A device and method for realizing simultaneous denitrification of municipal wastewater and photovoltaic cell wastewater based on a reinforced autotrophic / heterotrophic coupled granular sludge process

Abstract

The application discloses a device and method for realizing simultaneous nitrogen removal of urban sewage and photovoltaic cell wastewater based on a reinforced autotrophic / heterotrophic coupled granular sludge process. The device mainly comprises a horizontal flow defluorination reaction sedimentation tank, an intelligent adjusting tank, an aerobic deep oxidation system and a reinforced autotrophic / heterotrophic coupled granular system. The method realizes efficient simultaneous nitrogen removal of urban sewage and photovoltaic cell wastewater through a double-flow inlet strategy: the residual micro-particles and calcium ions after defluorination pretreatment are used as crystal nuclei to promote the granulation of subsequent sludge; the impact resistance of the coupled granular sludge is enhanced through a biofilm carrier; and the intelligent adjusting tank is used to realize precise water distribution, so that the reinforced autotrophic / heterotrophic coupled granular system can stably and efficiently remove nitrogen. The application not only realizes simultaneous deep treatment of urban sewage and photovoltaic cell wastewater, but also strengthens the structural stability of the granular sludge by using the calcium components in the wastewater, solves the problem of difficulty in forming the granular sludge and improves the nitrogen removal performance.

Description

Technical Field

[0001] This invention relates to a process technology for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, belonging to the field of wastewater denitrification technology. Background Technology

[0002] With the rapid development of new energy technologies and the continuous expansion of the photovoltaic industry, a large amount of photovoltaic cell wastewater is generated. This type of wastewater contains high concentrations of fluoride ions (F). - Pollutants such as nitrogen (NH4+-N) and ammonia nitrogen (NH4+-N) are present. Meanwhile, due to rapid urbanization, urban sewage discharge has increased significantly, leading to increasingly prominent eutrophication problems in water bodies. Nitrogen, as a key factor inducing eutrophication, poses a serious threat to ecological security and human health due to its excessive accumulation.

[0003] Under the dual carbon targets, traditional biological nitrogen removal technologies face severe challenges due to high consumption, high energy consumption, and high sludge production. Short-cut denitrification coupled with anaerobic ammonium oxidation (PD / A) is considered a highly promising energy-saving, carbon-reducing, and nitrogen-removing technology due to its advantages such as requiring no external carbon source, no aeration, and low sludge production. This technology utilizes denitrifying bacteria to reduce NO₃⁻-N to NO₂⁻-N, followed by anaerobic ammonium oxidation bacteria converting NO₂⁻-N and NH₄⁺-N into N₂. If autotrophic / heterotrophic coupled granular sludge can be used as a carrier to simultaneously treat municipal sewage and photovoltaic cell wastewater, treatment efficiency will be greatly improved and operating costs reduced.

[0004] However, the high toxicity (high fluoride environment) of photovoltaic cell wastewater is harmful to microorganisms. Furthermore, in practical engineering, anaerobic ammonia-oxidizing bacteria are difficult to accumulate, and granular sludge has a long formation cycle and is prone to instability. Therefore, how to synergistically utilize the CaF2, AlF3 precipitates, and residual Ca produced in the upstream wastewater treatment processes is a key challenge. 2+ The use of biofilm carriers to induce and enhance the rapid formation of autotrophic / heterotrophic coupled granular sludge, thereby achieving simultaneous deep denitrification of both types of wastewater, is a key technical challenge that urgently needs to be addressed. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a novel synergistic treatment process: NH₄⁺-N in urban wastewater is converted to NO₃⁻-N using an aerobic deep oxidation system, and then introduced as an electron acceptor into an autotrophic / heterotrophic coupled granular sludge system; simultaneously, photovoltaic wastewater provides NH₄⁺-N substrate. This method utilizes the fine precipitates and residual Ca produced by pre-fluoride removal pretreatment. 2+ As nuclei and bridging ions respectively, and with the enhancement effect of biofilm carriers, they effectively promoted the rapid formation and structural stability of autotrophic / heterotrophic coupled granular sludge, ultimately achieving simultaneous and efficient denitrification treatment of urban sewage and photovoltaic cell wastewater.

