A wastewater biodegradability early warning method and system based on the ratio of baseline current to impact response of microbial fuel cells

Abstract

This invention provides a wastewater biodegradability early warning method and system based on the baseline current and impact response ratio of microbial fuel cells. The method uses two microbial fuel cells with identical structural parameters as a reference reactor and a sample reactor, respectively. They are placed in the same environmental chamber and respectively purged with a standard control solution and the wastewater to be tested. The two output currents are collected simultaneously, and the response ratio is calculated after signal processing. Based on the magnitude and duration of the deviation of the response ratio from the steady-state historical average, an abnormal biodegradability early warning signal is output in stages. At the same time, a baseline adaptive calibration and equipment fault self-diagnosis mechanism are set up, which can effectively offset the baseline drift caused by environmental common-mode interference and biofilm decay, improve the reliability of early warning, and reduce operation and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of wastewater quality monitoring technology, specifically to a wastewater biodegradability early warning method and system based on the ratio of baseline current to impact response of microbial fuel cells. Background Technology

[0002] Wastewater biodegradability is a core parameter characterizing the ease with which organic matter in wastewater can be degraded by microorganisms. It directly determines the process parameter settings, load control strategies, and toxicity shock control effectiveness of wastewater treatment biological systems. Achieving continuous, real-time, and accurate monitoring of wastewater biodegradability is a key technological requirement for ensuring the stable operation of wastewater treatment plants, reducing the risk of effluent exceeding standards, and improving process control efficiency.

[0003] The current mainstream biodegradability assessment method in the industry is the five-day biochemical oxygen demand (BOD5) determination method. This method has a long detection cycle, complicated operation process, high manpower and reagent consumption, and can only realize offline batch detection. It cannot continuously reflect the dynamic changes of influent water quality, and it is difficult to capture sudden toxic shocks and high load fluctuations in a timely manner. It cannot meet the engineering needs of wastewater treatment plants for real-time process control and abnormal early warning.

[0004] Microbial fuel cell (MFC) technology relies on the extracellular electron transfer characteristics of electroactive microorganisms on the anode surface to directly convert the content of biodegradable organic matter in wastewater into a quantifiable current signal. It has outstanding advantages such as fast response speed, no need for external chemical reagents, and long-term continuous operation. It provides a feasible technical path for the online rapid detection of wastewater biodegradability and is an important research direction in the field of online water quality monitoring.

[0005] However, existing water quality monitoring solutions based on microbial fuel cells still suffer from several technical shortcomings, making it difficult to meet the stability and accuracy requirements of long-term online early warning. Most solutions use the absolute output current of a single-channel reactor as the basis for judgment. The output electrical signal is easily affected by fluctuations in environmental parameters such as ambient temperature, water pH, and conductivity, making it impossible to effectively distinguish whether signal changes are caused by alterations in wastewater biodegradability or by environmental fluctuations. This leads to a high false alarm rate and insufficient reliability of monitoring results. During long-term continuous operation, the anolyte biofilm inevitably undergoes activity decay and community succession, causing a slow drift in the output baseline current. Existing single-channel solutions cannot distinguish between biofilm activity decay and decreased influent biodegradability, requiring periodic manual zero-point calibration using a standard matrix. This significantly increases system maintenance costs and interrupts the monitoring process, affecting the continuity of online monitoring. Furthermore, some solutions using historical benchmarks for calibration can only eliminate system errors caused by batch reactor startups, failing to synchronously offset real-time environmental fluctuations during operation, thus also failing to guarantee the stability and accuracy of long-term online early warning. Summary of the Invention

[0006] The purpose of this invention is to provide a wastewater biodegradability early warning method and system based on the ratio of baseline current to impact response of microbial fuel cells, so as to solve the above-mentioned problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a wastewater biodegradability early warning method based on the ratio of baseline current to impact response of a microbial fuel cell, comprising the following steps: (1) Construction of the reference end: A microbial fuel cell was used as the reference reactor. A standard control solution with constant composition and concentration was continuously introduced into the anode chamber of the reference reactor at a constant volume flow rate, so that the reference reactor outputs a baseline current. ; (2) Sample end construction: A microbial fuel cell with the same structural parameters as the reference reactor was used as the sample reactor. The anode material, cathode structure, effective volume of the anode cavity, water distribution method, and external circuit resistance value of the sample reactor were completely identical to those of the reference reactor. The wastewater to be tested was continuously introduced into the anode chamber of the sample reactor at the same volumetric flow rate as the reference end, so that the sample reactor outputs an impact response current that changes with the wastewater quality. ; (3) Same environment arrangement: The reference reactor and the sample reactor are placed in the same closed environment cavity, so that the real-time temperature difference between the two in the cavity is ≤0.1℃; before entering the corresponding reactor, the pH difference between the standard control solution and the wastewater to be tested is ≤1 and the conductivity difference is ≤1000μS / cm. (4) Synchronous acquisition and ratio calculation: The output current signals of the two reactors are synchronously acquired at the same sampling frequency, and then sequentially processed based on... After outlier removal and moving average filtering according to the criteria, the biochemical response ratio is calculated. ,in ; (5) Graded early warning judgment: Historical average value of response ratio under steady-state water inflow conditions. As a baseline value for early warning, when the response ratio Deviation from historical average When the relative amplitude reaches a preset threshold and the duration of the deviation reaches a preset time, a corresponding level of biodegradability abnormality warning signal is output.

[0008] Furthermore, the standard control solution is an aqueous solution with sodium acetate as the single organic carbon source, in which nitrogen and phosphorus nutrients and trace elements are added, and a phosphate buffer system is used; The mass concentration of sodium acetate is determined as follows: Historical statistical data of influent BOD5 under steady-state operation of the wastewater treatment plant corresponding to the wastewater to be tested are obtained. 50%-100% of the median historical influent BOD5 value is taken as the target BOD5 concentration, with priority given to 70%-100% of the median historical influent BOD5 value. The mass concentration of anhydrous sodium acetate is calculated according to the theoretical equivalent of 0.52 g BOD5 / g anhydrous sodium acetate, ensuring that the target BOD5 concentration of the standard control solution is not less than 20 mg / L and not more than 200 mg / L, and ensuring that the baseline current output by the reference reactor is on the same order of magnitude as the impact response current output by the sample reactor under steady-state influent conditions. The pH value of the standard control solution is 7.0±0.2, and the basic conductivity is 800 μS / cm-1800 μS / cm. Before being introduced into the reference reactor, the standard control solution is filtered through a sterile filter membrane with a pore size of 0.22 μm.

[0009] Furthermore, the reference reactor and the sample reactor are either single-chamber air cathode type or double-chamber proton exchange membrane type microbial fuel cells; the anodes of both reactors are made of carbon felt material, and the cathodes are both loaded with platinum-carbon catalysts at a catalyst loading of 0.5 mg / cm³. 2 All external circuits are connected in series with precision fixed resistors; the effective projected area of ​​the anode, the catalyst loading of the cathode, the electrode spacing, and the setting positions of the inlet and outlet of the two reactors are completely identical. Furthermore, the anodes of both reactors are loaded with electroactive biofilms, which are prepared and their consistency verified through the following steps: Using inoculated sludge from the same source, the MLSS of the inoculated sludge being 3000 mg / L-4000 mg / L, and inoculated into the anode chambers of the two reactors in equal amounts, according to a volume ratio of 35%-40% of the effective volume of the anode chamber; The acclimatization culture medium with sodium acetate as the organic carbon source was continuously infused with water for acclimatization. The hydraulic retention time was 15-30 minutes, and the acclimatization environment temperature was 25℃-28℃. The acclimatization ended when the relative standard deviation of the daily average current for 3 consecutive days was ≤10%, and the hourly current fluctuation within each day did not exceed 15% of the daily average and there was no continuous unidirectional upward or downward trend. After acclimatization, a consistency check is performed: Standard control solutions of the same concentration are simultaneously introduced into both reactors. After 24 hours of stable operation, a relative deviation of ≤10% between the two output currents indicates that the consistency check has passed. The relative deviation is calculated based on the larger of the two current averages, using the following formula: .

