Nano-iron reinforced hydrolysis acidification-denitrification integrated treatment device and method

Abstract

The application discloses a kind of nano iron reinforced hydrolytic acidification-denitrification integrated treatment device and method, belong to low biodegradability industrial wastewater treatment field.The device is equipped with water regulating zone and nano iron reinforced synergistic reaction zone in integrated front-end reaction module.Processing, by adding nano iron material to synergistic reaction zone, while refluxing subsequent aerobic unit containing nitrate nitration liquid, under the regulation of nano iron, organic hydrolytic acidification and partial denitrification reaction are realized simultaneously, and the system is maintained stable operation by on-line monitoring and automatic control.The application integrates hydrolytic acidification and denitrification process in the same front-end unit, effectively solves the problems of low carbon-nitrogen ratio industrial wastewater carbon release and denitrification synergy, high subsequent treatment load, long process, etc., significantly improves the biodegradability and denitrification efficiency of wastewater, and is suitable for pharmaceutical, chemical, petrochemical and other low C / N industrial wastewater treatment, with compact process, stable operation, good treatment effect and other advantages.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment and relates to a front-end co-treatment device for industrial wastewater with low biodegradability, specifically a nano-iron-enhanced hydrolysis acidification-denitrification co-integrated treatment device and method. Background Technology

[0002] Low C / N ratio industrial wastewater is typically rich in recalcitrant organic components. Engineering processes often employ multi-unit series processes such as hydrolysis acidification, anoxic denitrification, and aerobic oxidation to sequentially achieve goals such as macromolecular organic matter decomposition, denitrification, and deep organic matter removal. However, these separate processes have significant limitations in practical applications: On the one hand, the hydrolysis acidification unit and the anoxic unit have been set up independently for a long time, resulting in a long treatment process and a large number of structures. This leads to the separation of front-end carbon release and subsequent denitrification in terms of space and function, and insufficient connection between carbon source release and carbon source utilization. On the other hand, the subsequent anoxic unit still needs to bear a large denitrification load. In the treatment of low C / N industrial wastewater, problems such as limited denitrification efficiency, high load of subsequent treatment units, and insufficient overall system synergy are likely to occur.

[0003] To improve the treatment efficiency of wastewater with low biodegradability, the industry is gradually introducing zero-valent iron (nZVI) into treatment systems to enhance organic matter conversion and biological reaction processes. Existing research and technology have confirmed that nZVI can optimize treatment effects by improving the biodegradability of organic wastewater, supplementing electron donors, and enhancing microbial activity. Among these, nano-nZVI, with its large specific surface area, high reactivity, and strong electron transfer capacity, shows great potential for enhanced treatment of industrial wastewater with low biodegradability. After participating in anaerobic processes, nZVI can regulate the redox environment of the system, promote organic matter conversion, and create suitable reaction conditions for denitrification.

[0004] Current technologies related to nano-zero valent iron mostly focus on local enhancement of single treatment stages such as anaerobic units and hydrolysis acidification units, which only improve local treatment performance. However, no targeted process structure optimization scheme has been developed to address the problem of insufficient carbon release-denitrification synergy caused by the separate hydrolysis acidification and anoxic units.

[0005] Among existing related patents, application number 202311819616.7 (publication date 2023.12.27) discloses a sulfur autotrophic denitrification process for anaerobic reactors enhanced with nano-iron oxides, which can improve the treatment efficiency of high nitrate wastewater; application number 202310959191.3 (publication date 2023.09.15) uses a combination of nano-iron / carbon micro-electrolysis pretreatment and anaerobic membrane treatment to treat recalcitrant organic wastewater, significantly improving pollutant removal rate, and the process is simple and has low operating costs. The above patents all focus on enhancing a single process of anaerobic digestion or denitrification, failing to address the pain points of insufficient synergy between hydrolysis acidification and denitrification in the front-end treatment of low C / N ratio industrial wastewater, and excessively high loads on subsequent units. Therefore, the development of a nano-iron-enhanced front-end synergistic treatment device and method is urgently needed. Summary of the Invention

