Biological treatment process for high-sulfur wastewater in sodium hydrosulfide production

Abstract

The invention relates to the field of wastewater treatment, and discloses a biological treatment process for sodium hydrosulfide production high-sulfur wastewater, which comprises the following steps: S1, culturing and activating active bacteria; s2, pretreating high-sulfur wastewater generated in the production process of sodium hydrosulfide; s3, introducing the wastewater into a multi-stage microbial battery reaction system; s4, dynamically regulating and controlling a microbial metabolism path in the multi-stage reaction system by arranging an intelligent bio-membrane reactor; s5, passing through a dual-electrode system and a tail end filtering device of a by-product control system; and S6, recovering electric energy generated in the microbial battery reaction system through an energy recovery system. Through a multi-stage microbial battery series connection structure, a continuous reaction path from high-concentration degradation to terminal deep purification is formed, the technical effects of keeping stable reaction efficiency and low residual rate under the condition of treating sulfides with different concentrations are achieved, and the problems that degradation capability is easy to attenuate and tail water fluctuates severely in a later treatment stage are solved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide production. Background Art

[0002] The industrial production of sodium hydrosulfide is accompanied by the continuous or intermittent discharge of large amounts of high-sulfur-loaded wastewater. This type of wastewater typically contains high concentrations of reducing sulfur compounds such as hydrogen sulfide and sulfite, has an alkaline pH, and is highly corrosive and toxic. Currently, a variety of technical routes have been proposed for the treatment of high-sulfur wastewater, including rapid reaction methods based on chemical oxidants, physicochemical treatment methods based on neutralization and precipitation, and biological treatment methods that utilize sulfur-oxidizing bacteria for metabolic conversion. Among them, microbial electrochemical systems (Microbial Fuel Cell, MFC) have gradually attracted attention in research and application due to their ability to simultaneously degrade pollutants and convert energy. Some studies have attempted to use MFC structures to perform electrochemical-assisted degradation of sulfur-containing wastewater to improve reaction efficiency and controllability of by-products.

[0003] However, judging from existing applications, such systems still face many challenges in actual operation. On the one hand, when dealing with complex sulfur components and large fluctuations in emission concentrations, traditional single-stage or two-stage biological reaction systems are difficult to cover the entire process from high-concentration degradation to deep purification, and sulfide residues are prone to accumulation at the end stage. On the other hand, existing microbial electrochemical treatment pathways mostly rely on naturally formed potential differences to drive reactions, lacking a fine-tuning mechanism for electrode potential, resulting in a lack of stability in the electron transfer process. In addition, in terms of system responsiveness, most current treatment devices use fixed operating parameters and are unable to adapt to the common flow, water quality, and pH fluctuations in actual drainage conditions, and rarely have process feedback and adjustment capabilities. In addition, most devices do not integrate energy recovery or self-powered modules, resulting in the electron flow generated during the reaction not being fully utilized, affecting the overall energy efficiency performance. This shows that existing technologies still have room for further improvement and systematic integration in terms of structural level optimization, electronic behavior control, system adaptability, and energy integration and utilization. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide, which solves the problems of low treatment efficiency of high-sulfur wastewater, unstable reaction and insufficient energy efficiency in the production process of sodium hydrosulfide.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide, comprising the following steps:

[0006] S1. Activate and culture the sodium hydrosulfide-specific composite bacteria to activate the strains, and then add the activated strains to the reactors at all levels of the microbial reaction system;

[0007] S2. Pre-treat the high-sulfur wastewater generated during the sodium hydrosulfide production process by removing large particle impurities through filtration and precipitation, and adjust the pH value to 6.5-8.5 to create a reaction environment suitable for microbial reaction;

[0008] S3. Introducing the pretreated wastewater into a multi-stage microbial battery reaction system, wherein the system includes at least three stages of reactors, and sequentially degrading sulfides of different concentrations, wherein:

[0009] The first-stage reactor is used to oxidize high-concentration hydrogen sulfide to sulfate;

[0010] The second stage reactor is used to further degrade the medium concentration sulfide;

[0011] The third-stage reactor is used to completely remove low-concentration residual sulfides;

