MBR membrane cleaning effect testing device

Abstract

The utility model provides an MBR membrane cleaning effect testing device which comprises an MBR device, an aeration assembly, a first pressure sensor assembly, a water outlet assembly, a small membrane assembly, a second pressure sensor assembly, a weighing assembly and a water inlet assembly, the aeration component is arranged at the bottom in the MBR device, and the cleaned membrane component to be detected is mounted in the MBR device; the water inlet assembly is communicated with the lower part of the MBR device through a first pipeline; the membrane component with the cleaning effect to be detected is connected with the first pressure sensor component through a second pipeline, and the second pipeline is connected with the water outlet component through a third pipeline; the aeration assembly is communicated with the MBR device through a fourth pipeline; the small membrane assembly is arranged on the upper portion of the MBR device and connected with the weighing assembly through a fifth pipeline, and a second pressure sensor assembly is arranged on the fifth pipeline. The MBR membrane cleaning effect is tested, and the testing effect is more accurate.

Description

Technical Field

[0001] This utility model belongs to the field of membrane cleaning technology, and in particular relates to an MBR membrane cleaning effect testing device. Background Technology

[0002] With rapid economic and population growth, urban sewage discharge is constantly increasing, making effective sewage treatment technologies crucial for protecting the aquatic environment and human health. MBR (Membrane Bioreactors) combines biological treatment with ultrafiltration / microfiltration technologies and has been proven effective in treating wastewater since its development over 30 years ago. Although MBRs offer advantages such as high effluent quality, small footprint, and low sludge production, they still face the challenge of membrane fouling. Membrane fouling not only reduces treatment capacity but also increases energy consumption. In practical applications of MBRs, long operating times and multiple cycles are common, making membrane cleaning an important means of maintaining long-term MBR operation.

[0003] Currently, the evaluation of membrane cleaning effectiveness relies solely on the recovery of membrane flux after cleaning. However, even when the flux recovery is similar after cleaning using different methods, the membrane surface characteristics may differ, thus affecting the rate of fouling during subsequent use. Therefore, in multi-cycle operation, relying solely on membrane flux to evaluate the cleaning effect may not be comprehensive enough. Chinese utility model patent CN117323828A discloses a method and device for evaluating membrane fouling index. CN115672046A discloses a method for detecting the fouling index of ultrafiltration and nanofiltration membranes. Both patents only involve the determination of the membrane fouling index but do not link it to the membrane cleaning recovery rate to evaluate the membrane cleaning effect. Utility Model Content

[0004] In view of this, the present invention aims to propose an MBR membrane cleaning effect testing device. The MBR membrane cleaning evaluation method combines the recovery of membrane flux and the subsequent membrane fouling rate to solve the problem that traditional membrane cleaning may not be comprehensive enough in evaluating the membrane cleaning effect by relying solely on the recovery of membrane flux after cleaning.

[0005] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0006] An MBR membrane cleaning effect testing device includes an MBR device, an aeration component, a first pressure sensor component, an effluent component, a small membrane component, a second pressure sensor component, a weighing component, and an influent component.

[0007] The aeration components are located at the bottom of the MBR unit, and the cleaned membrane module to be tested is installed inside the MBR unit.

[0008] The inlet assembly is connected to the lower part of the MBR unit via the first pipe;

[0009] The membrane module whose cleaning effect is to be tested is connected to the first pressure sensor module through a second pipe, and the second pipe is connected to the water outlet module through a third pipe.

[0010] The aeration components are connected to the MBR unit via a fourth pipe;

[0011] The small membrane module is located in the upper part of the MBR unit. The small membrane module is connected to the weighing component through the fifth pipe, and the fifth pipe is equipped with a second pressure sensor component.

[0012] Furthermore, the water inlet assembly includes a water inlet tank and a first peristaltic pump;

[0013] The water inlet tank is connected to the interior of the MBR unit through the first pipe, and the first peristaltic pump is installed on the first pipe.

[0014] Furthermore, the aeration component includes an aeration pump and an aeration plate. The aeration pump is connected to the aeration plate through a fourth pipe, and the aeration plate is provided with several aeration holes.

[0015] The aeration plate is installed inside the MBR unit and is positioned below the membrane module whose cleaning effect is to be tested.

[0016] Furthermore, the first pressure sensor assembly includes a first pressure sensor and a paperless recorder. The first pressure sensor is disposed on the second pipe and is electrically connected to the controller.