[0006] The purpose of this invention is achieved through the following technical solution: a device and method for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, characterized in that it mainly includes the following devices: a photovoltaic cell wastewater tank (1), a horizontal flow defluorination reaction sedimentation tank (4), a sludge storage tank (8), an urban sewage tank (10), an intelligent regulating tank (12), an aerobic deep oxidation system (16), an aeration device (19), and an enhanced autotrophic / heterotrophic coupled granular system (22).

[0007] The connection relationships are as follows: The photovoltaic cell wastewater tank (1) is equipped with a first online monitoring device (2), and the photovoltaic cell wastewater tank (1) is connected to the horizontal flow defluorination reaction sedimentation tank (4) through the first inlet pump (3); the horizontal flow defluorination reaction sedimentation tank (4) is equipped with a first dosing device (5) and a second dosing device (6), the horizontal flow defluorination reaction sedimentation tank (4) is connected to the sludge storage tank (8) through the first sludge discharge pump (7), and the horizontal flow defluorination reaction sedimentation tank (4) is connected to the intelligent regulating tank (12) through the first inlet valve (9); the urban sewage tank (10) is equipped with a second online monitoring device (11), and the urban sewage tank (10) is connected to the aerobic deep oxidation system (16) through the third inlet pump (15). The aerobic deep oxidation system (16) is equipped with a second stirring device (17), a third online monitoring device (18), an aeration device (19), and an aeration pipeline (20). The aerobic deep oxidation system (16) is connected to the intelligent regulating tank (12) through a fourth inlet pump (21). The intelligent regulating tank (12) is equipped with a first intelligent control unit (13). The intelligent regulating tank (12) is connected to the enhanced autotrophic / heterotrophic coupled granular system (22) through a second inlet pump (14). The enhanced autotrophic / heterotrophic coupled granular sludge system (22) is equipped with a first stirring device (23), a first carbon source addition device (24), a fourth online monitoring device (25), and a first effluent pump (26).

[0008] A device and method for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, characterized by comprising the following steps:

[0009] (1) Pretreatment of photovoltaic cell wastewater

[0010] The first influent pump is started, and the photovoltaic cell wastewater enters the horizontal flow defluoridation reaction sedimentation tank from the photovoltaic cell wastewater tank. The first and second dosing devices are started. The first dosing device adds Ca(OH)2 to generate calcium fluoride (CaF2) precipitate, reducing the fluoride ion concentration to 15-30 mg / L. The second dosing device adds Al2(SO4)3 to generate aluminum fluoride (AlF3) precipitate and adjusts the pH to 6.0-7.0 to further remove residual fluoride ions, controlling the fluoride ion concentration in the effluent to 5-10 mg / L. The settled sludge from the horizontal flow defluoridation reaction sedimentation tank is discharged to the sludge storage tank through the first sludge discharge pump, with a sludge age not exceeding 2 days. The hydraulic retention time is 1.5-2.5 h. The effluent enters the intelligent equalization tank and mixes with the effluent from the aerobic deep oxidation system.

[0011] (2) Start-up of the aerobic deep oxidation system

[0012] The system is inoculated with excess sludge from a municipal wastewater treatment plant, with the sludge concentration controlled at 2.5–4.5 gVSS / L after inoculation. The operation phase involves influent, mixing, aeration, sedimentation, effluent, and idle. Municipal wastewater is pumped into the aerobic deep oxidation system by a third influent pump. After mixing for 0.5–1.5 hours, the aeration device is started, with an aeration time of 4.0–8.0 hours, controlling dissolved oxygen at 0.5–1.0 mg / L. After sedimentation for 0.5–1.0 hours, the supernatant is discharged at a discharge ratio of 45–55%, and the effluent enters the intelligent equalization tank. The system is then idle for 0.5–1.0 hours. When the ammonia nitrogen removal rate reaches over 95% for 7 consecutive days, the aerobic deep oxidation system is considered successfully started.

