Sewage treatment process for producing carbon source based on sodium hydrosulfite

Abstract

The invention belongs to the technical field of sewage treatment processes, particularly relates to a sewage treatment process for producing a carbon source based on sodium hydrosulfite, and aims to solve the problems that in an existing traditional method, only COD (Chemical Oxygen Demand) is taken as a single index, an easily-degraded quick-release carbon source and a difficultly-degraded slow-release carbon source cannot be distinguished, carbon source adding depends on artificial experience for a long time, and the cost is low. In order to solve the problem that the addition amount of a carbon source is inaccurate due to the fact that an accurate mathematical model cannot be established in the prior art, the invention provides the following scheme: the method comprises the following steps: S1, stirring crude methanol, and pre-oxidizing part of refractory organic matters; according to the method, hazardous wastes produced by sodium hydrosulfite are converted into a standardized and functionalized targeted composite carbon source, and a carbon source functional spectrum and a model predictive control model are constructed, so that the crossing of empirical extensive addition of the carbon source to on-demand accurate intelligent addition is realized, the pollution problem is solved, and meanwhile, the target carbon source is obtained. The denitrification efficiency and the operation economy of sewage treatment are obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment process, and in particular to a sewage treatment process based on carbon source produced by sodium hydrosulfite. BACKGROUND

[0002] Industrial sodium hydrosulfite (commonly known as "sodium hydrosulfite") will produce a large amount of by-product crude methanol in the production process. The by-product has complex composition, in addition to containing 60%-75% of methanol, usually also contains 8%-15% of sodium formate, 2%-5% of sulfite and a small amount of ethylene glycol, sulfide and other organic impurities. Its composition fluctuates greatly, direct discharge will cause serious environmental pollution and resource waste, in the field of sewage treatment, in order to solve the problem of insufficient carbon source in biological denitrification of low carbon-nitrogen ratio sewage, additional carbon source needs to be added. At present, sewage treatment plants often use sodium acetate, glucose or commercial methanol as traditional carbon source. These carbon sources are expensive, which constitutes one of the main operation costs of sewage treatment plants.

[0003] In the prior art, the traditional method only takes COD (chemical oxygen demand) as a single index, which cannot distinguish between the easily degradable "fast-release carbon source" and the difficultly degradable "slow-release carbon source", resulting in that the carbon source addition long-term relies on artificial experience, an accurate mathematical model cannot be established, and the carbon source addition amount is inaccurate. Therefore, the present application provides a sewage treatment process based on carbon source produced by sodium hydrosulfite to solve the above problems. SUMMARY

[0004] The present application provides a sewage treatment process based on carbon source produced by sodium hydrosulfite, which adopts the following technical scheme:

[0005] The sewage treatment process based on carbon source produced by sodium hydrosulfite provided in the present application adopts the following technical scheme: A sewage treatment process based on carbon source produced by sodium hydrosulfite, comprising the following steps: S1: stirring and treating the crude methanol, and pre-oxidizing part of the difficultly degradable organic matter; S2: gradient classification of the pretreated material; S3: online component and function analysis of the liquid product after fine filtration, and construction of carbon source function map; S4: standardization classification of the product according to the carbon source function map; S5: simulation of the consumption process of the fast-release and slow-release carbon source under the action of microorganisms, and adjustment of the addition amount; S6: collection of the residual liquid, and low-temperature evaporation and concentration; S7: Real-time monitoring of the change trend of the transmembrane pressure difference and the water quality of the feed liquid and maintenance; S8: Real-time monitoring of the energy consumption of the equipment and automatic adjustment of the equipment operating frequency.

[0006] Further, in S1, the crude methanol is pumped into a vortex ultrasonic homogenization tank, which includes mechanical stirring (30-60 rpm) and low-frequency ultrasonic waves (25-40 kHz), to stir and homogenize the crude methanol and break up the colloidal and suspended matter aggregates.

