A wastewater treatment method based on A2O-MBR membrane technology

Abstract

The application provides a sewage treatment method based on A2O-MBR membrane technology, and belongs to the technical field of sewage treatment. The technical scheme is as follows: step one, pretreating sewage; step two, feeding the pretreated sewage into an improved A2O biological treatment section; step three, carrying out sludge refluxing between the anaerobic section, the anoxic section and the aerobic section; step four, carrying out MBR membrane separation on the sewage treated by the improved A2O biological treatment; step five, carrying out advanced treatment on the effluent after the MBR membrane separation; and step six, intelligently controlling and energy-saving adjusting the system operation process and monitoring system operation parameters in real time. The application has the beneficial effects that: the application combines biological denitrification and dephosphorization, membrane separation and intelligent control, improves the sewage treatment efficiency and the effluent stability, reduces membrane pollution and operation energy consumption, and takes into account sludge reduction and water reuse.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment method based on A²O-MBR membrane technology. Background Technology

[0002] Traditional A²O processes have certain limitations in wastewater treatment applications. First, nitrogen and phosphorus removal efficiency is limited. Due to conflicting carbon source distribution, there is competition between denitrification and phosphorus release, making simultaneous and efficient removal of total nitrogen (TN) and total phosphorus (TP) difficult. Second, sludge settling is poor, and sludge concentration fluctuations in the biological treatment stage easily lead to sludge bulking, which in turn affects the stability of the effluent from the secondary settling tank. Third, traditional A²O processes typically require multiple stages of structures connected in series, resulting in a large footprint and high infrastructure costs.

[0003] Although MBR technology can replace secondary sedimentation tanks through membrane separation, it still has problems such as rapid membrane fouling, high energy consumption, and poor adaptability to high-concentration wastewater when used alone. Summary of the Invention

[0004] The purpose of this invention is to provide a wastewater treatment method based on A²O-MBR membrane technology that combines biological nitrogen and phosphorus removal, membrane separation and intelligent control to improve wastewater treatment efficiency and effluent stability, reduce membrane fouling and operating energy consumption, and take into account sludge reduction and reclaimed water reuse.

[0005] This invention is achieved through the following measures: A wastewater treatment method based on A²O-MBR membrane technology, characterized by the following steps: Step 1: Pre-treating the wastewater by using a screen to intercept suspended solids, using a vortex grit chamber to remove sand and inorganic particles, and adding a pH adjuster; Step 2: Sending the pre-treated wastewater into a modified A²O biological treatment section, where it undergoes segmented influent treatment in proportions of anaerobic, anoxic, and aerobic sections; Step 3: Performing sludge recirculation between the anaerobic, anoxic, and aerobic sections; Step 4: Performing MBR membrane separation on the wastewater after modified A²O biological treatment; Step 5: Perform advanced treatment on the effluent after MBR membrane separation, including chemical phosphorus removal and sodium hypochlorite disinfection, to obtain reclaimed water; Step 6: Implement intelligent control and energy-saving adjustment of the system operation process, monitor system operating parameters in real time, calculate the TMP rise rate based on continuously collected transmembrane pressure difference (TMP) data, and input the TMP value, TMP rise rate, and real-time water quality parameters into the prediction model to output the next membrane cleaning time or the estimated remaining operating time; dynamically adjust the aeration rate and reflux ratio based on the prediction results and water quality changes, and perform variable frequency control.

[0006] The invention also has the following specific features: In step one, the screen includes a coarse screen with a gap of 20 mm and a fine screen with a gap of 3 mm. The pH adjuster is sodium bicarbonate, and the pH value of the wastewater is controlled between 6.8 and 7.2.

[0007] In step two, the anaerobic, anoxic, and aerobic sections of the modified A²O biological treatment section are set in proportions of 50%, 30%, and 20%, respectively.

[0008] In step two, the hydraulic retention time of the anaerobic section is 2-3 hours, the hydraulic retention time of the anoxic section is 4-5 hours, and the hydraulic retention time of the aerobic section is 8-10 hours. In the anoxic section, a slow-release carbon source of polycaprolactone is added, while in the aerobic section, microporous aeration discs are used for aeration, and the dissolved oxygen in the aerobic section is controlled at 2-3 mg / L.