[0010] Furthermore, the standard control solution and the wastewater to be tested are respectively delivered by two peristaltic pumps. The flow rate of the two peristaltic pumps is calibrated by gravimetric method. During calibration, the mass flow rate is converted into volume flow rate by taking into account the density of the corresponding liquid. After calibration, the relative deviation of the rated volume flow rate of the two inlet liquids is ≤1%. The hydraulic residence time of the anode chambers of the two reactors is 15min-60min. Before the wastewater to be tested is introduced into the sample reactor, it is processed sequentially through a grid unit and a precision filter unit with a pore size of 20μm-50μm to remove suspended solids and particulate impurities with a particle size larger than the filter pore size.

[0011] Furthermore, the sealed environment cavity is a sealed circulating water bath cavity with a water bath temperature control accuracy of ±0.2℃; within the normal fluctuation range of ambient temperature, the difference in the relative change rate of the output current of the two reactors is ≤10%.

[0012] Furthermore, step (4) includes the following sub-steps: The output current of the two reactors is collected synchronously at a sampling frequency of 0.5Hz-2Hz, and the sampling time difference between the two signals is ≤20ms; use The criterion performs outlier removal on the raw current data: using the current data within the current sliding window as samples, the sample mean is calculated. with sample standard deviation The value falls within the interval Sampling points outside the specified range are identified as outliers, and the outliers are replaced by the linear interpolation result of adjacent valid sampling values ​​within the window. After removing outliers, the two current data streams were subjected to moving average filtering for durations of 3-10 minutes to obtain the baseline current average and the impulse response current average. The formula for calculating the moving average is as follows: in This represents the total number of sampling points within the sliding window. For the first Current values ​​at each sampling point For the first The average current value corresponding to each sliding window; Response ratio calculated based on the average current values ​​of the two paths. Response ratio The calculation period is equal to the window duration of the moving average filter.

[0013] Furthermore, the historical mean mentioned in step (5) Establish and continuously update in the following ways: Response ratio data for 7-30 days under continuous operation of the wastewater treatment plant were collected, and steady-state operating conditions were screened using a 24-hour statistical period. The criteria for determining steady-state operating conditions were: the relative standard deviation of the response ratio within the statistical period ≤10%, the relative fluctuation of influent COD ≤20% during the same period, and the relative fluctuation of influent BOD5 detected offline during the same period ≤15%. After screening the response ratio data corresponding to the steady-state conditions, the arithmetic mean was calculated as the initial historical mean. ; During system operation, the historical average is adjusted every 3-7 days. A rolling update is performed. The rolling update adopts a full replacement method, and the average value of the steady-state operating condition response ratio data within the most recent 7-30 days is recalculated. Historical operating data outside this time range is not included in this calculation. If the amount of valid steady-state operating condition data that meets the conditions within the current statistical window is less than 30% of the total data volume of the window, the statistical time window will be extended until the minimum data volume requirement is met, or the original historical average will be used until the next update cycle.

[0014] Furthermore, in step (5), both the warning of decreased biochemical susceptibility and the warning of high load shock are divided into two levels, and their respective judgment rules are as follows: Early warning of decreased biochemical susceptibility: when the response ratio Below the historical average for 20-40 minutes consecutively When the biodegradability is between 75% and 85%, a Level 1 warning signal for decreased biodegradability is output; when the response ratio is... Below the historical average for 40-120 minutes consecutively When the biodegradability reaches 65%-75%, a secondary warning signal for decreased biodegradability is output. High load shock warning: when the response ratio Higher than the historical average for 20-40 minutes consecutively When the load is between 115% and 125%, a first-level high-load impact warning signal is output; when the response ratio is... 40-120 minutes above the historical average When the load reaches 125%-140%, a level-two high-load impact warning signal is output; The rules for raising, lowering, and lowering the warning level are as follows: After a Level II warning is triggered, if the response ratio... If the alert level rises back to the Level 1 warning range and continues for the duration required to trigger a Level 1 warning, it will automatically downgrade to a Level 1 warning; after the warning is triggered, when the response ratio... When the alert level returns to normal and the duration is equal to the warning trigger duration of the corresponding level, the warning signal of the corresponding level will be automatically lifted. The upper and lower limits of the normal range correspond to the first-level warning thresholds: the deviations of the first-level biochemical degradation threshold and the first-level high-load impact threshold from their historical averages are equal, with the lower limit of the normal range being the first-level biochemical degradation threshold and the upper limit being the first-level high-load impact threshold; for example, when the first-level biochemical degradation warning threshold is the historical average... When it reaches 85%, the corresponding Level 1 high-load impact warning threshold is the historical average. 115%, the normal range is When the Level 1 biochemical degradation warning threshold is the historical average When it reaches 80%, the corresponding Level 1 high-load impact warning threshold is the historical average. 120%, the normal range is .

[0015] Furthermore, the method also includes baseline adaptive calibration and equipment fault self-diagnosis steps, as detailed below: The daily average value and intraday relative standard deviation of the baseline current of the reference reactor are calculated every 24 hours. When the intraday relative standard deviation is ≤10%, the daily baseline current is determined to meet the steady-state judgment condition. Simultaneously, it is confirmed that the influent is in a steady-state water quality condition, that is, the daily response ratio relative standard deviation is ≤10% and no warning is triggered. Synchronous drift analysis and fault judgment are only performed under steady-state water quality conditions. The cumulative change rate of the daily average current of the two reactors is calculated every 24 hours for 7 consecutive days. The daily average current of the initial operating day is used as the calculation benchmark. If the difference between the cumulative change rates of the two currents is ≤10%, it is determined that the two signals are synchronously drifting, and the response ratio can automatically cancel the drift effect. If the daily average current of a single reactor changes by more than 15% of the previous day's daily average, and the difference between the daily change rates of the two currents is greater than 15%, and it is confirmed that there are no abnormal fluctuations in water quality on that day and the response ratio is within the normal range, then the single reactor is judged to be operating abnormally; the system outputs a device maintenance prompt and suspends the early warning output until the fault is resolved.

[0016] In a second aspect, the present invention provides a wastewater biodegradability early warning system based on a microbial fuel cell, comprising a reactor unit, an influent pretreatment unit, an influent control module, a signal acquisition module, and an early warning control module; The reactor unit includes a reference reactor and a sample reactor, both of which are microbial fuel cells with identical structural parameters. They have the same anode material, cathode structure, effective volume of the anode cavity, water distribution method, and external circuit resistance. Both anodes are loaded with electroactive biofilms that have been acclimatized and passed consistency verification. The two reactors are placed in the same closed circulating water bath cavity with a water bath temperature control accuracy of ±0.2℃. The real-time temperature difference between the two reactors at their installation positions inside the cavity is ≤0.1℃. The influent pretreatment unit is connected to the inlet end of the reference reactor and the sample reactor, respectively. It includes a grid unit for pretreating the wastewater to be tested and a precision filter unit with a pore size of 20μm-50μm, as well as a sterilization filter unit with a pore size of 0.22μm for pretreating the standard control solution. The liquid inlet control module includes two peristaltic pumps calibrated by gravity, used to introduce standard control solution into the anode chamber of the reference reactor and wastewater to be tested into the anode chamber of the sample reactor, respectively. The volumetric flow rates of the two inlets are consistent, and the relative deviation of the rated flow rate is ≤1%. The signal acquisition module is equipped with a multi-channel data acquisition card with a resolution of no less than 16 bits, which is used to synchronously acquire the output current signals of the two reactors at a sampling frequency of 0.5Hz-2Hz, with a sampling time difference of ≤20ms between the two signals; the signal acquisition module has a built-in outlier removal unit and a moving average filtering unit, which are used to sequentially perform outlier removal processing and moving average filtering processing based on the 3σ criterion on the acquired current signals. The early warning control module has a built-in ratio calculation unit, threshold storage unit and early warning output unit, which is used to execute the above-mentioned wastewater biodegradability early warning method, calculate the biodegradability response ratio and output the corresponding level of biodegradability abnormality early warning signal.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention sets up two sets of microbial fuel cells with completely identical structural parameters to operate synchronously, and places them in the same sealed environmental cavity. This allows environmental parameters such as temperature, pH, and conductivity to have a synchronous and common-mode influence on the electroactive biofilms of the two reactors. By calculating the ratio of the impact response current to the baseline current, the synchronously changing environmental interference factors in the two signals can be automatically canceled out. This accurately distinguishes whether the current fluctuation is caused by changes in the biodegradability of wastewater or changes in environmental conditions, effectively eliminating the interference of environmental noise on the early warning results, significantly reducing the probability of false alarms caused by environmental fluctuations, and significantly improving the stability and accuracy of the monitoring results.

