Biological fermentation conversion method in municipal sludge reduction

Abstract

The present application relates to sludge resource processing technology field, disclose a kind of biological fermentation conversion method in urban sludge reduction, comprising: collecting the time series data of apparent viscosity of urban sludge fluid oxidation-reduction potential, determine the correlation characteristic quantity of the space steric hindrance intensity of extracellular polymer, according to the change slope of correlation characteristic quantity to identify extracellular polymer network disintegration critical point;Oxygen flow is introduced in disintegration critical point to produce oxidative stress to digest extracellular polymer and release organic matrix, and in deep anaerobic interval, carbon-based electron shuttle is added to construct direct interspecies electron transport channel, the present application uses physical and chemical parameters coupling feedforward to guide biochemical intervention, digest the space steric hindrance of dense sludge floc, promote substrate rapid hydrolysis, shorten biological conversion cycle by metabolic pathway remodeling, improve methanogenic efficiency, realize the efficient reduction of urban sludge.

Description

Technical Field

[0001] This invention relates to a biological fermentation and transformation method for reducing urban sewage sludge volume, belonging to the field of sewage sludge resource utilization technology. Background Technology

[0002] Currently, anaerobic fermentation is used for municipal sludge treatment. This process utilizes microbial metabolism to convert organic matter into biogas, achieving the goals of sludge reduction and energy utilization. This technology is characterized by low treatment costs and high energy recovery rates, making it a mainstream method for the resource-based treatment of municipal sludge. However, the extracellular polymers in sludge flocs create a dense three-dimensional network structure, generating significant mass transfer resistance and limiting the penetration of hydrolytic enzymes into the flocs. This results in a limited hydrolysis rate during fermentation. Simultaneously, thermodynamic equilibrium restricts the interspecies hydrogen transfer process between acid-producing bacteria and methanogenic archaea. Under multiphase fluid environments or high-load conditions, metabolic kinetic mismatch can easily lead to the accumulation of volatile fatty acids, increasing the risk of system acidification.

[0003] To improve degradation efficiency, existing technologies employ methods such as hot water hydrolysis or ultrasonic crushing to break down the sludge structure. However, these methods involve external equipment and generate high operating energy consumption. Some solutions use indicators such as redox potential or apparent viscosity to monitor the fermentation state, but their regulation logic is mostly based on static thresholds. Due to the lack of correlation with the nonlinear transition characteristics of the extracellular polymer network disintegration process, it is difficult to identify the critical point of biochemical phase change at the data level, resulting in a lag in the control strategy. In addition to the bottleneck of hardware physical intervention, existing technologies also have limitations at the level of logic algorithms in their control strategies. For example, Chinese invention patent application with publication number CN118084192A... An anaerobic membrane bioreactor and anaerobic fermentation method were developed. The aeration device controlled by redox potential was used to aerate the bioreactor. When treating municipal sludge with a solid content of 8% to 12%, the evolution of the physical topology of the sludge flocs was nonlinear and hysteretic. The response of a single redox potential chemical signal could not map the dynamic dissolution phase of the extracellular polymer spatial steric hindrance. The control model, which is detached from the rheological properties of fluid physicochemicals and relies on biochemical potential feedback, is difficult to accurately capture the critical point of sludge flocs from dense to loose disintegration. This leads to a deviation between the timing of biochemical intervention and the material state, and the extracellular polymer shield cannot be broken down. The feedback lag can easily cause oxidative stress damage to methanogens.

[0004] Therefore, how to achieve in-situ disintegration of extracellular polymeric networks and construct efficient interspecies electron transport channels to improve the degradation rate of organic matter and ensure the stability of system operation without introducing external physical disruption equipment has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A bio-fermentation conversion method for reducing the volume of urban sewage sludge, comprising the following steps:

[0006] Step S101: Real-time acquisition of redox potential time series data and apparent viscosity time series data of high solids content urban sludge fluid during anaerobic fermentation process;

[0007] Step S102: Based on the redox potential time series data and the apparent viscosity time series data, establish a nonlinear mapping logic that reflects the spatial steric hindrance characteristics of the extracellular polymer network inside the urban sludge fluid, and calculate the extracellular polymer spatial steric hindrance correlation characteristic quantity that characterizes the spatial steric hindrance intensity of the extracellular polymer according to the nonlinear mapping logic.

[0008] Step S103: Calculate the dynamic change slope of the extracellular polymer spatial steric hindrance correlation characteristic during the fermentation cycle, and match the dynamic change slope with the preset sludge rheological critical feature library to lock the disintegration critical point of the extracellular polymer network in the urban sludge fluid from a dense state to a loose state. The sludge rheological critical feature library is composed of multiple sets of rheological mutation feature vectors of sludge with different solids content.

[0009] Step S104: At the moment corresponding to the disintegration critical point, a micro-oxygen flow is introduced into the urban sludge fluid. Transient oxidative stress is induced inside the urban sludge fluid through controlled dissolved oxygen. The transient oxidative stress is used to dissolve the extracellular polymer network, so that the organic matrix wrapped inside the extracellular polymer is released into the liquid phase of the urban sludge fluid.

