Self-adaptive rainwater impact load coping method for sewage treatment plant

Abstract

The invention relates to the technical field of municipal drainage or environmental engineering, in particular to a self-adaptive rainwater impact load coping method for a sewage treatment plant. The system is mainly composed of an initial rainwater regulation and storage tank, a quality-divided pretreatment unit, a multi-point water inlet multi-section AO coupling 3W method biological reaction tank, a secondary sedimentation tank and a water quality and quantity real-time monitoring and feedback system. The storage pond is used for buffering initial rainwater; the quality-divided pretreatment unit is used for respectively pretreating sewage and first rain; the biological reaction tank is sequentially divided into an anaerobic zone, two sections of anoxic / aerobic zones and a 3W coupling reaction zone. The anaerobic zone uses sewage COD to synthesize an internal carbon source PHAs and release phosphorus; the front section is mainly used for decarburization and denitrification of sewage; and the regulated and stored initial rainwater is directly introduced into a tail section '3W' coupling region in proportion through model calculation, and is further decarburized and denitrified after being mixed with sewage. According to the invention, through coupling of a multi-section AO method and a 3W method and a quality-based and point-based water inlet strategy, in combination with self-adaptive regulation and control, the reaction efficiency is improved to the greatest extent, and the initial rainwater impact load is effectively coped with.

Description

Technical Field

[0001] This invention relates to the field of municipal drainage or environmental engineering technology, specifically to a method for a wastewater treatment plant to adaptively cope with rainwater impact loads. Background Technology

[0002] Urban rainwater contains large amounts of organic matter, pathogens, heavy metals, grease, suspended solids, and other pollutants, making it a significant cause of black and odorous water in rivers. Currently, rainwater treatment has become an important means for many cities and regions to control non-point source pollution and improve river water quality. Existing rainwater treatment technologies mainly fall into two categories: a) On-site treatment, primarily including primary enhanced treatment such as screening, sand removal, sedimentation, and filtration. This method has a large treatment capacity but mainly focuses on removing pollutants such as COD and SS, resulting in relatively low effluent standards; b) Wastewater treatment plant treatment, which involves collecting rainwater through interceptor pipes and transporting it to urban wastewater treatment plants for further treatment. This method achieves higher effluent standards but is often limited by the wastewater treatment plant's capacity to handle shock loads, resulting in a smaller treatment capacity.

[0003] To improve the treatment efficiency of wastewater treatment plants, the industry has developed highly efficient biological nitrogen and phosphorus removal technologies such as the multi-point influent multi-stage AO process. This process injects raw wastewater into different anoxic and anaerobic zones of the biological treatment tank in stages, creating a good pollutant concentration gradient and sludge concentration gradient within the system. This increases the average sludge concentration and sludge age within the tank without increasing the effluent sludge concentration, thus enhancing nitrogen and phosphorus removal efficiency. On the other hand, the "3W" method, as a strategy to cope with rainy season loads, utilizes the low pollutant concentration and carbon-based nature of rainwater. It directly introduces rainwater into the final stage of the biological treatment tank, using the remaining capacity of the aerobic zone at the end to quickly consume the COD in the rainwater while avoiding interference with the sensitive anaerobic and anoxic environments upstream.

[0004] However, while multi-point influent, multi-stage AO (Automatic Aeration) processes can efficiently treat conventional wastewater, and the "3W" (Warfare, Water, Wastewater) approach offers a solution for stormwater treatment, the two have not yet been organically coupled to address the impact load problem of high proportions of initial stormwater runoff. Existing facilities either have poor treatment effects or limited treatment capacity and weak shock resistance when dealing with initial stormwater runoff. To cope with potential shock loads, wastewater treatment plants often need to construct huge treatment structures to maintain sufficient redundancy, which results in significant investment and land resource waste during the dry season, making it neither economical nor intensive. Therefore, there is an urgent need for an integrated solution that can adapt to changes in stormwater and wastewater loads, efficiently coordinate the treatment of both water qualities, and avoid excessive redundancy. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses a method for adaptively coping with high proportions of initial rainwater runoff in urban wastewater treatment plants during the rainy season. This method buffers initial rainwater in a regulating tank, pre-treats it separately from wastewater, and then employs a multi-point influent, multi-stage AO coupling "3W" process: wastewater enters the front-end anaerobic / anoxic zone, while initial rainwater is directed to the terminal coupling zone. Combined with a real-time monitoring and simulation feedback system, the influent ratio and flow rate are adaptively controlled to achieve efficient nitrogen and phosphorus removal and resistance to shock loads. This method is used to treat dry season wastewater and high proportions of initial rainwater, achieving high effluent standards.

