring of membrane fouling potential, comprising the following steps: irradiating flowing sewage with excitation light to generate emitted light, and collecting the fluorescence signal of the emitted light; processing the fluorescence signal and calculating to obtain the fluorescence parameter of the sewage; according to the relationship equation between the fluorescence parameter and the membrane fouling potential, obtaining the membrane fouling potential of the irradiated sewage. When the concentration of the sewage is low, the relationship equation is a linear equation y =k x +b. When the concentration of the sewage is high, the relationship equation is an exponential equation y =ke ax , where y is the membrane fouling potential, x is the fluorescence parameter, and k, a, and b are all constants.

[0007] Compared with the prior art, the beneficial effects of the present invention are: by establishing a regression model of the fluorescence parameter and the membrane fouling potential, the membrane fouling potential of organic matter in sewage can be real-time monitored by using fluorescence spectroscopy, with high sensitivity and simple testing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a flowchart of the method for real-time monitoring of membrane fouling potential provided by an embodiment of the present invention.

[0009] Figure 2 is a graph showing the change trends of fluorescence peak intensity, fluorescence peak area, and membrane fouling potential provided by an embodiment of the present invention.

[0010] Figure 3 is a curve graph showing the change of membrane fouling potential with the fluorescence peak intensity value provided by an embodiment of the present invention.

[0011] Figure 4 is a curve graph showing the change of membrane fouling potential with the fluorescence peak area value provided by an embodiment of the present invention.

[0012] Figure 5 is a structural diagram of a device for real-time monitoring of membrane fouling potential provided by an embodiment of the present invention.

[0013] DESCRIPTION OF THE MAIN ELEMENT SYMBOLS

[0014]

[0015] The following specific embodiments will further illustrate the present invention in conjunction with the above drawings. DETAILED DESCRIPTION OF THE INVENTION

[0016] The method for real-time monitoring of membrane fouling potential of the present invention will be further described in detail below in conjunction with the drawings.

[0017] Please refer to Figure 1, an embodiment of the present invention provides a method for real-time monitoring of membrane fouling potential, including the following steps:

[0018] Step S1: Irradiate the flowing sewage with excitation light to generate emitted light, and collect the fluorescence signal of the emitted light;

[0019] Step S2: Process the fluorescence signal and calculate to obtain the fluorescence parameters of the sewage;

[0020] Step S3: According to the exponential equation y =ke ax or the linear equation y =k x +b, obtain the membrane fouling potential of the irradiated sewage, where y is the membrane fouling potential, x is the fluorescence parameter, and k, a, and b are all constants.

[0021] In step S1, the excitation light is provided by an excitation light source. The selection of the wavelength of the excitation light is related to the sample to be measured. Specifically, the wavelength of the excitation light should be close to the wavelength of the maximum fluorescence peak of the sample to be measured. The wavelength range of the excitation light is 200 nm to 400 nm. In this embodiment, the wavelength of the excitation light is 280 nm. When the flowing sewage is irradiated with the excitation light, the content of organic matter in the sewage is different, and the fluorescence signal generated after irradiation is also different. In this embodiment, the flowing sewage is realized by introducing a sewage sample into a cuvette through a peristaltic pump. The cuvette is provided with an inlet and an outlet. The inlet is connected to the inlet pipe, and the outlet is connected to the outlet pipe. To prevent short-circuiting and resulting in uneven liquid mixing, the inlet is arranged at the lower part of the cuvette, and the outlet is arranged at the upper part of the cuvette. Specifically, the sewage sample is introduced into the cuvette through the inlet by a peristaltic pump and then flows out through the outlet. Among them, to prevent the generation of bubbles, the water flow rate should not be too large. The cuvette can be a fluorescence cuvette or a micro cuvette. In this embodiment, the sewage is a BSA solution prepared by using bovine serum albumin (BSA) as an organic matter model. The wavelength range of the emitted light is 200 nm to 800 nm.

