Ex-situ microbial remediation method for river sewage

Abstract

The application relates to the technical field of microbial remediation methods, and specifically discloses an ex-situ microbial remediation method for river sewage, aiming to solve the multiple contradictions of redundancy of existing ex-situ microbial remediation technology, single function of bacterial flora, weak environmental adaptability and difficulty in giving consideration to high efficiency and engineering simplicity. The method comprises the following steps: guiding the river sewage out and pretreating the river sewage to remove large-particle impurities; introducing a biological reactor to inoculate a composite functional bacterial flora composed of the genus Raoultella, the genus Pseudomonas and the genus Bacillus in proportion; implementing gradient dissolved oxygen regulation to realize simultaneous nitrification and denitrification; adding iron-manganese modified biochar as a microbial carrier and an electron mediator; and recycling the biochar after solid-liquid separation and reaction. Through the above technical scheme, the application can realize multi-target and simultaneous high-efficiency removal of ammonia nitrogen, refractory organic matter and trace heavy metals, simplify a process flow, improve system stability and low-temperature adaptability, and support modular deployment and intelligent operation and maintenance.

Description

Technical Field

[0001] This invention relates to the fields of environmental engineering and water pollution control technology, specifically to a method for the ex-situ microbial remediation of river wastewater. Background Technology

[0002] With the acceleration of urbanization, river water pollution has become increasingly severe. The continuous input of complex pollutants such as ammonia nitrogen, chemical oxygen demand (COD), and recalcitrant organic matter has seriously damaged the self-purification capacity and biodiversity of aquatic ecosystems. Ex-situ microbial remediation technology, due to its environmental friendliness, high degradation efficiency, and modular implementation, is considered one of the key pathways for addressing urban river wastewater treatment. This technology involves drawing polluted water out of the site and utilizing the metabolic activities of functional microorganisms in a controlled reaction system to achieve efficient transformation and removal of pollutants, providing a feasible alternative for high-pollution scenarios that are difficult to cover with traditional in-situ remediation.

[0003] Among these, ex-situ biological treatment methods based on specific functional strains have received widespread attention in recent years. A typical approach, such as using *Laurella* for a two-stage heterotrophic nitrification-aerobic denitrification treatment, has shown some effectiveness in removing single nitrogenous pollutants. However, its process is highly dependent on physicochemical auxiliary units such as centrifugation and multi-stage filtration, resulting in a complex system structure, high energy consumption, and difficulty in adapting to the engineering characteristics of large-flow, low-concentration, and continuous discharge of river wastewater. Furthermore, these methods generally rely on single or a few functional bacterial species, lacking broad-spectrum degradation capabilities for complex pollutant components (such as aromatic organic matter and trace heavy metal coexistence systems), and exhibit significantly reduced stability in the face of actual water quality fluctuations.

[0004] Existing technologies also attempt to introduce microbial electrochemical systems to enhance pollutant transformation; however, such devices are typically constructed under strictly anaerobic conditions, relying on electrodes, ion exchange membranes, and external power sources to form a closed electrochemical circuit. This not only results in high equipment costs, but also means that their reaction mechanisms are primarily adapted to gaseous substrates (such as...). The reduction process of [unclear] makes it difficult to effectively couple the ammonia nitrogen oxidation and organic matter mineralization requirements in river wastewater, which are dominated by aerobic / facultative anaerobic metabolism. In summary, current ex-situ microbial remediation technologies generally suffer from multiple contradictions, including process redundancy, limited microbial community function, weak environmental adaptability, and difficulty in balancing high efficiency and engineering simplicity. There is an urgent need for a novel remediation method that combines an integrated and optimized functional microbial community synergistic system with a simplified operation process to achieve simultaneous and efficient removal of multiple pollutants while meeting the requirements of low cost and easy deployment in engineering applications. Summary of the Invention

[0005] The purpose of this invention is to provide a method for extrinsic microbial remediation of river wastewater, comprising the following specific steps:

[0006] Step 1: The polluted river water is pumped out from its original location and transported to the pretreatment unit for physical interception to remove suspended solids and floating impurities with a particle size greater than 2 mm. The hydraulic retention time is adjusted to 30 minutes to obtain preliminarily purified wastewater.