[0006] To achieve the above objectives, the present invention specifically adopts the following solution:

[0007] S1: After water quality testing, urban sewage enters the sewage pumping station and pretreatment unit for pretreatment.

[0008] S2: Initial rainwater inflow is stored in the initial rainwater storage tank and then enters the initial rainwater pumping station and pretreatment unit for pretreatment.

[0009] S3: The pretreated urban sewage and the pretreated initial rainwater are introduced into different locations of the multi-point influent biological reactor, wherein the urban sewage is introduced into the anaerobic tank and the second anoxic tank of the biological reactor at different points, and the initial rainwater is introduced into the third anoxic tank of the biological reactor; the biological reactor is coupled with multi-stage AO and "3W" process.

[0010] S4: In the biological reactor, the urban sewage and initial rainwater are biologically treated, and the treated mixture enters the secondary sedimentation tank for sedimentation. The sedimented sludge is partially returned to the anaerobic tank through the sludge return pipe.

[0011] S5: The system monitors the influent water quality, the water quality and flow rate in the biological reactor in real time through a simulation system, and adaptively adjusts the amount of sewage entering the anaerobic tank and the second-stage anoxic tank and the amount of initial rainwater entering the third-stage anoxic tank based on the simulation calculation results.

[0012] Furthermore, the bioreactor includes an anaerobic tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, a third anoxic tank, and a third aerobic tank arranged sequentially along the water flow direction.

[0013] Furthermore, in step S4, the average sludge concentration in the bioreactor is maintained at 3500–4500 mg / L by inoculating activated sludge.

[0014] Furthermore, in step S4, the proportion of sludge returned from the secondary sedimentation tank to the anaerobic tank is 100%.

[0015] Furthermore, at the end of the third aerobic tank, the mixed liquor is returned to the third anoxic tank at a ratio of 50% to 100% through an internal return pipe.

[0016] Furthermore, the second anoxic tank is equipped with a device for measuring NO3. - -N water quality instrument 1, the second aerobic tank is equipped with a device for measuring NH4. + -N water quality instrument 2, the third section of the anoxic tank is equipped with a device for measuring NO3. - -N water quality instrument three, the third section of the aerobic tank is equipped with a device for measuring NH4. + -N water quality meter four.

[0017] Furthermore, in step S5, the operation simulation system receives monitoring data from the wastewater influent water quality instrument, the initial rainwater influent water quality instrument, and various water quality instruments in the biological reactor. After performing simulation calculations, it feeds back control signals to the weir and flow meter 1 and weir and flow meter 2 in the wastewater pumping station and pretreatment unit, and the valve and flow meter 3 in the initial rainwater pumping station and pretreatment unit, in order to control the influent volume and proportion.

[0018] Furthermore, the urban sewage enters the anaerobic tank and the front section of the second anoxic tank at different points according to the water quality.

[0019] Furthermore, the initial rainwater enters the third anoxic tank 46 and is mixed with the treated urban sewage for further treatment.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention utilizes an initial rainwater storage tank to collect and buffer the initial rainwater, which is characterized by short arrival times and high flow rates. This effectively smooths out peak flows and reduces the impact of instantaneous hydraulic and pollution loads on subsequent biological treatment units, creating conditions for stable operation. By implementing a separate pretreatment and point-of-inflow strategy for wastewater and initial rainwater, high-concentration urban wastewater is introduced into the anaerobic and anoxic zones at the front end of the biological reactor. This ensures the smooth progress of key biochemical reactions such as anaerobic phosphorus release and internal carbon source synthesis, while also guaranteeing the system's nitrogen and phosphorus removal efficiency.