[0007] Further, in S1, the pH is precisely controlled to 6.8-7.2 by adding dilute sulfuric acid through a pH-ORP linkage control system, and the concentration of dilute sulfuric acid is 5%-8%. A small amount of potassium monopersulfate (PMS) is automatically added according to the real-time ORP value (set range -50 to -100 mV). This step aims to achieve "targeted detoxification", which preferentially oxidizes the biologically toxic sulfite to harmless sulfate and pre-oxidizes part of the refractory organic matter to improve the biodegradability of the system.

[0008] Further, in S2, the pretreated material is delivered to a hydrocyclone, which uses strong centrifugal force to quickly separate inorganic particles and part of heavy organic matter with large density as a high-efficiency coarse filter, greatly reducing the burden on the subsequent membrane system. A wide-flow anti-pollution tubular ultrafiltration membrane group is arranged in the hydrocyclone. The material of the wide-flow anti-pollution tubular ultrafiltration membrane group is modified PVDF, and the molecular weight cut-off is 80,000-150,000 Dalton. The membrane assembly has a wide channel and is designed for high-organic and high-viscosity liquids, with high flux and strong anti-pollution performance. This coupled separation system can intelligently switch operating modes according to the turbidity of the incoming material, with wide adaptability.

[0009] Further, in S3, online component and function analysis is performed on the liquid product after fine filtration, and a carbon source function map is constructed according to the analysis results. The carbon source function map includes rapid-release carbon source content (RCC), slow-release carbon source content (SCC), and biological toxicity potential index (BTP). Rapid-release carbon source content (RCC): The COD consumption within the first 30 minutes is determined by online respirometry, which represents components such as methanol that can be directly utilized. The calculation formula is: RCC= (COD consumption within the first 30 minutes) / (total COD) x 100%; Slow-release carbon source content (SCC): It is estimated by (total COD-RCC), which represents components such as sodium formate and ethylene glycol that can be utilized in large quantities after hydrolysis. The calculation formula is: SCC= (total COD-RCC corresponding COD consumption) / (total COD) x 100%; Biotoxicity potential (BTP): Microbial metabolic activity is monitored by a microbiosensor to ensure complete detoxification and meet product biosafety standards.

[0010] Further, in the S4, the product is standardized and classified into different types of targeted composite carbon sources according to the carbon source functional map, including Type-F (fast-acting type), Type-S (slow-release type), and Type-B (balanced type); Type-F (fast-acting type): suitable for scenarios with high impact load and the need for rapid denitrification; Type-S (slow-release type): suitable for scenarios with stable water quality and the need for continuous denitrification; Type-B (balanced type): the default general type, ensuring a reasonable ratio of fast-acting and slow-release components.

[0011] Further, in the S5, a model predictive controller (MPC) is deployed in the denitrification zone of the wastewater treatment system. The model predictive controller takes the influent flow rate (Q), influent nitrate nitrogen (NO3 - -N), influent ammonia nitrogen (NH4 + -N), water temperature (T), and carbon source functional map (RCC / SCC) as real-time inputs. The model predictive controller kernel is embedded with a multi-substrate denitrification kinetics model, which simulates the consumption process of fast-release and slow-release carbon sources under microbial action. The model predictive controller uses a model predictive control algorithm. Model predictive control algorithm: objective function (cost function):

[0012] Where: X t+k is the system state at time t+k; is the desired value of the system state at time t+k; U t+k is the control input at time t; U reft+k is the desired value of the control input at time t+k; N P is the prediction horizon length; Q, R, P are weight matrices of state, control input, and terminal state, respectively, used to balance the relative importance between different variables; System dynamic constraints:

[0013] Where, is a function that describes how the system state changes with the current state and control input. In the denitrification process in wastewater treatment, this function involves the denitrification kinetics model:

[0014] Where: denotes the nitrate nitrogen concentration; is the maximum specific growth rate of heterotrophic denitrifying bacteria; is the concentration of heterotrophic denitrifying bacteria; S N is the nitrate nitrogen concentration; K N is the half-saturation constant of nitrate nitrogen; S C is the carbon source concentration; K C is the half-saturation constant of carbon source; is the yield coefficient of heterotrophic denitrifying bacteria; is the decay rate of heterotrophic denitrifying bacteria; is the time step.