[0009] In step three, the recirculation ratio from the aerobic section to the anoxic section is 100%-150%, and the recirculation ratio from the anoxic section to the anaerobic section is 50%-80%.

[0010] In step four, a PVDF (polyvinylidene fluoride) hollow fiber membrane is used for MBR membrane separation. The membrane has a pore size of 0.1-0.2 μm and a membrane flux of 15-20 L / m²·h. In step four, the MBR membrane separation adopts an intermittent suction operation mode, running for 8 minutes and then stopping for 2 minutes. Backwashing was performed using a mixture of sodium hypochlorite and citric acid, with a backwashing cycle of 24 hours. The sludge concentration was maintained at 8000-12000 mg / L MLSS.

[0011] In step five, chemical phosphorus removal involves adding polyaluminum chloride (PAC) to the effluent after MBR membrane separation to reduce total phosphorus to below 0.3 mg / L. Then, sodium hypochlorite is used for disinfection. The disinfected effluent is used for plant landscaping or industrial cooling water.

[0012] In step six, the real-time monitored system operating parameters include COD, NH3-N, TN, TP, and transmembrane pressure difference TMP; The TMP rise rate is calculated based on the TMP difference between adjacent sampling times and the corresponding time interval. The prediction model is built based on historical operating data, which includes at least historical TMP time series data, TMP rise rate data, and COD, NH3-N, TN, and TP data for the corresponding time period, and uses historical cleaning time or historical cleaning interval as training labels. The trained prediction model receives the current TMP value, TMP rise rate, and current water quality parameters, and outputs the next membrane cleaning time or the estimated remaining runtime.

[0013] The beneficial effects of this invention are as follows: By combining biological nitrogen and phosphorus removal, membrane separation, and intelligent control, this invention improves wastewater treatment efficiency and effluent stability, reduces membrane fouling and operating energy consumption, and also takes into account sludge reduction and reclaimed water reuse. By coupling the modified A²O process with MBR membrane technology, the carbon source competition problem can be improved, and the nitrogen and phosphorus removal capacity can be enhanced. Backwashing with a mixture of sodium hypochlorite and citric acid helps delay membrane fouling and improves the operating status of the membrane modules. Maintaining a high sludge concentration reduces excess sludge production. By monitoring and controlling parameters such as COD, NH3-N, TN, TP, and TMP in a coordinated manner, and inputting TMP values, TMP rise rates, and real-time water quality parameters into a predictive model to predict cleaning cycles, intelligent control and energy-saving regulation have clear data sources, prediction targets, and control paths, thereby improving the automation and stability of system operation. Detailed Implementation

[0014] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0015] Example 1 A wastewater treatment method based on A²O-MBR membrane technology includes the following steps: Step 1: Pre-treatment of wastewater. The wastewater is graded and intercepted using coarse screens with a 20mm gap and fine screens with a 3mm gap to remove suspended solids; a vortex grit chamber is used to remove sand and inorganic particles; sodium bicarbonate is added as a pH adjuster to control the wastewater pH to 6.8.

[0016] Step 2: Implement modified A²O biological treatment. The modified A²O biological treatment section is divided into anaerobic, anoxic, and aerobic sections in a ratio of 50%, 30%, and 20%, respectively. The hydraulic retention time (HRT) of the anaerobic section is 2 hours; the HRT of the anoxic section is 4 hours, with polycaprolactone slow-release carbon source added; and the HRT of the aerobic section is 8 hours, using microporous aeration discs for aeration, with dissolved oxygen (DO) controlled at 2-3 mg / L.

[0017] Step 3: Perform sludge recirculation. The recirculation ratio from the aerobic zone to the anoxic zone is 150%, and the recirculation ratio from the anoxic zone to the anaerobic zone is 80%.