[0022] This process couples a multi-point influent, multi-stage AO process with the "3W" method, precisely introducing the relatively dilute initial rainwater, primarily composed of carbon-based pollutants, into the "3W" coupled reaction zone at the end of the biological treatment tank. This allows the rainwater to rapidly consume its COD without interfering with the upstream fine nitrogen and phosphorus removal, achieving highly efficient synergistic treatment of the two water qualities. By optimizing the influent point distribution, this coupled process creates a high-to-low sludge concentration gradient within the biological reactor. Without increasing the effluent sludge concentration, it raises the average sludge concentration and sludge age within the tank, thereby enhancing treatment efficiency. By installing online water quality instruments at key nodes and constructing a real-time monitoring, simulation, and feedback system, the influent ratio and flow rate of wastewater and initial rainwater can be dynamically adjusted based on the influent water quality and tank conditions. This achieves adaptive optimization control of the treatment process, maximizing the treatment potential of the biological reactor. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the operation of a specific embodiment of the present invention.

[0024] The following are the numbered components in the diagram: 1. Sewage pumping station and pretreatment unit; 2. Initial rainwater storage tank; 3. Initial rainwater pumping station and pretreatment unit; 4. Biological reactor; 5. Secondary sedimentation tank; 6. Operation simulation system;

[0025] 1.1 Wastewater influent water quality instruments; 1.2 Weir and flow meter one; 1.3 Weir and flow meter two;

[0026] 3.1 Initial rainwater inlet water quality instruments; 3.2 Valves and flow meters;

[0027] 4.1 Anaerobic tank; 4.2 First-stage anoxic tank; 4.3 First-stage aerobic tank; 4.4 Second-stage anoxic tank; 4.5 Second-stage aerobic tank; 4.6 Third-stage anoxic tank; 4.7 Third-stage aerobic tank; 4.8 Water quality instrument 1; 4.9 Water quality instrument 2; 4.10 Water quality instrument 3; 4.11 Water quality instrument 4; 4.12 Internal return pipe;

[0028] 5.1 Sludge return pipe. Detailed Implementation

[0029] The following detailed description provides specific embodiments to illustrate the present invention. Obviously, the described embodiments are only a portion, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] The present invention relates to a method for wastewater treatment plants to adaptively cope with rainwater impact loads, which is described below in conjunction with the appendix. Figure 1The operation process of the technical solution is explained in detail. First, urban sewage enters the system through pipelines. After the main water quality indicators are detected by the sewage inlet water quality instrument 1.1, it enters the sewage pump station and pretreatment unit 1 for physical pretreatment such as screen interception and grit removal.

[0031] Meanwhile, the initial rainwater enters the initial rainwater storage tank 2 through the collection system. This storage tank serves to buffer and balance the water volume and quality, effectively reducing the impact of sudden large flow rates. After storage, the initial rainwater enters the initial rainwater pumping station and pretreatment unit 3, and the water quality is monitored by the initial rainwater inlet water quality instrument 3.1, followed by appropriate pretreatment.

[0032] The pretreated municipal wastewater enters biological reactor 4 through two independent pathways: one pathway, via a weir and flow meter 1.3, delivers wastewater to the anaerobic tank 4.1 at the front end of biological reactor 4; the other pathway, via a weir and flow meter 1.2, delivers wastewater to the front end of the second anoxic tank 4.4 in the middle of biological reactor 4. The wastewater distribution ratio is calculated and controlled by the subsequent operation simulation system 6 based on real-time water quality conditions.