[0017] The first pressure sensor is electrically connected to the paperless recorder, and the first pressure sensor is electrically connected to the controller.

[0018] Furthermore, the water outlet assembly includes a second peristaltic pump and a water outlet tank. The second pipe is connected to the water outlet tank through a third pipe, and the second peristaltic pump is installed on the third pipe.

[0019] Furthermore, the second pressure sensor assembly includes a second pressure sensor, a small diaphragm assembly is connected to the weighing assembly via a fifth pipe, the second pressure sensor is mounted on the fifth pipe, and the second pressure sensor is electrically connected to the controller.

[0020] Furthermore, the weighing assembly includes a third peristaltic pump, a beaker, and an electronic balance. The small membrane assembly is connected to the beaker via a fifth pipe. The third peristaltic pump is mounted on the fifth pipe, and the electronic balance is located below the beaker and is mounted on a flat surface.

[0021] Compared with existing technologies, the MBR membrane cleaning effect testing device of this utility model has the following advantages:

[0022] This application involves installing the cleaned membrane module to be tested inside an MBR device to induce membrane fouling. After fouling, the cleaned membrane module is cleaned. The membrane in the cleaned membrane module is cut into small pieces and formed into small membrane modules. The membrane in the new membrane module is cut into small new pieces and installed onto the small membrane modules. The new membrane modules and small membrane modules are then subjected to simulated domestic wastewater pollution characteristics within the MBR device. The effectiveness of the cleaned membrane module is tested through the small membrane modules, resulting in more accurate test results. Attached Figure Description

[0023] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0024] Figure 1 This is a schematic diagram of the MBR membrane module fouling and small membrane module MFI measurement device described in Embodiment 1 of this utility model;

[0025] Figure 2 (a) Membrane flux and cleaning efficiency of small membrane modules after cleaning using schemes A and B; (b) Membrane flux and K of small membrane modules after cleaning using schemes A and B. v Linear fitting plot;

[0026] Figure 3 (a) Substitute the operating flux of 18 LMH into Figure 2 (b) K is obtained by fitting the formula. fv (a) Value; (b) V calculated using Table 4 S value;

[0027] Figure 4 (a) The change of transmembrane pressure difference over time when the MBR membrane module is cleaned and put back into use after Scheme A; (b) The change of transmembrane pressure difference over time when the MBR membrane module is cleaned and put back into use after Scheme B (A1 and A2; B1 and B2 are parallel groups that are put into operation at the same time).

[0028] Figure 5 (a) K after cleaning of MBR membrane modules A and B schemes fV (a) Value; (b) Operating time of the MBR membrane module after cleaning using schemes A and B and then putting it back into use.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Inlet tank; 2. First peristaltic pump; 3. First pipeline; 4. MBR unit; 5. Aeration plate; 6. Membrane module assembly; 7. Second pipeline; 8. First pressure sensor; 9. Paperless recorder; 10. Third pipeline; 11. Second peristaltic pump; 12. Outlet tank; 13. Aeration pump; 14. Fourth pipeline; 15. Small membrane module; 16. Second pressure sensor; 17. Fifth pipeline; 18. Third peristaltic pump; 19. Beaker; 20. Electronic balance. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] A membrane cleaning effect testing device for a membrane reactor (MBR) includes an MBR unit 4, an aeration component, a first pressure sensor component 8, an effluent component, a small membrane component 15, a second pressure sensor component 16, a weighing component, and an inlet component. The aeration component is located at the bottom of the MBR unit 4, and the cleaned membrane component 6 to be tested is installed inside the MBR unit 4. The inlet component is connected to the lower part of the MBR unit 4 through a first pipe 3. The membrane component 6 to be tested is connected to the first pressure sensor component 8 through a second pipe 7, and the second pipe 7 is connected to the effluent component through a third pipe 10. The aeration component is connected to the MBR unit 4 through a fourth pipe 14. The small membrane component 15 is located at the upper part of the MBR unit 4, and the small membrane component 15 is connected to the weighing component through a fifth pipe 17, on which the second pressure sensor component 16 is mounted.

[0034] The water inlet assembly includes a water inlet tank 1 and a first peristaltic pump 2; the water inlet tank 1 is connected to the interior of the MBR device 4 through a first pipe 3, and the first peristaltic pump 2 is installed on the first pipe 3.

