Intelligent sewage treatment method

Abstract

This invention relates to the field of wastewater treatment technology, and more particularly to an intelligent wastewater treatment method. Wastewater is introduced into the anaerobic section of a biological treatment zone, which includes at least a first anaerobic section and a second anaerobic section connected in series. The wastewater is controlled to enter the second anaerobic section. After treatment in the anaerobic section, the wastewater enters an aerobic section for nitrification and phosphorus uptake. After treatment in the anoxic section, the wastewater enters a secondary sedimentation tank for solid-liquid separation. The sludge settled at the bottom of the secondary sedimentation tank is returned to the front end of the first anaerobic section at a first return ratio. The sludge settled at the bottom of the secondary sedimentation tank is also returned to the front end of the anoxic section at a second return ratio. Once the microbial state is stable, the concentration parameters in the effluent from the first anaerobic section are monitored in real time, and the first or second return ratio is dynamically adjusted to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism. This invention solves the technical problem of insufficient utilization of internal carbon sources, requiring reliance on external carbon sources.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an intelligent wastewater treatment method. Background Technology

[0002] Biological nitrogen and phosphorus removal processes for wastewater are core technologies for ensuring water quality and preventing eutrophication. Among these, anaerobic-aerobic-anoxic (AOA) processes are widely used in urban and industrial wastewater treatment due to their rational flow and high treatment efficiency. However, existing processes generally suffer from a fundamental contradiction: the competition between the two biological processes of nitrogen and phosphorus removal for carbon sources. In my country, many wastewater treatment plants face the challenge of low influent carbon-to-nitrogen ratios (C / N), and insufficient carbon sources have become a major bottleneck in achieving stable and simultaneous high-standard removal of nitrogen and phosphorus.

[0003] Current mainstream solutions all have significant drawbacks. One is the external carbon source addition method, such as adding sodium acetate or glucose to supplement readily degradable organic matter. While this can improve denitrification efficiency, it significantly increases reagent costs and operating expenses, and may lead to secondary problems such as increased sludge production. The second is the chemical phosphorus removal method, such as adding coagulants like iron and aluminum salts to remove phosphorus through chemical precipitation. While this method is fast-acting, it also leads to increased operating costs, increased chemical sludge production, and neglects the potential of biological phosphorus removal.

[0004] Chinese Patent Application No. CN115259375A discloses an apparatus and method for enhancing anaerobic ammonia oxidation and denitrification phosphorus removal in an AOA (Anaerobic Oxidation) process through segmented influent. This apparatus, based on the AOA process, incorporates a second influent stage leading into the anoxic zone, along with corresponding control strategies. Organic matter in the first influent stage is stored as an internal carbon source in the anaerobic zone. Nitrogen and nitrite produced in the aerobic zone enter the subsequent anoxic zone, where ammonia nitrogen from the second influent stage is removed through internal denitrification coupled with anaerobic ammonia oxidation. Furthermore, the pre-anaerobic internal carbon source storage and the introduced phosphorus promote the enrichment of denitrifying phosphorus-removing bacteria, enabling denitrification phosphorus removal in the subsequent anoxic zone. By adding a second influent stage, the ammonia nitrogen concentration entering the anoxic zone is controlled more simply and precisely than DO (Dissolved Oxygen) control strategies, which are beneficial for the enrichment of anaerobic ammonia-oxidizing bacteria. The segmented influent AOA process, through anaerobic ammonia oxidation and denitrification phosphorus removal, reduces the carbon source requirement for nitrogen and phosphorus removal in wastewater, achieving efficient and energy-saving nitrogen and phosphorus removal from low-C / N domestic wastewater.

[0005] Therefore, it can be seen that the device and method for enhancing the anaerobic ammonia oxidation and denitrification phosphorus removal process of AOA by segmented water intake has the problem of insufficient utilization of internal carbon sources and reliance on external carbon sources. Summary of the Invention

[0006] Therefore, the present invention provides an intelligent wastewater treatment method to overcome the problem of insufficient utilization of internal carbon sources and reliance on external carbon sources in the prior art.

[0007] To achieve the above objectives, the present invention provides an intelligent wastewater treatment method, comprising: Step S1: Introduce wastewater into the anaerobic section of the biological treatment zone. The anaerobic section includes at least a first anaerobic section and a second anaerobic section connected in series. Control the wastewater to enter the second anaerobic section. Step S2: The wastewater treated in the anaerobic stage enters the aerobic stage for nitrification and phosphorus uptake. Step S3: The wastewater treated in the anoxic section enters the secondary sedimentation tank for solid-liquid separation. Step S4: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the first anaerobic section at a first return ratio; Step S5: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the anoxic section at a second return ratio; Step S6: After the microbial state is stable, dynamically adjust the first reflux ratio or the second reflux ratio based on the concentration parameters in the effluent of the first anaerobic section in real time, so as to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism.