[0013] (3) Enhance the startup of autotrophic / heterotrophic coupled particle systems

[0014] During the start-up phase, a loading strategy of inoculating autotrophic / heterotrophic coupled granular sludge and introducing a biofilm carrier was adopted. The sludge concentration after inoculation was controlled at 3.0–6.0 gVSS / L. The operation phase consisted of influent, stirring, sedimentation, effluent, and idle periods. The mixed liquor from the intelligent equalization tank was pumped into the enhanced autotrophic / heterotrophic coupled granular system by the second influent pump. The first intelligent control unit regulated the first influent valve and the pump speed of the fourth influent pump, as well as adjusted the dosage of the carbon source dosing device, to ensure that the mass ratio of COD to NO₃⁻-N in the influent was 2.5–3.5, and the mass ratio of NH₄⁺-N to NO₃⁻-N was 1:(1–1.5). During the reaction phase, the first stirring device was started, and the stirring time was 2.0–5.0 h. After sedimentation for 0.5–1.0 h, the supernatant was discharged, with a effluent ratio of 45–55%. The system was then idle for 0.5–1.0 h. h; When the total nitrogen removal rate reaches 90% or more for 7 consecutive days, it signifies that the enhanced autotrophic / heterotrophic coupled particle system has been successfully started.

[0015] (4) Enhance the joint operation of autotrophic / heterotrophic coupled particle system and aerobic deep oxidation system.

[0016] The first influent pump is started, and the photovoltaic cell wastewater enters the horizontal flow defluoridation reaction sedimentation tank from the photovoltaic cell wastewater tank; the first and second dosing devices are started to generate CaF2 and AlF3 precipitates, reducing the fluoride ion concentration to 5-10 mg / L, and controlling the effluent Ca... 2+ Concentrations of 50–150 mg / L were achieved using biofilms and Ca... 2+ Enhanced autotrophic / heterotrophic coupled granular sludge biofilm formation and granulation; effluent enters the intelligent equalization tank. Urban sewage is pumped into the aerobic deep oxidation system via a third influent pump; after stirring for 0.5–1.5 h, the aeration device is started, with an aeration time of 4.0–8.0 h, and dissolved oxygen controlled at 0.5–1.0 mg / L; after sedimentation for 0.5–1.0 h, the supernatant is discharged, with a effluent ratio of 45–55%. The effluent from the intelligent equalization tank enters the enhanced autotrophic / heterotrophic coupled granular system, with the influent mixed liquor meeting the following mass ratios: COD to NO₃⁻ N mass ratio of 2.5–3.5, and NH₄⁺ to NO₃⁻ N mass ratio of 1:(1–1.5); after influent discharge, stirring is performed for 2–5 h, and after sedimentation for 0.5–1.0 h, the supernatant is discharged, with a effluent ratio of 45–55%. The systems operate in conjunction.

[0017] The apparatus and method for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, as disclosed in this invention, have the following advantages:

[0018] (1) The synergistic denitrification mechanism is efficient and the substrate ratio is stable.

[0019] This process enhances the short-range denitrification capacity of heterotrophic bacteria in reducing NO₃⁻ to NO₂⁻ through specific microenvironment regulation of granular sludge, and effectively inhibits its further reduction to N₂, thus providing a sufficient and stable source of NO₂⁻ for the system. Combined with the NH₄⁺ introduced from photovoltaic cell wastewater, which provides an ideal substrate ratio for anaerobic ammonia oxidizing bacteria, simultaneous and efficient removal of nitrogen from both types of wastewater is achieved.

[0020] (2) Significantly saves energy and reduces consumption and sludge production

[0021] Compared to traditional nitrification-denitrification processes, anaerobic ammonia oxidation requires no oxygen supply, and the short-cut denitrification process utilizes nitrate as an electron acceptor, significantly reducing the system's aeration requirements and saving considerable operating energy. Furthermore, the growth rate coefficients of anaerobic ammonia oxidizing bacteria and short-cut denitrifying bacteria are low, resulting in a much lower amount of residual sludge compared to traditional activated sludge processes, reducing the cost and difficulty of subsequent sludge disposal.

[0022] (3) The unique layered structure enhances system stability and load capacity.