[0007] Step 2: The preliminarily purified wastewater is introduced into a bioreactor and inoculated with an active microbial preparation consisting of a complex functional bacterial community. This community includes *Raoultella* strains with both heterotrophic nitrification and aerobic denitrification capabilities, *Pseudomonas* strains capable of degrading aromatic organic matter, and *Bacillus* strains with adsorption and conversion capabilities for trace heavy metals. The ratio of viable bacteria counts for each strain is controlled at 1.5:1:0.8, and the total inoculation concentration is [missing information - likely a concentration per liter]. CFU;

[0008] Step 3: Implement gradient dissolved oxygen regulation in the bioreactor. In the initial stage of the reaction, maintain the dissolved oxygen concentration at 6 mg / L for 4 hours to promote ammonia nitrogen oxidation and aerobic degradation of organic matter. Then gradually reduce it to 2 mg / L and maintain it for 8 hours to activate the facultative anaerobic metabolic pathway in the microbial community and achieve simultaneous nitrification and denitrification.

[0009] Step 4: Add modified biochar to the bioreactor as a microbial carrier and electron mediator. The modified biochar is treated with iron-manganese bimetallic oxide loading, and the specific surface area reaches 850 square meters per gram. The addition amount is 0.8 grams per liter of reaction solution, which is used to enhance the adhesion stability of the microbial community and promote the extracellular electron transfer process.

[0010] Step 5: After the biodegradation reaction is completed, the reaction solution is introduced into the solid-liquid separation unit. The biochar particles with functional bacteria attached are recovered by gravity sedimentation combined with microporous membrane filtration. The recovery rate is not less than 95%, and effluent that meets the discharge standards is obtained.

[0011] Step 6: After rinsing the recovered biochar granules with physiological saline, they are recycled back into the bioreactor for the next cycle. The continuous operation cycle is no less than 30 times. Each time, 15% of the lost fresh biochar and the corresponding proportion of functional bacteria are added to maintain the long-term operational stability of the system.

[0012] Preferably, in step 1, the flow rate adjustment range of the pumping system is from 5 cubic meters to 50 cubic meters per hour, the pretreatment unit is equipped with an automatic backwashing grille with a grille width of 2 mm, and the backwashing cycle is set to once every 6 hours.

[0013] Preferably, the composite functional microbial community in step 2 is prepared using a staged activation culture process. First, each single microbial species is amplified to the stable phase in its own optimal culture medium, and then transferred to a co-culture medium simulating the actual wastewater composition for synergistic acclimatization. The acclimatization period is 14 days, during which the pollutant load is gradually increased, and finally a stable symbiotic system with metabolic complementarity and strong stress resistance is formed.

[0014] Preferably, the bioreactor in step 2 is a cylindrical completely mixed reactor with an effective volume of 10 cubic meters. It is equipped with a double-layer baffle structure to optimize the flow field distribution and avoid the formation of dead zones. At the same time, it is equipped with an online monitoring probe to collect pH value, redox potential and temperature data in real time, with a sampling frequency of once per minute.

[0015] Preferably, in step 3, dissolved oxygen regulation is achieved through a frequency converter-controlled aeration device. Air is released through a ceramic microporous aeration head to form bubbles with a diameter of less than 3 mm. The air-to-water ratio is controlled at 8:1, the oxygen utilization efficiency is greater than 75%, and the blower output power is dynamically adjusted according to the real-time feedback of dissolved oxygen data, with the error range controlled within ±0.2 mg / L.

[0016] Preferably, the method for preparing modified biochar in step 4 includes: using coconut shell as raw material, pyrolyzing it at 700 degrees Celsius for 6 hours under a nitrogen atmosphere to obtain raw biochar, then impregnating it with a mixed solution of ferric chloride and manganese sulfate with a concentration of 0.3 mol / L for 12 hours, and then drying and calcining it a second time to make the iron and manganese oxides uniformly dispersed on the surface of the pores.

[0017] Preferably, in step 5, the microporous filter membrane is made of polyvinylidene fluoride with a pore size of 0.22 micrometers, an operating pressure of 0.1 MPa, a membrane flux maintained at more than 50 liters per square meter per hour, and is equipped with an ultrasonic-assisted cleaning module that is activated once every 2 hours of operation for 3 minutes each time.

[0018] Preferably, the effluent quality in step 5 meets the Class A limit requirements of the pollutant discharge standard for urban wastewater treatment plants, wherein the chemical oxygen demand is less than 50 mg / L, the ammonia nitrogen concentration is less than 5 mg / L, the total nitrogen concentration is less than 15 mg / L, and the turbidity is less than 3 NTU.