[0018] 2. In this invention, the two reactors are inoculated with the same source sludge, simultaneously acclimatized and cultivated, and operated under the same conditions. The aging rate of the anolyl electroactive biofilm is basically consistent with the activity decay. During long-term operation, the reference baseline current and the sample impact response current show a proportional synchronous drift trend. At this time, the numerator and denominator of the response ratio are synchronously scaled, and the ratio itself can remain stable, automatically offsetting the baseline drift caused by biofilm decay. There is no need to perform manual zero-point calibration periodically, which significantly reduces the workload of on-site operation and maintenance, while ensuring the continuity of the online monitoring process.

[0019] 3. This invention relies on the rapid response characteristics of microbial fuel cell electrical signals, combined with signal processing methods such as outlier removal and moving average filtering. It employs a dual judgment rule based on deviation amplitude and duration to quickly identify two types of influent anomalies: decreased biodegradability due to toxicity inhibition and high organic load shock. Simultaneously, it sets two warning levels with corresponding rules for warning level escalation and automatic deactivation, allowing for the output of corresponding warning signals based on the severity of the anomaly. This provides a tiered decision-making basis for wastewater treatment plant processes such as influent scheduling, aeration control, and sludge return ratio adjustment, effectively mitigating operational risks such as biochemical sludge poisoning and effluent quality exceeding standards. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0021] For ease of understanding, the following explains some key terms in this embodiment: Baseline current The current value that is stably output when a standard control solution with constant composition and concentration is introduced into the reference reactor represents the electrical signal reference corresponding to the fixed biochemical matrix. Impact response current The dynamic current value output when the wastewater to be tested is introduced into the sample reactor, and its value changes in real time with the concentration of organic components and inhibitory toxins in the wastewater; Response ratio The ratio of the sample impulse response current to the reference baseline current is used to quantify the biodegradability of the wastewater under test relative to the standard matrix. The calculation formula is as follows: Moving average filtering: A signal processing method that sets a fixed duration window and takes the arithmetic mean of continuously acquired raw current time series data to eliminate instantaneous random current noise.

[0022] Example 1 (Online Early Warning of Biodegradability of Municipal Wastewater) This embodiment is applied to the inlet of a municipal wastewater treatment plant, targeting conditions where the influent water quality fluctuates regularly and the ambient temperature changes with the seasons.

[0023] Early warning system settings The wastewater biodegradability early warning system in this embodiment includes an influent pretreatment unit, a reference reactor, a sample reactor, an influent control module, a signal acquisition module, and an early warning control module.

[0024] Reactor Unit: Both the reference reactor and the sample reactor employ a single-chamber air-cathode microbial fuel cell, with identical structural parameters: the anode chamber has an effective volume of 50 mL, the anode uses 5 mm thick carbon felt with an effective projected area of ​​16 cm², and the carbon felt is graphitized and fixed to the center of the chamber by titanium wire; the cathode uses waterproof and breathable carbon cloth loaded with 0.5 mg / cm² platinum-carbon catalyst, tightly bonded to the sidewall of the chamber by sealing rings; the external circuits of both reactors are connected in series at 1000V. The system uses precision-set resistors with identical electrode spacing, cavity height, and inlet / outlet positions. Water is introduced via a bottom-distribution, top-exit plug flow pattern. Both reactors are housed within the same sealed circulating water bath environment cavity, with a water bath temperature control accuracy of ±0.2℃. The temperature difference between the two reactors inside the cavity is ≤0.1℃, ensuring synchronized ambient temperatures throughout the process.

[0025] Inlet water pretreatment unit: The sample end inlet water passes through a grid and a 50μm precision filter unit to remove suspended solids and particulate impurities larger than the filter pore size before entering the anode chamber of the sample reactor, preventing impurities from clogging the carbon felt pores and scouring the biofilm; the reference end standard control solution is treated by a 0.22μm sterilization filter unit before being introduced into the reference reactor to prevent bacteria from colonizing the anode and causing the baseline intra-day relative standard deviation to exceed 10%.

[0026] Liquid inlet control module: Two synchronously calibrated peristaltic pumps are installed, with a relative flow deviation of ≤1% between the two pipelines; one pump delivers standard sodium acetate control solution to the reference reactor, and the other pump delivers pretreated municipal wastewater to the sample reactor, with identical volumetric flow rates for both inlets. The peristaltic pumps are calibrated using a gravimetric method: the mass of liquid output per unit time is weighed using an electronic balance, converted to volumetric flow rate, and the pump speed is adjusted. A deviation of ≤1% in three consecutive measurements indicates successful calibration.

[0027] Signal acquisition module: Equipped with a 16-bit high-precision multi-channel data acquisition card, the two-channel sampling time synchronization difference is ≤20ms, synchronously acquiring the voltage across the resistors of the two external circuits of the reactor and converting it into real-time output current; built-in signal noise reduction algorithm unit, which can perform outlier removal and moving average filtering.

[0028] Early warning control module: It has a built-in ratio calculation unit, threshold storage unit and early warning output unit, and executes the early warning process described in this invention. The early warning signal supports three output methods: local audible and visual alarm, upper computer interface prompt and remote communication push. It can realize automatic determination of early warning level upgrade and early warning cancellation.

[0029] Anodic biofilm domestication Sludge returned from the secondary sedimentation tank of a municipal wastewater treatment plant was collected, with the sludge MLSS controlled at 3000 mg / L-4000 mg / L. After washing the supernatant three times with phosphate buffer to remove impurities, the sludge was inoculated into the anode chambers of two reactors at a volume ratio of 40% of the effective volume of the anode chamber. The remaining chamber space was filled with acclimation culture medium. The acclimation culture medium used sodium acetate as the carbon source, supplemented with nitrogen, phosphorus nutrients and trace elements. The specific formula was: sodium acetate 50 mg / L, ammonium chloride 15 mg / L, potassium dihydrogen phosphate 3 mg / L, magnesium sulfate 0.5 mg / L, calcium chloride 0.1 mg / L, and ferric chloride 0.05 mg / L. A 10 mmol / L phosphate buffer system was used to control the pH at 7.0 ± 0.2.

[0030] The acclimatization process employed a continuous water intake mode, with a hydraulic retention time controlled at 30 minutes and an ambient temperature stabilized between 25℃ and 28℃. After three consecutive days of operation, the arithmetic mean of the current over 24 hours was calculated daily as the baseline value. When the relative standard deviation (RSD) of the daily baseline value for three consecutive days was ≤10%, and the hourly current fluctuation within each day did not exceed 15% of the daily average and showed no continuous unidirectional upward or downward trend, the electroactive biofilm formed on the anode surface was deemed to meet the steady-state acclimatization criteria.