[0022] In step S2, the fluorescence signal of the collected emitted light can be transmitted to a spectrometer through an optical fiber, and after being processed by the spectrometer, it is then transmitted to a data processor for processing and analysis, and the fluorescence parameters are calculated. The data processor can be a computer or a mobile terminal device. The data processor can record and process and analyze the processed fluorescence signal, and by setting the time interval and integration time of the output data, analyze and calculate to obtain the fluorescence parameters of the sewage. The fluorescence parameters include the maximum fluorescence peak intensity and the area of the fluorescence peak.

[0023] In step S3, the exponential equation or linear equation relationship between the fluorescence parameter and the membrane fouling potential can be obtained by establishing a regression model through regression analysis. Specifically, the method for establishing a regression model between the fluorescence parameter of the sewage and the membrane fouling includes the following steps: testing the membrane fouling potential of sewage at different concentrations through a dead-end filtration device of an ultrafiltration cup; collecting the fluorescence parameters of the above-mentioned sewage at various concentrations, and establishing a regression model based on the membrane fouling potential of sewage at different concentrations and the fluorescence parameters of the sewage at the corresponding concentrations, to obtain an exponential relationship equation or a linear relationship equation between the fluorescence parameter of the sewage and the membrane fouling potential. When the pollutant concentration in the sewage is low, the regression model can be expressed as a linear relationship equation. When the pollutant concentration in the sewage is high, due to the interference of factors such as luminescent substances, the regression model no longer conforms to the linear relationship equation and will be expressed as an exponential relationship equation. Of course, as can be seen from Figure 3 and Figure 4 , the exponential relationship equation is also applicable to the case where the pollutant concentration is low. Here, due to the different types of pollutants in the sewage, the selection of the high or low pollutant concentration is different according to the characteristics of different pollutants. In addition, the constants in the exponential equation or the linear equation are also calculated to obtain different values according to different water quality characteristics.

[0024] In this embodiment, a dead-end filtration device of an ultrafiltration cup is used to test the membrane fouling potential, and the slope V~J / J 0 of the linear segment of the filtration curve ( K )(cm -1 ) is used as a scale for evaluating the membrane fouling potential, where V is the cumulative filtration volume per unit membrane area (cm 3 / cm 2 ), J is the filtration flux of the water sample (m 3 / m 2 s), J 0 is the filtration flux of the background salt solution (m 3 / m 2 s). In this embodiment, when the concentration of the BSA solution is lower than 100 mg / L, the regression model will be expressed as a linear relationship equation. When the concentration of the BSA solution is higher than 100 mg / L, the regression model will be expressed as an exponential relationship equation. Here, the step of testing the membrane fouling potential of sewage at different concentrations through a dead-end filtration device of an ultrafiltration cup only needs to be completed once. A regression model is established based on the tested membrane fouling potential to obtain the relationship equation between the fluorescence parameter and the membrane fouling potential, and subsequent steps do not need to use the dead-end filtration device of the ultrafiltration cup for testing every time.

[0025] After the relationship equation between the fluorescence parameter and the membrane fouling potential is established, the fluorescence parameter of the sewage can be monitored in real time online, and then the real-time membrane fouling potential can be calculated through this fluorescence parameter, avoiding the cumbersome and time-consuming method of using a dead-end filtration device of an ultrafiltration cup every time to test the membrane fouling potential. Further, the membrane fouling potential of the sewage can be monitored in real time online by testing the fluorescence parameter of the sewage, and the occurrence of a high fouling potential situation can be warned in time.

[0026] Example 1

[0027] Please refer to Figure 5 , the present invention uses a device 100 for real-time monitoring of the membrane fouling potential to monitor the membrane fouling potential in real time. The device 100 for real-time monitoring of the membrane fouling potential includes: a peristaltic pump 10, a cuvette 20, an excitation light source 30, a spectrometer 40, and a data processor 50. Among them, the cuvette 20 is a fluorescence cuvette with an optical path of 1 cm. The optical fiber connected to the excitation light source 30 and the optical fiber connected to the spectrometer 40 are perpendicular to the cuvette 20, and the orientations of the two optical fibers are perpendicular.