[0033] The pretreated initial rainwater is directly introduced into the front section of the third anoxic tank 4.6 at the end of the biological reactor 4 through valve and flow meter 3.2. The biological reactor 4 adopts a multi-point inlet, multi-stage AO coupled "3W" process, and is arranged sequentially along the water flow direction as anaerobic tank 4.1, first anoxic tank 4.2, first aerobic tank 4.3, second anoxic tank 4.4, second aerobic tank 4.5, third anoxic tank 4.6, and third aerobic tank 4.7.

[0034] In bioreactor 4, activated sludge is inoculated and maintained to stabilize the average sludge concentration at 3500–4500 mg / L. Municipal wastewater entering anaerobic tank 4.1 undergoes anaerobic phosphorus release and utilizes the COD in the wastewater to synthesize internal carbon sources PHAs. Subsequently, the mixed liquor flows sequentially through the first anoxic tank 4.2 and the first aerobic tank 4.3 for preliminary denitrification and decarbonization reactions.

[0035] The municipal wastewater diverted to the second-stage anoxic tank 4.4 is mixed with the mixed liquor from the previous stage to further enhance denitrification. The mixed liquor then enters the second-stage aerobic tank 4.5 for nitrification. Afterward, the pre-treated municipal wastewater is thoroughly mixed with the directly injected initial rainwater in the third-stage anoxic tank 4.6.

[0036] The mixed wastewater and initial rainwater undergo denitrification in the third-stage anoxic tank 4.6, and then enter the third-stage aerobic tank 4.7 for final nitrification and organic matter degradation. To enhance the denitrification effect, at the end of the third-stage aerobic tank 4.7, 50% to 100% of the mixed liquor is returned to the third-stage anoxic tank 4.6 through the internal return pipe 4.12.

[0037] After biological treatment, the mixed liquor flows out from the end of the biological reactor 4 and enters the secondary sedimentation tank 5 for solid-liquid separation. The supernatant is discharged as qualified effluent or reused, while the settled activated sludge is returned to the anaerobic tank 4.1 at the beginning of the biological reactor 4 through the sludge return pipe 5.1 at a 100% return ratio to maintain a high concentration of activated sludge in the system.

[0038] To achieve adaptive control, online water quality monitoring instruments were installed at key nodes within bioreactor 4: Water quality instrument 4.8 was installed in the second anoxic tank 4.4 to monitor NO3. - -N concentration; a water quality instrument (4.9) is installed in the second aerobic tank (4.5) to monitor NH4+ concentration. + -N concentration; a water quality instrument (4.10) is installed in the third anoxic tank (4.6) to monitor NO3 concentration. - -N concentration; Water quality instrument 4.11 is installed in the third aerobic tank (4.7) to monitor NH4 concentration. + -N concentration.

[0039] Real-time monitoring data collected by the wastewater influent water quality meter 1.1, the initial rainwater influent water quality meter 3.1, and the water quality meters (4.8, 4.9, 4.10, 4.11) in the biological reactor 4 are all uploaded to the operation simulation system 6. The operation simulation system 6 performs simulation calculations based on the received water quality and quantity data, combined with the built-in mathematical model, and dynamically analyzes the system's operating status.

[0040] Finally, the simulation system 6 feeds back the calculated optimized control signals to the front-end execution units: specifically, to weir gate and flow meter 1.2 and weir gate and flow meter 1.3, to adjust the distribution and proportion of urban sewage entering the anaerobic tank 4.1 and the second anoxic tank 4.4; simultaneously, it feeds back to valve and flow meter 3.2 to adjust the initial rainwater volume entering the third anoxic tank 4.6. Through this closed-loop control system, adaptive and precise adjustment of the influent flow rate and proportion for different water qualities is achieved, ensuring that the biological reactor 4 always operates under optimal conditions and efficiently copes with the impact load of rainwater at the beginning of the rainy season.