[0010] Step S105: Monitor the redox potential of the urban sludge fluid. When the redox potential drops to the deep anaerobic range of -400mV to -450mV, add a carbon-based electron shuttle to the urban sludge fluid. Use the carbon-based electron shuttle to construct a solid conductive channel between acid-producing bacteria and methanogenic archaea, and change the metabolic coupling mode between microorganisms in the urban sludge fluid from interspecies hydrogen transfer to direct interspecies electron transfer.

[0011] Preferably, the calculation of the extracellular polymer spatial steric hindrance correlation feature in step S102 specifically includes: using the collected redox potential time series data and apparent viscosity time series data as sludge biochemical reaction feature parameters, extracting the coupling features between the physical features and biochemical responses of the multiphase microbial community metabolic processes in urban sludge fluid, and converting the coupling features into extracellular polymer spatial steric hindrance correlation feature quantities that quantify the spatial steric hindrance effect of the extracellular polymer network on substrate transfer.

[0012] Preferably, in step S103, the dynamic change slope is obtained by calculating the first derivative of the steric hindrance correlation characteristic of the extracellular polymer. When the dynamic change slope reaches the preset disintegration judgment threshold, it is determined that the urban sludge fluid has entered the instability stage of the extracellular polymer network, and the disintegration critical point is locked by combining the transient decrease characteristics of the apparent viscosity time series data.

[0013] Preferably, in step S105, the carbon-based electron shuttle comprises biochar or graphite powder, the particle size of the carbon-based electron shuttle is 10 μm to 50 μm, and the specific surface area is not less than 200 m². 2 / g; After the carbon-based electron shuttle is added, the redox active sites on its surface are used as electron acceptors and donors to reduce the dependence of the organic acid conversion process on the hydrogen partial pressure.

[0014] Preferably, in step S105, the carbon-based electron shuttle and the organic matrix released in step S104 form a metabolic matrix microregion with conductive properties inside the urban sludge fluid. By shortening the migration path of metabolites between microbial cells, the methanogenic potential of the urban sludge fluid during anaerobic fermentation is released in advance.

[0015] Preferably, the solids content of the urban sludge fluid is to The temperature of the urban sludge fluid was controlled between 35°C and 38°C during the fermentation cycle. The method reduced the volatile solids content in the urban sludge fluid by the temporal succession of the oxidative stress effect of micro-oxygen flow and the direct electron transfer effect of carbon-based electron shuttles.

[0016] Preferably, after step S105, the method further includes: continuously monitoring the gas production rate of the urban sludge fluid, performing correlation analysis between the gas production rate and the redox potential change curve during the fermentation cycle, and correcting the disintegration judgment threshold in the sludge rheological critical feature library based on the correlation analysis results.

[0017] Preferably, in step S103, if the slope of the dynamic change of the extracellular polymeric steric hindrance-related characteristic quantity does not reach the disintegration determination threshold within a preset time, then in step S104, the aeration intensity Q of the micro-oxygen flow is increased.

[0018] Preferably, a bio-fermentation transformation method for reducing urban sludge volume uses feedforward guidance of the disintegration critical point to connect the biochemical oxidation of micro-oxygen flow with the bioelectrochemical conduction of carbon-based electron shuttles in the time dimension. By utilizing the logical coupling of redox potential time series data and apparent viscosity time series data, the thermodynamic pathway of substrate degradation in urban sludge fluid is induced.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. In bio-fermentation transformation, by temporally coupling an external micro-aerobic dissolved gas circuit with the anaerobic fermentation environment, controlled micro-dissolved oxygen is used to induce transient oxidative stress inside the sludge, causing the dense extracellular polymer network to undergo biochemical degradation and reducing the spatial steric hindrance of the sludge flocs. This synchronous evolution of physical structure and biochemical characteristics allows the originally encapsulated organic matrix to be released, and the hydrolysis reaction rate is improved, solving the rate-limiting problem caused by the lag in the hydrolysis step during the anaerobic digestion of urban sludge.

[0021] 2. The carbon-based electron shuttle intervenes at the critical point of the system's transition to a deep anaerobic state, combining with the intercellular gaps of microorganisms formed by the previous microaerobic disturbances. It constructs a solid conductive channel between acid-producing bacteria and methanogenic archaea. This channel reconstructs the electron flow path, transforming the metabolic coupling between microorganisms from interspecies hydrogen transfer with a higher thermodynamic threshold to direct interspecies electron transfer. This effectively reduces the dependence of the organic acid conversion process on hydrogen partial pressure, shortens the bioconversion cycle, and improves the system's gas production efficiency.

[0022] 3. The computer-aided design module dynamically identifies topological singularities reflecting the steric hindrance dissipation state by mapping the characteristics of the redox potential and apparent viscosity time series. This allows the optimal spatiotemporal coordinates for material addition to be determined at the feedforward level. This decision-making mechanism based on data topology evolution eliminates the signal hysteresis and nonlinear bias of physical sensors in multiphase fluid environments, avoiding resource misallocation or process failure due to deviations in dosing timing, and enhancing the determinism of the entire fermentation system under complex operating conditions. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the entire process of anaerobic fermentation and conversion of urban sludge for volume reduction in this invention.