[0012] S4. Dynamically regulate the microbial metabolic pathways in the multi-stage reaction system by setting up an intelligent biofilm reactor;

[0013] S5. Remove byproducts and precipitates that may be generated during the reaction through the dual-electrode system and terminal filtration device of the byproduct control system;

[0014] S6. Recover the electrical energy generated in the microbial battery reaction system through the energy recovery system to provide energy for the monitoring system and auxiliary devices in the entire wastewater treatment process;

[0015] Furthermore, in step S2, high-sulfur wastewater is often accompanied by organic particles, inorganic sediments and some metal ions. If not effectively pretreated, it will affect the activity of microorganisms and cause electrode clogging. The present invention can effectively improve the pretreatment efficiency through the combination of physical sedimentation and multi-stage filtration, while avoiding the problem of sludge backflow caused by the traditional single precipitation method. More importantly, by controlling the pH in the range of neutral to slightly alkaline, it not only enhances the activity of microorganisms, but also stabilizes the existence form of sulfide in the wastewater, making it exist in the form of H2S and HS - Mainly, thus facilitating the subsequent bioelectrochemical conversion process;

[0016] In step S3, the present invention uses a microbial battery system for wastewater treatment. The core of the system is to transfer the electrons released during microbial metabolism to an external circuit, thereby achieving a synchronous process of pollutant degradation and electrical energy recovery. When treating high-sulfur wastewater, microorganisms obtain energy by oxidizing reducing substances such as H2S and release electrons to the electrode system, realizing the conversion of sulfide to sulfate or elemental sulfur. Compared with traditional aerobic / anaerobic systems, this technology significantly improves the efficiency of electron utilization and can achieve selective response to different pollutant concentrations by regulating the current intensity, avoiding the problem of limited treatment capacity of a single microbial community system. In addition, the multi-level structure enables the system to have a spatial division of labor strategy of "front-end efficient loading and back-end fine processing", which can achieve a higher degree of pollutant removal without increasing the volume.

[0017] In step S4, during the treatment of high-sulfur wastewater, the metabolic state of microorganisms is extremely susceptible to fluctuations in external conditions, such as pH, dissolved oxygen, potential, and conductivity. Once environmental conditions deviate from the optimal range, this will directly lead to a decrease in degradation rate, reduced electron transfer efficiency, and even biofilm shedding. The present invention adopts an intelligent sensing and control strategy to dynamically adjust the system's current density, gas supply, and temperature control conditions by real-time monitoring of microenvironmental parameters inside and outside the biofilm, combined with data analysis and historical model comparison, to maintain the continuous operation of microorganisms within the optimal metabolic range.

[0018] In step S5, the sulfide oxidation reaction has a multi-path mechanism. Under certain conditions, polyvalent sulfur intermediates or colloidal sulfur precipitates may be generated. If not removed promptly, these can clog the reactor or react with the electrode surface, causing depolarization. The present invention optimizes reaction conditions through electrode material selection and potential control strategies to promote the conversion of reaction products toward harmless, dischargeable sulfates. Simultaneously, a multi-stage filtration component at the end intercepts residual particles and cell debris to prevent fluctuations in effluent quality. This byproduct control mechanism ensures the continuity and effluent safety of the entire system, constituting a key safeguard for stable system operation.

[0019] In step S6, the essence of the MFC reaction is the generation and transfer of electrons. The present invention realizes the stable collection and utilization of energy by rationally designing the loop structure and voltage conversion module. Unlike a simple "treatment-discharge" system, the present invention forms an internal energy circulation system of "treatment-energy supply-self-regulation", which effectively reduces dependence on external energy and enhances the system's autonomous operation capability. This energy recovery mechanism makes wastewater treatment not only no longer an energy consumption item, but instead a new path for energy conversion, which is another key innovation of the present invention that is both environmentally friendly and economical.

[0020] Preferably, in step S1, the activation culture comprises:

[0021] Add 0.3-1% sodium hydrosulfide exclusive compound bacteria, 1-1.5g / L glucose and tap water to the culture tank, adjust the pH to 7-8, and culture under aeration at 25-35℃ for 48 hours. Control the DO at 2-4mg / L.