[0035] The aeration assembly includes an aeration pump 13 and an aeration plate 5. The aeration pump 13 is connected to the aeration plate 5 through a fourth pipe 14. The aeration plate 5 has several aeration holes. The aeration plate 5 is installed inside the MBR device 4 and is located below the membrane module 6 whose cleaning effect is to be tested.

[0036] The first pressure sensor 8 assembly includes a first pressure sensor 8 and a paperless recorder 9. The first pressure sensor 8 is disposed on the second pipe 7 and is electrically connected to the controller. The first pressure sensor 8 is electrically connected to the paperless recorder 9 and the controller.

[0037] The water outlet assembly includes a second peristaltic pump 11 and a water outlet tank 12. The second pipe 7 is connected to the water outlet tank 12 through the third pipe 10. The second peristaltic pump 11 is installed on the third pipe 10. The second pressure sensor 16 assembly includes a second pressure sensor 16. The small membrane assembly 15 is connected to the weighing assembly through the fifth pipe 17. The second pressure sensor 16 is electrically connected to the controller and is installed on the fifth pipe 17.

[0038] The weighing assembly includes a third peristaltic pump 18, a beaker 19, and an electronic balance 20. The small membrane assembly 15 is connected to the beaker 19 through a fifth pipe 17. The third peristaltic pump 18 is installed on the fifth pipe 17. The electronic balance 20 is installed below the beaker 19 and is installed on a flat surface.

[0039] The first pressure sensor 8 and the second pressure sensor 16 adopt existing technology. The first pressure sensor 8 and the second pressure sensor 16 are capable of measuring water pressure. The first pressure sensor 8 and the second pressure sensor 16 adopt existing technology.

[0040] A method for evaluating membrane cleaning in a membrane bioreactor, characterized by: simulating the pollution characteristics of domestic wastewater, subjecting the membrane module to membrane fouling, and then cleaning the membrane module;

[0041] The flux recovery of the membrane module after cleaning was tested;

[0042] Based on the flux recovery of the membrane module after cleaning and the membrane fouling index when the cleaned membrane module is put back into use, the initial transmembrane pressure difference, MFI, and operating time when the cleaned membrane module is put back into use can be predicted.

[0043] Furthermore, the flux recovery test of the cleaned membrane module includes cake layer formation, intermediate pore blockage, standard pore blockage, and complete pore blockage. Based on the different conditions, the membrane fouling index when the cleaned membrane module is put back into use is calculated.

[0044] Cake formation, intermediate pore blockage, standard pore blockage, and complete pore blockage are defined as follows: cake formation refers to the formation of a cake layer on the membrane surface instead of the contaminants entering the membrane pores; intermediate pore blockage refers to the complete blockage of the membrane pores by contaminants, which also adhere to the membrane surface; standard pore blockage occurs when the diameter of the contaminants is smaller than the diameter of the membrane pores, depositing and adhering inside the pores, thus shrinking the pore size; and complete pore blockage occurs when all contaminants block the membrane pores. This ideal condition assumes that no particles are located on top of other particles (i.e., no cake formation) or on the membrane surface between pores.

[0045] Furthermore, the membrane in the cleaned membrane module is cut into small pieces, and the small pieces are formed in the small membrane module 15;

[0046] The membrane fouling index is determined as follows: The cleaned membrane module or small membrane module 15 is subjected to simulated domestic wastewater pollution tests. Fouling filtration experiments are conducted at different high fluxes (J1, J2, J3, J4) to obtain data on the transmembrane pressure difference p, the initial transmembrane pressure difference p0, and the cumulative permeate V during the filtration process. S Linearly fits were performed on the four formulas for filter cake formation, intermediate pore blockage, standard pore blockage, or complete pore blockage contamination. The R values ​​obtained from these four fitting formulas were then compared. 2 Value, R 2 The slope of the linear fitting equation with the largest value is used to obtain the membrane fouling index K under different high flux conditions in small membrane module 15. v (K v1 K v2 K v3 K v4 ), and the fitted K v Linear fitting is performed with the corresponding high flux, and then the running flux is substituted into the fitting result to predict the membrane fouling index value of the membrane module or small membrane module 15 after cleaning.

[0047] Furthermore, the method for calculating the relative transmembrane pressure difference when the filter cake layer is clogged:

[0048] p' is the relative transmembrane pressure difference when the filter cake layer is clogged. The relative transmembrane pressure difference is the ratio of the transmembrane pressure difference during the filtration process to the initial transmembrane pressure difference, and it is dimensionless.

[0049] p represents the transmembrane pressure difference during the filtration process when the filter cake layer is clogged, in kPa.