[0008] Further, step S4 includes, Step S41: Based on the comparison of the sludge concentration of the mixed liquor of the sludge returned to the first anaerobic section and the original sludge from the first anaerobic section with the preset sludge concentration range, it is preliminarily determined whether the amount of microbial carrier in the first anaerobic section is qualified. If the sludge concentration in the mixed liquor is within the preset sludge concentration range, the amount of microbial carrier is determined to be qualified. If the sludge concentration in the mixed liquor is less than the preset sludge concentration range, it is determined that the amount of microbial carrier is too low. If the sludge concentration in the mixed liquor is greater than the preset sludge concentration range, it is determined that the amount of microbial carrier is too high. Step S42: Based on the low amount of microbial carrier, determine to increase the first reflux ratio and monitor the sludge level in the secondary sedimentation tank; Alternatively, based on the excessive amount of microbial carriers, the amount of residual sludge discharged may be increased.

[0009] Furthermore, step S4 also includes, Step S43: Based on the qualified microbial carrier quantity in the first anaerobic section, determine whether the microbial activity is qualified by comparing the sludge parameters in the first anaerobic section with the preset sludge parameter range. If the sludge parameters are within the preset sludge parameter range, the microbial activity is determined to be qualified. If the sludge parameters are less than the preset sludge parameter range, it is determined that the microbial activity is insufficient; If the sludge parameters are greater than the preset sludge parameter range, it is determined that the microbial activity is too high.

[0010] Further, step S43 includes, Step S431: Based on the insufficient microbial activity, determine whether the influent water quality contains inhibitory or toxic substances; Step S432: Determine the settling ratio and effluent suspended solids concentration of the secondary sedimentation tank based on the excessively high microbial activity.

[0011] Furthermore, the concentration parameters include nitrate concentration and phosphate concentration.

[0012] Further, step S6 includes, Step S61: Based on the comparison result of the nitrate concentration in the effluent of the first anaerobic section monitored in real time with the preset nitrate concentration threshold, determine whether the first reflux ratio or the second reflux ratio is qualified. If the nitrate concentration is greater than the preset nitrate concentration threshold for more than a preset number of consecutive times, the first reflux ratio and the second reflux ratio are determined to be unqualified. If the nitrate concentration is less than or equal to the preset nitrate concentration threshold, the first reflux ratio and the second reflux ratio are deemed qualified.

[0013] Furthermore, step S6 also includes, Step S62: Based on the comparison between the real-time monitored phosphate concentration in the effluent of the first anaerobic section and the preset phosphate concentration threshold, determine whether the first reflux ratio is qualified. If the phosphate concentration is greater than the preset phosphate concentration threshold for more than a preset number of consecutive times, the first reflux ratio is determined to be qualified. If the phosphate concentration is less than or equal to the preset phosphate concentration threshold, the first reflux ratio is determined to be unqualified.

[0014] Furthermore, the first reflux ratio is reduced based on the first reflux ratio being deemed unqualified due to the phosphate concentration in the first anaerobic section. Based on the nitrate concentration in the first anaerobic section, which causes the first reflux ratio to be unqualified, determine whether to increase the first reflux ratio or decrease the second reflux ratio.

[0015] Furthermore, step S6 also includes, Step S63: Based on the comparison result of the nitrate concentration of the effluent from the anoxic section monitored in real time with the preset nitrate concentration threshold, determine whether the second reflux ratio is qualified. If the nitrate concentration is greater than the preset nitrate concentration threshold for more than a preset number of consecutive times, the second reflux ratio is determined to be unqualified. If the nitrate concentration is less than or equal to the preset nitrate concentration threshold, the second reflux ratio is determined to be qualified.

[0016] Furthermore, based on the nitrate concentration in the effluent from the anoxic section, the second reflux ratio is determined to be substandard, and adjustments are made by increasing the second reflux ratio.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the first and second anaerobic sections of the anaerobic stage, the present invention controls all sewage to enter the second anaerobic section, so that polyphosphate-accumulating bacteria (PAOs) can release phosphorus in an environment without external carbon sources and without the presence of nitrates, utilizing the internal carbon sources stored in their cells. After phosphorus release, under aerobic conditions, they can absorb an excessive amount of phosphorus, achieving biological phosphorus removal. Compared with traditional methods, the present invention sets different functional zones by different influent modes, so as to completely separate biological phosphorus release and denitrification, achieving efficient utilization of carbon sources and achieving better treatment results.

[0018] Furthermore, in the traditional AOA sludge double recirculation method for nitrogen and phosphorus removal, when the wastewater enters the anaerobic section, the sludge recirculated to the front end of the anaerobic section carries some nitrates. In order to remove nitrates, the denitrifying bacteria in the anaerobic section will compete with polyphosphate-accumulating bacteria (PAOs) for carbon sources, which weakens the biological phosphorus removal effect and thus affects the phosphorus removal efficiency of the AOA system.