[0028] Example 2

[0029] A method for real-time monitoring of the membrane fouling potential includes the following steps:

[0030] (1) Irradiate the flowing sewage with excitation light having a wavelength of 280 nm, and the sewage is continuously input into the cuvette through a peristaltic pump at a flow rate of 5 mL / min.

[0031] The sewage is a BSA solution prepared using bovine serum albumin (BSA) as an organic matter model, where the concentration gradient of the prepared BSA content is 10, 25, 50, 75, 100, 125, 175, and 200 mg / L, and 168 mg / L of NaHCO3 and 702 mg / L of NaCl are used as the salt background solution. To simulate the trend of changes in the organic matter content in dynamic sewage over time, in this embodiment, the salt background solution and the BSA solution are sequentially used as the influent in ascending order of concentration, and the influent concentration is changed every 30 minutes. In this embodiment, the cuvette is a fluorescence cuvette with an optical path of 1 cm. A sealing rubber stopper is provided above the cuvette, and an influent diversion needle and an effluent diversion needle are inserted, and the needles are respectively connected to the influent pipe and the effluent pipe. To prevent short-circuiting during the water conveyance process, resulting in a difference between the solution in the cuvette and the measured solution, in this embodiment, the influent diversion needle is inserted into the bottom of the cuvette from the corner of the cuvette, and the position of the diversion needle cannot be in the optical path to avoid affecting the optical path. The effluent diversion needle is on the opposite side of the influent diversion needle and the bottom of the effluent diversion needle is at the upper part of the cuvette, so as to form a good flow pattern to ensure that the sample in the cuvette is the measured sample. The fluorescence signal of the sewage is collected by a spectrometer, and the fluorescence spectrum data is output in real time every 5 minutes.

[0032] (2) Parameters such as the fluorescence peak intensity and fluorescence peak of the sewage are obtained through computer analysis and calculation. Please refer to Figure 2 and Table 1. As the test time changes, the fluorescence peak intensity and fluorescence peak area increase, and the membrane fouling potential also increases.

[0033] Table 1 Variation value table of fluorescence peak intensity, fluorescence peak area and membrane fouling potential

[0034]

[0035] (3) Please refer to Figures 3 to 4 and Table 2. As the fluorescence parameters change, the relationship between the fluorescence parameters and the membrane fouling potential conforms to a linear relationship or an exponential relationship. When the concentration of the BSA solution is less than 100 mg / L, the fluorescence parameters and the membrane fouling potential can be represented by either a linear equation or an exponential equation; when the concentration of the BSA solution is greater than 100 mg / L, the fluorescence parameters and the membrane fouling potential are represented by an exponential equation.

[0036] In this embodiment, the linear equation of the model between the fluorescence parameters and the membrane fouling potential of the sewage obtained through the regression model is y = k x + b, where y is the membrane fouling potential, x is the fluorescence parameter (maximum fluorescence peak intensity or fluorescence peak area), and both k and b are constants. AsFigure 3 and 4 As shown in and , for the maximum fluorescence peak intensity ~ membrane fouling potential model, b = 0.3845, k = 0.0009; for the fluorescence peak area ~ membrane fouling potential model, b = 0.4287, k = 0.00001. The exponential equation of the model between the fluorescence parameters of the sewage and the membrane fouling potential obtained by the regression model is y =ke ax , where y is the membrane fouling potential, x is the fluorescence parameter (maximum fluorescence peak intensity or fluorescence peak area), and both k and a are constants. As Figure 3 and 4 shown, for the maximum fluorescence peak intensity ~ membrane fouling potential model, a = 0.561, k = 0.000716; for the fluorescence peak area ~ membrane fouling potential model, a = 0.561, k = 0.000012.

[0037] Table 2 Variation numerical table of fluorescence parameters and membrane fouling index

[0038]

[0039] The method for real-time monitoring of membrane fouling potential provided by the present invention has the following advantages: By establishing a regression model of fluorescence parameters and membrane fouling potential, the membrane fouling potential of organic substances in sewage can be monitored in real time by using fluorescence spectroscopy method, with high sensitivity, simple test method, and can give an early warning of sudden high pollution situations in a timely manner.