[0050] p0 is the initial transmembrane pressure difference when the filter cake layer is clogged, kPa0;

[0051] The V S The cumulative permeation rate when the filter cake layer becomes clogged, in L / m³. 2 ;

[0052] The K v This represents the membrane fouling index when the filter cake layer becomes clogged.

[0053] And / or, the method for calculating the relative transmembrane pressure difference when the intermediate orifice is blocked:

[0054] p' is the relative transmembrane pressure difference when the intermediate pore is blocked. The relative transmembrane pressure difference is the ratio of the transmembrane pressure difference during the filtration process to the initial transmembrane pressure difference, and it is dimensionless.

[0055] p represents the transmembrane pressure difference during the filtration process when the intermediate pore is blocked, in kPa.

[0056] p0 is the initial transmembrane pressure difference when the intermediate pore is blocked, in kPa.

[0057] The V S The cumulative permeation rate when the intermediate pore is blocked, in L / m 2 ;

[0058] The K v This represents the membrane fouling index when the intermediate pore is blocked.

[0059] And / or, the method for calculating the relative transmembrane pressure difference when the standard orifice is blocked:

[0060] p' is the relative transmembrane pressure difference when the standard pore is blocked. The relative transmembrane pressure difference is the ratio of the transmembrane pressure difference during the filtration process to the initial transmembrane pressure difference, and it is dimensionless.

[0061] p represents the transmembrane pressure difference during the filtration process when the standard pore is clogged, in kPa.

[0062] p0 is the initial transmembrane pressure difference when the standard orifice is blocked, in kPa.

[0063] The V S The cumulative permeation rate when the standard orifice is blocked, in L / m 2 ;

[0064] The K v This represents the membrane fouling index when the standard pores are blocked.

[0065] And / or, the method for calculating the relative transmembrane pressure difference when the pore is completely blocked:

[0066] p' is the relative transmembrane pressure difference when the pore is completely blocked. The relative transmembrane pressure difference is the ratio of the transmembrane pressure difference during the filtration process to the initial transmembrane pressure difference, and it is dimensionless.

[0067] p represents the transmembrane pressure difference during the filtration process when the pores are completely blocked, in kPa.

[0068] p0 is the initial transmembrane pressure difference when the pore is completely blocked, in kPa.

[0069] The V S The cumulative permeation rate when the pore is completely blocked, in L / m 2 ;

[0070] The K v The membrane fouling index is the result of complete pore blockage.

[0071] Furthermore, the test for flux recovery of the membrane module after cleaning also includes situations where the flux of the cleaned membrane module is the same as that of the new module.

[0072] The membrane in the cleaned membrane module is cut into small pieces, and the small pieces are formed on the small membrane module 15. The membrane in the new membrane module is cut into small pieces, and the small pieces are installed on the small membrane module 15. The new membrane module and the small membrane module 15 are subjected to simulated domestic wastewater pollution characteristics.

[0073] The ratio of the transmembrane pressure difference between the cleaned membrane module and the small membrane module 15 is equal to the ratio of their membrane resistances. The ratio of the membrane resistances of the small membrane module 15 is obtained by measuring the flux of the new membrane module and the cleaned membrane module under the same pressure. By incorporating the transmembrane pressure difference when the new membrane module is initially used, the transmembrane pressure difference of the MBR membrane module after cleaning can be predicted.

[0074] Furthermore, the ratio of the transmembrane pressure difference between the cleaned membrane module and the small membrane module 15 is equal to the ratio of their membrane resistances, as shown in the following formula:

[0075]

[0076] The formula for predicting the initial transmembrane pressure difference when the membrane module is put back into operation after cleaning is as follows:

[0077]

[0078] The P m0 The transmembrane pressure difference (kPa) during the initial operation of the new membrane module;

[0079] The R c Membrane resistance (m) after cleaning small membrane module 15 -1 );

[0080] The R m The new membrane resistance (m) of small membrane module 15 -1 );

[0081] The J C Membrane flux (LMH) after cleaning was measured for small membrane module 15;

[0082] The J m Membrane flux (LMH) of the new membrane was measured for small membrane module 15;

[0083] Furthermore, the method for predicting the cycle runtime is as follows: K is measured at different high fluxes in the small membrane module 15. v By linearly fitting the value to its corresponding flux, and then substituting the membrane operating flux into the fitting equation, the membrane fouling index K for different cleaning schemes after offline cleaning and continued operation can be calculated. fv ;

[0084] Through the initial transmembrane pressure difference (p) of the small membrane module 15 m0The flux (Jm, J) of the small membrane module 15 and the small membrane module 15 C It can calculate the initial transmembrane pressure p when the membrane module is put back into service after cleaning. C0 By using one of equations (7), (8), (9), or (10), the initial transmembrane pressure V of the cleaned membrane module when it is put back into operation can be obtained under the transmembrane pressure difference p during the filtration process. S Let p be the transmembrane pressure difference when the rating device stops operating; this can predict the operating time of the rating device after one cycle of cleaning under different cleaning schemes.