[0041] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for an adaptive response of a sewage treatment plant to stormwater surcharge load, characterized in that, Comprise: S1: the urban sewage inlet water is detected in quality, and then is introduced into the sewage pump house and the pretreatment unit (1) to carry out pretreatment; S2: the initial rainwater inlet water is stored in the initial rainwater storage tank (2) after storage, and then is introduced into the initial rainwater pump house and the pretreatment unit (3) to carry out pretreatment; S3: the pretreated urban sewage and the pretreated initial rainwater are introduced into different positions of the multi-point inlet biological reaction tank (4), wherein the urban sewage is introduced into the anaerobic tank (4.1) and the second stage anoxic tank (4.4) of the biological reaction tank (4) in points, the initial rainwater is introduced into the third stage anoxic tank (4.6) of the biological reaction tank (4); the biological reaction tank (4) is coupled with multi-stage AO and "3W" process; S4: in the biological reaction tank (4), the urban sewage and the initial rainwater are biologically treated, the mixed liquid after treatment is introduced into the secondary sedimentation tank (5) to carry out sedimentation, and part of the sludge after sedimentation is returned to the anaerobic tank (4.1) through the return sludge pipe (5.1); S5: the water quality and flow of the inlet water, the water quality in the biological reaction tank (4) are monitored in real time through the operation simulation system (6), and the sewage amount entering the anaerobic tank (4.1) and the second stage anoxic tank (4.4) and the initial rainwater amount entering the third stage anoxic tank (4.6) are adaptively adjusted according to the simulation calculation result.

2. The method of claim 1, wherein, The biological reaction tank (4) comprises the anaerobic tank (4.1), the first stage anoxic tank (4.2), the first stage aerobic tank (4.3), the second stage anoxic tank (4.4), the second stage aerobic tank (4.5), the third stage anoxic tank (4.6) and the third stage aerobic tank (4.7) which are sequentially arranged along the water flow direction.

3. The method of claim 1, wherein, In the S4 step, the average sludge concentration in the biological reaction tank (4) is maintained at 3500-4500 mg / L by inoculating active sludge.

4. The method for a wastewater treatment plant to adaptively respond to rainwater impact load according to claim 1, characterized in that, In the S4 step, the proportion of the return sludge of the secondary sedimentation tank (5) to the anaerobic tank (4.1) is 100%.

5. The method of claim 2, wherein, The end of the third stage aerobic tank (4.7) returns the mixed liquid to the third stage anoxic tank (4.6) by the internal return pipe (4.12) at a proportion of 50%-100%.

6. The method of claim 1, wherein, The second stage anoxic tank (4.4) is provided with a water quality instrument one (4.8) for measuring NO3 - -N, the second stage aerobic tank (4.5) is provided with a water quality instrument two (4.9) for measuring NH4 + -N, the third stage anoxic tank (4.6) is provided with a water quality instrument three (4.10) for measuring NO3 - -N, and the third stage aerobic tank (4.7) is provided with a water quality instrument four (4.11) for measuring NH4 + -N.

7. The method for a wastewater treatment plant to adaptively respond to rainwater impact load according to claim 1, characterized in that, In the S5 step, the operation simulation system (6) receives the monitoring data from the sewage inlet water quality instrument (1.1), the initial rainwater inlet water quality instrument (3.1) and each water quality instrument in the biological reaction tank (4), and feeds back the control signal to the weir gate and flowmeter one (1.2), the weir gate and flowmeter two (1.3) in the sewage pump house and the pretreatment unit (1) and the valve and flowmeter three (3.2) in the initial rainwater pump house and the pretreatment unit (3) after simulation calculation, so as to control the inlet water amount and proportion.

8. The method for a wastewater treatment plant to adaptively respond to rainwater impact load according to claim 1, characterized in that, The urban sewage is introduced into the anaerobic tank (4.1) and the front stage of the second stage anoxic tank (4.4) in different proportions according to the water quality.

9. The method for a wastewater treatment plant to adaptively respond to rainwater impact load according to claim 1, characterized in that, The initial rainwater is mixed with the treated urban sewage before being introduced into the front stage of the third stage anoxic tank (4.6) for treatment.

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