[0024] Figure 2 This is a flow path diagram of the micro-oxygen control and media addition of the bio-fermentation system of the present invention.

[0025] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0027] A bio-fermentation conversion method for reducing the volume of urban sewage sludge includes the following steps:

[0028] Step S101: Real-time acquisition of redox potential time series data and apparent viscosity time series data of high solids content urban sludge fluid during anaerobic fermentation process;

[0029] Step S102: Based on the redox potential time series data and the apparent viscosity time series data, establish a nonlinear mapping logic that reflects the spatial steric hindrance characteristics of the extracellular polymer network inside the urban sludge fluid, and calculate the extracellular polymer spatial steric hindrance correlation characteristic quantity that characterizes the spatial steric hindrance intensity of the extracellular polymer according to the nonlinear mapping logic.

[0030] Step S103: Calculate the dynamic change slope of the extracellular polymer spatial steric hindrance correlation characteristic during the fermentation cycle, and match the dynamic change slope with the preset sludge rheological critical feature library to lock the disintegration critical point of the extracellular polymer network in the urban sludge fluid from a dense state to a loose state. The sludge rheological critical feature library is composed of multiple sets of rheological mutation feature vectors of sludge with different solids content.

[0031] Step S104: At the moment corresponding to the disintegration critical point, a micro-oxygen flow is introduced into the urban sludge fluid. Transient oxidative stress is induced inside the urban sludge fluid through controlled dissolved oxygen. The transient oxidative stress is used to dissolve the extracellular polymer network, so that the organic matrix wrapped inside the extracellular polymer is released into the liquid phase of the urban sludge fluid.

[0032] Step S105: Monitor the redox potential of the urban sludge fluid. When the redox potential drops to the deep anaerobic range of -400mV to -450mV, add a carbon-based electron shuttle to the urban sludge fluid. Use the carbon-based electron shuttle to construct a solid conductive channel between acid-producing bacteria and methanogenic archaea, and change the metabolic coupling mode between microorganisms in the urban sludge fluid from interspecies hydrogen transfer to direct interspecies electron transfer.

[0033] Preferably, the calculation of the extracellular polymer spatial steric hindrance correlation feature in step S102 specifically includes: using the collected redox potential time series data and apparent viscosity time series data as sludge biochemical reaction feature parameters, extracting the coupling features between the physical features and biochemical responses of the multiphase microbial community metabolic processes in urban sludge fluid, and converting the coupling features into extracellular polymer spatial steric hindrance correlation feature quantities that quantify the spatial steric hindrance effect of the extracellular polymer network on substrate transfer.

[0034] Preferably, in step S103, the dynamic change slope is obtained by calculating the first derivative of the steric hindrance correlation characteristic of the extracellular polymer. When the dynamic change slope reaches the preset disintegration judgment threshold, it is determined that the urban sludge fluid has entered the instability stage of the extracellular polymer network, and the disintegration critical point is locked by combining the transient decrease characteristics of the apparent viscosity time series data.

[0035] Preferably, in step S104, the aeration intensity Q of the micro-oxygen flow is adjusted in a closed loop based on the rate of change of the extracellular polymeric steric hindrance-related characteristic quantity. The aeration intensity Q is calculated as follows: Where k is the preset stress regulation coefficient, f is the extracellular polymeric steric hindrance correlation characteristic, and t is the fermentation time.

[0036] Preferably, in step S105, the carbon-based electron shuttle comprises biochar or graphite powder, the particle size of the carbon-based electron shuttle is 10 μm to 50 μm, and the specific surface area is not less than 200 m². 2 / g; After the carbon-based electron shuttle is added, the redox active sites on its surface are used as electron acceptors and donors to reduce the dependence of the organic acid conversion process on the hydrogen partial pressure.

[0037] Preferably, in step S105, the carbon-based electron shuttle and the organic matrix released in step S104 form a metabolic matrix microregion with conductive properties inside the urban sludge fluid. By shortening the migration path of metabolites between microbial cells, the methanogenic potential of the urban sludge fluid during anaerobic fermentation is released in advance.

[0038] Preferably, the solids content of the urban sludge fluid is to The temperature of the urban sludge fluid was controlled between 35°C and 38°C during the fermentation cycle. The method reduced the volatile solids content in the urban sludge fluid by the temporal succession of the oxidative stress effect of micro-oxygen flow and the direct electron transfer effect of carbon-based electron shuttles.

[0039] Preferably, after step S105, the method further includes: continuously monitoring the gas production rate of the urban sludge fluid, performing correlation analysis between the gas production rate and the redox potential change curve during the fermentation cycle, and correcting the disintegration judgment threshold in the sludge rheological critical feature library based on the correlation analysis results.

[0040] Preferably, in step S103, if the slope of the dynamic change of the extracellular polymeric steric hindrance-related characteristic quantity does not reach the disintegration determination threshold within a preset time, then in step S104, the aeration intensity Q of the micro-oxygen flow is increased.