[0019] Furthermore, this invention introduces all influent into the second anaerobic stage, making the first anaerobic stage a reaction zone without external carbon input. Under these conditions, nitrates carried by the returned sludge are preferentially removed by denitrifying bacteria through an endogenous denitrification process. This process does not consume external carbon sources. After the nitrates are depleted, polyphosphate-accumulating organisms (PAOs) can utilize their internally stored carbon sources (PHAs) for metabolism and release phosphates. This design completely separates the competition for carbon sources between denitrification and biological phosphorus release in terms of space, fundamentally resolving the contradiction in traditional processes where enhanced denitrification weakens phosphorus removal.

[0020] Furthermore, based on the influent operation mode of the first and second anaerobic stages, the efficient and phased utilization of carbon sources is achieved: the first anaerobic stage is dedicated to internal carbon source metabolism (endogenous denitrification and phosphorus release driven by internal carbon sources), while the second anaerobic stage fully utilizes exogenous carbon in the influent for traditional biological phosphorus release. This not only enhances the endogenous denitrification capacity in the AOA process and improves nitrogen removal efficiency, but also significantly improves and stabilizes the biological phosphorus removal effect by tapping into the phosphorus removal potential of internal carbon sources.

[0021] Furthermore, due to the improved efficiency of biological phosphorus removal, the system's dependence on chemical phosphorus removal agents is significantly reduced. At the same time, the enhanced endogenous denitrification reduces the need for additional external carbon sources (such as sodium acetate), thus achieving the dual goals of energy saving and consumption reduction. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the steps of an intelligent wastewater treatment method according to an embodiment of the present invention. Figure 2 This is a process flow diagram of the intelligent wastewater treatment method according to an embodiment of the present invention; Figure 3 This is a logic diagram for dynamically adjusting the reflux ratio of the anaerobic section concentration parameter in the intelligent wastewater treatment method of this invention. Figure 4 This is a logic diagram for dynamically adjusting the reflux ratio of phosphate concentration in the anoxic section of the intelligent wastewater treatment method according to an embodiment of the present invention. Figure 5 This is a diagram showing the reactor water quality changes in the intelligent wastewater treatment method according to an embodiment of the present invention; In the diagram, 1-first anaerobic section, 2-second anaerobic section, 3-aerobic section, 4-anoxic section, 5-secondary sedimentation tank, 6-effluent tank, 7-residual sludge discharge tank, 8-second sludge return pipe, 9-first sludge return pipe, 10-influent tank. Detailed Implementation

[0023] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0024] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0025] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0026] Please see Figure 1 and Figure 2 As shown, Figure 1 This is a flowchart illustrating the steps of the intelligent wastewater treatment method according to an embodiment of the present invention. Figure 2 This is a process flow diagram of the intelligent wastewater treatment method according to an embodiment of the present invention.

[0027] The intelligent wastewater treatment method of this invention includes: Step S1: Introduce wastewater into the anaerobic section of the biological treatment zone. The anaerobic section includes at least a first anaerobic section and a second anaerobic section connected in series. Control the wastewater to enter the second anaerobic section. Step S2: The wastewater treated in the anaerobic stage enters the aerobic stage for nitrification and phosphorus uptake. Step S3: The wastewater treated in the anoxic section enters the secondary sedimentation tank for solid-liquid separation. Step S4: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the first anaerobic section at a first return ratio; Step S5: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the anoxic section at a second return ratio; Step S6: After the microbial state is stable, dynamically adjust the first reflux ratio or the second reflux ratio based on the concentration parameters in the effluent of the first anaerobic section in real time, so as to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism.

[0028] In this embodiment of the invention, the first anaerobic section and the second anaerobic section optimize the biological phosphorus removal process through functional zoning and synergistic effects. The first anaerobic section, as a pretreatment zone, uses endogenous carbon as an electron donor to treat the nitrates brought in by the secondary sedimentation tank return flow. After treatment by the first anaerobic section, the second anaerobic section is basically free of nitrates. The organic matter in the wastewater is completely absorbed and utilized by polyphosphate-accumulating bacteria (PAOs). The PAOs fully release phosphorus and convert volatile fatty acids (VFAs) into internal carbon sources (PHAs), preparing for the superphosphate uptake in the subsequent aerobic section.

[0029] Specifically, the hydraulic retention times of the anaerobic section, the aerobic section, and the anoxic section are 3.32h, 3.92h, and 5.71h, respectively, wherein the hydraulic retention time of the first anaerobic section is 1.68h, and the hydraulic retention time of the second anaerobic section is 1.64h.