[0019] Preferably, during the recycling of biochar particles in step 6, the regeneration needs are assessed by periodically detecting changes in their surface functional groups and metal loading saturation. When the methylene blue adsorption value decreases by more than 30% or the manganese leaching concentration is higher than 0.5 mg / L, a high-temperature regeneration activation program is initiated, and the adsorption and catalytic performance is restored by calcining at 800 degrees Celsius for 2 hours under an inert atmosphere.

[0020] Preferably, it also includes establishing an IoT-based remote monitoring platform, integrating a PLC control system and a wireless transmission module, collecting operating parameters of each process section in real time and uploading them to a cloud server, supporting mobile access and abnormal alarm push notifications, and allowing maintenance personnel to remotely adjust dissolved oxygen setpoints, dosage, and sludge discharge cycles through a human-machine interface.

[0021] Compared with the prior art, the beneficial effects of the present invention are: the ex-situ microbial remediation method for river wastewater:

[0022] By constructing a composite functional microbial community composed of *Raoultella*, *Pseudomonas*, and *Bacillus*, the simultaneous removal of ammonia nitrogen, recalcitrant organic matter, and trace heavy metals was achieved, overcoming the treatment blind spots caused by the functional limitations of single microbial species. A gradient dissolved oxygen regulation strategy was employed to precisely match the biochemical requirements of different metabolic pathways, completing the entire process of nitrification, denitrification, and organic matter mineralization within a single reactor. This eliminated the complex structure of traditional multi-stage series reaction systems, significantly simplifying the process flow. The introduction of iron-manganese modified biochar as a multifunctional carrier not only enhanced the immobilized growth of microorganisms and electron transfer efficiency but also promoted the intermediate products of pollutants through surface catalysis. The rapid conversion of materials enhances the overall reaction kinetics performance; combined with the efficient recovery and recycling mechanism of biochar, it significantly reduces the consumption of externally added materials, extends the system operating cycle, and reduces the production of residual sludge; the entire method ensures high removal efficiency while possessing good adaptability to water quality fluctuations and low-temperature tolerance, and can achieve modular deployment and intelligent management and control. It is particularly suitable for the actual working conditions of large flow, low concentration, and continuous discharge of sewage in urban rivers, and solves the fundamental contradiction between engineering practicality, operational economy, and ecological safety of existing ex-situ remediation technologies, providing a reliable and sustainable technical path for comprehensive urban water environment management. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figure 1 This invention provides a technical solution: an ex-situ microbial remediation method for river wastewater, comprising the following specific steps:

[0026] Step 1: The polluted river water is pumped out from its original location and transported to the pretreatment unit for physical interception to remove suspended solids and floating impurities with a particle size greater than 2 mm. The hydraulic retention time is adjusted to 30 minutes to obtain preliminarily purified wastewater.

[0027] The flow rate regulation of the pumping system must meet the hydraulic load requirements of the reactor. The core calculation relationship is as follows:

[0028]

[0029] in, for ( ), , .

[0030] Step 2: The preliminarily purified wastewater is introduced into a bioreactor and inoculated with an active microbial preparation consisting of a complex functional bacterial community. This community includes *Raoultella* strains with both heterotrophic nitrification and aerobic denitrification capabilities, *Pseudomonas* strains capable of degrading aromatic organic matter, and *Bacillus* strains with adsorption and conversion capabilities for trace heavy metals. The ratio of viable bacteria counts for each strain is controlled at 1.5:1:0.8, and the total inoculation concentration is [missing information - likely a concentration per liter]. CFU;

[0031] Calculation of inoculum size for multifunctional microbial communities:

[0032] ;

[0033] Formula for increasing pollutant load gradient during microbial acclimatization:

[0034] ;

[0035] in, For the first Pollutant load , As the initial pollutant load, This refers to the load increase rate.

[0036] Step 3: Implement gradient dissolved oxygen regulation in the bioreactor. In the initial stage of the reaction, maintain the dissolved oxygen concentration at 6 mg / L for 4 hours to promote ammonia nitrogen oxidation and aerobic degradation of organic matter. Then gradually reduce it to 2 mg / L and maintain it for 8 hours to activate the facultative anaerobic metabolic pathway in the microbial community and achieve simultaneous nitrification and denitrification.

[0037] Dissolved oxygen regulation precision control formula:

[0038] ;

[0039] in, Set as the target dissolved oxygen concentration (aerobic stage) hypoxia stage ), The measured values ​​are real-time values ​​collected by the online monitoring probe.

