Evaluation method for trend of membrane pollution and blockage caused by sewage

Abstract

The invention provides a method for evaluating the tendency of ultrafiltration membrane pollution blockage caused by sewage. The evaluation method comprises the following steps: taking a sewage sample to be treated as a water sample to be detected; controlling the to-be-detected water sample to pass through the filter membrane; recording the accumulated volume V500 of the sewage passing through the filter membrane at the 500th second, indicating that the degree of sewage blockage of the ultrafiltration membrane is smaller when the value of the V500 is larger, and otherwise, indicating that the degree of sewage blockage of the ultrafiltration membrane is larger; the method can effectively guide the design and planning of the regeneration process of the complex component sewage with the turbidity larger than 1.0 NTU, makes decisions for selection of an ultrafiltration membrane process, how to upgrade and reconstruct a front-end process of an existing ultrafiltration membrane workshop, an ultrafiltration membrane regeneration strategy and the like, rapidly provides data support, is simple, and is easy to obtain and assemble required equipment and materials. The test work can be quickly carried out aiming at a small amount of sewage samples.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and more specifically, relates to a method for assessing the tendency of wastewater to cause membrane fouling. Background Technology

[0002] Ultrafiltration membranes are widely used in wastewater regeneration processes, but they suffer from the problem of membrane fouling leading to decreased membrane flux and consequently reduced permeate production. Therefore, in process design, there is a lack of a method to predict the fouling trend of wastewater quality on ultrafiltration membranes, making it difficult to determine whether to use ultrafiltration for different water qualities, or to decide how to upgrade existing ultrafiltration processes in regeneration plants.

[0003] Current membrane fouling index testing methods and standards only apply to reverse osmosis or nanofiltration processes, lacking methods for assessing the fouling trend of ultrafiltration membranes. The influent quality of ultrafiltration membrane filtration processes differs significantly from that of reverse osmosis or nanofiltration processes, exhibiting higher concentrations of suspended solids, organic matter, and metal ions, and turbidity >1.0 NTU. Therefore, it is impossible to predict the fouling trend of the wastewater in ultrafiltration processes using methods provided by relevant standards such as Water Fouling Index Measurement (DL / T 588-2015), Reverse Osmosis Feed Water Modified Fouling Index Measurement Method (GB / T 45141-2025), and ASTM D8002-15 Standard Test Method for Modified Fouling Index (MFI-0.45) of Water, because these methods all specify that "this standard applies to the determination of the fouling index of reverse osmosis feed water with turbidity not exceeding 1.0 NTU."

[0004] Existing methods for predicting ultrafiltration membrane fouling employ big data modeling and neural network modeling techniques, relying on a large amount of existing operational data and datasets. However, for water samples that have not undergone ultrafiltration membrane processing, it is difficult to obtain a large amount of operational data in a short period of time. In addition, existing methods are all designed for online monitoring and early warning of existing ultrafiltration membrane facilities. These methods are complex, require sophisticated equipment and materials, and are difficult to quickly conduct tests on a small number of water samples.

[0005] This invention provides a method for assessing the tendency of wastewater to foul ultrafiltration membranes. Based on existing standard methods, the measurement method is optimized, which significantly reduces the time required for assessment, facilitates rapid laboratory operation and conclusion, and fills the gap in the assessment technology and method for assessing the tendency of wastewater to foul ultrafiltration membranes. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for assessing the tendency of wastewater to cause membrane fouling. This method solves the problems mentioned in the background art, such as the complexity of existing methods for predicting ultrafiltration membrane fouling, the complexity of the required equipment and materials, and the difficulty in quickly conducting tests on a small number of water samples.

[0007] To achieve the above objectives, the present invention provides a method for assessing the tendency of wastewater to cause fouling of ultrafiltration membranes, the method comprising: The wastewater sample to be treated was used as the water sample to be tested. Control the passage of the water sample to be tested through the ultrafiltration membrane; Record the cumulative volume V of wastewater passing through the ultrafiltration membrane at the 500th second. 500 V 500 A higher value indicates a lesser degree of fouling of the ultrafiltration membrane, and vice versa.

[0008] Preferably, taking the wastewater sample to be treated as the water sample to be tested includes: For wastewater with complex components and turbidity > 1.0 NTU, samples were taken and used as test samples to evaluate the fouling trend of ultrafiltration membranes.

[0009] Preferably, the amount of wastewater sample to be treated is 1 to 10 L.

[0010] Preferably, the evaluation method further includes, before controlling the water sample to be tested to pass through the filter membrane: The testing device was constructed according to the standard method for determining the water pollution index.

[0011] Preferably, controlling the water sample to be tested to pass through the filter membrane includes: Observe the pressure gauge reading connected to the inlet of the microporous filter. When the pressure reaches 207 kPa, open the sampling valve connected to the container holding the wastewater to be tested.