[0030] In this embodiment of the invention, the hydraulic retention time of the first anaerobic stage is determined to ensure the consumption of nitrates brought by the return sludge. The endogenous denitrification rate is relatively slow, and sufficient time is required to ensure that nitrates are completely removed, creating a strict anaerobic environment for subsequent phosphorus release. After the nitrates are depleted, polyphosphate-accumulating bacteria (PAOs) also need time to release phosphorus using internal carbon sources (PHA). The hydraulic retention time of the first anaerobic stage ensures that polyphosphate-accumulating bacteria (PAOs) can maintain stable phosphorus release even under conditions without external carbon. In this embodiment of the invention, the hydraulic retention time of the second anaerobic section is determined to ensure that polyphosphate-accumulating organisms (PAOs) can efficiently utilize exogenous readily degradable organic matter in the influent for traditional and efficient phosphorus release after receiving all the influent.

[0031] Specifically, the hydraulic retention time of the secondary sedimentation tank is 4.5 hours.

[0032] In this embodiment of the invention, the hydraulic retention time of the secondary sedimentation tank is determined to ensure that the activated sludge flocs have sufficient static settling time to achieve thorough sludge-water separation, thereby ensuring that the concentrations of suspended solids (SS) and total phosphorus (TP) in the effluent meet the standards. At the same time, it prevents polyphosphate-accumulating organisms (PAOs) from releasing phosphorus twice due to excessively long hydraulic retention time, which could lead to an increase in the phosphorus concentration in the effluent.

[0033] Specifically, step S4 includes, Step S41: Based on the comparison of the sludge concentration of the mixed liquor of the sludge returned to the first anaerobic section and the original sludge from the first anaerobic section with the preset sludge concentration range, it is preliminarily determined whether the amount of microbial carrier in the first anaerobic section is qualified. If the sludge concentration in the mixed liquor is within the preset sludge concentration range, the amount of microbial carrier is determined to be qualified. If the sludge concentration in the mixed liquor is less than the preset sludge concentration range, it is determined that the amount of microbial carrier is too low. If the sludge concentration in the mixed liquor is greater than the preset sludge concentration range, it is determined that the amount of microbial carrier is too high. Step S42: Based on the low amount of microbial carrier, determine to increase the first reflux ratio and monitor the sludge level in the secondary sedimentation tank; Alternatively, based on the excessive amount of microbial carriers, the amount of excess sludge discharged may be increased; In this embodiment of the invention, the preset sludge concentration range is determined by the system's historical best operating data and can be adjusted according to seasonal changes in the influent load. Preferably, the preset sludge concentration range is 2500–4500 mg / L. If the amount of microbial carrier is too low, it is determined that the microorganisms in the first anaerobic section are insufficient to carry out the endogenous denitrification and phosphorus release reaction. The PLC control unit generates a command to increase the first return ratio to control the regulating valve installed on the return sludge pipeline. To avoid hydraulic shock caused by flow changes, a small step gradual adjustment is adopted, with each adjustment range being 5%–10% of the current return ratio. After adjustment, a hydraulic retention time is waited before monitoring the mixed liquor sludge concentration. The next adjustment is determined based on the feedback result until the mixed liquor sludge concentration returns to the preset sludge concentration range. At the same time, the sludge level in the secondary sedimentation tank is monitored by an online sludge level gauge. If the sludge level in the secondary sedimentation tank is too high or there is a risk of sludge loss due to the increase in return, the stability of the secondary sedimentation tank is prioritized, the increase in the first return ratio is suspended, and an alarm is issued. In this embodiment of the invention, based on the excessive amount of microbial carriers, it is determined that the sludge age is too long, leading to a decrease in sludge activity. The PLC control unit generates a command to increase the sludge discharge volume and controls the regulating valve installed on the remaining sludge pipeline to extend the single sludge discharge time. In the intermittent sludge discharge mode, the daily sludge discharge time is increased by 20% to 30%. For example, if the original sludge discharge strategy is to discharge sludge 4 times a day, 15 minutes each time, it can be changed to extend the sludge discharge time to 18 to 19.5 minutes each time.

[0034] Step S43: Based on the qualified microbial carrier quantity in the first anaerobic section, determine whether the microbial activity is qualified by comparing the sludge parameters in the first anaerobic section with the preset sludge parameter range. If the sludge parameters are within the preset sludge parameter range, the microbial activity is determined to be qualified. If the sludge parameters are less than the preset sludge parameter range, it is determined that the microbial activity is insufficient; If the sludge parameters are greater than the preset sludge parameter range, it is determined that the microbial activity is too high; Step S431: Based on the insufficient microbial activity, determine whether the influent water quality contains inhibitory or toxic substances; Step S432: Determine the settling ratio and effluent suspended solids concentration of the secondary sedimentation tank based on the excessively high microbial activity; In this embodiment of the invention, the sludge parameter is the ratio of the volatile suspended solids concentration (MLVSS) of the mixed liquor to the MLSS of the mixed liquor. The preset sludge parameter range is 0.65 to 0.75. Preliminary warnings are given based on the drastic fluctuations in monitoring data from online water quality instruments (such as TOC, ammonia nitrogen, and nitrate analyzers). Finally, laboratory sampling is used to perform chromatographic (GC-MS), spectral (ICP), and other analyses to confirm whether the influent water quality contains inhibitory or toxic substances. In this embodiment of the invention, the settling ratio and effluent suspended solids concentration of the secondary sedimentation tank are determined based on an online settling ratio monitor and an online turbidity meter. If both the settling ratio and effluent suspended solids concentration are within the historical normal range, it indicates that the current excessively high activity level is safe and monitoring should continue. If the settling ratio or effluent suspended solids concentration increases, it is determined to increase the sludge discharge to reduce the sludge age. After adjustment, the settling ratio and effluent suspended solids concentration are monitored until they return to the historical normal range.