[0022] After activation, the bacterial density was tested and the microscopic examination showed that it reached 1×10 9 CFU / ml means the activation culture is complete;

[0023] The desulfurizing bacteria agent is a composite bacterial community, mainly including Bacillus, yeast and Bacillus subtilis.

[0024] Preferably, in step S2, wastewater pretreatment includes:

[0025] A two-stage filtration method of coarse filtration + fine filtration is used to remove particulate matter. The fine filtration uses a fiber filter with a pore size of less than 10μm.

[0026] Use a sedimentation tank to allow the water to settle for no less than 2 hours to remove inorganic suspended matter and some heavy metals;

[0027] The pH of the wastewater is adjusted to 6.8-7.5 by adding sodium hydroxide or sulfuric acid to adapt to the subsequent microbial reaction environment.

[0028] Preferably, in the step S3, the configuration of the first-stage reactor includes:

[0029] The sulfur-oxidizing bacteria group, mainly composed of Thiobacillus denitrificans, is used to achieve biological oxidation of high-concentration hydrogen sulfide;

[0030] Maintain a current density of 10-100 mA / m in the anode region of the reactor. 2 , to enhance the metabolic rate of microorganisms;

[0031] The reactor temperature was controlled between 25 and 35°C.

[0032] Preferably, in the step S3, the second stage reactor comprises:

[0033] Setting up facultative anaerobic bacteria to adapt to the gradual conversion of medium concentration of sulfide;

[0034] The microbial battery system provides 50-200 mA / m 2 A stable current to maintain biochemical reactions;

[0035] Increase the dissolved oxygen concentration through intermittent aeration.

[0036] Preferably, in the S3 step, the third-stage reactor comprises:

[0037] The microbial population selected was the Paracoccus pantotrophus species which has a high affinity for low concentrations of sulfide;

[0038] Maintain 100~500mA / m in the electrode system 2 The current density;

[0039] Set the reaction time to no less than 8 hours to allow the sulfide to be completely degraded.

[0040] Preferably, in step S4, the intelligent biofilm reactor includes:

[0041] Output includes redaction, encryption, and response execution of blocking operations;

[0042] The sensor is connected to the central control system and transmits data to the cloud server in real time through the wireless data module;

[0043] The control system dynamically adjusts reaction conditions based on historical operating data to control the microbial metabolic pathway;

[0044] The intelligent biofilm reactor automatically adjusts system temperature, pH and current parameters based on real-time collected sensor data.

[0045] Preferably, in step S4, the dynamic regulation includes:

[0046] A multivariable prediction model was constructed to determine treatment trends, and a fuzzy control algorithm was used to adjust ventilation volume, current density, and liquid level control;

[0047] For abnormal parameter fluctuations, the system automatically triggers the dynamic control safety bypass and backwash functions to ensure stable process operation.

[0048] Preferably, in step S5, the dual-electrode system in the by-product control system includes:

[0049] The anode is made of conductive graphite felt material to promote efficient oxidation of hydrogen sulfide;

[0050] The cathode uses titanium-based platinum coating material to improve the electron conduction rate;

[0051] The system maintains the optimal reaction potential through a constant potential control device to inhibit the generation of by-products.

[0052] Preferably, in step S5, the terminal filtering device includes:

[0053] Multi-stage ceramic membrane components, with pore sizes ranging from 0.5 to 5 μm, filter reaction residues and microbial sludge step by step;

[0054] The matching backwash system is backwashed regularly to maintain filtration efficiency;

[0055] The effluent quality meets the first-level discharge standard.

[0056] Preferably, in step S6, the energy recovery system includes:

[0057] The current generated by the microbial battery is stably output through the DC-DC conversion module and supplied to the monitoring sensors, control systems and dosing equipment;

[0058] An electric energy storage unit is provided for peak load regulation or off-grid emergency operation;

[0059] The energy conversion efficiency is greater than 50%, achieving closed-loop operation with partial self-sufficiency of energy for the system.

[0060] The present invention provides a biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide production. It has the following beneficial effects:

[0061] 1. This invention utilizes a multi-stage microbial cell structure in series, creating a continuous reaction path from high-concentration degradation to deep purification at the end. This achieves the technical effect of maintaining stable reaction efficiency and low residual rates under conditions of varying sulfide concentrations. Compared to the simplified solutions typically employing single or two-stage reactors in the prior art, this approach addresses the issues of degradation capacity degradation and volatile tailwater during the latter stages of treatment.