[0040] Calculation of air-to-water ratio for aeration system:

[0041] ;

[0042] Step 4: Add modified biochar to the bioreactor as a microbial carrier and electron mediator. The modified biochar is treated with iron-manganese bimetallic oxide loading, and the specific surface area reaches 850 square meters per gram. The addition amount is 0.8 grams per liter of reaction solution, which is used to enhance the adhesion stability of the microbial community and promote the extracellular electron transfer process.

[0043] Step 5: After the biodegradation reaction is completed, the reaction solution is introduced into the solid-liquid separation unit. The biochar particles with functional bacteria attached are recovered by gravity sedimentation combined with microporous membrane filtration. The recovery rate is not less than 95%, and effluent that meets the discharge standards is obtained.

[0044] Biochar recovery rate calculation:

[0045]

[0046] in, The mass of the biochar recovered after solid-liquid separation. This refers to the total mass of biochar added in step 4.

[0047] Step 6: After rinsing the recovered biochar granules with physiological saline, they are recycled back into the bioreactor for the next cycle. The continuous operation cycle is no less than 30 times. Each time, 15% of the lost fresh biochar and the corresponding proportion of functional bacteria are added to maintain the long-term operational stability of the system.

[0048] Biochar regeneration evaluation index: Methylene blue adsorption value reduction rate:

[0049] ;

[0050] in, The methylene blue adsorption value of fresh biochar , The methylene blue adsorption value is the value of the biochar after recycling.

[0051] Experimental Example

[0052] To verify the actual treatment effect of the remediation method of the present invention, a polluted urban river (mainly polluted by domestic sewage and a small amount of industrial wastewater) was selected as the treatment object, and a pilot-scale experiment was carried out for 30 consecutive days. The experimental device was designed according to the effective volume of a bioreactor. The setup, specific experimental data, and results are as follows:

[0053] (a) Water quality of the influent to the experiment

[0054] During the experiment, the water quality indicators of the influent to the polluted river were as shown in Table 1 below:

[0055]

[0056] (II) Experimental Operating Parameters

[0057] Pumping system design flow rate: (according to calculate, =10 , =12h);

[0058] Total inoculation concentration of the complex functional microbial community: 1.2× CFU / L, strain ratio (Raoultella: Pseudomonas: Bacillus) = 1.5:1:0.8;

[0059] Gradient dissolved oxygen regulation: aerobic phase (4h) DO=6mg / L, hypoxic phase (8h) DO=2mg / L;

[0060] Modified biochar dosage: 0.8 g / L; regeneration triggering conditions: methylene blue adsorption value decreases by >30% or Mn dissolution >0.5 mg / L;

[0061] Solid-liquid separation unit: PVDF microporous filter membrane (pore size 0.22μm), operating pressure 0.1MPa.

[0062] (III) Experimental Treatment Results

[0063] Pollutant removal efficiency: The experiment ran continuously for 30 days. The average removal rates of various water quality indicators and the effluent quality are shown in Table 2 below:

[0064]

[0065] As shown in Table 2, the method of this invention has a high efficiency in removing COD, ammonia nitrogen, total nitrogen, total phosphorus, and trace heavy metals from river wastewater. All effluent indicators consistently meet the Class A limits of the pollutant discharge standards for urban wastewater treatment plants. Specifically, ammonia nitrogen and trace heavy metals (…) The removal rates of all samples exceeded 84%, demonstrating the synergistic advantages of the composite functional microbial community and modified biochar.

[0066] Effect of biochar recycling: During the experiment, the biochar was recycled a total of 30 times. The methylene blue adsorption value and Mn dissolution concentration of the biochar were measured on days 10, 20, and 30. The results are shown in Table 3 below:

[0067]

[0068] As shown in Table 3, after 30 cycles of biochar recycling, the methylene blue adsorption value decreased by 31.2%, and the Mn leaching concentration was 0.52 mg / L, meeting the regeneration triggering conditions. After regeneration by calcination at 800℃ in an inert atmosphere for 2 hours, the methylene blue adsorption value recovered to 208 mg / g, with an adsorption performance recovery rate of 96.7%, and the Mn leaching concentration decreased to 0.09 mg / L, indicating that the biochar regeneration effect is significant and can be recycled.

[0069] System stability and low-temperature adaptability verification: During days 15-20 of the experiment, a simulated low-temperature environment (water temperature dropped from 25℃ to 12℃) was used to detect changes in the system's treatment effect. The results are shown in Table 4 below:

[0070]

[0071] As shown in Table 4, when the water temperature drops to 12℃, the removal rates of various pollutants only decrease slightly. Specifically, the COD removal rate decreases by 3.8 percentage points, the ammonia nitrogen removal rate decreases by 5.3 percentage points, and the total nitrogen removal rate decreases by 5.1 percentage points. The system can still maintain a stable treatment effect, demonstrating the good low-temperature adaptability of the method of this invention.