[0015] Further, in the S6, the cyclone underflow is collected and transported to the low-temperature vacuum evaporation system along with the residual liquid generated by the reverse washing of the ultrafiltration membrane. The residual liquid is subjected to low-temperature vacuum evaporation, and the main component of the evaporation concentrate is high-purity sodium formate (the concentration can be increased to more than 40%). The sodium formate can be further crystallized and dried into solid product, which can be sold as a commodity or used in other industrial processes, realizing productized recovery of the residual liquid and completely eliminating secondary pollution.

[0016] Further, in the S7, the development speed of membrane pollution is predicted by real-time monitoring of the transmembrane pressure difference (TMP) change trend and the feed liquid water quality, and the optimal backwashing program (air-water pulse) and chemical cleaning cycle (using 0.1% NaOH and 0.5% citric acid for alternate cleaning) are automatically triggered to ensure the system to run in the best state for a long time.

[0017] Further, in the S8, the energy consumption of key units such as water pumps, stirring, and membrane systems is monitored in real time by the energy management system (EMS), and the equipment operation frequency is automatically adjusted (such as using a variable frequency pump) to select high energy consumption operations (such as chemical cleaning) during the low price period to achieve energy efficiency optimization and cost minimization of the whole process, forming a comprehensive closed-loop optimization from technology to economy.

[0018] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application constructs a carbon source function map containing "rapid-release carbon source content (RCC)", "slow-release carbon source content (SCC)", and "biological toxicity potential index (BTP)", which finely characterizes the carbon source from the perspective of microbial availability, overcomes the extensive nature of traditional methods which only use COD as a single indicator, and lays a scientific foundation for subsequent precise dosing; 2. This solution standardizes the product into different models such as fast-acting (Type-F), slow-release (Type-S), and balanced (Type-B), which can be optimally matched to the needs of different wastewater treatment scenarios (such as shock loads and stable operation). Combined with the model predictive control (MPC) algorithm, it realizes the leap from "experience-based" to "model prediction and dynamic optimization" in carbon source addition. Under the premise of ensuring that the effluent quality (especially nitrate nitrogen) meets the standards, it effectively reduces the excessive addition of carbon sources. 3. This solution deeply integrates multiple aspects such as intelligent control (MPC), membrane fouling prediction and cleaning (TMP monitoring), energy management (EMS), and residual liquid recovery (sodium formate purification). It optimizes core processes through model predictive control, ensures long-term stable system operation through intelligent maintenance, minimizes energy consumption through energy management, and completely eliminates secondary pollution through the product-based recovery of residual liquid, forming a comprehensive closed-loop optimization from a technical to an economic perspective.

[0019] This invention transforms the hazardous waste from sodium hydrosulfite production into a standardized and functionalized targeted composite carbon source. By constructing a carbon source functional map and a model prediction and control model, it achieves a leap from empirical and extensive addition of carbon sources to precise and intelligent addition on demand. This not only completely solves the pollution problem, but also significantly improves the denitrification efficiency and operational economy of wastewater treatment. Attached Figure Description