[0031] After acclimatization, a consistency check is performed between the two reactors: standard control solution of the same concentration is simultaneously introduced into the two reactors, and after 24 hours of stable operation, the relative deviation of the two baseline currents is calculated. If the deviation is ≤10%, the consistency check is considered passed; if the deviation is >10%, acclimatization and cultivation are repeated until the consistency requirements are met.

[0032] Early warning method execution process S1, Parameter Construction A standard sodium acetate control solution was continuously introduced into the anode chamber of the reference reactor. This standard control solution used sodium acetate as the sole organic carbon source, supplemented with nitrogen, phosphorus nutrients, and trace elements necessary for microbial growth. The buffer system was identical to the acclimation culture medium. The sodium acetate concentration of the standard control solution was determined based on historical statistical data of the influent BOD5 under steady-state operation of the wastewater treatment plant under test: the median BOD5 value of the influent over the past 12 months was used, and 50%-100% of this median value was taken as the target BOD5 concentration of the standard solution. This was then converted to the sodium acetate mass concentration using the theoretical BOD5 equivalent of 0.52 g BOD5 / g anhydrous sodium acetate, with 70%-100% of the median value preferentially selected as the target BOD5 concentration. The final sodium acetate mass concentration was controlled within the range of 20 mg / L-200 mg / L. In this embodiment, the median BOD5 of the municipal influent is approximately 120 mg / L. Taking 70% of this median, i.e., 84 mg / L, as the target BOD5 concentration for the standard solution, and converting this to 162 mg / L sodium acetate as the carbon source concentration for the standard solution, the corresponding theoretical BOD5 is approximately 84 mg / L, which falls within the range of 50%-100% and 70%-100% of the historical BOD5 median values. The influent flow rate was controlled at 1.67 mL / min using a peristaltic pump, and the hydraulic retention time was stabilized at 30 min. After 72 hours of continuous operation, the daily relative standard deviation of the reference reactor output current was ≤10%, obtaining a baseline current that meets the steady-state requirements. .

[0033] S2, Sample End Construction The sample reactor and the reference reactor underwent biofilm acclimatization and startup simultaneously; the influent flow rate and hydraulic retention time were exactly the same as those of the reference reactor; pretreated municipal wastewater was continuously fed into the anode chamber as the wastewater to be tested; the sample reactor outputs an impact response current that dynamically changes with the influent water quality. The two reactors have completely identical structural parameters, eliminating system deviations caused by the inherent structure of the equipment.

[0034] S3, Same as the surrounding environment Two microbial fuel cells are housed in the same sealed circulating water bath environment to ensure synchronized temperature fluctuations throughout the process, eliminating the asymmetric impact of temperature differences on the activity of the two biofilms. The standard control solution is prepared using a buffer system matched to the conductivity and pH of municipal wastewater, with the baseline conductivity controlled at 800-1200 μS / cm and the pH stabilized at 7.0±0.2. When the pH and conductivity of the wastewater under test undergo normal fluctuations, the relative rate of change in current output is synchronized due to the consistent response characteristics of the biofilms in both reactors. Subsequent ratio calculations can offset the interference of such common fluctuations on the test results. During year-round operation, the influent temperature fluctuates between 10℃ and 32℃, the pH fluctuates between 6.5 and 8.0, and the conductivity changes with rainwater runoff. The chamber ensures that the temperatures of the two reactors remain synchronized, and the impact of temperature changes on the biofilm activity of both reactors is consistent.

[0035] S4. Synchronous Acquisition and Ratio Calculation The original output current of the two reactors is collected synchronously at a sampling frequency of 1Hz, with a sampling time difference of ≤20ms between the two channels.

[0036] The collected raw current data is first subjected to outlier removal, using... Criterion: Calculate the sample mean using the current data within the current sliding window as the sample. with standard deviation It will exceed Values ​​within the range are identified as outliers and replaced using linear interpolation of adjacent valid values ​​within the window.

[0037] After outlier removal, a moving average filter is applied, with a moving window duration of 5 minutes and containing 300 sampling points. The formula for calculating the average current value of each window is: in, This represents the total number of sampling points within the sliding window. For the first The original current values ​​at each sampling point For the first The average current value corresponding to each sliding window; the average baseline current is calculated respectively. With average impulse response current .

[0038] The response ratio is calculated every 5 minutes, with the calculation cycle matching the sliding window duration. The calculation formula is as follows: Continuously output timing response ratio data.

[0039] S5. Tiered Early Warning Judgment First, establish and continuously update the historical average. : Response ratio data for 15 consecutive days under steady-state operation conditions of the wastewater treatment plant were collected. Valid data were screened according to steady-state condition criteria: using a 24-hour statistical period, the relative standard deviation (RSD) of the response ratios within the period was calculated, and simultaneously matched with concurrent online COD monitoring data. A steady-state condition was defined as follows: when the RSD ≤ 10%, the relative fluctuation of influent COD ≤ 20% (based on the average COD value within the period, the ratio of the maximum deviation to the average), and the relative fluctuation of influent BOD5 from offline monitoring ≤ 15%, the condition was considered stable, and the corresponding ratio data were included in the valid sample. Offline BOD5 monitoring data was used for quarterly retrospective calibration of the steady-state determination threshold. After excluding data from non-steady-state conditions such as equipment maintenance, rainstorm overflows, and plant water outages, the arithmetic mean of the valid samples was taken as the initial historical mean. The calculation formula is: in, The total number of valid samples. For the first The response ratio of a steady-state sample.

[0040] The system automatically updates the historical average every 7 days. The average value is recalculated using steady-state operating condition ratio data from the most recent 15 days to reflect the slow, natural changes in biofilm activity. Rolling updates use a full replacement approach, retaining only valid data from the most recent 15 days; operational data outside this timeframe is not included in this calculation.

[0041] Grading and early warning rules for declining biochemical properties: When the response ratio 30 consecutive minutes below the historical average When the biodegradability reaches 80%, the system outputs a Level 1 warning signal for declining biodegradability, prompting maintenance personnel to pay attention to changes in the influent water quality. When the response ratio 60 consecutive minutes below the historical average When the biodegradability reaches 70%, the system outputs a Level 2 warning signal for decreased biodegradability, and links with the host computer to push an emergency response reminder, indicating the risk of toxic substance impact.

[0042] High-load shock classification and early warning rules: When the response ratio 30 consecutive minutes above the historical average When the load reaches 120%, a first-level high-load impact warning signal is output, indicating a slight increase in the organic load of the influent; When the response ratio 60 consecutive minutes above the historical average When the load reaches 130%, a level-two high-load shock warning signal is output, indicating that the biochemical system is at risk of overload operation and that the aeration rate and sludge return ratio need to be increased.

[0043] Rules for raising, lowering, and lifting warning levels: If, after a Level II warning is triggered, the response ratio rises back to the Level I warning range and the duration of the rise reaches the trigger duration of a Level I warning, the warning will be automatically downgraded to Level I. After the warning is triggered, when the response ratio returns to the normal range ( When the duration of the warning is equal to the warning trigger duration of the corresponding level, the warning signal of the corresponding level will be automatically deactivated.

[0044] Baseline adaptive calibration process The system automatically reads and records the daily average baseline current of the reference reactor every 24 hours to verify baseline current stability: a daily relative standard deviation (RSD) of ≤10% is considered to indicate that the baseline meets the steady-state criteria. The sample reactor current is affected by fluctuations in influent water quality and is not used for separate baseline stability assessment; it is only used for synchronous drift analysis.