[0085] And / or, when the cleaned membrane module forms a filter cake layer, the predicted cumulative permeate flow rate at the time of filter cake layer clogging is calculated as follows:

[0086]

[0087] Equation (7) is the equation that best fits the membrane fouling mechanism when the filter cake layer is formed;

[0088] p represents the transmembrane pressure difference (kPa) during the filtration process when the filter cake layer of the membrane module becomes clogged after cleaning.

[0089] The V S The predicted cumulative permeate flow rate of the membrane module after cleaning, in L / m 2 ;

[0090] The p c0 The initial transmembrane pressure (kPa) when the membrane module is put back into service after cleaning;

[0091] The p m0 The transmembrane pressure of small membrane module 15 during initial operation, in kPa;

[0092] The J C LMH is the predicted membrane flux of the membrane module after cleaning.

[0093] The J m The membrane flux of small membrane module 15 is expressed in LMH.

[0094] The K fv The membrane fouling index of the membrane module when it is running on the evaluation device after cleaning;

[0095] And / or, when the intermediate pore is blocked, the method for calculating the predicted cumulative permeate volume of the membrane module after cleaning when the intermediate pore is blocked is as follows:

[0096]

[0097] Equation (8) is the equation that best fits the membrane fouling mechanism when the intermediate pore is blocked;

[0098] p is the transmembrane pressure difference during the filtration process when the intermediate pore of the membrane module is blocked after cleaning, in kPa;

[0099] The V S The predicted cumulative permeate flow rate of the membrane module after cleaning, in L / m 2 ;

[0100] The p c0 The initial transmembrane pressure (kPa) when the membrane module is put back into service after cleaning;

[0101] The p m0 The transmembrane pressure of small membrane module 15 during initial operation, in kPa;

[0102] The J C LMH is the predicted membrane flux of the membrane module after cleaning.

[0103] The J m The membrane flux of small membrane module 15 is expressed in LMH.

[0104] The K fv The membrane fouling index of the membrane module when it is running on the evaluation device after cleaning;

[0105] And / or, when the standard pores are blocked, the method for calculating the predicted cumulative permeate volume when the intermediate pores of the membrane module are blocked after cleaning is as follows:

[0106]

[0107] Equation (9) is the equation that best fits the standard pore blockage when the membrane fouling mechanism is met;

[0108] p represents the transmembrane pressure difference during the filtration process when the standard pores of the membrane module are clogged after cleaning, in kPa.

[0109] The V S The predicted cumulative permeate flow rate of the membrane module after cleaning, in L / m 2 ;

[0110] The p c0 The initial transmembrane pressure (kPa) when the membrane module is put back into service after cleaning;

[0111] The p m0 The transmembrane pressure of small membrane module 15 during initial operation, in kPa;

[0112] The J C LMH is the predicted membrane flux of the membrane module after cleaning.

[0113] The J m The membrane flux of small membrane module 15 is expressed in LMH.

[0114] The K fv The membrane fouling index of the membrane module when it is running on the evaluation device after cleaning;

[0115] And / or, in the case of complete pore blockage, the method for calculating the cumulative permeate volume of the membrane module after cleaning when the intermediate pores are blocked is as follows:

[0116]

[0117] Equation (10) is the equation that best fits the membrane fouling mechanism when the pores are completely blocked.

[0118] p is the transmembrane pressure difference during the filtration process when the membrane module is completely clogged after cleaning, in kPa;

[0119] The V S The predicted cumulative permeate flow rate of the membrane module after cleaning, in L / m 2 ;

[0120] The p c0 The initial transmembrane pressure (kPa) when the membrane module is put back into service after cleaning;

[0121] The p m0 The transmembrane pressure of small membrane module 15 during initial operation, in kPa;

[0122] The J C LMH is the predicted membrane flux of the membrane module after cleaning.