[0012] Preferably, if a leak is found around the microporous filter used to install the filter membrane, the filter membrane should be replaced and the test performed.

[0013] Preferably, the cumulative volume V of wastewater passing through the filter membrane at the 500th second of recording is... 500 include: Use a stopwatch to time the process for 500 seconds, and read and record the cumulative volume V of wastewater passing through the filter membrane at the 500th second of filtration. 500 ...

[0014] Preferably, the set threshold is [value missing].

[0015] Preferably, after the measurement is completed, check whether the filter membrane is damaged or has an off-flow. If it is damaged or has an off-flow, replace the ultrafiltration membrane and re-evaluate.

[0016] This invention provides a method for assessing the tendency of wastewater to foul ultrafiltration membranes. The method is characterized by recording the cumulative volume V of wastewater passing through the membrane at the 500th second as the water sample passes through it. 500 Units: L, V 500 The higher the value, the less fouling of the ultrafiltration membrane, and vice versa. It can effectively guide the design and planning of wastewater regeneration processes for complex components with turbidity > 1.0 NTU, and provide rapid data support for decision-making on ultrafiltration membrane process selection, how to upgrade and transform the front-end processes of existing ultrafiltration membrane workshops, and ultrafiltration membrane regeneration strategies. The method is simple, the required equipment and materials are relatively easy to obtain and assemble, and it can quickly carry out testing on a small number of wastewater samples.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0019] Figure 1 A flowchart is shown for a method for assessing the tendency of wastewater to foul ultrafiltration membranes according to an embodiment of the present invention. Detailed Implementation

[0020] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0021] like Figure 1 As shown, this invention provides a method for assessing the tendency of wastewater to cause fouling of ultrafiltration membranes. The method includes: The wastewater sample to be treated was used as the water sample to be tested. Control the water sample to be tested to pass through the filter membrane; Record the cumulative volume V of wastewater passing through the filter membrane at the 500th second. 500 V 500 A higher value indicates a lesser degree of fouling of the ultrafiltration membrane, and vice versa.

[0022] Specifically, to address the problems of existing methods for predicting fouling in ultrafiltration membrane processes being complex, requiring sophisticated equipment and materials, and making it difficult to quickly conduct tests on small amounts of water samples, this application provides a method for assessing the tendency of wastewater to cause membrane fouling. This method records the cumulative volume V of wastewater passing through the filter membrane at the 500th second when the water sample to be tested passes through the membrane. 500 Units: L, V 500 The higher the value, the less fouling of the ultrafiltration membrane, and vice versa. The wastewater to be treated includes various types of domestic sewage, industrial wastewater, secondary effluent from sewage treatment plants, total discharge from reclaimed water plants, and landscape water bodies with turbidity > 1.0 NTU.

[0023] This evaluation method can effectively guide the design and planning of wastewater regeneration processes for complex components with turbidity > 1.0 NTU, and provide rapid data support for decision-making on the selection of ultrafiltration membrane processes, how to upgrade and transform the front-end processes of existing ultrafiltration membrane workshops, and ultrafiltration membrane regeneration strategies.

[0024] This assessment method uses the testing devices and materials of the Water Pollution Index Determination (DL / T 588-2015) standard. Mature technology and equipment are relatively easy to obtain and assemble, eliminating the need for massive historical data accumulation, manual training, or chemical reagent procurement. The test platform setup time is significantly shortened, making it highly valuable for practical engineering applications.

[0025] This evaluation method allows for testing with a laboratory sample of the wastewater to be tested, even without any existing data on the operation or testing of ultrafiltration membrane technology in the wastewater being tested, thus providing a rapid conclusion.

[0026] Preferably, taking the wastewater sample to be treated as the water sample to be tested includes: For wastewater with complex components and turbidity > 1.0 NTU, samples were taken and used as test samples to evaluate the filter membrane fouling trend.

[0027] Specifically, addressing the trend of ultrafiltration membrane fouling caused by wastewater with complex components and turbidity > 1.0 NTU that cannot be determined, this evaluation method significantly reduces the time required to set up the testing platform, shortens the evaluation time, and facilitates rapid laboratory operation and result acquisition. This evaluation method can effectively guide the design and planning of wastewater regeneration processes, provide rapid data support for decision-making on the selection of ultrafiltration membrane processes and how to upgrade and transform the front-end processes of existing ultrafiltration membrane workshops, and shorten the design and planning cycle.

[0028] Preferably, the amount of wastewater sample to be treated is 1 to 10 L.

[0029] Specifically, only 1 to 10 liters of wastewater sample is needed, which allows for rapid testing of small amounts of wastewater samples and improves work efficiency.

[0030] Preferably, the evaluation method further includes, before controlling the water sample to be tested to pass through the filter membrane: The testing device was constructed according to the standard method for determining the water pollution index.

[0031] Specifically, the testing device should be built according to the standard method in the Water Pollution Index Determination (DL / T 588-2015), regardless of brand or model.