[0041] Preferably, a bio-fermentation transformation method for reducing urban sludge volume uses feedforward guidance of the disintegration critical point to connect the biochemical oxidation of micro-oxygen flow with the bioelectrochemical conduction of carbon-based electron shuttles in the time dimension. By utilizing the logical coupling of redox potential time series data and apparent viscosity time series data, the thermodynamic pathway of substrate degradation in urban sludge fluid is induced.

[0042] Example 1: When the system faces the centralized treatment of municipal sludge with a solids content of 8% to 12%, the dense extracellular polymer network on the surface of the sludge flocs creates a steric hindrance effect, hindering the release of internal organic matrix. Furthermore, there is a kinetic mismatch in the metabolic rates of acid-producing bacteria and methanogenic archaea under the interspecies hydrogen transfer pathway, which easily leads to the accumulation of volatile fatty acids and system acidification shock under high organic loads. The system relies on a sensor array deployed inside the fermentation reactor to collect real-time data on the redox potential and apparent viscosity of the municipal sludge fluid during the anaerobic fermentation process at 35℃ to 38℃. The coupling characteristics between the physical characteristics and biochemical responses of the multiphase microbial community metabolic process are extracted. A multiple regression algorithm is used to transform these coupling characteristics into extracellular polymer spatial hindrance correlation features that quantify the steric hindrance effect of the extracellular polymer network on substrate transfer.

[0043] The system calculates the first derivative of the aforementioned extracellular polymer spatial steric hindrance-related characteristic quantity to obtain its dynamic change slope during the fermentation cycle. The system control unit continuously performs feature matching calculations on this dynamic change slope and a sludge rheological critical feature library composed of rheological catastrophe feature vectors of multiple sets of sludge with different solids contents. When the obtained dynamic change slope reaches the disintegration judgment threshold set in the critical feature library, combined with the transient decrease characteristics of apparent viscosity time series data, the system locks the disintegration critical point of the extracellular polymer network in the municipal sludge fluid transitioning from a dense state to a loose state. During the above feature matching calculation, the control unit does not directly perform numerical comparisons with unequal dimensions, but uses principal component analysis (PCA) to extract and reduce the dimensionality of the multidimensional rheological catastrophe feature vectors, mapping them to corresponding dimensions. Using a single-dimensional slope benchmark sequence with the same background solids content, the system calculates in real time the Euclidean distance difference between the current dynamic slope and the matching scalar value in the benchmark sequence. A matching determination is generated only when this distance difference converges within a preset tolerance margin. At the moment corresponding to the critical disintegration point, the external control loop introduces a micro-oxygen flow into the municipal sludge fluid. Controlled dissolved oxygen induces transient oxidative stress within the fluid to dissolve the extracellular polymer network and release the internally encapsulated organic matrix into the liquid phase. Based on the mass balance law and enzyme reaction kinetics, the hydrolysis rate of macromolecules within the heterogeneous system is positively correlated with the induced dissolved oxygen mass transfer flux. The system establishes the correlation logic between control input parameters and changes in physicochemical characteristics according to physical laws. The aeration intensity of this micro-oxygen flow is adjusted according to a closed-loop formula. The calculation yields the following values: Q is the aeration intensity of the introduced micro-oxygen flow, k is the preset stress adjustment coefficient, which is obtained by applying a gradient micro-oxygen flow to sludge samples with the same solids content and fitting the peak value of the extracellular polymer hydrolysis rate, f is the extracellular polymer steric hindrance correlation characteristic quantity calculated above, and t is the fermentation time.

[0044] After the transient oxidative stress of the aforementioned micro-oxygen flow eliminates the steric hindrance of extracellular polymers, the system continuously monitors the redox potential of the municipal sludge fluid. When the redox potential drops to the deep anaerobic range of -400mV to -450mV, the dosing mechanism adds carbon-based electron shuttles with a particle size of 10μm to 50μm and a specific surface area of ​​not less than 200m² / g to the municipal sludge fluid. The carbon-based electron shuttles, composed of biochar or graphite powder, utilize their surface redox active sites as electron acceptors and donors to construct a structure between the exposed cell walls of acid-producing bacteria and methanogenic archaea. The solid conductive channel transforms the metabolic coupling mechanism within the system from interspecies hydrogen transfer with a higher thermodynamic threshold to direct interspecies electron transfer. The carbon-based electron shuttle and the aforementioned released organic matrix form a conductive metabolic matrix microregion within the urban sludge fluid, shortening the migration path of metabolites between microbial cells and avoiding the limitation of substrate degradation thermodynamic pathways by changes in hydrogen partial pressure. The substrate transfer channels from volatile fatty acids to methanogenic archaea within the system remain unobstructed. Under this biochemical evolution phase, the urban sludge fluid releases methanogenic potential and achieves an objective mass reduction in volatile solids content.