[0006] Objective: To address the problems of poor synergy between upstream hydrolysis acidification for carbon release and subsequent anoxic denitrification, high load on subsequent treatment units, long system flow, and low operating efficiency in the treatment of low C / N ratio industrial wastewater, this invention provides a nano-iron-enhanced integrated hydrolysis acidification-denitrification treatment device and method. This invention constructs a nano-iron-enhanced synergistic reaction environment in the upstream treatment unit, enabling the simultaneous occurrence of organic matter hydrolysis acidification and denitrification processes within the same unit. This improves the efficiency of the connection between upstream carbon release and denitrification, reduces the load on subsequent treatment units, and enhances the overall stability and treatment effect of the low C / N ratio industrial wastewater treatment system.

[0007] Technical solution: A nano-iron enhanced hydrolysis acidification-denitrification synergistic integrated treatment device, which includes a monitoring module, a control module, a nano-iron dosing module, a reflux module, an integrated front-end reaction module and a subsequent treatment unit. The modules are connected by pipelines or signals to form a synergistic treatment system. Integrated front-end reaction module: used for the front-end co-treatment of low C / N ratio industrial wastewater, divided into an influent regulation zone and a nano-iron enhanced co-reaction zone. The influent regulation zone is responsible for the influent distribution and water quality buffering of the wastewater to be treated. The nano-iron enhanced co-reaction zone, under the action of nano-iron and with the participation of nitrate-containing reflux liquid, simultaneously completes the organic matter hydrolysis acidification and partial denitrification reaction. Nano-iron dosing module: Used to add nano-iron material to the nano-iron-enhanced synergistic reaction zone, consisting of a nano-iron storage unit, a metering unit, and a dosing unit; the nano-iron material used is one or more of nano-zero-valent iron, supported nano-zero-valent iron, composite nano-iron, and nano-iron oxide; Reflux module: Used to introduce nitrate-containing reflux liquid from subsequent treatment units into the nano-iron enhanced synergistic reaction zone, consisting of reflux pipeline, reflux pump, and flow regulation unit; nitrate-containing reflux liquid is taken from the effluent of the aerobic unit or nitrification liquid of subsequent treatment units; Monitoring module: Used to detect the operating parameters of the nano-iron-reinforced synergistic reaction zone and transmit the data to the control module. Detected parameters include ORP and NO3. - -N and one or more other water quality parameters that reflect the state of synergistic reaction; Control module: Connected to the monitoring module, nano-iron dosing module, and reflux module respectively, receiving monitoring data and adjusting the nano-iron dosing amount and reflux conditions based on the results; it can adjust the dosage of nano-iron and reflux conditions according to ORP and NO3. - The changes in parameters including -N and COD, and the construction of synergistic efficiency index by one or more parameters, are used to quantify the degree of synergy between organic matter conversion and partial denitrification in the front-end reaction unit, and to maintain the nano-iron-enhanced synergistic reaction zone in the optimal operating state of hydrolysis acidification and denitrification synergistic. The subsequent treatment unit is located at the rear of the integrated front-end reaction module and performs advanced treatment on the effluent from the front-end reaction module. It includes an anoxic unit and an aerobic unit. Part of the effluent from the aerobic unit is returned to the nano-iron enhanced synergistic reaction zone via the reflux module, and the other part is discharged as the final effluent from the system.

[0008] Based on the above-described apparatus, the present invention also provides a method for treating industrial wastewater with a low carbon-to-nitrogen ratio, comprising the following steps: S1. Introduce the low carbon-to-nitrogen ratio industrial wastewater to be treated into the integrated front-end reaction module; S2. Nano-iron material is added to the integrated front-end reaction module via the nano-iron dosing module; S3. Nitrate-containing reflux liquid is introduced into the integrated front-end reaction module via the reflux module; S4. Use the monitoring module to detect the influent water quality parameters and the reaction process operating parameters, and transmit the detected data to the control module; S5. Construct a synergistic control index based on the monitoring results, and adjust the amount of nano-iron and reflux conditions according to the synergistic control index so that organic matter hydrolysis acidification and partial denitrification reactions can be realized simultaneously in the integrated front-end reaction module. S6. The effluent from the integrated front-end reaction module is introduced into the subsequent treatment unit for further processing.