[0032] Preferably, controlling the water sample to be tested to pass through the filter membrane includes: Observe the pressure gauge reading connected to the inlet of the microporous filter. When the pressure reaches 207 kPa, open the sampling valve connected to the container holding the wastewater to be tested.

[0033] Preferably, if a leak is found around the microporous filter used to install the filter membrane, the filter membrane should be replaced and the test performed.

[0034] Preferably, the cumulative volume V of wastewater passing through the filter membrane at the 500th second is recorded. 500 include: Use a stopwatch to time the process for 500 seconds, and read and record the cumulative volume V of wastewater passing through the filter membrane at the 500th second of filtration. 500 .

[0035] Preferably, after the measurement is completed, check whether the ultrafiltration membrane is damaged or has an off-flow. If it is damaged or has an off-flow, replace the ultrafiltration membrane and re-evaluate.

[0036] In summary, the assessment method for the tendency of wastewater to cause membrane fouling in this application is compared with existing methods for determining the water pollution index (DL / T 588-2015), the method for determining the corrected pollution index of reverse osmosis feed water (GB / T 45141-2025), and ASTM D. The specific comparison method is as follows: Three types of wastewater samples were collected, all with turbidity > 1.0 NTU; Assessing relative stability: using the relative standard deviation (RSD), the formula is:

[0037] Generally, RSD > 5% is considered to indicate poor stability; RSD < 5% is considered to indicate good stability; and RSD < 1% is considered to indicate excellent stability. Assessment of repeatability: The repeatability limit (r), based on the t-distribution, is used to determine the permissible difference between any two measurements of each water sample. The formula is:

[0038] The repeatability limit r indicates that the absolute difference between any two measurements of each water sample should not exceed r. For example, if r = 0.5, then a difference of > 0.5 between two measurements is considered suspicious and has poor reproducibility. Where the standard deviation SD is: Formula:

[0039] The detection results, stability, and repeatability results of the four methods are shown in the table below.

[0040]

[0041] The above results show that, compared with the water pollution index determination method (DL / T 588-2015) in the comparative methods, this application can accurately characterize the differences between the three water samples. Compared with the reverse osmosis feed water corrected pollution index determination method (GB / T 45141-2025) and ASTMD in the comparative methods, the standard deviation of the reverse osmosis feed water corrected pollution index determination method (GB / T 45141-2025) and ASTMD is greater than 5%, and the data difference exceeds the repeatability limit r, resulting in test results with low stability and poor repeatability. The test results of this application have a standard deviation of less than 5%, and the data difference is within the repeatability limit r, indicating good data stability and high reproducibility. Therefore, it is obvious that the three existing methods compared in this application are not applicable to wastewater with turbidity > 1.0 NTU and cannot accurately characterize its tendency to cause membrane fouling of ultrafiltration membranes.

[0042] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for evaluating the tendency of membrane fouling by sewage, characterized by, The evaluation method comprises: Taking a sewage sample to be treated as a water sample to be detected; Controlling the water sample to be detected to pass through a filter membrane; Record the cumulative volume V of the sewage passing through the filter membrane at the 500th second 500 , V 500 The larger the value indicates the smaller the degree of causing the fouling of the ultrafiltration membrane, and vice versa.

2. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 1, characterized in that, The step of taking a sewage sample to be treated as a water sample to be detected comprises: For complex sewage to be treated with turbidity > 1.0 NTU, after taking the sample, the sample is taken as a water sample to be detected to evaluate the fouling trend of the ultrafiltration membrane.

3. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 2, characterized in that, The amount of the sewage sample to be taken is 1-10 L.

4. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 1, characterized in that, The evaluation method further comprises, before the step of controlling the water sample to be detected to pass through a filter membrane: According to the standard method for determining the water pollution index, a detection device is built.

5. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 4, characterized in that, The step of controlling the water sample to be detected to pass through a filter membrane comprises: Observing the indicated value of a pressure gauge connected to the inlet end of the microporous filter, and opening a sampling valve connected to a container containing the sewage to be detected when the indicated value is 207 kPa.

6. The method of claim 4, wherein the membrane fouling tendency is determined by the following equation: ###0001### wherein, A is the area of the membrane, V is the volume of the feed, t is the time, and C is the concentration of the foulant in the feed. If leakage is found around the microporous filter for installing the filter membrane, the filter membrane should be replaced for determination.

7. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 1, characterized in that, The record cumulative volume V of the sewage passing through the filter membrane at the 500th second 500 comprising: Time 500 s with a stopwatch, read and record the cumulative volume V of sewage through the filter membrane at the 500th second of filtration 500 .

8. The method for assessing the tendency of wastewater to cause membrane fouling according to claim 1, characterized in that, After the determination is completed, it is checked whether the filter membrane is damaged or deflected, and if so, the ultrafiltration membrane is replaced for reevaluation.

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