[0045] Example 2: In this example, a continuous stirred anaerobic reactor with an effective volume of 50L was assembled as a closed-loop verification platform. The reactor was externally equipped with a water bath circulation jacket, and the temperature control accuracy was limited to 0.1℃. Multiple layers of impellers were installed on the central shaft inside the reactor, and the stirring speed was maintained at 120rpm. Urban sludge fluid with a solids content of 10.5% produced from the dewatering workshop of the same municipal wastewater treatment plant was selected as the test sample. Gaussian white noise with a signal-to-noise ratio of 20dB was injected into the analog signal receiving front end of the sensor array, and a 50Hz power frequency interference harmonic was superimposed to construct a test signal source containing electromagnetic disturbances. Six parallel fermentation experiments were set up, with the first group serving as a control group. No additional... The constant-temperature anaerobic fermentation process with added gas and materials is divided into six groups. The second group is a partially missing control group, in which micro-oxygen flow is triggered according to characteristic quantities during the fermentation process, and no carbon-based electron shuttle is added. The third group is the lower limit test group, in which biochar with a particle size of 10 μm and a specific surface area of ​​280 m² / g is added as a carbon-based electron shuttle after the introduction of micro-oxygen flow. The fourth group is the median test group, in which biochar with a particle size of 25 μm and a specific surface area of ​​235 m² / g is added. The fifth group is the upper limit test group, in which biochar with a particle size of 50 μm and a specific surface area of ​​205 m² / g is added. The sixth group is the out-of-range control group, in which biochar with a particle size of 85 μm and a specific surface area of ​​150 m² / g is added.

[0046] The temperature of all reactor systems was maintained at 36.5℃. Noisy raw redox potential and apparent viscosity time-series data were acquired by the sensor array. The processing module used a sliding window mean filtering algorithm to remove power frequency interference and Gaussian white noise from the raw signals, outputting physical characterization curves. The processing module extracted physicochemical characteristics and calculated the extracellular polymeric steric hindrance correlation characteristic quantity, monitoring data stream indicators. In the fourth group, at 42.5 hours after fermentation start-up, the dynamic change slope of the extracellular polymeric steric hindrance correlation characteristic quantity rose to 0.18, reaching the disintegration judgment threshold calibrated in the rheological critical characteristic library. Within the same sampling period, the filtered apparent viscosity value decreased from a stable period of 4.35 Pa·s to 2.72 Pa·s. Based on this multidimensional data mutation characteristic, the control unit locked the disintegration critical point of the extracellular polymeric network inside the municipal sludge fluid. At the disintegration critical point, the external control loop introduced micro-oxygen flow into the corresponding reactor. The aeration intensity of the micro-oxygen flow was based on a closed-loop adjustment formula. The formula is defined as follows: Q is the instantaneous aeration intensity of the microaeration flow, k is the stress regulation coefficient, f is the steric hindrance correlation characteristic of extracellular polymers, and t is the fermentation time. The value of the stress regulation coefficient k is determined based on the balance between oxidative stress intensity and the tolerance limit of methanogenic archaea toxicity. By pre-inputting a gradient microaeration flow of 0.5 m³ / h to 5.0 m³ / h into sludge samples with the same solids content and fitting the peak value of extracellular polymer hydrolysis rate, the value of k is established as 12.5. The control unit substitutes the dynamic change slope of 0.18 into the formula and calculates the output instantaneous aeration intensity as 2.25 m³ / h. Here, although the stress regulation coefficient k is in the single solids... The fixed-beam system is presented as an overall scalar constant, but its underlying physical essence is the product of the intrinsic mass transfer constant and the effective volume of the reactor. In the actual engineering scale-up stage, the system performs a proportional linear scaling calculation on this reference constant according to the specific geometric working volume of the target anaerobic digester, so that the calculated absolute aeration flow rate can adaptively match the actual engineering treatment scale, and always maintain the gas-liquid mass transfer dynamic boundary conditions in the sludge fluid per unit volume constant. This improves the general industrial scaling scalability of the empirical control formula, which is no longer limited by the specific laboratory volume. The micro-oxygen flow is injected into the reactor at this intensity to induce transient oxidative stress.

[0047] The redox potential measured by the sensor array showed a decreasing trend with the injection of micro-oxygen flow. When the redox potential probe value dropped to -428mV, the dosing mechanism quantitatively added biochar of the corresponding specifications to groups three through six respectively. The biochar used its surface redox active sites as electron acceptors and donors to construct a solid conductive channel between the cell walls of acid-producing bacteria and methanogenic archaea. The terminal physicochemical indicators of each group of samples were measured after a 20-day fermentation cycle. The volatile solids removal rate of group one was 31.4%, and the methanogenic yield per unit of volatile solids was 142.6 mL / g. Group two initially eliminated steric hindrance through micro-oxygen flow stress. Due to the metabolic rate mismatch between acid-producing bacteria and methanogenic archaea in the middle and late stages of fermentation, volatile fatty acids accumulated, and its volatile solids removal rate was 43.2%. The biochar particle size used in group six exceeded the specific range, resulting in surface redox activity... Insufficient site density and discontinuities in the direct interspecies electron transport network resulted in a volatile solids removal rate of 39.7%. The volatile solids removal rate of the third group was 58.1%, with a methanogenic yield of 241.3 mL / g. The volatile solids removal rate of the fourth group was 59.3%, with a methanogenic yield of 248.5 mL / g. The volatile solids removal rate of the fifth group was 56.8%, with a methanogenic yield of 235.2 mL / g. The above quantitative indicators showed a nonlinear correlation with the parameter range. The extracellular polymer network dissolution mechanism induced by micro-oxygen flow and the direct interspecies electron transport channel constructed by carbon-based electron shuttles had a synergistic promoting effect. Carbon-based electron shuttles with particle sizes in the range of 10 μm to 50 μm constituted the working window for reshaping the thermodynamic pathway of substrate degradation. Exceeding the boundary of this physical parameter triggered a degradation effect of decreased electron transport efficiency and accumulation of metabolites within the system.