[0009] Preferably, in step S2, the nano-iron material is added between the water inlet zone and the mixing reaction zone to improve the contact efficiency between the nano-iron and pollutants and microbial systems.

[0010] Preferably, in step S3, the nitrate-containing reflux liquid is taken from the effluent of the subsequent aerobic unit or the nitrified liquid.

[0011] Preferably, in step S4, the influent water quality parameters include one or more of COD, BOD, pH, and total nitrogen, and the reaction process operating parameters include one or more of ORP, nitrate concentration, VFA, ammonia nitrogen, and total nitrogen.

[0012] Preferably, in step S5, the operating status is controlled by using ORP as the core indicator, combined with changes in COD and nitrate concentrations.

[0013] The control module constructs a target optimization function based on the synergistic control index according to nitrate concentration, COD, and ORP parameters, the expression of which is:

[0014] In the formula, The dosage of nano-iron, For reflux ratio, The residence time of the reaction. The nitrate removal rate, COD removal rate Indicates real-time redox potential. As the optimal benchmark Values The above formula uses Quantifying the redox state in the reaction zone enables the quantification of adaptation to the reducing environment. , and These are the weighting coefficients, which can be obtained through training with sample data. It can be dynamically adjusted according to the process stage (such as start-up / stable operation period): Start-up phase: Focus Environmental adaptation Take the higher value, 0.5-0.6. , Take the relatively low value; Stabilization period: Focus on denitrification and COD removal. , Take the highest value (total 0.7~0.8). Adaptation and adjustments.

[0015] The control module aims to maximize the objective function. , , Adjustments are made to bring the nano-iron-enhanced synergistic reaction zone to its optimal operating state.

[0016] Preferably, in step S5, the control module coordinates one or more of the following based on the change of the coordinated control index: the amount of nano-iron added, the reflux ratio, and the reaction residence time, so as to maintain the integrated front-end reaction module in an optimal operating state in which hydrolysis acidification and partial denitrification are carried out in synergy.

[0017] The control module's regulation process is as follows: S51, Get Real-time Values, calculate the redox state characterization term Calculate the COD removal rate based on the COD concentrations of the influent and effluent. Calculate the nitrate removal rate based on the nitrate concentration in the reaction zone. .

[0018] S52. Calculation of the collaborative control index, including substituting the collected parameters into the optimized objective function. Calculate the collaborative control index under the current operating state to quantitatively evaluate the comprehensive matching degree of ORP environment, COD removal and denitrification efficiency.

[0019] S53, Dynamic parameter closed-loop control, with objective function Maximizing as the core objective, adjusting in real time based on exponential deviation. (Dosage of nano-iron) (reflux ratio) (Duration of stay): If the collaborative control index is too low, priority should be given to adjustment. Optimize the baseline ORP value (if the ORP is too high, increase the amount of nano-iron added and strengthen the reduction environment); Synchronous Linkage Optimize nitrate mass transfer, Adapt to substrate degradation time to ensure synergistic matching between core ORP indicators and COD and nitrate parameters; The parameters are continuously iterated until the synergistic control index reaches the optimal threshold, so that the nano-iron-enhanced synergistic reaction zone is stably in the optimal operating state.

[0020] Preferably, in step S6, the subsequent treatment unit may be an aerobic unit or an anoxic-aerobic combined treatment unit.

[0021] Furthermore, in this method, after the nano-iron enters the front-end reaction unit, it regulates the redox environment of the system, promotes the transformation of complex organic matter into easily utilized small molecule organic matter, and constructs a reaction environment in which hydrolysis acidification and partial denitrification proceed in synergy. This enables the front-end unit to have both organic matter conversion and partial denitrification functions, effectively reducing the load on subsequent treatment units.