[0123] The J m The membrane flux of small membrane module 15 is expressed in LMH.

[0124] The K fv The membrane fouling index is the membrane fouling index of the membrane module when it is running on the evaluation device after cleaning.

[0125] Example 1:

[0126] S1. Equipment Connection: Connect the inlet tank 1, MBR unit 4, and outlet tank 12 sequentially via peristaltic pumps 2 and 11 through first pipe 3 and third pipe 10. Immerse the cleaned membrane bioreactor module 6 in the MBR unit 4. The cleaned membrane bioreactor module 6 is then connected sequentially to the first pressure sensor 8 and paperless recorder 9 via second pipe 7. Aeration pump 13 is connected to the aeration device in the MBR unit 4 via fourth pipe 14. The small membrane module 15, connected to pressure sensor 16, extends into beaker 19 via fifth pipe 17. Beaker 19 is placed on electronic balance 20. The connected equipment is as follows: Figure 1 As shown.

[0127] S2. Obtaining the fouled membrane: A laboratory-scale MBR (Mechanical Bioreactor) device was used to foul the PVDF hollow fiber membrane. The MBR device was made of plexiglass and had a volume of 4.86 L (18 cm × 12 cm × 45 cm). The effective volume of the MBR was 4 L, and the sludge concentration was controlled at 6000-7000 mg / L during the experiment. The feed water was artificially synthesized simulated domestic wastewater, with specific proportions shown in Table 1. The membrane flux was set to 18 LMH by adjusting the speed of the first peristaltic pump. The membrane flux was measured every 12 hours, and the speed of the first peristaltic pump was appropriately increased when the membrane flux decreased. The pumping-stopping time ratio was 8 min: 2 min. When the TMP reached 50 kPa, the membrane filtration system stopped, the membrane fouling process was completed, and the membrane module was removed from the reactor for subsequent experiments. The experimental setup diagram is shown below. Figure 1 .

[0128] Table 1 Composition of Simulated Domestic Wastewater

[0129]

[0130]

[0131] S3, Membrane Cleaning Solution

[0132] Two simple cleaning methods were selected for membrane cleaning in the experiment:

[0133] Option A: Soak in deionized water for 1 hour, then soak in 2000 mg / L NaClO for 1 hour.

[0134] Option B: Soak in deionized water for 1 hour, then soak in 37.5 g / L citric acid for 1 hour; then soak in 2000 mg / L NaClO for 1 hour.

[0135] S4. Determination of pure water flux and cleaning efficiency of the membrane after cleaning.

[0136] The membrane fibers of the membrane bioreactor module were cut and cleaned in batches using cleaning schemes A and B. After cleaning, they were dried to form small membrane modules with an effective fiber length of 16 cm and a membrane area of ​​0.001 m². 2 The membrane was stabilized by pre-pressing it with deionized water at 60 kPa for 40 min, and then the pure water flux was measured according to the following formula.

[0137]

[0138] Where J is the membrane flux (LMH); V represents the filtration volume (L); and A represents the membrane area (m²). 2 t represents the time (h) for collecting the liquid.

[0139] The cleaning efficiency is evaluated as a percentage reduction in membrane flux. The formula is as follows:

[0140]

[0141] In the formula: where R is the cleaning efficiency, %; J C For membrane flux after cleaning, LMH; J f For fouling membrane flux, LMH; J m For small membrane flux, LMH.

[0142] Determination of S5 and MFI values

[0143] (1) After cleaning the membrane module and measuring the pure water flux, adjust the membrane flux to 40 LMH (60 LMH, 80 LMH, 100 LMH) and place it in the MBR device. Record the pressure gauge reading p (kPa) and the cumulative filtration volume V every 5 minutes. S (L / m 2 If the flux decreases, the speed of the first peristaltic pump is adjusted to keep the membrane flux constant.

[0144] The four fouling mechanisms are cake formation, intermediate pore clogging, standard pore clogging, and complete pore clogging. Cake formation refers to the formation of a cake layer on the membrane surface instead of entering the membrane pores. Intermediate pore clogging refers to the complete blockage of membrane pores by contaminants, which also adhere to the membrane surface. Standard pore clogging occurs when the diameter of the contaminants is smaller than the diameter of the membrane pores, depositing and adhering inside the pores, thus shrinking the pore size. Complete pore clogging occurs when all contaminants clog the membrane pores. This ideal condition assumes that no particles are located on top of other particles (i.e., no cake formation) or on the membrane surface between pores.