[0035] Specifically, the concentration parameters include nitrate concentration and phosphate concentration.

[0036] Specifically, the intelligent wastewater treatment method of the present invention has a multi-parameter conflict decision mechanism. When the judgment conclusions of different parameters produce opposite commands for the same operation (such as adjusting the first reflux ratio), the command is executed according to the following priority: The instruction to determine the nitrate concentration is given the highest priority based on ensuring the anaerobic environment of the first anaerobic section. Based on ensuring the stability of the amount of microbial carrier, the instruction to determine the concentration of the mixed liquor sludge has the next highest priority. Instructions based on phosphate concentration and MLVSS / MLSS ratio are issued after the above conditions are met.

[0037] In this embodiment of the invention, after executing a high-priority instruction, the low-priority parameters will be re-evaluated after 1-2 hydraulic residence times. If the problem still exists, the corresponding instruction will be triggered again and an alarm requiring comprehensive diagnosis will be issued.

[0038] Please see Figure 3 As shown, it is a logic judgment diagram of the dynamic adjustment of the reflux ratio of the concentration parameter in the intelligent sewage treatment method of the present invention. Specifically, step S6 includes, Step S61: Based on the comparison result of the nitrate concentration in the effluent of the first anaerobic section monitored in real time with the preset nitrate concentration threshold, determine whether the first reflux ratio or the second reflux ratio is qualified. If the nitrate concentration is greater than the preset nitrate concentration threshold for more than a preset number of consecutive times, the first reflux ratio and the second reflux ratio are determined to be unqualified. If the nitrate concentration is less than or equal to the preset nitrate concentration threshold, the first reflux ratio and the second reflux ratio are determined to be qualified. Step S62: Based on the comparison between the real-time monitored phosphate concentration in the effluent of the first anaerobic section and the preset phosphate concentration threshold, determine whether the first reflux ratio is qualified. If the phosphate concentration is greater than the preset phosphate concentration threshold for more than a preset number of consecutive times, the first reflux ratio is determined to be qualified. If the phosphate concentration is less than or equal to the preset phosphate concentration threshold, the first reflux ratio is determined to be unqualified.

[0039] Specifically, the first reflux ratio is reduced based on the first reflux ratio being deemed unacceptable due to the phosphate concentration in the first anaerobic section.

[0040] Specifically, the first reflux ratio is increased or the second reflux ratio is decreased based on the first nitrate concentration in the first anaerobic section causing the first reflux ratio to be unqualified.

[0041] In this embodiment of the invention, based on the fact that the nitrate concentration exceeds the preset nitrate concentration threshold for a preset number of consecutive times, it is determined that the endogenous denitrification capacity of the first anaerobic section is insufficient to rapidly consume the introduced nitrate. The first return ratio is increased to increase the sludge concentration in the first anaerobic section and enhance the endogenous denitrification capacity. The second return ratio is decreased to reduce the nitrate concentration returned to the first anaerobic section. In this embodiment of the invention, the preset nitrate concentration threshold of the first anaerobic stage is 0.5 mg / L, the preset phosphate concentration threshold of the first anaerobic stage is 2.0 mg / L, and the preset number of times for each step is independently set to 3 to 6 times; In this embodiment of the invention, based on the phosphate concentration being less than or equal to the preset phosphate concentration threshold, the first reflux ratio is reduced and the nitrate concentration is monitored, so as to extend the sludge age by reducing the first reflux ratio to allow for sufficient phosphorus release. The reduction of the first reflux ratio is determined to be reasonable based on the comparison result between the monitored nitrate concentration and the preset nitrate concentration threshold.

[0042] Please see Figure 4 As shown, it is a logic judgment diagram of the dynamic adjustment of nitrate concentration and reflux ratio in the anoxic section of the intelligent sewage treatment method of the present invention. Step S63: Based on the comparison result of the nitrate concentration of the effluent from the anoxic section monitored in real time with the preset nitrate concentration threshold, determine whether the second reflux ratio is qualified. If the nitrate concentration is greater than the preset nitrate concentration threshold for more than a preset number of consecutive times, the second reflux ratio is determined to be unqualified. If the nitrate concentration is less than or equal to the preset nitrate concentration threshold, the second reflux ratio is determined to be qualified.