[0045] During continuous operation, when the anode biofilms of both reactors age synchronously and environmental parameters change synchronously, the baseline current... With impulse response current The system exhibits proportional synchronous drift (synchronous rise or synchronous fall). The synchronous drift determination rule is as follows: After the system completes a baseline stability check every 24 hours, it automatically calculates the cumulative rate of change of the daily average current values ​​of the two channels over seven consecutive days (using the daily average current value of day 0 as the baseline). If the difference between the two rates of change is ≤10%, it is determined that the two signals are synchronously drifting. At this time, the response ratio... It can remain basically stable and automatically offset the effects of baseline drift through ratio calculation, without the need for manual zero-point calibration.

[0046] If the daily average value of the baseline current of a single reactor changes by more than 15% of the previous day's average, and the difference in the rate of change between the two currents is greater than 15%, then the single reactor is judged to be operating abnormally. The system will push a fault repair prompt and suspend the early warning output until the fault is resolved.

[0047] The critical node current-to-response ratio data for this embodiment after 90 days of continuous operation are shown in the table below: Table 1. Changes in the 90-day operating baseline and response ratio of municipal wastewater treatment. Note: The ratio offset relative to the initial value is calculated based on the response ratio on day 0, using the formula as follows: ,in This represents the initial response ratio on day 0. For the first The response ratio per day.

[0048] As shown in the table above, after 90 days of operation, the biofilm in both reactors declined synchronously, with the baseline current... With impulse response current The response ratio decreased by 21% synchronously. The offset is only 0.1%, far less than 3%, and the influence of baseline drift is automatically offset by ratio calculation, eliminating the need for manual zero-point calibration.

[0049] Operating condition verification Two typical abnormal operating conditions occurred during operation: 1. Toxicity shock condition: Wastewater entering the plant is mixed with a small amount of disinfectant, response ratio Continued for 35 minutes to decrease Upon reaching the criteria for a Level II early warning, the system triggered a Level II warning for decreased biodegradability; maintenance personnel promptly switched the water intake to the emergency regulating tank, and after 2 hours... The sludge in the biological treatment tank returned to normal levels, and no poisoning or inactivation was observed.

[0050] 2. High organic load conditions: During the rainy season, kitchen waste liquid is centrally collected and discharged into the pipe network, resulting in a high response ratio. Rise to The system continued to issue a level-two high-load warning for 62 minutes; maintenance personnel increased the aeration power of the biological treatment tank in advance, and the number of times the COD exceeded the standard in the effluent decreased by 85% that month.

[0051] Example 2 (Early warning of biodegradability of integrated chemical wastewater in industrial parks) This embodiment is applied to the inlet of a comprehensive wastewater treatment plant in an industrial park, targeting conditions such as large fluctuations in wastewater load, intermittent presence of phenolic inhibitory toxins, and large temperature differences between day and night.

[0052] Early warning system configuration Reactor Unit: Both the reference reactor and the sample reactor employ a dual-chamber proton exchange membrane microbial fuel cell. The anode chamber has an effective volume of 30 mL, and the anode uses 4 mm thick carbon felt with an effective projected area of ​​10 cm². The cathode chamber has the same effective volume as the anode and uses a carbon paper cathode loaded with 0.5 mg / cm² platinum-carbon catalyst. The two chambers are separated by a Nafion 117 proton exchange membrane. The external circuit is uniformly connected in series with a 2000Ω ohmmeter. Precision resistors are used; the electrode structures, chamber dimensions, cathode materials, proton exchange membrane models, and water distribution methods of the two reactors are completely identical, and they are placed in the same circulating water bath environment chamber with a water bath temperature control accuracy of ±0.2℃ to ensure synchronous temperature fluctuations in both environments. A 50 mmol / L phosphate buffer solution is continuously circulated into the cathode chamber as the cathode electrolyte, at the same flow rate as the anode chamber.

[0053] Water inlet pretreatment unit: The sample inlet water passes through a sedimentation tank and a precision filter unit with a pore size of 20μm to remove suspended solids and oil impurities before entering the sample reactor; the reference standard solution is treated by a sterilization filter component with a pore size of 0.22μm before being introduced into the reference reactor.

[0054] Liquid inlet control module: Equipped with two synchronous peristaltic pumps, the two liquid inlet volume flow rates are completely equal, and the relative deviation of the flow rate after calibration by gravimetric method is ≤1%.

[0055] Signal acquisition module: The sampling frequency is fixed at 0.5Hz, the synchronization difference between the two sampling channels is ≤20ms, and it has built-in outlier removal and moving average filtering algorithms.

[0056] Early warning control module: It has a built-in ratio calculation, threshold storage and early warning output unit, and executes all the early warning judgment logic and upgrade / downgrade and cancellation rules described in this invention.

[0057] Anodic biofilm domestication Anaerobic sludge from the industrial park's wastewater treatment plant was collected, with the sludge MLSS controlled at 3000 mg / L-4000 mg / L. After being washed three times with phosphate buffer to remove impurities, the sludge was inoculated into the anode chambers of two reactors in equal volumes, accounting for 35% of the effective volume of the anode chamber. The acclimation culture medium used 30 mg / L sodium acetate as the carbon source, with nitrogen, phosphorus nutrients and trace elements added. The pH of the buffer system was controlled at 7.2 ± 0.2.

[0058] During the acclimation process, the hydraulic retention time was controlled at 15 minutes, and the ambient temperature was stabilized at 25℃-28℃. After four consecutive days of operation, if the relative standard deviation (RSD) of the daily average current for three consecutive days was ≤10%, and the hourly current fluctuation within each day did not exceed 15% of the daily average and showed no continuous unidirectional upward or downward trend, the electroactive biofilm formed at the anode was deemed to meet the steady-state acclimation criteria. After acclimation, a consistency verification was performed; a relative deviation of the baseline current between the two reactors of ≤10% was considered a successful verification.

[0059] Early warning method execution process S1, Parameter Construction A 58 mg / L sodium acetate standard solution was introduced into the reference reactor. The concentration was determined by converting 60% of the historical median BOD5 value under steady-state operating conditions of the industrial park's wastewater. The historical median BOD5 value of the industrial park's wastewater was approximately 50 mg / L. Taking 60% of the median value, i.e., 30 mg / L, as the target BOD5 concentration of the standard solution, the converted sodium acetate concentration was approximately 58 mg / L, corresponding to a theoretical BOD5 of approximately 30 mg / L. This falls within the range of 50%-100% of the historical median BOD5 value and meets the lower limit requirement of not less than 20 mg / L. The hydraulic retention time was controlled at 15 min; stable operation was maintained for 72 h, and the output baseline current met the steady-state requirements. The standard control solution was supplemented with the same nutrients and buffer system as the acclimatization stage, and the basic conductivity was matched to the background value of the park wastewater, which was 1200-1800 μS / cm.

[0060] S2, Sample End Construction The sample reactor and the reference reactor were simultaneously acclimatized and the influent flow rate and hydraulic residence time were simultaneously controlled. Pretreated integrated chemical wastewater from the industrial park was continuously fed into the anode, and the output impulse response current was generated. .

[0061] S3, Same as the surrounding environment The two reactors are placed in the same circulating water bath chamber to ensure synchronized temperature fluctuations throughout the process, eliminating the asymmetric impact of diurnal temperature differences on the activity of the two biofilms. A standard solution buffer system is matched to the baseline pH and conductivity levels of the wastewater, ensuring that fluctuations in wastewater pH and conductivity have a synchronized relative impact on the current of the biofilms in both reactors. Interference from fluctuations in common water quality parameters is offset through ratio calculations. The degree to which temperature changes affect the biofilm activity of both reactors is consistent.

[0062] S4. Synchronous Acquisition and Ratio Calculation Two raw currents are simultaneously acquired at a sampling frequency of 0.5Hz; firstly, using... Outliers were removed using the criteria, and then a moving average filter with a duration of 3 minutes was used for noise reduction. The window contained 90 sampling points, and the average current calculation formula was the same as in Example 1.