[0018] Step 4: Perform MBR membrane separation. A PVDF hollow fiber membrane with a pore size of 0.1 μm and a membrane flux of 15 L / m²·h was selected. An intermittent suction operation mode was adopted, with a 2-minute pause after every 8 minutes of operation. Backwashing was performed using a mixture of sodium hypochlorite and citric acid, with a backwashing cycle of 24 hours. The sludge concentration was maintained at 8000 mg / L MLSS.

[0019] Step 5: Advanced treatment. Polyaluminum chloride (PAC) is added to the MBR effluent for chemical phosphorus removal, reducing TP to below 0.3 mg / L; then sodium hypochlorite is used for disinfection; the disinfected effluent is used for plant landscaping or industrial cooling water.

[0020] Step Six: Implement Intelligent Control and Energy-Saving Adjustment. Real-time data collection of COD, NH3-N, TN, TP, and transmembrane pressure differential (TMP) is performed, forming an operational dataset according to a preset sampling period. The TMP rise rate is calculated based on continuously collected TMP time-series data, with the current TMP value and rise rate serving as the basis for membrane fouling early warning. A prediction model is established based on historical operational data, which includes at least historical TMP time-series data, TMP rise rate data, and corresponding COD, NH3-N, TN, and TP data for the corresponding time periods, using historical cleaning times or intervals as training labels. The trained prediction model receives the current TMP value, TMP rise rate, and current water quality parameters, outputting the next membrane cleaning time or the estimated remaining runtime to obtain a cleaning cycle prediction result. Based on the cleaning cycle prediction result and real-time water quality changes, the aeration rate and reflux ratio are dynamically adjusted, and system energy consumption is reduced through frequency conversion control.

[0021] Example 2 A wastewater treatment method based on A²O-MBR membrane technology includes the following steps: Step 1: Pre-treatment of wastewater. Wastewater is graded and intercepted using coarse screens (20mm gap) and fine screens (3mm gap) to remove suspended solids; a vortex grit chamber is used to remove sand and inorganic particles; sodium bicarbonate is added as a pH adjuster to control the wastewater pH to 7.2.

[0022] Step 2: Implement modified A²O biological treatment. The modified A²O biological treatment section is divided into anaerobic, anoxic, and aerobic sections in a ratio of 50%, 30%, and 20%, respectively. The hydraulic retention time (HRT) of the anaerobic section is 3 hours; the HRT of the anoxic section is 5 hours, with polycaprolactone slow-release carbon source added; the HRT of the aerobic section is 10 hours, using microporous aeration discs for aeration, and the dissolved oxygen (DO) is controlled at 2-3 mg / L.

[0023] Step 3: Perform sludge recirculation. The recirculation ratio from the aerobic zone to the anoxic zone is 100%, and the recirculation ratio from the anoxic zone to the anaerobic zone is 50%.

[0024] Step 4: Perform MBR membrane separation. A PVDF hollow fiber membrane with a pore size of 0.2 μm and a membrane flux of 20 L / m²·h was selected. An intermittent suction operation mode was adopted, with a 2-minute pause after every 8 minutes of operation. Backwashing was performed using a mixture of sodium hypochlorite and citric acid, with a backwashing cycle of 24 hours. The sludge concentration was maintained at 12000 mg / L MLSS.

[0025] Step 5: Advanced treatment. Polyaluminum chloride (PAC) is added to the MBR effluent for chemical phosphorus removal, reducing TP to below 0.3 mg / L; then sodium hypochlorite is used for disinfection; the disinfected effluent is used for plant landscaping or industrial cooling water.

[0026] Step Six: Implement Intelligent Control and Energy-Saving Adjustment. Real-time data collection of COD, NH3-N, TN, TP, and transmembrane pressure differential (TMP) is performed, forming an operational dataset according to a preset sampling period. The TMP rise rate is calculated based on continuously collected TMP time-series data, with the current TMP value and rise rate serving as the basis for membrane fouling early warning. A prediction model is established based on historical operational data, which includes at least historical TMP time-series data, TMP rise rate data, and corresponding COD, NH3-N, TN, and TP data for the corresponding time periods, using historical cleaning times or intervals as training labels. The trained prediction model receives the current TMP value, TMP rise rate, and current water quality parameters, outputting the next membrane cleaning time or the estimated remaining runtime to obtain a cleaning cycle prediction result. Based on the cleaning cycle prediction result and real-time water quality changes, the aeration rate and reflux ratio are dynamically adjusted, and system energy consumption is reduced through frequency conversion control.