[0043] Specifically, the second reflux ratio is determined to be unqualified based on the nitrate concentration of the effluent from the anoxic section, and is adjusted by increasing the second reflux ratio.

[0044] In this embodiment of the invention, the preset nitrate concentration threshold for the anoxic section is 5.0–10.0 mg / L; In this embodiment of the invention, the first reflux ratio is 50% to 200%, and the second reflux ratio is 100% to 400%. Preferably, the first reflux ratio is 100%, and the second reflux ratio is 100%. In this embodiment of the invention, the PLC control unit generates commands to increase or decrease the first or second reflux ratio to determine the control valve installed on the reflux sludge pipeline. To avoid hydraulic shock caused by flow rate changes, a small-step gradual adjustment is adopted, with each adjustment range being 2% to 5% of the current reflux ratio. After adjustment, a hydraulic retention time is waited before monitoring the nitrate or phosphate concentration. The next adjustment is determined based on the feedback results. When the determination of nitrate concentration and phosphate concentration conflict with the adjustment direction of the first reflux ratio, the determination of nitrate concentration is given priority to ensure the anaerobic environment of the first anaerobic section. In this embodiment of the invention, the pretreatment process for wastewater before it is introduced into the biological treatment zone includes, but is not limited to, the wastewater flowing through a pre-settling grit chamber, a coarse screen, a fine screen, and an aerated grit chamber.

[0045] In this embodiment of the invention, the actual influent water quality is shown in Table 1, with influent NH4... + The average concentrations of -N and TN were 33 mg / L and 46 mg / L, respectively, with a B / C ratio of 0.35 and a C / N (BOD / TN) ratio of 2.4.

[0046] Table 1. Main Indicators of Actual Influent Water Quality

[0047] Example 1 Step S1: Introduce wastewater into the anaerobic section of the biological treatment zone. The anaerobic section includes at least a first anaerobic section and a second anaerobic section connected in series. Control all wastewater to enter only the second anaerobic section. Step S2: The wastewater treated in the anaerobic stage enters the aerobic stage for nitrification and phosphorus uptake. Step S3: The wastewater treated in the anoxic section enters the secondary sedimentation tank for solid-liquid separation. Step S4: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the first anaerobic section at a first return ratio; Step S5: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the anoxic section at a second return ratio; Step S6: Based on real-time monitoring of the concentration parameters in the effluent of the first anaerobic section, dynamically adjust the first reflux ratio or the second reflux ratio to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism.

[0048] Comparative Example 1 Step S1: Introduce wastewater into the anaerobic section of the biological treatment zone. The anaerobic section includes at least a first anaerobic section and a second anaerobic section connected in series. Control all wastewater to enter the first anaerobic section and the second anaerobic section in sequence. Step S2: The wastewater treated in the anaerobic stage enters the aerobic stage for nitrification and phosphorus uptake. Step S3: The wastewater treated in the anoxic section enters the secondary sedimentation tank for solid-liquid separation. Step S4: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the first anaerobic section at a first return ratio; Step S5: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the anoxic section at a second return ratio; Step S6: Based on real-time monitoring of the concentration parameters in the effluent of the first anaerobic section, dynamically adjust the first reflux ratio or the second reflux ratio to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism.

[0049] The operating effects of Example 1 and Comparative Example 1 of this invention are significantly different by setting different inlet points. The effluent water quality is shown in Table 3. Example 1 is superior because the biological phosphorus removal stage does not compete with denitrification for carbon sources, thus achieving further removal of total nitrogen and fully exploiting the total nitrogen removal capacity. This allows the total nitrogen in the effluent to be stably controlled within 5 mg / L. Furthermore, after optimizing the removal of total nitrogen, there was no significant change in the total phosphorus in the effluent, and the biological phosphorus removal capacity of the system was not weakened. This indicates that the anaerobic stage still maintains a high level of biological phosphorus removal even without inlet water.

[0050] Table 2. Effluent water quality indicators of Example 1 and Comparative Example 1

[0051] Example 1 and Comparative Example 1 of this invention focus on strictly controlling the effluent TP concentration at 0.3 mg·L⁻¹. -1 Under the following conditions, the dosage of carbon source, dosage of phosphorus removal agent, and total phosphorus removal effect during a six-month actual operation are shown in Tables 2 and 3. The results indicate that the phosphorus removal agent dosage in Example 1 is 36.8 mg·L⁻¹. -1 The carbon source concentration was 1.3 mg·L⁻¹. -1 The concentration of the phosphorus removal agent in Comparative Example 1 was 35.6 mg·L⁻¹. -1 The carbon source concentration was 12.5 mg·L⁻¹. - 1. Traditional methods often require more carbon sources for enhanced denitrification, which may lead to a decrease in phosphorus removal efficiency. Compared with Comparative Example 1, Example 1 significantly reduced the amount of external carbon source. As shown in Table 2, the total nitrogen in the effluent of Example 1 was significantly better than that of Comparative Example 1. This indicates that under the operating mode of Example 1, enhanced denitrification and the ability to maintain efficient biological phosphorus removal were achieved simultaneously.