[0145] (2) Based on the four pollution mechanism formulas, the obtained data were compared by linear fitting R. 2 To verify the pollution mechanism.

[0146] (3) According to R 2 The slope obtained from the formula corresponding to the maximum value is the MFI value K. v .

[0147] S6. Validation of the new evaluation method

[0148] In the MBR unit, membrane fouling was performed according to the membrane fouling method in S2. After fouling was completed, the entire cleaned membrane bioreactor module was removed and cleaned according to the cleaning method in S3. After cleaning, it was put back into the MBR unit for operation at a constant flux of 18 LMH. The paperless recorder recorded the pressure gauge reading p (kPa) every 10 minutes. The p value of the cleaned membrane bioreactor module when it was put back into use was determined based on the pressure reading p. C0 The new evaluation method was validated by comparing and ranking the MFI value, runtime, and prediction results of small membrane modules.

[0149] (1) Analysis of prediction results for small membrane modules

[0150] Based on the experimental results of the small membrane module, p, p0, and V were obtained. S A linear fit was performed on the membrane fouling mechanism. Based on the R² value of the fitted equation for the membrane fouling mechanism... 2 As shown in Table 2, the membrane fouling mechanism after cleaning with schemes A and B at 40 LMH, 60 LMH, 80 LMH, and 100 LMH is most consistent with the formation of filter cake.

[0151] Table 2. R-values ​​of membrane fouling mechanisms fitted to small membrane modules after cleaning schemes A and B. 2 Compare

[0152]

[0153] As shown in Figure (2a), the cleaning efficiency of scheme A is about 56.4%, and the cleaning efficiency of scheme B is about 73%. Based on the cleaning efficiency, the order is A < B.

[0154] K is obtained under the above different fluxes. v The results obtained by linearly fitting the value with the corresponding membrane flux are shown in Figure (2b). Substituting the operating flux of 18 LMH into the fitting formula, the K value can be calculated for the MBR to continue operation after offline cleaning in both Schemes A and B. fv The values ​​are 3.10 × 10⁻³ m. 2 / L, 8.54×10-3m 2 / L( Figure 3 a).

[0155] Since the contamination mechanism is consistent with filter cake formation, the obtained values ​​are substituted into the formula. In, J m It is 141.45 LMH, p m0 For 3 kPa, Scheme A, J C For 83.14LMH, Scheme J C 104.96 LMH Figure 2 a) This gives us p and V. S The expressions (Table 3) are used to obtain p for schemes A and B. C0 The values ​​are 5.10 kPa and 4.43 kPa respectively. Substituting the p = 50 kPa at the end of the run, we can obtain the V of scheme A. S 3461 L / m 2 V of scheme B S 1381 L / m 2 ( Figure 3 b).

[0156] Table 3 shows p and V after cleaning for schemes A and B.S Fitting formula

[0157] Cleaning solution Fitting formula A <![CDATA[p=0.013V S +5.10]]> B <![CDATA[p=0.033V S +4.43]]>

[0158] For K fv The value comparison shows that scheme A < B, which predicts that the MFI ranking will be A < B when the MBR membrane module is cleaned and put back into use. For p C0 The comparison shows that scheme A > B. This predicts that the initial transmembrane pressure difference ranking when the MBR membrane module is cleaned and put back into use is A > B. For V S The comparison shows that scheme A > B, which predicts that the operating time of the MBR membrane module after cleaning with scheme A will be longer than that after cleaning with scheme B.

[0159] The above results demonstrate that different cleaning schemes will result in different rankings of the membrane cleaning effect depending on whether the evaluation is based solely on cleaning efficiency or on a combination of membrane cleaning efficiency and MFI.

[0160] (2) Validation of the new evaluation method in MBR membrane modules

[0161] Figures (4a-b) show the change in transmembrane pressure difference over time during the MBR membrane module's restart after cleaning. The initial transmembrane pressure difference of the small membrane was approximately 3 kPa, and the usage time was approximately 18 days. The p values ​​for schemes A and B are... C0 The values ​​are 10.5 kPa and 9.5 kPa, respectively. Based on p... C0 The order is A > B, which is consistent with the prediction results for the small membrane module (Table 3).