[0020] Figure 1 This is a flowchart of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 2 This is a flowchart of step S1 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 3 This is a flowchart of step S2 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 4 This is a flowchart of step S3 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 5 This is a flowchart of step S4 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 6 This is a flowchart of step S5 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 7 This is a flowchart of step S6 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 8 This is a flowchart of step S7 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 9This is a flowchart of step S8 of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Figure 10 This is an overall flow chart of a wastewater treatment process based on sodium hydrosulfite to produce a carbon source, as proposed in this invention. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0022] Reference Figures 1-10 A wastewater treatment process based on sodium hydrosulfite as a carbon source includes the following steps: S1: Crude methanol is pumped into a vortex ultrasonic homogenizer, which includes mechanical stirring (30-60 rpm) and low-frequency ultrasound (25-40 kHz) to stir and homogenize the crude methanol, breaking down colloids and suspended aggregates. Through a pH-ORP linkage control system, dilute sulfuric acid is added to precisely adjust the pH to 6.8-7.2, with a concentration of 5%-8%. Based on the real-time ORP value (set range -50 to -100 mV), a trace amount of potassium persulfate (PMS) is automatically added. This step aims to achieve "targeted detoxification," preferentially oxidizing the highly biotoxic sulfites into harmless sulfates and pre-oxidizing some recalcitrant organic matter to improve the biodegradability of the system. S2: The pretreated material is conveyed to the hydrocyclone. The hydrocyclone uses strong centrifugal force to quickly separate dense inorganic particles and some heavy organic matter, serving as a high-efficiency coarse filter, which greatly reduces the burden on the subsequent membrane system. The hydrocyclone is equipped with a wide-channel anti-fouling tubular ultrafiltration membrane module. The wide-channel anti-fouling tubular ultrafiltration membrane module is made of modified PVDF with a molecular weight cutoff of 80,000-150,000 Dalton. This membrane module has wide channels and is designed for high organic matter and high viscosity liquids. It has high flux and strong fouling resistance. This coupled separation system can intelligently switch the operating mode according to the turbidity of the incoming material, making it highly adaptable. S3: Perform online component and functional analysis on the finely filtered liquid product, and construct a carbon source functional map based on the analysis results. The carbon source functional map includes the immediate-release carbon source content (RCC), the sustained-release carbon source content (SCC), and the biotoxicity potential index (BTP). Immediate-release carbon source content (RCC): Measured using an online respiration meter, this indicates the amount of COD consumed in the first 30 minutes, characterizing readily available components such as methanol. The calculation formula is: RCC = (COD consumption in the first 30 minutes) / (Total COD) × 100%; Slow-release carbon source content (SCC): Estimated by (total COD - RCC), it characterizes components such as sodium formate and ethylene glycol that require hydrolysis before they can be utilized in large quantities. The calculation formula is: SCC = (COD consumption corresponding to total COD - RCC) / (total COD) × 100%; Biotoxicity Potential Index (BTP): Monitors microbial metabolic activity through miniature biosensors to ensure thorough detoxification and that the product meets biosafety standards; S4: Based on the carbon source functional map, the products are standardized and classified into different types of targeted composite carbon sources, including Type-F (fast-acting), Type-S (slow-release), and Type-B (balanced). Type-F (Rapid-acting): RCC≥70%, suitable for scenarios with high shock loads and requiring rapid denitrification; Type-S (Slow-release): SCC≥60%, suitable for scenarios with stable water quality and requiring continuous nitrogen removal; Type-B (Balanced): 40%≤RCC≤60%, is the default universal model, ensuring a reasonable ratio of fast-acting and slow-release components; S5: In the denitrification zone of the wastewater treatment system, deploy a Model Predictive Controller (MPC). The MPC uses influent flow rate (Q) and influent nitrate nitrogen (NO3) as parameters. - -N), influent ammonia nitrogen (NH4) + As real-time inputs, the model predictive controller kernel embeds a multi-substrate denitrification kinetic model, which is used to simulate the consumption process of immediate and slow-release carbon sources under the action of microorganisms. The model predictive controller adopts the model predictive control algorithm. Model predictive control algorithm: Objective function (cost function):

[0023] Where: X t+k It is the system state at time t+k; It is the expected value of the system state at time t+k; it is the expected value of the system state at time U. t+k Control input; U reft+k N is the expected value of the control input at time t+k; P It is the prediction time domain length; Q, R, and P are the weight matrices of the state, control input, and terminal state, respectively, used to balance the relative importance of different variables; System dynamic constraints:

[0024] in, It is a function that describes how the system state changes with the current state and control input. In the denitrification process of wastewater treatment, this function involves the denitrification kinetic model:

[0025] in: Indicates the concentration of nitrate nitrogen; This is the maximum specific growth rate of heterotrophic denitrifying bacteria; It is the concentration of heterotrophic denitrifying bacteria; S N It is the concentration of nitrate nitrogen; K N It is the half-saturation constant of nitrate nitrogen; S C It is the carbon source concentration; K C It is the half-saturation constant of the carbon source; It is the yield coefficient of heterotrophic denitrifying bacteria; It is the decay rate of heterotrophic denitrifying bacteria; It is the time step.