[0022] Furthermore, based on the above scheme, the method of the present invention is applicable to the front-end co-treatment process of pharmaceutical, chemical, petrochemical, fine chemical and other low C / N, low biodegradability industrial wastewater.

[0023] Beneficial effects: This invention uses nano-iron reinforcement and nitration liquor reflux as its core design features, simultaneously achieving hydrolysis acidification carbon release and denitrification within the same reaction unit. It establishes a synergistic link between carbon source release and carbon source utilization from a mechanistic perspective. The specific working principle is as follows: (1) Redox Environment Regulation: After nano-iron (mainly nano-zero-valent iron) is added to the reaction system, it continuously provides electrons and regulates ORP, rapidly constructing a weakly reducing environment suitable for the coexistence of hydrolysis acidification and denitrification, avoiding the limitations of single anaerobic or anoxic conditions. This invention uses ORP as the sole characterization index of redox state, directly integrating it into the objective function through normalization term, ensuring that environmental regulation is always anchored to the core benchmark, breaking the limitations of single-parameter regulation, realizing the dynamic linkage of ORP (environment), COD (substrate), and nitrate (efficiency), avoiding overall imbalance caused by single-parameter optimization, and using weight coefficients to dynamically adapt to the process stage, taking into account both the environmental construction in the start-up period and the efficiency improvement in the stable period, adapting to the full-cycle management of complex wastewater conditions.

[0024] (2) The biodegradability of organic matter is improved by nano-iron catalytic cracking of difficult-to-degrade macromolecular organic matter in wastewater, converting it into small molecule volatile acids (VFAs) such as acetic acid and propionic acid that are easily utilized by microorganisms, thus supplementing the carbon source required for denitrification in situ and solving the problem of insufficient carbon source in wastewater with low carbon-to-nitrogen ratio.

[0025] (3) The aerobic nitrification liquid that is simultaneously hydrolyzed and acidified and denitrified carries in nitrate nitrogen. Under the combined action of nano-iron enhancement and microorganisms, the carbon source generated by hydrolysis and acidification is directly utilized by denitrifying bacteria, achieving simultaneous carbon release and nitrogen removal. The two reactions are completed synergistically in the same unit.

[0026] (4) The integrated front-end unit of the system load reduction system simultaneously completes the organic matter conversion and part of the total nitrogen removal, which greatly reduces the treatment load of the subsequent anoxic and aerobic units, shortens the overall process flow, and improves the system stability and treatment efficiency.

[0027] Based on the above effects, the present invention also includes the following effects: Highly integrated process: It combines hydrolysis acidification and denitrification into one process, resulting in a shorter process flow, smaller footprint, and solving the problem of poor connection between segments in traditional processes.

[0028] Enhanced adaptability to low C / N ratio wastewater: Nano-iron in situ improves biodegradability and supplements electron donors, enabling efficient nitrogen removal without the need for additional carbon sources.

[0029] Higher processing efficiency: Simultaneous carbon release and nitrogen removal, with COD and total nitrogen reduced at the front end, significantly reducing the load on subsequent units.

[0030] Stable and controllable operation: The device is equipped with online monitoring and automatic control of ORP and nitrate, making the system more resistant to water quality fluctuations.

[0031] Wide range of applications: This invention can be used for low C / N and difficult-to-degrade industrial wastewater in pharmaceutical, chemical, and petrochemical industries, and has strong versatility. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the integrated treatment device for nano-iron-enhanced hydrolysis acidification-denitrification described in this invention. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are all available from publicly available commercial sources.

[0034] Example 1: Integrated treatment of pharmaceutical industry wastewater with low B / C ratio and low biodegradability

[0035] 1) Take 10 L of wastewater from the front end of the pretreatment unit of a pharmaceutical company. The wastewater has a COD concentration of 3000 mg / L, a total nitrogen concentration of 85 mg / L, a BOD concentration of 420 mg / L, a pH of 7.0, and a B / C ratio of 0.14.