[0062] 2. The present invention's constant-potential electrode control strategy maintains the stability of the reaction potential during microbial electron transfer. This achieves the technical benefits of minimal electrode output fluctuation, controllable current density, and dynamic balance of electron supply and demand during long-term operation. Unlike traditional bioelectrochemical systems that rely on natural voltage for operation, this system avoids the problems of decreased microbial activity and fluctuations in system reaction efficiency caused by potential drift.

[0063] 3. This invention incorporates an intelligent control system with online feedback capabilities. By monitoring changes in multiple parameters within the reactor in real time, it dynamically adjusts the gas-liquid ratio, electrode potential, and internal flow conditions. This system rapidly adapts and maintains stable operation even under periodic fluctuations in wastewater quality loads. This differs from existing fixed operation methods without feedback or adjustment mechanisms, and addresses the issue of reactor instability or even poisoning under highly fluctuating loads.

[0064] 4. By combining an energy recovery module with a terminal fine filtration device, this invention establishes an internal electrical energy self-circulation mechanism, ensuring effective retention of suspended solids and colloids in the effluent. This reduces system operating energy consumption while ensuring stable effluent quality. Compared to conventional biological treatment processes with high energy dependence and extensive terminal control, this method effectively overcomes the technical shortcomings of high operating costs, frequent maintenance, and effluent water volatility.

[0065] 5. This invention utilizes a composite bacterial activation culture solution, pre-cultivating and optimizing the bacterial composition to achieve rapid wastewater treatment startup and high sulfide removal rates. Compared to existing methods without activation culture, this invention significantly shortens startup time, avoids the problem of prolonged bacterial adaptation, and improves wastewater treatment efficiency. It also does not rely on any external chemical agents, reducing chemical residues and side reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a flow chart of the process steps of the present invention. DETAILED DESCRIPTION

[0067] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0068] Example 1:

[0069] Please see the attached Figure 1 This embodiment is applicable to the treatment of high-sulfur wastewater generated in the pilot-scale sodium hydrosulfide production process. The sulfide concentration in the wastewater is 800 mg / L and the initial pH is 9.2. The process of the present invention is used for treatment. The operation is as follows:

[0070] S1. Bacteria culture:

[0071] A proprietary composite bacterial strain (0.5‰ sodium hydrosulfide), 1.2g / L glucose, and tap water were added to the culture propagation tank. The pH was adjusted to 7.5, and aeration culture was performed at 28°C with a DO control of 3.0mg / L for 48 hours. After 48 hours of culture, the bacterial density was measured. Activation was complete when microscopic examination reached 1×10^9 CFU / ml. The activated bacteria were then added to each reactor in the multi-stage microbial battery reaction system to ensure smooth microbial metabolism in the wastewater treatment system.

[0072] S2, preprocessing stage:

[0073] The raw wastewater first undergoes two-stage filtration, with a 1mm stainless steel mesh used for coarse filtration and a polypropylene fiber mesh with a pore size of 5μm used for fine filtration;

[0074] Then it enters the sedimentation tank and is allowed to settle for 2.5 hours;

[0075] The pH was adjusted to 7.2 by adding 1 mol / L sulfuric acid solution.

[0076] S3. Multi-stage microbial battery reaction:

[0077] First-stage reactor: inoculated with Thiobacillus denitrificans strain, set the reactor current density to 80 mA / m 2 , the temperature is controlled at 30°C and the wastewater residence time is 6 hours;

[0078] Second stage reactor: using facultative anaerobic bacteria (mainly Sulfurospirillum), current density 150mA / m 2 , intermittent aeration 30 minutes / 3 hours;

[0079] The third reactor was inoculated with Paracoccus pantotrophus and the current density was set to 300 mA / m 2 , the hydraulic retention time is 10 hours.

[0080] S4. Intelligent biofilm regulation system:

[0081] Configure a multi-parameter sensor array to monitor pH, temperature, ORP and DO;

[0082] The system uploads data to the control center through a wireless module and adjusts the aeration valve and constant potentiostat based on the fuzzy control algorithm to maintain reaction stability.