[0052] Table 3. Dosing details for Example 1 and Comparative Example 1

[0053] In this embodiment of the invention, based on the biological phosphorus removal mechanism of the anaerobic process unit where no external wastewater enters the first anaerobic section, the anaerobic section of Example 1 was continuously monitored for 50 days. The test results showed that, despite the absence of external wastewater in the first anaerobic section, the average TP concentration in the anaerobic effluent reached 2.38 mg·L⁻¹. -1 The average nitrate concentration was 0.43 mg·L⁻¹. -1 Meanwhile, the average TP concentration in the external reflux was 0.50 mg·L⁻¹. -1 The average nitrate concentration was 1.19 mg·L⁻¹. -1 This indicates that there is a significant gradient difference in TP concentration between the influent and effluent of the anaerobic section. In actual operation, the anaerobic section still exhibits significant phosphorus release even in the absence of an external carbon source. This phenomenon suggests that under strict anaerobic conditions, polyphosphate-accumulating organisms (PAOs) can release phosphates even without the participation of an external carbon source.

[0054] In this embodiment of the invention, to further explore the mechanism in Example 1, two 30 L sealable plexiglass containers equipped with stirring devices were used as the reaction apparatus. Sludge from the anaerobic section of a normally operating wastewater treatment production line was used as the inoculum sludge in this experiment, with an inoculum sludge concentration (MLSS) of 11510 mg·L⁻¹. -1 25 L of the inoculated mud-water mixture was taken from each container for the experiment, and the actual measured MLSS of the mixture was 4466 mg·L⁻¹. -1 The sludge used in the experiment was introduced into the reactor via a filling method. Immediately after the experiment began, water samples were taken to test for DO, COD, TN, TP, and NH4. + -N, NO3 - -N and PO4 3- -P indicates that the detection results will be used as the initial concentration for each indicator. Samples were then taken at 10 min, 20 min, 1 h, and 4 h to measure the aforementioned indicators. During the experiment, NO3 was monitored. - After N-oxide is completely removed by denitrification using an internal carbon source, NO3 is added to the reactor in the first, second, and third stages, respectively. - -N, observe the changes in TP; In this embodiment of the invention, the reaction time is 0-16h for the first stage, 18-28h for the second stage, and 30-42h for the third stage; Please see Figure 5 As shown, it is a diagram of reactor water quality changes in an example of the intelligent wastewater treatment method in this invention. In this embodiment of the invention, based on the fact that DO remained at a low level throughout the entire experimental phase, it was determined that the experimental process was always under strict hypoxia and anaerobic conditions, and that COD showed a relatively stable trend, confirming that the COD during the experimental process was not utilized by microorganisms. Furthermore, based on the NH4... + The concentration of -N did not show a significant upward trend, confirming that the water quality changes were not caused by microbial disintegration. In this embodiment of the invention, the NO3 in the first stage - -N showed a clear decreasing trend, and after 10 hours of reaction, the NO3 in the system... - -N started at 21.50 mg·L⁻¹ -1 The NO3 level was reduced to almost zero. This was based on the fact that, in the initial stage of the experiment, the denitrifying bacteria in the reactor utilized an internal carbon source for denitrification in the absence of an external carbon source, thus leading to a decrease in NO3. - -N concentration decreased rapidly, accompanied by an initial decrease in NO3. - -N concentration decreases, PO4 3- -P also decreased from the initial 0.63 mg / L to 0.29 mg / L, but when NO3... - When the -N concentration decreased to below 1 mg / L, the soluble phosphorus concentration increased significantly. After a period of phosphorus release, the PO4 concentration in the system... 3- The -P concentration reached 3.52 mg / L. During this process, there was no significant change in COD within the system, indicating that no external carbon source was utilized, and the NH4+ concentration within the system was also low. + -N did not follow PO4 3- The increase in -P concentration can rule out PO4 released from microbial decomposition as the cause. 3- -P causes an increase in the total phosphorus concentration in the system. This process should be a phosphorus release reaction carried out by microorganisms using intracellular carbon sources. In this embodiment of the invention, to eliminate the possibility that this phenomenon in the first stage is accidental, the second stage involves the addition of 10 mg / L of NO3. - -N. Add NO3 - After -N, the phosphorus release phenomenon immediately disappears; over time, NO3... - -N concentration decreased rapidly again, accompanied by PO42-. 3- The decrease in -P concentration is a result of denitrification phosphorus uptake from the internal carbon source, based on NO3. - After -N reacts completely, PO4 3- The concentration of -P increased again to 5 mg / L. This further confirms the absence of NO3 in the system. - In the presence of -N, microorganisms can utilize internal carbon sources to release phosphorus. Based on the third stage, 8 mg / L of NO3 is continued to be added. --N, NO3 in the reactor - -N and PO4 3- The trend of -P changes is exactly the same as that in Phase 1 and Phase 2.