[0048] Example 3: Under the anaerobic fermentation conditions of urban sludge, there is a nonlinear deviation between the fluid physical state sensing time-series data with a solids content of 8% to 12% and the disintegration phase of the internal extracellular polymer network. The lack of correlation calculation rules leads to the timing of microaeration flow intervention deviating from the set benchmark point. Local over-aeration poses a technical risk of oxidative poisoning of methanogenic archaea. The control unit is configured with a sliding sampling window with a time length of 15 minutes. The sensor array acquires the apparent viscosity time-series data and redox potential time-series data within this time window. The processing module calculates the statistical variance of the apparent viscosity time-series data within the sliding sampling window. Based on this, the processing module calculates the first derivative of the redox potential time-series data with respect to time. The processing module then calculates the absolute value of the aforementioned statistical variance and the first derivative. The output coupling characteristic quantity is obtained by multiplying the values. Before performing the multiplication operation, the processing module pre-extracts the maximum value of the apparent viscosity variance and the global maximum value of the absolute value of the redox potential derivative under the calibration conditions as normalization reference benchmarks. The statistical variance and the absolute value of the first derivative calculated in real time are divided by their respective reference benchmarks and converted into dimensionless relative variation coefficients with values ​​ranging from 0 to 1. The processing module then performs a multiplication operation on these two dimensionless relative variation coefficients, so that the output coupling characteristic quantity is freed from the constraints of the original physical dimensions and becomes a normalized numerical index that purely reflects the comprehensive correlation strength between the intensity of physical rheology and the rate of change of biochemical potential. This coupling characteristic quantity characterizes the correlation between the physical characteristics and biochemical responses of the metabolic process of multiphase microbial communities.

[0049] The system internally employs a linear regression model to transform coupled characteristic quantities. The weight coefficients of this linear regression model are obtained through an offline calibration procedure. During the offline calibration phase, the test unit extracts multiple sets of municipal sludge samples with a solids content ranging from 8% to 12%. The drive mechanism applies constant-speed mechanical shearing to the samples, while the sensor array synchronously acquires data. The processing module calculates the coupled characteristic quantities at corresponding times. The testing instrument uses three-dimensional fluorescence spectroscopy to periodically measure the protein and polysaccharide concentrations in the corresponding sample liquid phases. The calibration module calculates the rate of increase in protein and polysaccharide concentrations over time, and determines the moment when this rate of increase reaches its peak as the benchmark point for extracellular polymer network disintegration. At this benchmark point, the corresponding coupled characteristic quantity values ​​are extracted as dependent variables. The calibration module applies the least squares method to fit and generate regression weight matrices corresponding to different solids content parameters, constructing a critical characteristic library of sludge rheology. The model is set as a polynomial linear combination, and its input feature vector consists of the apparent viscosity component and the redox potential component after range standardization. The standardization operation maps the two to a dimensionless range of 0 to 1 to eliminate the dimensional differences of the underlying sensor data. The regression weight matrix contains the corresponding viscosity weight coefficient, potential weight coefficient, and cross-coupling term coefficient. After least squares iterative optimization, definite coefficient values ​​are generated. Through the above dimensionless processing and deterministic matrix multiplication operation, the nonlinear biochemical law of multi-source sensor data is visualized as a scalar value that purely characterizes the relative strength of spatial steric hindrance. The processing module calls the matching weight matrix in the library based on the measured solid content and converts the coupling feature quantity calculated in real time into extracellular polymer spatial steric hindrance related feature quantity. The control unit sets the value of the related feature quantity corresponding to the aforementioned disintegration benchmark point as the disintegration judgment threshold.