[0072] Comparative experiment with single-microbial remediation methods: A control group (inoculated only with *Raoultella* strains, other experimental conditions were the same as in this invention) was set up, and parallel comparative experiments were conducted. The results are shown in Table 5 below:

[0073]

[0074] As shown in Table 5, compared with single-bacterial remediation methods, the composite functional microbial community of the present invention, through metabolic complementarity, not only significantly improved the removal rates of COD and total nitrogen (by 25.8 and 25.1 percentage points, respectively), but also achieved efficient removal of trace heavy metals. In contrast, single-bacterial communities have almost no removal effect on heavy metals, which fully verifies the synergistic advantages of the composite functional microbial community.

[0075] Furthermore, in step 1, the flow rate adjustment range of the pumping system is from 5 cubic meters to 50 cubic meters per hour, the pretreatment unit is equipped with an automatic backwashing grille with a grille width of 2 mm, and the backwashing cycle is set to once every 6 hours.

[0076] Furthermore, in step 2, the composite functional microbial community is prepared using a phased activation culture process. First, each individual microbial species is amplified to the stable phase in its own optimal culture medium, and then transferred to a co-culture medium simulating the actual wastewater composition for synergistic acclimatization. The acclimatization period is 14 days, during which the pollutant load is gradually increased, ultimately forming a stable symbiotic system with metabolic complementarity and strong stress resistance.

[0077] Furthermore, in step 2, the bioreactor is a cylindrical completely mixed reactor with an effective volume of 10 cubic meters. It is equipped with a double-layer baffle structure to optimize the flow field distribution and avoid the formation of dead zones. At the same time, it is equipped with an online monitoring probe to collect pH value, redox potential and temperature data in real time, with a sampling frequency of once per minute.

[0078] Furthermore, in step 3, dissolved oxygen regulation is achieved through a frequency converter-controlled aeration device. Air is released through ceramic microporous aeration heads to form bubbles with a diameter of less than 3 mm. The air-to-water ratio is controlled at 8:1, the oxygen utilization efficiency is greater than 75%, and the blower output power is dynamically adjusted according to the real-time feedback of dissolved oxygen data, with the error range controlled within ±0.2 mg / L.

[0079] Furthermore, the preparation method of modified biochar in step 4 includes: using coconut shell as raw material, pyrolyzing it at 700 degrees Celsius for 6 hours under a nitrogen atmosphere to obtain raw biochar, then impregnating it with a mixed solution of ferric chloride and manganese sulfate with a concentration of 0.3 mol / L for 12 hours, and then drying and calcining it a second time to make the iron and manganese oxides uniformly dispersed on the surface of the pores.

[0080] Furthermore, in step 5, the microporous filter membrane is made of polyvinylidene fluoride with a pore size of 0.22 micrometers, an operating pressure of 0.1 MPa, and a membrane flux maintained at more than 50 liters per square meter per hour. An ultrasonic-assisted cleaning module is also provided, which is activated once every 2 hours of operation and lasts for 3 minutes each time.

[0081] Furthermore, in step 5, the effluent quality meets the Class A limit requirements of the pollutant discharge standard for urban wastewater treatment plants, wherein the chemical oxygen demand is less than 50 mg / L, the ammonia nitrogen concentration is less than 5 mg / L, the total nitrogen concentration is less than 15 mg / L, and the turbidity is less than 3 NTU.

[0082] Furthermore, during the recycling of biochar particles in step 6, the regeneration requirements are assessed by periodically detecting changes in their surface functional groups and metal loading saturation. When the methylene blue adsorption value decreases by more than 30% or the manganese leaching concentration is higher than 0.5 mg / L, a high-temperature regeneration activation program is initiated, and the adsorption and catalytic performance is restored by calcining at 800 degrees Celsius for 2 hours under an inert atmosphere.

[0083] Furthermore, it also includes establishing an IoT-based remote monitoring platform that integrates a PLC control system and a wireless transmission module to collect operating parameters of each process section in real time and upload them to a cloud server. It supports mobile access and abnormal alarm push notifications, and maintenance personnel can remotely adjust dissolved oxygen setpoints, dosage, and sludge discharge cycles through a human-machine interface.