[0026] S6: Collect the residual liquid generated by the backwashing of the hydrocyclone and the ultrafiltration membrane, and transport it to the low-temperature vacuum evaporation system. The residual liquid is subjected to low-temperature vacuum evaporation. The main component of the evaporation concentrate is high-purity sodium formate (the concentration can be increased to more than 40%), which can be further crystallized and dried into sodium formate solid product, which can be sold as a commodity or used in other industrial processes, realizing the product recycling of residual liquid and completely eliminating secondary pollution. S7: By monitoring the transmembrane pressure difference (TMP) change trend and feed liquid quality in real time, the membrane fouling development rate is predicted, and the optimal backwashing program (air-water pulse) and chemical cleaning cycle (using 0.1% NaOH and 0.5% citric acid for alternating cleaning) are automatically triggered to ensure that the system operates stably in the best condition for a long time. S8: By monitoring the energy consumption of key units such as pumps, agitators, and membrane systems in real time through the Energy Management System (EMS), the operating frequency of the equipment is automatically adjusted (e.g., by using variable frequency pumps), and high-energy-consuming operations (e.g., chemical cleaning) are performed during periods of low electricity prices, so as to achieve optimal energy efficiency and lowest cost throughout the entire process, forming a comprehensive closed-loop optimization from technology to economics. Example 2

[0027] The difference between this embodiment and Embodiment 1 is as follows: S2: The pretreated material is transported to a hydrocyclone. The hydrocyclone uses strong centrifugal force to quickly separate dense inorganic particles and some heavy organic matter, serving as a highly efficient coarse filter, greatly reducing the burden on the subsequent membrane system. The hydrocyclone is equipped with a wide-channel anti-fouling tubular ultrafiltration membrane module. The wide-channel anti-fouling tubular ultrafiltration membrane module is made of modified PVDF with a molecular weight cutoff of 80,000-150,000 Daltons. This membrane module has wide channels and is designed for high organic matter and high viscosity liquids. It has high flux and strong anti-fouling properties. This coupled separation system can intelligently switch operating modes according to the turbidity of the incoming material, making it highly adaptable. Before the crude methanol enters S2, an online near-infrared spectrometer or Raman spectrometer is set up to quickly scan the "molecular fingerprint" of the raw material and identify the approximate concentrations of key components such as methanol, sodium formate, and sulfite in real time. This signal is transmitted to the separation intelligent decision-making system. The system automatically adjusts the inlet pressure and underflow opening of the hydrocyclone based on changes in the raw material composition, and dynamically optimizes the operation mode of the subsequent ultrafiltration membrane module (such as permeate pressure and backwashing frequency). For example, when a high inorganic salt content is detected, the hydrocyclone separation intensity is enhanced; when the viscosity increases, the membrane flux is reduced to prevent fouling. Example 3

[0028] The difference between this embodiment and Embodiment 1 is as follows: S3: Online component and functional analysis is performed on the liquid product after fine filtration, and a carbon source functional map is constructed based on the analysis results. The carbon source functional map includes the immediate-release carbon source content (RCC), the sustained-release carbon source content (SCC), and the biotoxicity potential index (BTP). Immediate-release carbon source content (RCC): Measured using an online respiration meter, this indicates the amount of COD consumed in the first 30 minutes, characterizing readily available components such as methanol. The calculation formula is: RCC = (COD consumption in the first 30 minutes) / (Total COD) × 100%; Slow-release carbon source content (SCC): Estimated by (total COD - RCC), it characterizes components such as sodium formate and ethylene glycol that require hydrolysis before they can be utilized in large quantities. The calculation formula is: SCC = (COD consumption corresponding to total COD - RCC) / (total COD) × 100%; Biotoxicity Potential Index (BTP): Monitors microbial metabolic activity using miniature biosensors to ensure thorough detoxification and that the product meets biosafety standards; Building upon existing methods such as RCC, SCC, and BTP, high-throughput sequencing and metatranscriptomics analysis were introduced as offline auxiliary techniques. By analyzing changes in the microbial community structure and expression levels of key functional genes (such as nar, nir, and nos denitrification genes) in activated sludge after using this carbon source, a more in-depth "carbon source metabolism map" was constructed. This map can reveal: Carbon source preference: Which microorganisms prefer to utilize which components; Metabolic pathway activation: Does the carbon source promote efficient denitrification pathways, or may it trigger other side reactions? Example 4