[0055] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An intelligent wastewater treatment method, characterized in that, include, Step S1: Introduce wastewater into the anaerobic section of the biological treatment zone. The anaerobic section includes at least a first anaerobic section and a second anaerobic section connected in series. Control all wastewater to enter only the second anaerobic section, so that the first anaerobic section becomes a reaction zone without external carbon input. The first anaerobic section is specifically used for internal carbon source metabolism, internal denitrification and internal carbon source driven phosphorus release. Step S2: The wastewater treated in the anaerobic stage enters the aerobic stage for nitrification and phosphorus uptake. Step S3: The wastewater treated in the anoxic section enters the secondary sedimentation tank for solid-liquid separation. Step S4: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the first anaerobic section at a first return ratio; Step S5: Based on the sludge settled at the bottom of the secondary sedimentation tank, it is returned to the front end of the anoxic section at a second return ratio; Step S6: After the microbial state is stable, dynamically adjust the first reflux ratio or the second reflux ratio based on the concentration parameters in the effluent of the first anaerobic section in real time, so as to maintain the first anaerobic section in an anaerobic environment suitable for internal carbon source metabolism. The concentration parameters include nitrate concentration and phosphate concentration; Step S61: Based on the comparison result of the nitrate concentration in the effluent of the first anaerobic section monitored in real time with the preset nitrate concentration threshold, determine whether the first reflux ratio or the second reflux ratio is qualified. If the nitrate concentration is greater than the preset nitrate concentration threshold for more than a preset number of consecutive times, the first reflux ratio and the second reflux ratio are determined to be unqualified. Step S62: Determine whether the first reflux ratio is qualified based on the comparison result of the phosphate concentration in the effluent of the first anaerobic section monitored in real time and the preset phosphate concentration threshold. If the phosphate concentration is less than or equal to the preset phosphate concentration threshold, the first reflux ratio is determined to be unqualified. The first reflux ratio is determined to be reduced based on the failure of the first reflux ratio due to the phosphate concentration in the first anaerobic section. Based on the nitrate concentration in the first anaerobic section causing the first reflux ratio to be unqualified, determine whether to increase the first reflux ratio or decrease the second reflux ratio; When the determination of nitrate concentration and phosphate concentration conflict with the direction of adjustment of the first reflux ratio, the determination of nitrate concentration shall be given priority to ensure the anaerobic environment of the first anaerobic section.

2. The intelligent wastewater treatment method according to claim 1, characterized in that, Step S4 includes, Step S41: Based on the comparison of the sludge concentration of the mixed liquor of the sludge returned to the first anaerobic section and the original sludge from the first anaerobic section with the preset sludge concentration range, it is preliminarily determined whether the amount of microbial carrier in the first anaerobic section is qualified. If the sludge concentration in the mixed liquor is within the preset sludge concentration range, the amount of microbial carrier is determined to be qualified. If the sludge concentration in the mixed liquor is less than the preset sludge concentration range, it is determined that the amount of microbial carrier is too low. If the sludge concentration in the mixed liquor is greater than the preset sludge concentration range, it is determined that the amount of microbial carrier is too high. Step S42: Based on the low amount of microbial carrier, determine to increase the first reflux ratio and monitor the sludge level in the secondary sedimentation tank; Alternatively, based on the excessive amount of microbial carriers, the amount of residual sludge discharged may be increased.

3. The intelligent wastewater treatment method according to claim 2, characterized in that, Step S4 also includes, Step S43: Based on the qualified microbial carrier quantity in the first anaerobic section, determine whether the microbial activity is qualified by comparing the sludge parameters in the first anaerobic section with the preset sludge parameter range. If the sludge parameters are within the preset sludge parameter range, the microbial activity is determined to be qualified. If the sludge parameters are less than the preset sludge parameter range, it is determined that the microbial activity is insufficient; If the sludge parameters are greater than the preset sludge parameter range, it is determined that the microbial activity is too high.

4. The intelligent wastewater treatment method according to claim 3, characterized in that, Step S43 includes... Step S431: Based on the insufficient microbial activity, determine whether the influent water quality contains inhibitory or toxic substances; Step S432: Determine the settling ratio and effluent suspended solids concentration of the secondary sedimentation tank based on the excessively high microbial activity.

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