[0027] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A wastewater treatment method based on A²O-MBR membrane technology, characterized in that, Includes the following steps: Step 1: Pre-treat the wastewater using a screen to intercept suspended solids, a vortex grit chamber to remove sand and inorganic particles, and add a pH adjuster. Step 2: Send the pre-treated wastewater to the modified A²O biological treatment section, where it is treated in stages according to the proportions of the anaerobic, anoxic, and aerobic sections. Step 3: Perform sludge recirculation between the anaerobic, anoxic, and aerobic sections. Step 4: Perform MBR membrane separation on the wastewater after modified A²O biological treatment. Step 5: Perform advanced treatment on the effluent after MBR membrane separation, including chemical phosphorus removal and sodium hypochlorite disinfection, to obtain reclaimed water. Step 6: Implement intelligent control and energy-saving regulation of the system operation process. Monitor system operating parameters in real time, calculate the TMP rise rate based on continuously collected transmembrane pressure difference (TMP) data, and input the TMP value, TMP rise rate, and real-time water quality parameters into a prediction model to output the next membrane cleaning time or the estimated remaining runtime. Dynamically adjust the aeration rate and recirculation ratio based on the prediction results and water quality changes, and implement variable frequency control.

2. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step one, the screen includes a coarse screen with a gap of 20 mm and a fine screen with a gap of 3 mm. The pH adjuster is sodium bicarbonate, and the pH value of the wastewater is controlled between 6.8 and 7.

2.

3. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step two, the anaerobic, anoxic, and aerobic sections of the modified A²O biological treatment section are set in proportions of 50%, 30%, and 20%, respectively.

4. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step two, the hydraulic retention time of the anaerobic section is 2-3 hours, the hydraulic retention time of the anoxic section is 4-5 hours, and the hydraulic retention time of the aerobic section is 8-10 hours. In the anoxic section, a slow-release carbon source of polycaprolactone is added, while in the aerobic section, microporous aeration discs are used for aeration, and the dissolved oxygen in the aerobic section is controlled at 2-3 mg / L.

5. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step three, the recirculation ratio from the aerobic section to the anoxic section is 100%-150%, and the recirculation ratio from the anoxic section to the anaerobic section is 50%-80%.

6. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step four, a PVDF hollow fiber membrane is used for MBR membrane separation. The membrane has a pore size of 0.1-0.2 μm and a membrane flux of 15-20 L / m²·h.

7. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step four, the MBR membrane separation adopts an intermittent suction operation mode, running for 8 minutes and then stopping for 2 minutes. Backwashing was performed using a mixture of sodium hypochlorite and citric acid, with a backwashing cycle of 24 hours. The sludge concentration was maintained at 8000-12000 mg / L MLSS.

8. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step five, chemical phosphorus removal involves adding polyaluminum chloride (PAC) to the effluent after MBR membrane separation to reduce total phosphorus to below 0.3 mg / L. Then, sodium hypochlorite is used for disinfection. The disinfected effluent is used for plant landscaping or industrial cooling water.

9. The wastewater treatment method based on A²O-MBR membrane technology according to claim 1, characterized in that, In step six, the real-time monitored system operating parameters include COD, NH3-N, TN, TP, and transmembrane pressure difference TMP; The TMP rise rate is calculated based on the TMP difference between adjacent sampling times and the corresponding time interval. The prediction model is built based on historical operating data, which includes at least historical TMP time series data, TMP rise rate data, and COD, NH3-N, TN, and TP data for the corresponding time period, and uses historical cleaning time or historical cleaning interval as training labels. The trained prediction model receives the current TMP value, TMP rise rate, and current water quality parameters, and outputs the next membrane cleaning time or the estimated remaining runtime.