[0084] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for extrinsic microbial remediation of river wastewater, characterized in that: The specific steps include the following: Step 1: The polluted river water is pumped out from its original location and transported to the pretreatment unit for physical interception to remove suspended solids and floating impurities with a particle size greater than 2 mm. The hydraulic retention time is adjusted to 30 minutes to obtain preliminarily purified wastewater. Step 2: The preliminarily purified wastewater is introduced into a bioreactor and inoculated with an active microbial preparation composed of a complex functional microbial community. The complex functional microbial community includes strains of Raoulbacterium that have both heterotrophic nitrification and aerobic denitrification capabilities, strains of Pseudomonas that can degrade aromatic organic matter, and strains of Bacillus that have the ability to adsorb and transform trace heavy metals. Step 3: Implement gradient dissolved oxygen regulation in the bioreactor for 4 hours to promote ammonia nitrogen oxidation and aerobic degradation of organic matter, then gradually reduce it to 2 mg / L and maintain it for 8 hours to activate the facultative anaerobic metabolic pathway in the microbial community and achieve simultaneous nitrification and denitrification. Step 4: Add modified biochar to the bioreactor as a microbial carrier and electron mediator. The modified biochar is treated with iron-manganese bimetallic oxide loading to enhance the adhesion stability of the microbial community and promote the extracellular electron transfer process. Step 5: After the biodegradation reaction is completed, the reaction solution is introduced into the solid-liquid separation unit. The biochar particles with attached functional bacteria are recovered by gravity sedimentation combined with microporous membrane filtration to obtain effluent that meets the discharge standards. Step 6: The recovered biochar particles are rinsed with physiological saline and then recycled back into the bioreactor for the next cycle.

2. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 1, the flow rate of the pumping system is adjustable from 5 cubic meters to 50 cubic meters per hour. The pretreatment unit is equipped with an automatic backwashing screen with a screen width of 2 mm and a backwashing cycle set to once every 6 hours.

3. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 2, the composite functional microbial community is prepared using a phased activation culture process. First, each single microbial species is amplified to the stable phase in its own optimal culture medium, and then transferred to a co-culture medium simulating the actual wastewater composition for synergistic acclimatization. During this period, the pollutant load is gradually increased, and finally a stable symbiotic system with metabolic complementarity and strong stress resistance is formed.

4. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 2, the bioreactor is a cylindrical completely mixed reactor with a double-layer baffle structure to optimize the flow field distribution and avoid the formation of dead zones. It is also equipped with an online monitoring probe to collect pH, redox potential and temperature data in real time, with a sampling frequency of once per minute.

5. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 3, dissolved oxygen regulation is achieved through a frequency converter-controlled aeration device. Air is released through a ceramic microporous aeration head to form bubbles with a diameter of less than 3 mm. The output power of the blower is dynamically adjusted according to the real-time feedback of dissolved oxygen data, with the error range controlled within ±0.2 mg / L.

6. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: The method for preparing modified biochar in step 4 includes: using coconut shell as raw material, pyrolyzing it at 700 degrees Celsius for 6 hours under a nitrogen atmosphere to obtain raw biochar, then mixing it with ferric chloride and manganese sulfate, and then drying and calcining it a second time to make the iron and manganese oxides uniformly dispersed on the surface of the pores.

7. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 5, the microporous filter membrane is made of polyvinylidene fluoride.

8. The method for extrinsic microbial remediation of river wastewater according to claim 1, characterized in that: In step 5, the effluent quality meets the Class A limit requirements of the pollutant discharge standard for urban wastewater treatment plants, wherein the chemical oxygen demand is less than 50 mg / L, the ammonia nitrogen concentration is less than 5 mg / L, the total nitrogen concentration is less than 15 mg / L, and the turbidity is less than 3 NTU.

9. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: In step 6, during the recycling of biochar particles, the regeneration needs are assessed by periodically detecting changes in their surface functional groups and metal loading saturation. When the methylene blue adsorption value decreases by more than 30% or the manganese leaching concentration is higher than 0.5 mg / L, a high-temperature regeneration activation program is initiated, and the adsorption and catalytic performance is restored by calcining at 800 degrees Celsius for 2 hours under an inert atmosphere.

10. The method for extant microbial remediation of river wastewater according to claim 1, characterized in that: It also includes establishing an IoT-based remote monitoring platform that integrates a PLC control system and a wireless transmission module to collect operating parameters of each process section in real time and upload them to a cloud server. It supports mobile access and abnormal alarm push notifications, and maintenance personnel can remotely adjust dissolved oxygen setpoints, dosage, and sludge discharge cycles through a human-machine interface.

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