[0029] The difference between this embodiment and Embodiment 1 is that, based on the carbon source functional spectrum, the products are standardized and classified into different types of targeted composite carbon sources, including Type-F (fast-acting), Type-S (slow-release), and Type-B (balanced). Type-F (Rapid-acting): RCC≥70%, suitable for scenarios with high shock loads and requiring rapid denitrification; Type-S (Slow-release): SCC≥60%, suitable for scenarios with stable water quality and requiring continuous nitrogen removal; Type-B (Balanced): 40%≤RCC≤60%, is the default universal model, ensuring a reasonable ratio of fast-acting and slow-release components; Develop a customer-facing cloud platform or app that allows operators at downstream wastewater treatment plants to: Submit your requirements in real time: Enter the current influent water quality, process unit, and target effluent standard; Get recommended solutions: Automatically recommend the most suitable carbon source model and dosage suggestion in the inventory to customers, and even initiate collaborative orders for "carbon source +" microbial agents; Initiating a customized order: If standard products cannot meet extreme and special needs, customers can directly initiate an order request for a "one-time customized carbon source" to the manufacturer through the platform, triggering the "dynamic formula" production mode in the first extension. Example 5

[0030] The difference between this embodiment and Embodiment 1 is as follows: S6: The residual liquid generated by the underflow of the hydrocyclone and the backwashing of the ultrafiltration membrane is collected and transported to the low-temperature vacuum evaporation system. The residual liquid is subjected to low-temperature vacuum evaporation. The main component of the evaporation concentrate is high-purity sodium formate (the concentration can be increased to more than 40%), which can be further crystallized and dried into sodium formate solid product, which can be sold as a commodity or used in other industrial processes, realizing the product recycling of residual liquid and completely eliminating secondary pollution. During the evaporation and concentration process, mechanical vapor recompression (MVR) or heat pump technology is integrated to recover and utilize the heat energy of the secondary steam generated by evaporation, reducing the energy consumption of the evaporation unit by more than 60%. It is linked with the anaerobic digestion facility in the area to directionally transport the concentrated liquid or other waste liquid rich in organic matter to the digester to jointly produce biogas, which is purified into biogas (Bio-CNG) and connected to the city pipeline network or used as vehicle fuel.

[0031] Experimental Example I. Experimental Objective 1. Compare the differences between traditional carbon sources (sodium acetate) and the targeted composite carbon sources (Type-F, Type-S, Type-B) produced by this process in terms of denitrification efficiency, carbon source dosage, and operating costs; 2. Verify the effectiveness of the carbon source functional maps (RCC, SCC, BTP) and model predictive control (MPC) in optimizing carbon source addition; 3. Assess the resource recovery capabilities (e.g., sodium formate recovery) and residual contaminant control (e.g., sulfites) of this process.

[0032] II. Experimental Methods Influent conditions: Simulating typical low C / N ratio wastewater, with a fixed influent flow rate of 10 m³ / h, and influent nitrate nitrogen (NO3) - The concentration of ammonia nitrogen (NH4+) in the influent is 30 mg / L. + The concentration of -N was 5 mg / L, and the water temperature was 20°C; Carbon source type: Traditional carbon source: commercial sodium acetate (as a control); The carbon source for this process is a targeted composite carbon source (Type-F, Type-S, Type-B) obtained from crude methanol by-product of sodium hydrosulfite processing. Its carbon source functional spectrum was determined by online analysis (see Table 1). Denitrification reactor: Four identical sequencing batch reactors (SBR) are used, each with a volume of 1 m³, each with a different carbon source. The reactors operate under the same conditions, with a hydraulic retention time of 4 hours. Control strategy: Traditional method: Carbon source is added at a fixed ratio based on human experience (COD / N = 5:1). This process uses a model predictive controller (MPC) to adjust the carbon source dosage in real time. Input parameters include influent flow rate, nitrate nitrogen, ammonia nitrogen, water temperature, and carbon source function spectrum. Monitoring indicators: effluent nitrate nitrogen, carbon source dosage, operating cost (based on carbon source price and energy consumption), and residual sulfite concentration are monitored hourly, and the amount of sodium formate recovered is recorded; Resource recovery: In this process, the residual liquid is concentrated by low-temperature vacuum evaporation to recover solid sodium formate; traditional methods do not recover it; Experimental period: 7 consecutive days of operation, with daily averages used for comparison.