[0063] The ratio is calculated every 3 minutes, with the calculation cycle matching the filter window duration. The calculation formula is as follows: .

[0064] S5. Tiered Early Warning Judgment Historical average Creation and Update: Response ratio data for 7 consecutive days under steady-state wastewater operation conditions in the industrial park were collected. The steady-state criteria were: RSD ≤ 10% within 24 hours and relative fluctuation of influent COD ≤ 20% (based on the average COD within the period, the ratio of the maximum deviation to the average), and relative fluctuation of influent BOD5 detected offline during the same period ≤ 15%. After removing non-steady-state data such as those from shutdowns and equipment maintenance, the arithmetic mean was taken as the initial historical mean. The system updates the historical average every 3 days. The mean is recalculated using the steady-state data from the most recent 7 days. Operating data outside this time range is not included in this calculation.

[0065] Early warning rule for decreased biochemical susceptibility: When the response ratio Below 0.85 for 20 consecutive minutes At that time, a Level 1 warning for decreased biodegradability will be issued; When the response ratio Below 0.75 for 40 consecutive minutes At that time, a level 2 warning of decreased biodegradability will be issued.

[0066] High-load shock early warning rules: When the response ratio Above 1.15 for 20 consecutive minutes At that time, a Level 1 high-load impact warning will be issued; When the response ratio Above 1.25 for 40 consecutive minutes At that time, a level-two high-load impact warning will be issued.

[0067] Rules for raising, lowering, and lifting warning levels: If, after a Level II warning is triggered, the response ratio rises back to the Level I warning range and the duration of the rise reaches the trigger duration of a Level I warning, the warning will be automatically downgraded to Level I. After the warning is triggered, when the response ratio returns to the normal range ( When the duration of the warning is equal to the warning trigger duration of the corresponding level, the warning signal of the corresponding level will be automatically deactivated.

[0068] Baseline adaptive calibration process The system automatically calibrates the baseline current of the reference reactor every 24 hours. A daily RSD ≤ 10% is considered to meet the steady-state criteria. The sample reactor current is affected by fluctuations in influent water quality and is not separately used for baseline stability assessment; it is only used for synchronous drift analysis. During continuous operation, when the anode biofilms of both reactors age synchronously and environmental parameters change synchronously, the baseline current... With impulse response current The system exhibits proportional synchronous drift (synchronous rise or synchronous fall). The synchronous drift determination rule is as follows: After the system completes a baseline stability check every 24 hours, it automatically calculates the cumulative rate of change of the daily average current values ​​of the two channels over seven consecutive days (using the daily average current value of day 0 as the baseline). If the difference between the two rates of change is ≤10%, it is determined that the two signals are synchronously drifting. At this time, the response ratio... It can remain basically stable and automatically offset the effects of baseline drift through ratio calculation, without the need for manual zero-point calibration.

[0069] If the daily average value of the baseline current of a single reactor changes by more than 15% of the previous day's average, and the difference in the rate of change between the two currents is greater than 15%, then the single reactor is judged to be operating abnormally. The system will push a fault repair prompt and suspend the early warning output until the fault is resolved.

[0070] The critical node current-to-response ratio data for this embodiment after 90 days of continuous operation are shown in the table below: Table 2. Changes in the 90-day operating baseline and response ratio for chemical wastewater treatment. Note: The ratio offset relative to the initial value is calculated based on the response ratio on day 0, using the formula as follows: ,in This represents the initial response ratio on day 0. For the first The response ratio per day.

[0071] As shown in the table above, after 90 days of operation, the biofilm in both reactors declined synchronously, with the baseline current... With impulse response current The synchronous decrease is about 22%, and the response ratio R offset is less than 0.3%, which is far below 3.5%, so no manual zero-point calibration is required.

[0072] Operating condition verification Two typical abnormal operating conditions occurred during operation: 1. A chemical workshop in the industrial park was illegally discharging phenol-containing waste liquid. Response ratio Decreased to 0.72 The warning lasted for 42 minutes, meeting the criteria for a Level II biodegradability decline warning. The system immediately issued a Level II warning. Maintenance personnel quickly cut off the water supply to the workshop and added buffer agents, preventing large-scale poisoning of the biochemical sludge.

[0073] 2. Response ratio for nighttime waste liquid storage tank overflow. Rising to 1.31 The high load lasted for 45 minutes, triggering a level 2 high load warning. The maintenance personnel promptly increased the reflux and aeration intensity of the biological treatment tank, and the effluent water quality remained stable and met the standards.

[0074] Comparative Example Two sets of comparative examples were set up, both using the existing single-channel microbial fuel cell testing scheme. They were operated in parallel under municipal sewage conditions completely identical to Example 1 and chemical wastewater conditions completely identical to Example 2, respectively, as benchmarks for performance comparison.

[0075] Comparative Example 1 (Single-channel municipal wastewater): A single microbial fuel cell with structural parameters identical to that of Example 1 was used. The anode used a mature electroactive biofilm that was inoculated and simultaneously acclimatized with the same source as in Example 1, and the acclimatization conditions were identical to those of Example 1. The municipal wastewater to be tested, which had undergone the same pretreatment, was continuously introduced into the anode chamber, with a hydraulic retention time of 30 min. The sampling frequency was 1 Hz, and a 5-minute moving average filter was used. Outlier removal. Early warning judgment is based on the historical baseline of the single-channel output current. The historical baseline is established as follows: the average of the daily current under steady-state conditions over 15 days is used as the initial baseline, and it is updated every 7 days. The early warning threshold adopts the same relative proportion rule as in Example 1 (a current below 70%-80% of the historical current baseline triggers a biodegradability decline warning, and a current above 120%-130% triggers a high load warning). The historical baseline is the steady-state daily average of the single-channel current. Other operating environments, operating cycles, and evaluation criteria are the same as in Example 1.

[0076] Comparative Example 2 (Single Channel for Chemical Wastewater): A single microbial fuel cell with structural parameters identical to that of Example 2 was used. The anode used a mature electroactive biomembrane that was inoculated and simultaneously acclimatized with the same source as in Example 2, and the acclimatization conditions were identical to those of Example 2. The anode chamber was continuously circulated with integrated chemical wastewater from an industrial park that had undergone the same pretreatment, with a hydraulic retention time of 15 minutes. The sampling frequency was 0.5 Hz, and a 3-minute moving average filter and 3σ outlier removal were used. The historical baseline was established as follows: the daily average current value under steady-state conditions for 7 days was collected and averaged as the initial baseline, and updated every 3 days. The warning threshold used the same relative proportion rule as in Example 2. All other operating conditions, operating cycles, and evaluation criteria were the same as in Example 2.

[0077] Performance comparison and effect verification The early warning effect verification data of typical abnormal operating conditions under Example 1 and Example 2 were compared with the corresponding comparative examples under the corresponding operating conditions. The data are shown in the table below: Table 3. Verification data on the early warning effect of typical abnormal operating conditions The core performance indicators for 90 consecutive days of operation are shown in the table below. False alarms are defined as: events where environmental parameter fluctuations trigger a current-triggered warning, but the BOD5 and COD water quality indicators measured manually during the same period are within the normal range; the accuracy rate for identifying abnormal operating conditions is calculated based on the total number of manually confirmed abnormal operating conditions, representing the percentage of correct warnings.