[0036] 2) The wastewater is introduced into the integrated front-end reaction module, and the reactor is controlled to be in a closed stirring state with a stirring speed of 200 r / min and a hydraulic retention time of 6 h.

[0037] 3) Nano-zero valent iron is added to the integrated front-end reaction module through the nano-iron dosing module at a dosage of 600 mg / L. The nano-iron dosing position is located between the inlet water adjustment zone and the nano-iron enhanced synergistic reaction zone.

[0038] 4) The nitrification liquid of the subsequent aerobic unit is introduced into the integrated front-end reaction module through the reflux module. The reflux ratio is controlled at 80%, and the nitrate nitrogen concentration in the reflux liquid is 35 mg / L.

[0039] 5) The changes in ORP, COD, nitrate concentration, total nitrogen and SCOD during the reaction process are detected by the monitoring module. During the operation of the reactor, ORP is maintained at -180~-120 mV.

[0040] 6) After the reaction, the COD of the effluent from the front-end reaction module decreased to 2100 mg / L, total nitrogen decreased to 63 mg / L, and nitrate nitrogen decreased from 35 mg / L to 18 mg / L, with a removal rate of 48.6%. Simultaneously, the SCOD of the effluent from the front-end reaction module increased from 620 mg / L to 980 mg / L, an increase of 58.1%, indicating that complex organic matter in the front-end unit was effectively converted and well integrated with the partial denitrification process. In contrast, without the addition of nano-iron and with other operating conditions remaining consistent, the COD of the effluent from the front-end reaction module was 2350 mg / L, total nitrogen was 71 mg / L, and nitrate nitrogen decreased to 24 mg / L, with a removal rate of 31.4%. The COD increased from 610 mg / L to 780 mg / L, an increase of 27.9%. Comparatively, in this embodiment, the front-end nitrate nitrogen removal rate increased by 17.2%, and the COD increase increased by 30.2%, indicating that the integration efficiency of the front-end carbon release and denitrification processes was significantly improved under nano-iron enhancement conditions.

[0041] 7) The effluent from the front-end reaction module was introduced into the subsequent aerobic treatment unit. After one continuous cycle, the COD of the aerobic effluent decreased to 180 mg / L, and the total nitrogen decreased to 18 mg / L. In contrast, without the addition of nano-iron, the COD of the subsequent aerobic effluent was 240 mg / L, and the total nitrogen was 24 mg / L. This demonstrates that after the enhanced front-end synergistic treatment with nano-iron, both the organic and nitrogen loads entering the subsequent units were reduced, effectively alleviating the pressure on subsequent treatment.

[0042] 8) The results show that by adding nano-iron and introducing nitrate-containing reflux liquid in the front-end reaction unit, the present invention can achieve the synergistic effect of hydrolysis acidification and partial denitrification in the treatment of low C / N industrial wastewater, thereby improving the connection efficiency of the front-end carbon release and denitrification process and reducing the load of subsequent treatment units.

[0043] Example 2: Integrated Front-End Treatment of Chemical Wastewater

[0044] 1) Take 10 L of low C / N industrial wastewater from a chemical enterprise. The wastewater has a COD concentration of 2600 mg / L, a total nitrogen concentration of 92 mg / L, a BOD concentration of 360 mg / L, a pH of 6.8, and a B / C ratio of 0.14.

[0045] 2) Introduce the wastewater into the integrated front-end reaction module and start stirring. The stirring speed is controlled at 250 r / min and the hydraulic retention time is 8 h.

[0046] 3) Nano-zero valent iron is added to the integrated front-end reaction module through the nano-iron dosing module at a dosage of 700 mg / L.

[0047] 4) The reflux liquid of the subsequent aerobic unit is introduced into the integrated front-end reaction module through the reflux module. The reflux ratio is controlled at 100%, and the nitrate nitrogen concentration in the reflux liquid is 40 mg / L.