[0040] In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope claimed by the present invention.

Claims

1. A method for real-time monitoring of membrane fouling potential, characterized in that, Including the following steps: Irradiate flowing sewage with excitation light to generate emitted light, and collect the fluorescence signal of the emitted light; Process the fluorescence signal and calculate to obtain the fluorescence parameters of the sewage; According to the exponential equation y = ke between the fluorescence parameter and the membrane fouling potential ax , the membrane fouling potential of the irradiated sewage is obtained, where y is the membrane fouling potential, x is the fluorescence parameter, and k and a are both constants. The exponential equation between the fluorescence parameter and the membrane fouling potential is obtained by establishing a regression model through the regression analysis method. The method for establishing the regression model between the fluorescence parameter and the membrane fouling potential includes the following steps: Test the membrane fouling potential of sewage at different concentrations through a dead-end filtration device of an ultrafiltration cup, and take the slope K of the linear segment of the filtration curve V~J / J0 as the scale for evaluating the membrane fouling potential, where V is the cumulative filtration volume per unit membrane area, J is the filtration flux of the water sample, and J0 is the filtration flux of the background salt solution; Collect the fluorescence parameters of the corresponding sewage at different concentrations, and establish a regression model based on the membrane fouling potential of the sewage at different concentrations and the corresponding fluorescence parameters.

2. The method for real-time monitoring of membrane fouling potential according to claim 1, wherein, The wavelength range of the excitation light is 200 nanometers to 400 nanometers.

3. The method for real-time monitoring of membrane fouling potential according to claim 1, wherein, The fluorescence signal is transmitted to a spectrometer through an optical fiber, and then after being processed by the spectrometer, it is transmitted to a data processor for processing and calculation.

4. The method for real-time monitoring of membrane fouling potential according to claim 3, characterized in that, The data processor is one of a computer or a mobile terminal device.

5. The method for real-time monitoring of membrane fouling potential according to claim 1, characterized in that, The fluorescence parameters include the maximum fluorescence peak intensity and the area of the fluorescence peak.

6. A method for real-time monitoring of membrane fouling potential, characterized in that, Including the following steps: Irradiate flowing sewage with excitation light to generate emitted light, and collect the fluorescence signal of the emitted light; Process the fluorescence signal and calculate to obtain the fluorescence parameters of the sewage; According to the relationship equation between the fluorescence parameter and the membrane fouling potential, the membrane fouling potential of the irradiated sewage is obtained. When the concentration of the sewage is low, the relationship equation is a linear equation y = kx + b. When the concentration of the sewage is high, the relationship equation is an exponential equation y = ke ax , where y is the membrane fouling potential, x is the fluorescence parameter, and k, a, and b are all constants. The exponential equation or linear equation between the fluorescence parameter and the membrane fouling potential is obtained by establishing a regression model through the regression analysis method. The method for establishing the regression model between the fluorescence parameter and the membrane fouling potential includes the following steps: Test the membrane fouling potential of sewage at different concentrations through a dead-end filtration device of an ultrafiltration cup, and take the slope K of the linear segment of the filtration curve V~J / J0 as the scale for evaluating the membrane fouling potential, where V is the cumulative filtration volume per unit membrane area, J is the filtration flux of the water sample, and J0 is the filtration flux of the background salt solution; Collect the fluorescence parameters of the corresponding sewage at different concentrations, and establish a regression model based on the membrane fouling potential of the sewage at different concentrations and the corresponding fluorescence parameters.

7. The method for real-time monitoring of membrane fouling potential according to claim 6, wherein, When the sewage is a bovine serum albumin solution and the concentration of the bovine serum albumin solution is less than 100 mg / L, the relationship equation is the linear equation y = kx + b.

8. The method for real-time monitoring of membrane fouling potential according to claim 6, characterized in that, When the sewage is a bovine serum albumin solution and the concentration of the bovine serum albumin solution is higher than 100 mg / L, the relational equation is an exponential equation y = ke ax .

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