[0078] Table 4 Overall Performance Comparison over 90-Day Operating Cycle Existing single-channel detection schemes directly use the absolute value of the output current as the basis for judgment. Fluctuations in ambient temperature, changes in influent pH and conductivity can all alter the extracellular electron transfer efficiency of electroactive microorganisms, thus causing fluctuations in the output current. These fluctuations are difficult to distinguish from current changes caused by changes in the biodegradability of wastewater, easily leading to false alarms. This invention places a reference reactor and a sample reactor with identical structural parameters in the same environmental space, so that the effects of environmental parameters such as temperature, pH, and conductivity on the two reactors are essentially synchronized, generating a synchronized common-mode influence on the current output; then, the response ratio is used to... The calculation cancels out the synchronously changing environmental impact factors in the numerator and denominator, so that the response ratio only reflects the difference in biodegradability of the wastewater under test relative to the standard substrate. The data in the table show that, compared with Comparative Example 1, the number of false alarms caused by environmental fluctuations in Example 1 decreased from 16 to 4 within a 90-day operating cycle; compared with Comparative Example 2, the number of false alarms in Example 2 decreased from 24 to 6; the relative reduction in false alarm rate reached 75% under both operating conditions.

[0079] During long-term operation of microbial fuel cells, the anode electroactive biofilm inevitably undergoes activity decay and community succession, causing a slow drift in the output baseline current. Existing single-channel detection schemes cannot distinguish between biofilm activity decay and decreased influent biodegradability, requiring periodic manual zero-point calibration using a standard matrix, resulting in high maintenance costs and impacting monitoring continuity during calibration. In this invention, the two reactors are inoculated from the same source, undergo simultaneous acclimatization, and operate under identical conditions. The aging rate and activity decay of the anode biofilm are essentially consistent, and the reference baseline current and sample response current change proportionally and synchronously. At this point, the numerator and denominator of the response ratio scale synchronously, maintaining a stable ratio and automatically offsetting the impact of baseline drift. As shown in the table, within a 90-day operating cycle, neither Example 1 nor Example 2 requires manual baseline calibration. Based on the number of manual calibrations, the on-site maintenance workload is reduced by more than 75% compared to the corresponding proportional scheme, while ensuring continuous online monitoring.

[0080] In existing single-channel detection schemes, environmental fluctuation noise and slow baseline drift are superimposed on abnormal water quality signals, which can easily lead to false positives and mask real water quality impact signals, resulting in missed detections. Furthermore, eliminating baseline drift interference requires a long observation period, leading to delayed early warning responses. This invention, by using ratio calculations to separate common-mode environmental interference and synchronous baseline drift, allows changes in the response ratio to directly correspond to the actual changes in influent biodegradability, significantly improving the signal-to-noise ratio. Combined with dual judgment rules for deviation amplitude and duration, it can quickly and accurately identify biodegradability anomalies. Data in the table shows that the accuracy rate of abnormal condition identification under municipal wastewater conditions increased from 62% in Comparative Example 1 to 95% in Example 1, and the toxicity impact early warning response time was shortened from over 180 minutes to 30-60 minutes; the accuracy rate of abnormal condition identification under chemical wastewater conditions increased from 55% in Comparative Example 2 to 92% in Example 2, and the toxicity impact early warning response time was shortened from over 240 minutes to 20-40 minutes. In conjunction with the two-level graded early warning mechanism, it can provide a tiered decision-making basis for the influent scheduling, aeration control, and sludge return ratio adjustment of the sewage treatment process, which is conducive to reducing the operational risks of sludge poisoning and effluent quality exceeding standards in the biological system.

[0081] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0082] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications and equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for early warning of wastewater biodegradability based on the ratio of baseline current to impact response of microbial fuel cells, characterized in that, Includes the following steps: (1) Construction of the reference end: A microbial fuel cell was used as the reference reactor. A standard control solution with constant composition and concentration was continuously introduced into the anode chamber of the reference reactor at a constant volume flow rate, so that the reference reactor outputs a baseline current. ; (2) Sample end construction: A microbial fuel cell with the same structural parameters as the reference reactor was used as the sample reactor. The anode material, cathode structure, effective volume of the anode cavity, water distribution method, and external circuit resistance value of the sample reactor were completely identical to those of the reference reactor. The wastewater to be tested was continuously introduced into the anode chamber of the sample reactor at the same volumetric flow rate as the reference end, so that the sample reactor outputs an impact response current that changes with the wastewater quality. ; (3) Same environment arrangement: The reference reactor and the sample reactor are placed in the same closed environment cavity, so that the real-time temperature difference between the two in the cavity is ≤0.1℃; before entering the corresponding reactor, the pH difference between the standard control solution and the wastewater to be tested is ≤1 and the conductivity difference is ≤1000μS / cm. (4) Synchronous acquisition and ratio calculation: The output current signals of the two reactors are synchronously acquired at the same sampling frequency, and then sequentially processed based on... After outlier removal and moving average filtering according to the criteria, the biochemical response ratio is calculated. ,in ; (5) Graded early warning judgment: Historical average value of response ratio under steady-state water inflow conditions. As a baseline value for early warning, when the response ratio Deviation from historical average When the relative amplitude reaches a preset threshold and the duration of the deviation reaches a preset time, a corresponding level of biodegradability abnormality warning signal is output.

2. The wastewater biodegradability early warning method according to claim 1, characterized in that, The standard control solution is an aqueous solution with sodium acetate as the single organic carbon source, in which nitrogen and phosphorus nutrients and trace elements are added, and a phosphate buffer system is used. The mass concentration of sodium acetate is determined as follows: Historical statistical data of influent BOD5 under steady-state operation of the wastewater treatment plant corresponding to the wastewater to be tested are obtained. 50%-100% of the median historical influent BOD5 value is taken as the target BOD5 concentration, with priority given to 70%-100% of the median historical influent BOD5 value. The mass concentration of anhydrous sodium acetate is calculated according to the theoretical equivalent of 0.52 g BOD5 / g anhydrous sodium acetate, ensuring that the target BOD5 concentration of the standard control solution is not less than 20 mg / L and not more than 200 mg / L, and ensuring that the baseline current output by the reference reactor is on the same order of magnitude as the impact response current output by the sample reactor under steady-state influent conditions. The pH value of the standard control solution is 7.0±0.2, and the basic conductivity is 800 μS / cm-1800 μS / cm. Before being introduced into the reference reactor, the standard control solution is filtered through a sterile filter membrane with a pore size of 0.22 μm.

3. The wastewater biodegradability early warning method according to claim 1, characterized in that, The reference reactor and sample reactor are either single-chamber air cathode type or double-chamber proton exchange membrane type microbial fuel cells; the anodes of both reactors use carbon felt material, and the cathodes are both loaded with platinum-carbon catalyst at a catalyst loading of 0.5 mg / cm³. 2 All external circuits are connected in series with precision fixed resistors; the effective projected area of ​​the anode, the catalyst loading of the cathode, the electrode spacing, and the setting positions of the inlet and outlet of the two reactors are completely identical. Both reactors have electroactive biofilms loaded on their anodes. These electroactive biofilms are prepared and their consistency verified through the following steps: Using inoculated sludge from the same source, the MLSS of the inoculated sludge being 3000 mg / L-4000 mg / L, and inoculated into the anode chambers of the two reactors in equal amounts, according to a volume ratio of 35%-40% of the effective volume of the anode chamber; The acclimatization culture medium with sodium acetate as the organic carbon source was continuously infused with water for acclimatization. The hydraulic retention time was 15-30 minutes, and the acclimatization environment temperature was 25℃-28℃. The acclimatization ended when the relative standard deviation of the daily average current for 3 consecutive days was ≤10%, and the hourly current fluctuation within each day did not exceed 15% of the daily average and there was no continuous unidirectional upward or downward trend. After acclimatization, a consistency check is performed: Standard control solutions of the same concentration are simultaneously introduced into both reactors. After 24 hours of stable operation, a relative deviation of ≤10% between the two output currents indicates that the consistency check has passed. The relative deviation is calculated based on the larger of the two current averages, using the following formula: .