[0048] 5) The ORP, VFA, nitrate concentration and total nitrogen changes during the reaction process are continuously monitored by the monitoring module, with the ORP maintained at -200~-130 mV during reactor operation.

[0049] 6) After the reaction, the COD of the effluent from the front-end reaction module decreased to 1750 mg / L, the total nitrogen decreased to 66 mg / L, the nitrate nitrogen in the reflux liquid decreased from 40 mg / L to 19 mg / L, and the VFA concentration increased significantly. This indicates that the front-end reactor, with the participation of nano-iron, formed a reaction environment conducive to the synergistic conversion of organic matter and partial denitrification. Preferably, according to the synergistic control exponential function calculation described in step S5, in this example, α=0.4, β=0.3, γ=0.3, and the preset target ORP0=-150mv is taken. The average ORP during the reaction process is taken as -165mv. Then J=0.4×0.525+0.3×0.327+0.3×0.85=0.578, indicating that under this operating condition, the combination of nano-iron dosage, reflux ratio, and reaction residence time is conducive to the front-end synergistic reaction unit approaching the optimal operating state. The optimal operating state can be determined in combination with the actual operating scenario, including the determination of the device's operating objectives and treatment objectives.

[0050] 7) The effluent from the front-end reaction module is further introduced into the subsequent anoxic-aerobic combined treatment unit. After one cycle, the COD of the final effluent from the system drops to 150 mg / L and the total nitrogen drops to 15 mg / L.

[0051] The results show that the present invention is applicable to the front-end co-treatment process of different types of low C / N industrial wastewater. By adjusting the dosage of nano-iron and the reflux conditions, the front-end unit can have both organic hydrolysis acidification and partial denitrification functions, and it is beneficial to reduce the operating load of the subsequent anoxic-aerobic treatment unit.

[0052] The above embodiments are for illustrative purposes only and do not represent the superiority or inferiority of the embodiments. Based on this invention, those skilled in the art can make reasonable modifications and improvements, and all modifications and improvements that do not depart from the spirit of this invention fall within the protection scope of this invention.

Claims

1. A nano-iron-enhanced hydrolysis acidification-denitrification synergistic integrated treatment device, characterized in that, The device includes a monitoring module, a control module, a nano-iron dosing module, a reflux module, an integrated front-end reaction module, and a post-processing unit. The modules are connected by pipelines or signals to form a collaborative processing system. Integrated front-end reaction module: used for the front-end co-treatment of low C / N ratio industrial wastewater, divided into an influent regulation zone and a nano-iron enhanced co-reaction zone. The influent regulation zone is responsible for the influent distribution and water quality buffering of the wastewater to be treated. The nano-iron enhanced co-reaction zone, under the action of nano-iron and with the participation of nitrate-containing reflux liquid, simultaneously completes the organic matter hydrolysis acidification and partial denitrification reaction. Nano-iron dosing module: Used to add nano-iron material to the nano-iron-enhanced synergistic reaction zone, consisting of a nano-iron storage unit, a metering unit, and a dosing unit; the nano-iron material used is one or more of nano-zero-valent iron, supported nano-zero-valent iron, composite nano-iron, and nano-iron oxide; Reflux module: Used to introduce nitrate-containing reflux liquid from subsequent treatment units into the nano-iron enhanced synergistic reaction zone, consisting of reflux pipeline, reflux pump, and flow regulation unit; nitrate-containing reflux liquid is taken from the effluent of the aerobic unit or nitrification liquid of subsequent treatment units; Monitoring module: Used to detect the operating parameters of the nano-iron-reinforced synergistic reaction zone and transmit the data to the control module. Detected parameters include ORP and NO3. - -N and one or more other water quality parameters that reflect the state of synergistic reaction; Control module: Connected to the monitoring module, nano-iron dosing module, and reflux module respectively, receiving monitoring data and adjusting the nano-iron dosing amount and reflux conditions based on the results; according to ORP and NO3... - By adjusting parameters including -N and COD, one or more of the following factors, such as the amount of nano-iron added, the reflux ratio, and the reaction residence time, the nano-iron-enhanced synergistic reaction zone is kept in the optimal operating state where hydrolysis acidification and denitrification are carried out in synergistic manner. The subsequent treatment unit is located at the rear of the integrated front-end reaction module and performs advanced treatment on the effluent from the front-end reaction module. It includes an anoxic unit and an aerobic unit. Part of the effluent from the aerobic unit is returned to the nano-iron enhanced synergistic reaction zone via the reflux module, and the other part is discharged as the final effluent from the system.