[0023] The granular sludge forms a unique layered structure: the outer layer consists of heterotrophic denitrifying bacteria that consume dissolved oxygen and organic matter, creating an ideal anaerobic, low-COD microenvironment for the inner layer of anaerobic ammonia-oxidizing bacteria. This dense granular structure exhibits excellent settling performance, maintaining a high biomass concentration, thereby increasing the system's volumetric loading and reducing the reactor volume. Simultaneously, the granular biofilm structure demonstrates strong tolerance to fluoride ions and heavy metals that may be present in photovoltaic wastewater, ensuring the long-term stable operation of the system.

[0024] (4) The intelligent control unit realizes dynamic and precise water distribution and process self-adaptation.

[0025] Through the intelligent control and regulation unit, the system can automatically adjust the opening of the inlet valve and the pump speed based on the real-time water quality fluctuations fed back by the first, second, third, and fourth online monitoring devices. This unit can precisely control the mixing ratio of the two types of wastewater in the intelligent regulation tank, ensuring that the mixed liquid entering the enhanced granulation system is always within the optimal C / N ratio and nitrogen ratio range. This effectively avoids the impact of photovoltaic wastewater fluctuations on the biological system and significantly improves the intelligence level and operational flexibility of the process. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device of the present invention. Figure 2 This is the operation flowchart of the first intelligent control unit.

[0027] 1-Photovoltaic cell wastewater tank; 2-First online monitoring device; 3-First inlet pump; 4-Horizontal flow defluoridation reaction sedimentation tank; 5-First dosing device; 6-Second dosing device; 7-First sludge pump; 8-Sludge storage tank; 9-First inlet valve; 10-Urban sewage tank; 11-Second online monitoring device; 12-Intelligent regulating tank; 13-First intelligent control unit; 14-Second inlet pump; 15-Third inlet pump; 16-Aerobic deep oxidation system; 17-First stirring device; 18-Third online monitoring device; 19-Aeration device; 20-Aeration pipeline; 21-Fourth inlet pump; 22-Enhanced autotrophic / heterotrophic coupled granular system; 23-Second stirring device; 24-First carbon source dosing device; 25-Fourth online monitoring device; 26-First effluent pump. Detailed Implementation

[0028] The present invention will be further described in conjunction with the accompanying drawings and embodiments. As shown in the figures, a device and method for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process is characterized by mainly including the following devices: a photovoltaic cell wastewater tank (1), a horizontal flow defluorination reaction sedimentation tank (4), a sludge storage tank (8), an urban sewage tank (10), an intelligent regulating tank (12), an aerobic deep oxidation system (16), an aeration device (19), and an enhanced autotrophic / heterotrophic coupled granular system (22).

[0029] The connection relationships are as follows: The photovoltaic cell wastewater tank (1) is equipped with a first online monitoring device (2), and the photovoltaic cell wastewater tank (1) is connected to the horizontal flow defluorination reaction sedimentation tank (4) through the first inlet pump (3); the horizontal flow defluorination reaction sedimentation tank (4) is equipped with a first dosing device (5) and a second dosing device (6), the horizontal flow defluorination reaction sedimentation tank (4) is connected to the sludge storage tank (8) through the first sludge discharge pump (7), and the horizontal flow defluorination reaction sedimentation tank (4) is connected to the intelligent regulating tank (12) through the first inlet valve (9); the urban sewage tank (10) is equipped with a second online monitoring device (11), and the urban sewage tank (10) is connected to the aerobic deep oxidation system (16) through the third inlet pump (15). The aerobic deep oxidation system (16) is equipped with a second stirring device (17), a third online monitoring device (18), an aeration device (19), and an aeration pipeline (20). The aerobic deep oxidation system (16) is connected to the intelligent regulating tank (12) through a fourth inlet pump (21). The intelligent regulating tank (12) is equipped with a first intelligent control unit (13). The intelligent regulating tank (12) is connected to the enhanced autotrophic / heterotrophic coupled granular system (22) through a second inlet pump (14). The enhanced autotrophic / heterotrophic coupled granular sludge system (22) is equipped with a first stirring device (23), a first carbon source addition device (24), a fourth online monitoring device (25), and a first effluent pump (26).