4. The wastewater biodegradability early warning method according to claim 1, characterized in that, The standard control solution and the wastewater to be tested are delivered by two peristaltic pumps. The flow rate of the two peristaltic pumps is calibrated by gravimetric method. During calibration, the mass flow rate is converted into volume flow rate by taking into account the density of the corresponding liquid. After calibration, the relative deviation of the rated volume flow rate of the two inlet liquids is ≤1%. The hydraulic residence time of the anode chambers of the two reactors is 15min-60min. Before the wastewater to be tested is introduced into the sample reactor, it is processed sequentially through a grid unit and a precision filter unit with a pore size of 20μm-50μm to remove suspended solids and particulate impurities with a particle size larger than the filter pore size.

5. The wastewater biodegradability early warning method according to claim 1, characterized in that, The sealed environment cavity is a sealed circulating water bath cavity with a water bath temperature control accuracy of ±0.2℃; within the normal fluctuation range of ambient temperature, the difference in the relative change rate of the output current of the two reactors is ≤10%.

6. The wastewater biodegradability early warning method according to claim 1, characterized in that, Step (4) includes the following sub-steps: The output current of the two reactors is collected synchronously at a sampling frequency of 0.5Hz-2Hz, and the sampling time difference between the two signals is ≤20ms; use The criterion performs outlier removal on the raw current data: using the current data within the current sliding window as samples, the sample mean is calculated. with sample standard deviation The value falls within the interval Sampling points outside the specified range are identified as outliers, and the outliers are replaced by the linear interpolation result of adjacent valid sampling values ​​within the window. After removing outliers, the two current data streams were subjected to moving average filtering for durations of 3-10 minutes to obtain the baseline current average and the impulse response current average. The formula for calculating the moving average is as follows: in This represents the total number of sampling points within the sliding window. For the first Current values ​​at each sampling point For the first The average current value corresponding to each sliding window; Response ratio calculated based on the average current values ​​of the two paths. Response ratio The calculation period is equal to the window duration of the moving average filter.

7. The wastewater biodegradability early warning method according to claim 1, characterized in that, The historical average mentioned in step (5) Establish and continuously update in the following ways: Response ratio data of the wastewater treatment plant corresponding to the wastewater under continuous operation for 7-30 days were collected. Steady-state operating conditions were screened using a 24-hour statistical period. The criteria for determining steady-state operating conditions were: the relative standard deviation of the response ratio within the statistical period ≤10%, the relative fluctuation of influent COD ≤20% during the same period, and the relative fluctuation of influent BOD5 detected offline during the same period ≤15%. After screening the response ratio data corresponding to the steady-state conditions, the arithmetic mean was calculated as the initial historical mean. ; During system operation, the historical average is adjusted every 3-7 days. Perform a rolling update; The rolling update adopts a full replacement method, recalculating the average value of the steady-state operating condition response ratio data within the most recent 7-30 days. Historical operating data outside this time range is not included in this calculation. If the amount of valid steady-state operating condition data that meets the conditions within the current statistical window is less than 30% of the total data volume of the window, the statistical time window will be extended until the minimum data volume requirement is met, or the original historical average will be used until the next update cycle.

8. The wastewater biodegradability early warning method according to claim 1, characterized in that, In step (5), both the warning of decreased biochemical susceptibility and the warning of high load shock are divided into two levels, and their respective judgment rules are as follows: Early warning of decreased biochemical susceptibility: when the response ratio Below the historical average for 20-40 minutes consecutively When the biodegradability is between 75% and 85%, a Level 1 warning signal for decreased biodegradability is output; when the response ratio is... Below the historical average for 40-120 minutes consecutively When the biodegradability reaches 65%-75%, a secondary warning signal for decreased biodegradability is output. High load shock warning: when the response ratio Higher than the historical average for 20-40 minutes consecutively When the load is between 115% and 125%, a first-level high-load impact warning signal is output; when the response ratio is... 40-120 minutes above the historical average When the load reaches 125%-140%, a level-two high-load impact warning signal is output; The rules for raising, lowering, and lowering the warning level are as follows: After a Level II warning is triggered, if the response ratio... If the alert level rises back to the Level 1 warning range and continues for the duration required to trigger a Level 1 warning, it will automatically be downgraded to a Level 1 warning. After the warning is triggered, when the response ratio When the alert level returns to normal and the duration is equal to the warning trigger duration of the corresponding level, the warning signal of the corresponding level will be automatically lifted. The upper and lower limits of the normal range correspond to the first-level warning threshold: the deviation of the first-level biochemical degradation threshold and the first-level high-load impact threshold from the historical average is equal. The lower limit of the normal range is the first-level biochemical degradation threshold, and the upper limit is the first-level high-load impact threshold.

9. The wastewater biodegradability early warning method according to claim 1, characterized in that, It also includes baseline adaptive calibration and equipment fault self-diagnosis steps, as detailed below: The daily average value and intraday relative standard deviation of the baseline current of the reference reactor are calculated every 24 hours. When the intraday relative standard deviation is ≤10%, the daily baseline current is determined to meet the steady-state judgment condition. Simultaneously, it is confirmed that the influent is in a steady-state water quality condition, that is, the daily response ratio relative standard deviation is ≤10% and no warning is triggered. Synchronous drift analysis and fault judgment are only performed under steady-state water quality conditions. The cumulative change rate of the daily average current of the two reactors is calculated every 24 hours for 7 consecutive days. The daily average current of the initial operating day is used as the calculation benchmark. If the difference between the cumulative change rates of the two currents is ≤10%, it is determined that the two signals are synchronously drifting, and the response ratio can automatically cancel the drift effect. If the daily average current of a single reactor changes by more than 15% of the previous day's daily average, and the difference between the daily change rates of the two currents is greater than 15%, and it is confirmed that there are no abnormal fluctuations in water quality on that day and the response ratio is within the normal range, then the single reactor is judged to be operating abnormally; the system outputs a device maintenance prompt and suspends the early warning output until the fault is resolved.

10. A wastewater biodegradability early warning system based on microbial fuel cells, characterized in that, It includes a reactor unit, an influent pretreatment unit, an influent control module, a signal acquisition module, and an early warning control module; The reactor unit includes a reference reactor and a sample reactor, both of which are microbial fuel cells with identical structural parameters. They have the same anode material, cathode structure, effective volume of the anode cavity, water distribution method, and external circuit resistance. Both anodes are loaded with electroactive biofilms that have been acclimatized and passed consistency verification. The two reactors are placed in the same closed circulating water bath cavity with a water bath temperature control accuracy of ±0.2℃. The real-time temperature difference between the two reactors at their installation positions inside the cavity is ≤0.1℃. The influent pretreatment unit is connected to the inlet end of the reference reactor and the sample reactor, respectively. It includes a grid unit for pretreating the wastewater to be tested and a precision filter unit with a pore size of 20μm-50μm, as well as a sterilization filter unit with a pore size of 0.22μm for pretreating the standard control solution. The liquid inlet control module includes two peristaltic pumps calibrated by gravity, used to introduce standard control solution into the anode chamber of the reference reactor and wastewater to be tested into the anode chamber of the sample reactor, respectively. The volumetric flow rates of the two inlets are consistent, and the relative deviation of the rated flow rate is ≤1%. The signal acquisition module is equipped with a multi-channel data acquisition card with a resolution of no less than 16 bits, which is used to synchronously acquire the output current signals of the two reactors at a sampling frequency of 0.5Hz-2Hz, with a sampling time difference of ≤20ms between the two signals; the signal acquisition module has a built-in outlier removal unit and a moving average filtering unit, which are used to sequentially perform outlier removal processing and moving average filtering processing based on the 3σ criterion on the acquired current signals. The early warning control module has a built-in ratio calculation unit, threshold storage unit and early warning output unit, which is used to execute the wastewater biodegradability early warning method according to any one of claims 1 to 9, calculate the biodegradability response ratio and output the corresponding level of biodegradability abnormality early warning signal.

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