[0050] The processing module continuously compares the real-time calculated extracellular polymeric steric hindrance correlation characteristic with the disintegration threshold. When the extracellular polymeric steric hindrance correlation characteristic rises to the disintegration threshold, the control unit generates a micro-oxygen aeration command. The external control loop drives the porous annular air distribution pipe array located at the bottom of the reactor to start alternating pulse aeration. The control unit sets the pulse aeration duration to 10 seconds and the interval duration to 30 seconds. This spatially distributed pulse injection physical action distributes the target aeration intensity to the interior of the municipal sludge fluid. The microbubble clusters dissolve under the shearing action of the impeller, causing transient oxidative stress inside the fluid. During this process, the trace dissolved oxygen injected by the pulse is limited by the mass transfer double membrane resistance at the gas-liquid interface and preferentially accumulates in the outer layer of the dense sludge flocs. Because the extracellular polymeric network surrounding the flocs is rich in polysaccharides that are easily oxidized, the micro-oxygen injection process is particularly effective. The biochemical consumption rate of dissolved oxygen by protein groups is numerically much greater than the physical diffusion rate of dissolved oxygen into the deep core of the floc. Trace oxygen molecules are consumed instantly upon invading the surface, thereby inducing a targeted hydrolysis reaction only against the outer polymer network in physical space. This physical barrier mechanism based on the efficient oxygen consumption barrier of the outer layer keeps the microenvironment of the floc core in its original deep anaerobic state, avoiding the risk of increased dissolved oxygen in the bulk phase to the methanogenic archaea in the core area. Data calculation rules and offline calibration procedures construct a causal chain from physical sensing signals to micro-oxygen intervention actions. The spatially distributed pulse aeration process limits the local physical enrichment of dissolved oxygen. The urban sludge fluid completes the dissolution of the extracellular polymer network within the set oxidative stress boundary. The reactor as a whole maintains a deep anaerobic environment, ensuring the operation of the methanogenic metabolic pathway.

[0051] Example 4: When the system faces the initial physicochemical property fluctuations of urban sludge disposal, the baseline metabolic behavior of the internal community of urban sludge fluid deviates from the system's preset critical rheological feature library. Before feeding, the control unit triggers an adaptive calibration procedure. The sampling pump extracts a quantitative fluid sample and injects it into the bypass calibration unit. The sensor array continuously acquires the apparent viscosity time series data and redox potential time series data of the sample in a constant temperature and sealed environment of 35°C to 38°C. The processing module calculates the statistical variance of the apparent viscosity time series data and the first derivative of the redox potential time series data. The calibration unit extracts the product of the aforementioned statistical variance and the absolute value of the first derivative as the baseline coupling feature quantity. The processing module uses the evolution curve of this baseline coupling feature quantity to correct the regression weight matrix in the critical rheological feature library of sludge. The system performs sample normalization and outputs a baseline ready signal.

[0052] After receiving the baseline ready signal, the control unit sequentially inputs multiple sets of gradually increasing micro-oxygen flows into the bypass calibration unit via the external control loop. The sensor array records the rate of decrease of the oxidation-reduction potential at each aeration intensity. The processing module extracts the aeration intensity with the shortest time required for the oxidation-reduction potential to reach the -400mV to -450mV deep anaerobic range without positive drift and records it as the safe aeration reference value. The calibration unit then substitutes this safe aeration reference value into the closed-loop adjustment formula. In the reverse operation, the system extracts the instantaneous aeration intensity Q and the dynamic change slope of the extracellular polymeric steric hindrance-related characteristic quantity f relative to time t under this state, and calculates the working condition adaptation value of the stress regulation coefficient k. The quantitative mapping relationship between physical sensor data and biochemical intervention actions establishes the parameter alignment benchmark, and the main reactor starts the bio-fermentation transformation process according to the alignment benchmark.

[0053] Example 5: Under the anaerobic fermentation conditions of high solids content municipal sludge, the municipal sludge fluid exhibits spatial heterogeneity. Local cavitation within the fluid, flowing through a single measurement node, causes a false drop in apparent viscosity, leading to the false triggering of micro-oxygen intervention commands. Before fermentation starts, the control unit loads the sampling window calibration procedure. The system reads the stirring rate of the impeller inside the reactor. The processing module calculates the average convective migration time of fluid particles between two adjacent measurement nodes based on the impeller diameter and the stirring rate. The processing module sets the time length of the sliding sampling window to the product of the average convective migration time and a multiplier factor, with the multiplier factor ranging from 3 to 5. The set time length covers the complete mixing cycle of fluid particles within the measurement area, filtering out random interference caused by high-frequency fluid pulsation on the apparent viscosity time series data.

[0054] Multiple sets of measurement nodes are distributed at different depths and radial positions inside the reactor. During the bio-fermentation conversion stage, each set of measurement nodes independently acquires the apparent viscosity time-series data of the corresponding region. The processing module calculates in parallel the statistical variance of the apparent viscosity time-series data of each set within the sliding sampling window and the dynamic change slope of the corresponding extracellular polymer spatial steric hindrance correlation characteristic. The control unit loads multi-node spatial verification logic. When more than half of the measurement nodes are detected to have their dynamic change slopes synchronously reach the disintegration judgment threshold, the control unit outputs a global disintegration confirmation signal. For isolated measurement nodes that have not reached the disintegration judgment threshold, the processing module marks the data of the corresponding region as local cavitation interference and blocks the data from entering the control loop. Based on the global disintegration confirmation signal, the system issues a micro-aeration command to the porous annular gas distribution tube array. The multi-point quantization verification logic intercepts abnormal data fluctuations of a single measurement node. The municipal sludge fluid acquires transient oxidative stress at the globally locked time node, and the system maintains the physicochemical environmental stability of the bio-fermentation conversion process.