[0083] S5. By-product control system:

[0084] The reactor anode is made of graphite felt and the cathode is a titanium-based platinum electrode, maintaining a constant potential of 0.8V;

[0085] The effluent enters the three-stage ceramic membrane filtration component (pore size 0.5μm, 1μm, 5μm), and the filtration cycle is cleaned every 4 hours.

[0086] S6, Energy Recovery System:

[0087] The current generated by the microbial battery is about 0.6V, which is supplied to the sensor and PLC through DC-DC conversion;

[0088] The power recovery efficiency reaches 52%.

[0089] Treatment effect: The sulfide removal rate reached 97.5%, the effluent pH was 7.1, the sulfate concentration was significantly increased, and there was no obvious accumulation of intermediate by-products.

[0090] Example 2:

[0091] This process is suitable for intermittent treatment of high-concentration sulfide wastewater during the periodic discharge of sodium hydrosulfide production. The sulfide concentration in the wastewater is 1200 mg / L, which is highly volatile. The biological treatment process of this invention can cope with load fluctuations.

[0092] S1. Bacteria culture:

[0093] A proprietary complex of 0.7‰ sodium hydrosulfide, 1.0g / L glucose, and tap water were added to the culture propagation tank. The pH was adjusted to 7.5, and aeration was performed at 30°C with a DO of 3.5mg / L for 48 hours. After 48 hours of incubation, the bacterial density was measured. Activation was complete when microscopic examination showed a density of 1×10^9 CFU / ml. The activated bacteria were then added to each reactor in the multi-stage microbial battery reactor system to ensure effective degradation of sulfide in the wastewater.

[0094] S2. Preprocessing:

[0095] After initial settling for 1.5 h, the wastewater was filtered using a 10 μm polyester filter cloth;

[0096] 1 mol / L sodium hydroxide solution was added to adjust the pH to 6.9.

[0097] S3. Multi-stage reaction system:

[0098] First-stage reactor: inoculated with fast-growing Thiobacillus, current density 100 mA / m 2 , the temperature is controlled at 32℃;

[0099] Second stage reactor: maintain current density at 180 mA / m 2 , DO was controlled at 1.5 mg / L, and the residence time was 4 hours;

[0100] The third stage reactor: current density is 500mA / m 2 , pH was automatically adjusted to 7.3, and the reaction time was 10 hours.

[0101] S4, Intelligent control system:

[0102] The control center operates using a simplified model, focusing on monitoring ORP trends;

[0103] Automatically triggers backwashing to avoid over-pressure on the membrane.

[0104] S5. By-product control:

[0105] The two-electrode system had a constant potential of 0.9 V;

[0106] The filtration part is equipped with two-stage ceramic membranes (1μm and 5μm), and is manually backwashed once a day in intermittent operation mode.

[0107] S6, Energy Recovery:

[0108] The average energy recovery power is about 0.3W / m 2, effectively drives the monitoring system, and the remaining energy is stored in the 2Ah battery for backup.

[0109] Example 3:

[0110] This example is used for low-load high-sulfur wastewater discharged from the end stage of sodium hydrosulfide production, with a sulfide concentration of 300 mg / L. The process of the present invention optimizes energy utilization efficiency to achieve stable operation and resource recovery.

[0111] S1. Bacteria culture:

[0112] A proprietary bacterial complex containing 0.3‰ sodium hydrosulfide, 1.5g / L glucose, and tap water were added to the culture propagation tank. The pH was adjusted to 7.0, and aeration was performed at 28°C with a DO of 3.0mg / L for 48 hours. After 48 hours of incubation, the bacterial density was measured. Activation was complete when microscopic examination showed a concentration of 1×10^9 CFU / ml. The activated bacteria were then added to each reactor in the multi-stage microbial battery reactor system to ensure the system's ability to successfully degrade low-concentration sulfide.

[0113] S2. Preprocessing:

[0114] Filtered with 5μm fiber filter, no precipitation required;

[0115] The pH was adjusted to 7.0 with a small amount of sulfuric acid.