[0033] III. Experimental Data Table 1. Functional analysis of carbon sources (carbon sources in this process)

[0034] Note: A lower BTP index indicates lower biotoxicity (safety threshold <0.5). Table 2 Comparison of Denitrification Performance and Operating Costs

[0035] Note: Operating costs include carbon source costs and energy consumption. The price of traditional carbon source sodium acetate is 3,000 yuan / ton (based on COD). The carbon source cost of this process is based on waste utilization, and the main consideration is the energy consumption for treatment (approximately 0.1 yuan / kg COD). The residual sulfite index demonstrates the "targeted detoxification" effect of this process; Sodium formate recovery is based on residual liquid concentration, with a purity of over 40%.

[0036] Table 3 Model Predictive Control (MPC) vs. Human Experience Control (Type-B Carbon Source in this Process)

[0037] Note: Cost savings, relative to manual experience-based control, are based on operating cost calculations. IV. Experimental Conclusions Denitrification efficiency: The targeted composite carbon sources (especially Type-F and Type-B) in this process have significantly lower nitrate nitrogen concentrations in the effluent than traditional carbon sources (p<0.05), indicating higher carbon source utilization efficiency; Carbon source dosage: The carbon source dosage is reduced by about 23-30% in this process, which is attributed to the accurate classification of carbon source functional maps and the optimized control of MPC. Operating costs: The operating costs of this process are reduced by approximately 36-38% compared to traditional methods, mainly due to savings in carbon source costs and optimized energy consumption; Environmentally friendly: This process effectively controls residual sulfites and recovers sodium formate, avoiding secondary pollution; Control stability: MPC control is more stable than manual experience, with smaller fluctuations in carbon source addition and more stable effluent quality.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A wastewater treatment process based on sodium hydrosulfite to produce a carbon source, characterized in that: Includes the following steps: S1: The crude methanol is stirred and some of the recalcitrant organic matter is pre-oxidized; S2: Perform gradient classification on the pretreated materials; S3: Perform online component and functional analysis on the finely filtered liquid product and construct a carbon source functional map; S4: Standardize and classify products according to carbon source functional maps; S5: Simulate the consumption process of immediate-release and slow-release carbon sources under the action of microorganisms, and adjust the dosage accordingly; S6: Collect the residual liquid and concentrate it by low-temperature evaporation; S7: Real-time monitoring and maintenance of the transmembrane pressure difference trend and feed liquid quality; S8: Monitors equipment energy consumption in real time and automatically adjusts equipment operating frequency.

2. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 1, characterized in that: In step S1, crude methanol is pumped into a vortex ultrasonic homogenizer, which includes mechanical stirring and low-frequency ultrasound to stir and homogenize the crude methanol, breaking up colloids and suspended aggregates.

3. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 2, characterized in that: In S1, the pH is precisely adjusted to 6.8-7.2 by adding dilute sulfuric acid through a pH-ORP linkage control system. The concentration of dilute sulfuric acid is 5%-8%, and a trace amount of potassium persulfate is automatically added according to the real-time ORP value.

4. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 3, characterized in that: In step S2, the pretreated material is transported to a hydrocyclone. The hydrocyclone uses strong centrifugal force to quickly separate dense inorganic particles and some heavy organic matter, serving as a high-efficiency coarse filter that greatly reduces the burden on the subsequent membrane system. The hydrocyclone is equipped with a wide-channel anti-fouling tubular ultrafiltration membrane module. The wide-channel anti-fouling tubular ultrafiltration membrane module is made of modified PVDF with a molecular weight cutoff of 80,000-150,000 Dalton.

5. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 4, characterized in that: In step S3, the liquid product after fine filtration is subjected to online component and functional analysis, and a carbon source functional map is constructed based on the analysis results. The carbon source functional map includes the content of immediate-release carbon source, the content of slow-release carbon source, and the biotoxicity potential index. Immediate-release carbon source content: COD consumption within the first 30 minutes was measured using an online respiration meter to characterize the components of methanol that are readily utilized. The calculation formula is: RCC = (COD consumption within the first 30 minutes) / (total COD) × 100%; Slow-release carbon source content: This is estimated to characterize the components of sodium formate and ethylene glycol that require hydrolysis before they can be utilized in large quantities. The calculation formula is: SCC = (Total COD - COD consumption corresponding to RCC) / (Total COD) × 100%; Biotoxicity potential index: By monitoring the metabolic activity of microorganisms through micro-biosensors, we ensure thorough detoxification and that the product meets biosafety standards.

6. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 5, characterized in that: In S4, based on the carbon source functional map, the products are standardized and classified into different types of targeted composite carbon sources, including Type-F, Type-S and Type-B. YPE-F: Suitable for scenarios with high shock loads and requiring rapid denitrification; Type-S: Suitable for scenarios with stable water quality and requiring continuous denitrification; Type-B: This is the default universal model, ensuring a reasonable ratio of fast-acting and slow-release components.

7. The wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 6, characterized in that: In S5, a model predictive controller is deployed in the denitrification zone of the wastewater treatment system. The model predictive controller takes influent flow rate, influent nitrate nitrogen, influent ammonia nitrogen, water temperature and carbon source functional map as real-time inputs. The kernel of the model predictive controller embeds a multi-substrate denitrification kinetic model. The multi-substrate denitrification kinetic model is used to simulate the consumption process of immediate and slow-release carbon sources under the action of microorganisms. The model predictive controller adopts a model predictive control algorithm. Model predictive control algorithm: Objective function: Where: X t+k It is the system state at time t+k; It is the expected value of the system state at time t+k; it is the expected value of the system state at time U. t+k Control input; U reft+k N is the expected value of the control input at time t+k; P It is the prediction time domain length; Q, R, and P are the weight matrices of the state, control input, and terminal state, respectively, used to balance the relative importance of different variables; System dynamic constraints: in, It is a function that describes how the system state changes with the current state and control input. In the denitrification process of wastewater treatment, this function involves the denitrification kinetic model: in: Indicates the concentration of nitrate nitrogen; This is the maximum specific growth rate of heterotrophic denitrifying bacteria; It is the concentration of heterotrophic denitrifying bacteria; S N It is the concentration of nitrate nitrogen; K N It is the half-saturation constant of nitrate nitrogen; S C It is the carbon source concentration; K C It is the half-saturation constant of the carbon source; It is the yield coefficient of heterotrophic denitrifying bacteria; It is the decay rate of heterotrophic denitrifying bacteria; It is the time step.

8. A wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 7, characterized in that: In step S6, the residual liquid generated by the hydrocyclone underflow and ultrafiltration membrane backwash is collected and transported to a low-temperature vacuum evaporation system to perform low-temperature vacuum evaporation on the residual liquid. The main component of the evaporation concentrate is high-purity sodium formate.

9. A wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 8, characterized in that: In S7, by real-time monitoring of the transmembrane pressure difference change trend and feed liquid quality, the membrane fouling development rate is predicted, and the optimal backwashing program and chemical cleaning cycle are automatically triggered to ensure that the system operates stably in the best condition for a long time.

10. A wastewater treatment process based on sodium hydrosulfite carbon source production according to claim 9, characterized in that: In S8, the energy management system monitors the energy consumption of key units such as water pumps, agitators, and membrane systems in real time, automatically adjusts the operating frequency of the equipment, and selects to perform high-energy-consuming operations during periods of low electricity prices, thereby achieving optimal energy efficiency and lowest cost throughout the entire process and forming a comprehensive closed-loop optimization from technology to economics.

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