2. A method for treating low C / N ratio industrial wastewater using the apparatus as described in claim 1, characterized in that, The implementation steps include: S1. Introduce the low carbon-to-nitrogen ratio industrial wastewater to be treated into the integrated front-end reaction module; S2. Nano-iron material is added to the integrated front-end reaction module via the nano-iron dosing module; S3. Nitrate-containing reflux liquid is introduced into the integrated front-end reaction module via the reflux module; S4. Use the monitoring module to detect the influent water quality parameters and the reaction process operating parameters, and transmit the detected data to the control module; S5. Based on the monitoring results, adjust the amount of nano-iron and the reflux conditions to enable the organic matter hydrolysis acidification and partial denitrification reaction to be realized simultaneously in the integrated front-end reaction module. S6. The effluent from the integrated front-end reaction module is introduced into the subsequent treatment unit for further processing.

3. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In step S2, nano-iron materials are added between the inlet water zone and the mixing reaction zone to improve the contact efficiency between nano-iron and pollutants and microbial systems.

4. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In step S3, the nitrate-containing reflux liquid is taken from the effluent of the subsequent aerobic unit or the nitrified liquid.

5. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In step S4, the influent water quality parameters include one or more of COD, BOD, pH, and total nitrogen, and the reaction process operating parameters include one or more of ORP, nitrate concentration, VFA, ammonia nitrogen, and total nitrogen.

6. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In step S5, the control module coordinates the dosage of nano-iron, reflux ratio and reaction residence time based on one or more parameters among ORP, COD, nitrate concentration and total nitrogen. The operating status is characterized by ORP as the core indicator, and is regulated by combining changes in COD and nitrate concentrations.

7. The method for treating industrial wastewater with a low carbon-to-nitrogen ratio according to claim 2 or 6, characterized in that, In step S5, the control module constructs a target optimization function based on the synergistic control index according to the nitrate concentration, COD, and ORP parameters. Its expression is: In the formula, The dosage of nano-iron, For reflux ratio, The residence time of the reaction. The nitrate removal rate, COD removal rate Indicates real-time redox potential. As the optimal benchmark Values The above formula uses Quantifying the redox state in the reaction zone enables the quantification of adaptation to the reducing environment. , and These are the weighting coefficients, which can be obtained through training with sample data. It can be dynamically adjusted according to the process stage: Start-up phase: Focus Environmental adaptation Take the higher value, 0.5-0.

6. , Take the relatively low value; Stabilization period: Focus on denitrification and COD removal. , Take a value of 0.7~0.

8. Adaptation and adjustments.

8. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In step S6, the subsequent treatment unit can be an aerobic unit or an anoxic-aerobic combined treatment unit.

9. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, In this method, after nano-iron enters the front-end reaction unit, it regulates the redox environment of the system, promotes the transformation of complex organic matter into easily utilized small molecule organic matter, and constructs a reaction environment in which hydrolysis acidification and partial denitrification proceed in tandem. This enables the front-end unit to have both organic matter conversion and partial denitrification functions, effectively reducing the load on subsequent processing units.

10. The method for treating low C / N ratio industrial wastewater according to claim 2, characterized in that, The method is applicable to the front-end co-treatment process of industrial wastewater from pharmaceutical, chemical, petrochemical, fine chemical, and other industries with low C / N and low biodegradability.

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