[0030] A device and method for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, characterized by comprising the following steps:

[0031] (1) Pretreatment of photovoltaic cell wastewater

[0032] The first influent pump is started, and the photovoltaic cell wastewater enters the horizontal flow defluoridation reaction sedimentation tank from the photovoltaic cell wastewater tank. The first and second dosing devices are started. The first dosing device adds Ca(OH)2 to generate calcium fluoride (CaF2) precipitate, reducing the fluoride ion concentration to below 30 mg / L. The second dosing device adds Al2(SO4)3 to generate aluminum fluoride (AlF3) precipitate and adjusts the pH to 6.5 to further remove residual fluoride ions, controlling the fluoride ion concentration in the effluent to below 10 mg / L. The settled sludge from the horizontal flow defluoridation reaction sedimentation tank is discharged to the sludge storage tank through the first sludge discharge pump, with a sludge age not exceeding 2 days. The hydraulic retention time is 2 hours. The effluent enters the intelligent equalization tank and mixes with the effluent from the aerobic deep oxidation system.

[0033] (2) Start-up of the aerobic deep oxidation system

[0034] Excess sludge from the municipal wastewater treatment plant was inoculated, and the sludge concentration was controlled at 4.5 gVSS / L after inoculation. The operation phase consisted of influent, stirring, aeration, sedimentation, effluent, and idle. The municipal wastewater was pumped into the aerobic deep oxidation system by the third influent pump. After stirring for 1 hour, the aeration device was started, and the aeration time was 8 hours, with dissolved oxygen controlled at 1 mg / L. After sedimentation for 0.5 hours, the supernatant was discharged with a discharge ratio of 50%, and the effluent entered the intelligent equalization tank. After idle for 0.5 hours, the ammonia nitrogen removal rate reached more than 95% for 7 consecutive days, and the aerobic deep oxidation system was successfully started.

[0035] (3) Enhance the startup of autotrophic / heterotrophic coupled particle systems

[0036] During the start-up phase, a loading strategy of inoculating autotrophic / heterotrophic coupled granular sludge and introducing a biofilm carrier was adopted, with the sludge concentration controlled at 5 gVSS / L after inoculation. The operation phase consisted of influent, stirring, sedimentation, effluent, and idle. The mixed liquor from the intelligent equalization tank was pumped into the enhanced autotrophic / heterotrophic coupled granular system by the second influent pump. The first intelligent control unit regulated the first influent valve and the pump speed of the fourth influent pump, as well as adjusted the dosage of the carbon source dosing device, to achieve an influent COD to NO3-N mass ratio of 2.8 and an NH4+ to NO3-N mass ratio of 1:1.3. During the reaction phase, the first stirring device was started and stirred for 5 hours. After sedimentation for 0.5 hours, the supernatant was discharged with a effluent ratio of 50%. The system was then idle for 0.5 hours. The total nitrogen removal rate reached over 90% for 7 consecutive days, indicating successful start-up of the enhanced autotrophic / heterotrophic coupled granular system.

[0037] (4) Enhance the joint operation of autotrophic / heterotrophic coupled particle system and aerobic deep oxidation system.

[0038] The first influent pump is started, and photovoltaic cell wastewater enters the horizontal flow defluoridation sedimentation tank from the photovoltaic cell wastewater tank; the first and second dosing devices are started to generate CaF2 and AlF3 precipitates, reducing the fluoride ion concentration to below 10 mg / L, and controlling the effluent Ca... 2+ For concentrations below 100 mg / L, utilize biofilms and Ca 2+ Enhanced autotrophic / heterotrophic coupled granular sludge biofilm formation and granulation; effluent enters the intelligent equalization tank. Urban sewage is pumped into the aerobic deep oxidation system via a third influent pump; after stirring for 1 hour, the aeration device is started, with an aeration time of 8 hours and dissolved oxygen controlled at 1 mg / L; after sedimentation for 0.5 hours, the supernatant is discharged, with a effluent ratio of 50%. The effluent from the intelligent equalization tank enters the enhanced autotrophic / heterotrophic coupled granular system, with the influent mixed liquor meeting the following mass ratios: COD to NO₃⁻-N 2.8 and NH₄⁺-N to NO₃⁻-N 1:1.3; after influent discharge, stirring for 5 hours, sedimentation for 0.5 hours, and then the supernatant is discharged, with a effluent ratio of 50%. The system operates continuously.