[0055] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0056] Finally, it should be noted that the above 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 preferred embodiments, those skilled in the art should understand that modifications or 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.

Claims

1. A bio-fermentation conversion method for reducing urban sewage sludge volume, characterized in that, Includes the following steps: Step S101: Real-time acquisition of redox potential time series data and apparent viscosity time series data of high solids content urban sludge fluid during anaerobic fermentation process; Step S102: Based on the redox potential time series data and the apparent viscosity time series data, establish a nonlinear mapping logic that reflects the spatial steric hindrance characteristics of the extracellular polymer network inside the urban sludge fluid, and calculate the extracellular polymer spatial steric hindrance correlation characteristic quantity that characterizes the spatial steric hindrance intensity of the extracellular polymer according to the nonlinear mapping logic. Step S103: Calculate the dynamic change slope of the extracellular polymer spatial steric hindrance correlation characteristic during the fermentation cycle, and match the dynamic change slope with the preset sludge rheological critical feature library to lock the disintegration critical point of the extracellular polymer network in the urban sludge fluid from a dense state to a loose state. The sludge rheological critical feature library is composed of multiple sets of rheological mutation feature vectors of sludge with different solids content. Step S104: At the moment corresponding to the disintegration critical point, a micro-oxygen flow is introduced into the urban sludge fluid. Transient oxidative stress is induced inside the urban sludge fluid through controlled dissolved oxygen. The transient oxidative stress is used to dissolve the extracellular polymer network, so that the organic matrix wrapped inside the extracellular polymer is released into the liquid phase of the urban sludge fluid. Step S105: Monitor the redox potential of the urban sludge fluid. When the redox potential drops to the deep anaerobic range of -400mV to -450mV, add a carbon-based electron shuttle to the urban sludge fluid. Use the carbon-based electron shuttle to construct a solid conductive channel between acid-producing bacteria and methanogenic archaea, and change the metabolic coupling mode between microorganisms in the urban sludge fluid from interspecies hydrogen transfer to direct interspecies electron transfer.

2. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, The calculation of extracellular polymer spatial steric hindrance correlation features in step S102 specifically includes: using the collected redox potential time series data and apparent viscosity time series data as sludge biochemical reaction characteristic parameters, extracting the coupling characteristics between the physical characteristics and biochemical responses of the multiphase microbial community metabolic processes in urban sludge fluid, and converting the coupling characteristics into extracellular polymer spatial steric hindrance correlation features that quantify the spatial steric hindrance effect of the extracellular polymer network on substrate transfer.

3. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, In step S103, the dynamic change slope is obtained by calculating the first derivative of the steric hindrance correlation characteristic of the extracellular polymer. When the dynamic change slope reaches the preset disintegration judgment threshold, it is determined that the urban sludge fluid has entered the instability stage of the extracellular polymer network, and the disintegration critical point is locked by combining the transient decrease characteristics of the apparent viscosity time series data.

4. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, In step S105, the carbon-based electron shuttle comprises biochar or graphite powder, the particle size of the carbon-based electron shuttle is 10 μm to 50 μm, and the specific surface area is not less than 200 m². 2 / g; After the carbon-based electron shuttle is added, the redox active sites on its surface are used as electron acceptors and donors to reduce the dependence of the organic acid conversion process on the hydrogen partial pressure.

5. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, In step S105, the carbon-based electron shuttle and the organic matrix released in step S104 form a metabolic matrix microregion with conductive properties inside the urban sludge fluid. By shortening the migration path of metabolites between microbial cells, the methanogenic potential of the urban sludge fluid in the anaerobic fermentation process is released in advance.

6. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, The solids content of the urban sludge fluid is 8% to 12%, and the temperature of the urban sludge fluid is controlled at 35℃ to 38℃ during the fermentation cycle. The method reduces the volatile solids content in the urban sludge fluid by the temporal succession of the oxidative stress effect of micro-oxygen flow and the direct electron transfer effect of carbon-based electron shuttles.

7. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, After step S105, the method further includes: continuously monitoring the gas production rate of urban sludge fluid, and performing correlation analysis between the gas production rate and the redox potential change curve during the fermentation cycle, and correcting the disintegration judgment threshold in the sludge rheological critical feature library based on the correlation analysis results.

8. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, In step S103, if the slope of the dynamic change of the extracellular polymeric steric hindrance-related characteristic quantity does not reach the disintegration determination threshold within a preset time, then in step S104, the aeration intensity Q of the micro-oxygen flow is increased.

9. The bio-fermentation conversion method for reducing urban sewage sludge according to claim 1, characterized in that, The bio-fermentation transformation method in urban sludge reduction uses feedforward guidance of the disintegration critical point to connect the biochemical oxidation of micro-oxygen flow with the bioelectrochemical conduction of carbon-based electron shuttles in the time dimension. By using the logical coupling of redox potential time series data and apparent viscosity time series data, the thermodynamic pathway of substrate degradation in urban sludge fluid is induced.

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