[0162] Further, we can obtain p, p C0 and V S By performing linear fitting on the obtained data according to the membrane fouling mechanism, the corresponding R0 can be obtained. 2 (Table 4). By comparing R... 2 It can be seen that the membrane fouling mechanism is still most consistent with the formation of the filter cake layer, indicating that the fouling mechanism of the small membrane module is the same as that of the MBR membrane module. Using the formula for the filter cake layer formation mechanism, the p / p0 and V values ​​during the entire MBR membrane module operation process are analyzed. S Linear fitting was performed, and the results are shown in Figure (5a). The K value of scheme A is... fv The value is 5.06 × 10 -5 m 2 / L, K of scheme B fv The value is 5.64 × 10 -5 m 2 / L, the MFI of scheme A is less than that of B, which is consistent with the prediction results of the small membrane module. Figure 3a) However, the MFI (Mean Fractional Fiber) is tens of times lower than that of small membrane modules. Generally speaking, the MFI of laboratory-scale projects is also higher than that of actual-scale projects. [8] .

[0163] As can be seen from Figure (4d), the time required for membranes in schemes A and B to be reused after cleaning is approximately 216 hours and 202 hours, respectively (V for schemes A and B). S Approximately 8100 L / m 2 76000L / m 2 Based on runtime, the result is that scheme A > B, which is consistent with the prediction results for small membrane modules. Figure 3 b).

[0164] Table 4 shows the R-values ​​for fitting the membrane fouling mechanism of MBR membrane modules after cleaning schemes A and B. 2 Compare

[0165]

[0166] Note: A1 and A2; B1 and B2 are parallel groups.

[0167] The above results indicate that:

[0168] (1) The evaluation of membrane cleaning effect based solely on the recovery of membrane flux after cleaning and the evaluation of membrane cleaning effect together with MFI will have different rankings: based solely on the recovery of membrane flux, the ranking is A < B; while based on the predicted runtime of small membrane modules after adding MFI, the ranking is A > B.

[0169] (2) Based on the validation results of the MBR membrane module, the MFI ranking during the membrane reuse process after cleaning is A < B; p C0 The ranking is A > B; the ranking of the runtime after the cleaning membrane is put back into use is A > B. All three results are the same as the prediction results of the small membrane module, which proves the feasibility of the new evaluation method for membrane cleaning.

[0170] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for testing the cleaning effect of an MBR membrane, characterized in that: Includes MBR unit, aeration assembly, first pressure sensor assembly, effluent assembly, small membrane assembly, second pressure sensor assembly, weighing assembly, and influent assembly; The aeration components are located at the bottom of the MBR unit, and the cleaned membrane module to be tested is installed inside the MBR unit. The inlet assembly is connected to the lower part of the MBR unit via the first pipe; The membrane module whose cleaning effect is to be tested is connected to the first pressure sensor module through a second pipe, and the second pipe is connected to the water outlet module through a third pipe. The aeration components are connected to the MBR unit via a fourth pipe; The small membrane module is located in the upper part of the MBR unit. The small membrane module is connected to the weighing component through the fifth pipe, and the fifth pipe is equipped with a second pressure sensor component.

2. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The water inlet assembly includes a water inlet tank and a first peristaltic pump; The water inlet tank is connected to the interior of the MBR unit through the first pipe, and the first peristaltic pump is installed on the first pipe.

3. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The aeration assembly includes an aeration pump and an aeration plate. The aeration pump is connected to the aeration plate through a fourth pipe, and the aeration plate is provided with several aeration holes. The aeration plate is installed inside the MBR unit and is positioned below the membrane module whose cleaning effect is to be tested.

4. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The first pressure sensor assembly includes a first pressure sensor and a paperless recorder. The first pressure sensor is disposed on the second pipe and is electrically connected to the controller. The first pressure sensor is electrically connected to the paperless recorder, and the first pressure sensor is electrically connected to the controller.

5. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The water outlet assembly includes a second peristaltic pump and a water outlet tank. A second pipe is connected to the water outlet tank through a third pipe, and the second peristaltic pump is installed on the third pipe.

6. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The second pressure sensor assembly includes a second pressure sensor, a small diaphragm assembly connected to the weighing assembly via a fifth pipe, the second pressure sensor being mounted on the fifth pipe, and the second pressure sensor being electrically connected to the controller.

7. The MBR membrane cleaning effect testing device according to claim 1, characterized in that: The weighing assembly includes a third peristaltic pump, a beaker, and an electronic balance. The small membrane assembly is connected to the beaker through a fifth pipe. The third peristaltic pump is installed on the fifth pipe, and the electronic balance is located below the beaker and is mounted on a flat surface.

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