[0116] S3. Multi-stage reaction system:

[0117] First stage reactor: current density is 30mA / m 2 , temperature 28℃;

[0118] Second stage reactor: current density is 80mA / m 2 , using natural diffusion to supply oxygen;

[0119] The third stage reactor: maintain the current density at 120mA / m 2 , operating cycle is 8 hours.

[0120] S4, intelligent control system:

[0121] The control system only retains the pH and current monitoring modules;

[0122] Aeration system cycles are controlled using predictive models based on historical data under low load conditions.

[0123] S5. By-product control:

[0124] The terminal filtration uses a single-layer ceramic membrane with a pore size of 5 μm, which is cleaned every 12 hours;

[0125] The electrode system is mainly focused on stable output, and the potential is controlled at 0.6V.

[0126] S6, Energy Recovery:

[0127] The energy recovery system output power is about 0.2W / m 2 ;

[0128] Most of the electrical energy is stored for backup, with an energy recovery efficiency of up to 58%.

[0129] Comparative Example 1:

[0130] Compared with Example 1, the difference is that the third-stage microbial battery reactor is cancelled, and the rest are the same.

[0131] Comparative Example 2:

[0132] Compared with Example 1, the difference is that the microbial battery system is not set with constant potential control, but operates in a natural voltage fluctuation mode, and the rest are the same.

[0133] Comparative Example 3:

[0134] Compared with Example 2, the difference is that no intelligent biofilm control system is set, and there is no online feedback adjustment function during the reaction process. The rest are the same.

[0135] Comparative Example 4:

[0136] Compared with Example 2, the difference is that the current density of the second-stage reactor is set to 20 mA / m 2 , which is lower than the effective reaction current density range defined in the claims, and the rest are the same.

[0137] Comparative Example 5:

[0138] Compared with Example 3, the difference is that no energy recovery module is provided, and the electricity generated by the microbial battery is not used to power the system. The rest are the same.

[0139] Comparative Example 6:

[0140] Compared with Example 3, the difference is that the pore size of the terminal filter unit is adjusted to 10 μm, which is not within the effective filtration range described in the claims, and the rest are the same.

[0141] Comparative Example 7:

[0142] Compared with Example 1, the difference is that the composite bacteria activation culture method is not adopted, but the commercially available sulfur removal bacteria agent is directly added to the reactor system without performing bacteria activation treatment. The rest are the same.

[0143] Comparative Example 8:

[0144] Compared with Example 2, the difference is that the natural degradation mechanism of the composite bacteria is not adopted, but a chemical oxidant (such as hydrogen peroxide) is regularly added to the reaction system to collaboratively remove sulfides. The rest are the same.

[0145] Comparative experiment:

[0146] Experiment 1:

[0147] Purpose of the experiment:

[0148] Verify the promoting effect of setting up a multi-stage microbial battery reaction system (especially the third stage) and constant potential control on the reaction efficiency, effluent stability and electron transfer process in the treatment of high-sulfur wastewater in sodium hydrosulfide production.

[0149] Experimental materials and equipment:

[0150] Source of raw water: The tail of sodium hydrosulfide production process, the sulfide concentration in the wastewater is about 800 mg / L, pH 9.2;

[0151] Adjustment reagent: 1mol / LH2SO4, used to adjust pH to neutral;

[0152] Three sets of experimental devices, corresponding to Example 1, Comparative Example 1, and Comparative Example 2 respectively;

[0153] Reactor setup: All reactors were made of the same material and had the same volume (1.5 L) and were maintained at a constant temperature of 30 °C;

[0154] Testing equipment: ORP electrode, pH meter, electrochemical workstation, current acquisition module, ion chromatograph.

[0155] Experimental steps:

[0156] The raw water was adjusted to pH 7.2, filtered and then injected into the reaction units of the respective devices.

[0157] Example 1: A three-stage MFC series system was set up, and different functional microbial groups were inoculated separately. Each stage was independently set to a constant potential (0.6V, 0.8V, 1.0V).

[0158] Comparative Example 1: The third-stage MFC was eliminated, and only two-stage reactors were set up, with the reaction conditions remaining the same as those of the first two stages.

[0159] Comparative Example 2: The three-stage settings are the same, but no constant potential control is set, and natural voltage operation is adopted.