[0039] Simulated wastewater was used in the experiment. The simulated photovoltaic wastewater had an NH4+ concentration of 65.0–72.0 mg / L and a fluoride ion concentration of 142.5–158.0 mg / L; the simulated municipal wastewater had an NH4+ concentration of approximately 60.0 mg / L and a COD concentration of 165–185 mg / L. After treatment by the aerobic deep oxidation system, the simulated municipal wastewater achieved an NH4+ oxidation rate of 95%, with a residual NH4+ concentration of approximately 3.0 mg / L in the effluent. The effluent from the aerobic deep oxidation system was mixed with the pretreated photovoltaic wastewater at a volume ratio of 1.5:1 to 2:1. The mixture was then fed into an enhanced autotrophic / heterotrophic granular sludge system for reaction. After 100 days of continuous operation, the total nitrogen in the effluent stabilized at 6.5–11.5 mg / L, with a total nitrogen removal rate of 82.5%–89.6%. The experimental results show that the device successfully achieved enhanced formation of granular sludge and completed efficient defluorination of photovoltaic cell wastewater and simultaneous deep denitrification of the two wastewater streams.

Claims

1. A device for simultaneous denitrification of urban sewage and photovoltaic cell wastewater based on an enhanced autotrophic / heterotrophic coupled granular sludge process, characterized in that, The following devices are included: photovoltaic cell wastewater tank (1), horizontal flow defluorination reaction sedimentation tank (4), sludge storage tank (8), urban sewage tank (10), intelligent regulating tank (12), aerobic deep oxidation system (16), aeration device (19), and enhanced autotrophic / heterotrophic coupled particle system (22). The connection relationships are as follows: The photovoltaic cell wastewater tank (1) is equipped with a first online monitoring device (2), and the photovoltaic cell wastewater tank (1) is connected to the horizontal flow defluorination reaction sedimentation tank (4) through the first inlet pump (3); the horizontal flow defluorination reaction sedimentation tank (4) is equipped with a first dosing device (5) and a second dosing device (6), the horizontal flow defluorination reaction sedimentation tank (4) is connected to the sludge storage tank (8) through the first sludge discharge pump (7), and the horizontal flow defluorination reaction sedimentation tank (4) is connected to the intelligent regulating tank (12) through the first inlet valve (9); the urban sewage tank (10) is equipped with a second online monitoring device (11), and the urban sewage tank (10) is connected to the aerobic deep oxidation system (16) through the third inlet pump (15). The aerobic deep oxidation system (16) is equipped with a second stirring device (17), a third online monitoring device (18), an aeration device (19), and an aeration pipeline (20). The aerobic deep oxidation system (16) is connected to the intelligent regulating tank (12) through a fourth inlet pump (21). The intelligent regulating tank (12) is equipped with a first intelligent control unit (13). The intelligent regulating tank (12) is connected to the enhanced autotrophic / heterotrophic coupled granular system (22) through a second inlet pump (14). The enhanced autotrophic / heterotrophic coupled granular sludge system (22) is equipped with a first stirring device (23), a first carbon source addition device (24), a fourth online monitoring device (25), and a first effluent pump (26).

2. The method of using the apparatus as described in claim 1, characterized in that, Includes the following steps: (1) Pretreatment of photovoltaic cell wastewater The first influent pump is started, and the photovoltaic cell wastewater enters the horizontal flow defluoridation reaction sedimentation tank from the photovoltaic cell wastewater tank. The first and second dosing devices are started. The first dosing device adds Ca(OH)2 to generate calcium fluoride (CaF2) precipitate, reducing the fluoride ion concentration to 15-30 mg / L. The second dosing device adds Al2(SO4)3 to generate aluminum fluoride (AlF3) precipitate and adjusts the pH to 6.0-7.0 to further remove residual fluoride ions, controlling the fluoride ion concentration in the effluent to 5-10 mg / L. The settled sludge from the horizontal flow defluoridation reaction sedimentation tank is discharged to the sludge storage tank through the first sludge discharge pump, with a sludge age not exceeding 2 days. The hydraulic retention time is 1.5-2.5 h. The effluent enters the intelligent equalization tank and mixes with the effluent from the aerobic deep oxidation system. (2) Start-up of the aerobic deep oxidation system The system is inoculated with excess sludge from a municipal wastewater treatment plant, with the sludge concentration controlled at 2.5–4.5 gVSS / L after inoculation. The operation phase involves influent, mixing, aeration, sedimentation, effluent, and a period of idle time. Municipal wastewater is pumped into the aerobic deep oxidation system by a third influent pump. After mixing for 0.5–1.5 hours, the aeration device is started, with an aeration time of 4.0–8.0 hours, controlling dissolved oxygen at 0.5–1.0 mg / L. After sedimentation for 0.5–1.0 hours, the supernatant is discharged at a discharge ratio of 45–55%, and the effluent enters the intelligent equalization tank. The system is then idle for 0.5–1.0 hours. When the ammonia nitrogen removal rate reaches over 95% for 7 consecutive days, the aerobic deep oxidation system is considered successfully started. (3) Enhance the startup of autotrophic / heterotrophic coupled particle systems During the start-up phase, a loading strategy of inoculating autotrophic / heterotrophic coupled granular sludge and introducing a biofilm carrier was adopted. The sludge concentration after inoculation was controlled at 3.0–6.0 gVSS / L. The operation phase consisted of influent, stirring, sedimentation, effluent, and idle periods. The mixed liquor from the intelligent equalization tank was pumped into the enhanced autotrophic / heterotrophic coupled granular system by the second influent pump. The first intelligent control unit regulated the first influent valve and the pump speed of the fourth influent pump, as well as adjusted the dosage of the carbon source dosing device, to ensure that the mass ratio of COD to NO₃⁻-N in the influent was 2.5–3.5, and the mass ratio of NH₄⁺-N to NO₃⁻-N was 1:(1–1.5). During the reaction phase, the first stirring device was started, and the stirring time was 2.0–5.0 h. After sedimentation for 0.5–1.0 h, the supernatant was discharged, with a effluent ratio of 45–55%. The system was then idle for 0.5–1.0 h. h; When the total nitrogen removal rate reaches 90% or more for 7 consecutive days, it signifies that the enhanced autotrophic / heterotrophic coupled particle system has been successfully started. (4) Enhance the joint operation of autotrophic / heterotrophic coupled particle system and aerobic deep oxidation system. The first influent pump is started, and the photovoltaic cell wastewater enters the horizontal flow defluoridation reaction sedimentation tank from the photovoltaic cell wastewater tank; the first and second dosing devices are started to generate CaF2 and AlF3 precipitates, reducing the fluoride ion concentration to 5-10 mg / L, and controlling the effluent Ca... 2+ Concentrations of 50–150 mg / L were achieved using biofilms and Ca... 2+ Enhanced autotrophic / heterotrophic coupled granular sludge biofilm formation and granulation; effluent enters the intelligent equalization tank; urban sewage is pumped into the aerobic deep oxidation system via a third influent pump; after stirring for 0.5~1.5 h, the aeration device is started, and the aeration time is 4.0~8.0 h, with dissolved oxygen controlled at 0.5~1.0 mg / L; after sedimentation for 0.5~1.0 h, the supernatant is discharged, with a effluent ratio of 45~55%; effluent from the intelligent equalization tank enters the enhanced autotrophic / heterotrophic coupled granular system, with the influent mixed liquor meeting the following conditions: COD to NO3-N mass ratio of 2.5~3.5, NH4+ to NO3-N mass ratio of 1:(1~1.5); after the influent is discharged, stirring is performed for 2~5 h, and after sedimentation for 0.5~1.0 h, the supernatant is discharged, with a effluent ratio of 45~55%.

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