[0160] All reactors were operated for 72 h, and the inlet flow rate was controlled at 20 mL / min with continuous flow.

[0161] Sampling was performed every 6 hours to test the sulfide concentration, voltage output and outlet pH.

[0162] The operational stability of each system (voltage fluctuation, electrode current) and abnormal conditions such as poisoning, foaming, and deposition were recorded (see Table 1 for details).

[0163] Table 1

[0164]

[0165] Summarize:

[0166] The structure of a multi-stage microbial cell reaction system significantly impacts the continuity and depth of high-sulfur wastewater treatment. The third-stage reactor in this example not only maintains an effective degradation rate even when sulfide concentrations drop to low to moderate levels, but also demonstrates a strong system load buffering capacity. Compared to a control example without this reactor, the system tail residue is significantly reduced, demonstrating that the multi-stage series structure synergistically enhances the reaction process through phased continuity and progressive degradation efficiency.

[0167] The constant potential control strategy significantly enhances the stability of microbial electrode reactions. In a comparative experiment without a constant potential, the voltage fluctuation range was significantly increased, leading to an imbalance in the electron supply and demand within the reactor and indirectly causing a decrease in metabolic rate. Keeping the electrode potential within a stable range helps maintain the activity of the biofilm and the consistency of the reaction direction, improving the efficiency of the entire electron transfer chain and the controllability of the reactor's energy output.

[0168] Further analysis of the sulfide removal rate curves for the three systems reveals that after a reaction time of more than 24 hours, the system with a complete tertiary structure and constant potential maintained stable removal efficiency, while the control group gradually experienced a slowdown in reaction and even a decrease in the potential plateau. This demonstrates that the reactor system is not solely dependent on the primary treatment load but requires a continuous reaction and stable energy supply mechanism at both the structural and electrical control levels to ensure medium- and long-term operational stability and sustained effectiveness.

[0169] Experiment 2:

[0170] Purpose of the experiment:

[0171] The purpose of this study was to test whether the intelligent biofilm control system can maintain system stability under load fluctuations during the treatment of sodium hydrosulfide high-sulfur wastewater, especially in terms of ORP, current response and effluent sulfur content fluctuations.

[0172] Experimental materials and equipment:

[0173] Raw water characteristics: Derived from the discharge port of a batch-type sodium hydrosulfide device, the wastewater is a typical intermittent type, with an initial sulfide content ranging from 1000-1300 mg / L and a pH of approximately 8.9;

[0174] Experimental system:

[0175] Example 2: An intelligent control system is provided, including pH, conductivity, ORP, temperature monitoring and data feedback modules;

[0176] Comparative Example 3: No control system is set, and all parameters are statically set;

[0177] Comparative Example 4: The control logic remains unchanged, but the second-stage current density is reduced to 20mA / m 2 ;

[0178] Monitoring indicators: ORP change trend, effluent sulfide residue, pH change range, system recovery time;

[0179] Auxiliary equipment: flow meter, gas distributor, data recorder.

[0180] Experimental steps:

[0181] All devices were initially started synchronously and connected to the same water source. Each group was fed with water for a period of 4 hours, after which the water supply was stopped to simulate periodic shocks.

[0182] In Example 2, parameters such as the aeration valve and electrode potential were adjusted in real time; in Comparative Example 3, the operating parameters remained unchanged; and in Comparative Example 4, the control methods were the same except for the current.

[0183] The sulfide concentration in the water and the solution ORP were measured every 4 hours, and the system response amplitude was recorded.

[0184] The operation cycle was repeated for a total of 72 hours to obtain the stability data of each group under impact load (see Table 2 for details).

[0185] Table 2

[0186]

[0187] Summarize:

[0188] The intelligent control system demonstrates a key stability-enhancing effect in the microbial cell reactor's treatment of high-sulfur wastewater. In particular, under conditions of intermittent water inflow or load fluctuations, the examples utilize dynamic feedback from monitoring the oxidation-reduction potential (ORP), current density, and pH to enable automated, real-time adjustment of system parameters, effectively suppressing process fluctuations that can occur during reactor shock.

[0189] In the control group without a control system or with an unreasonable current density setting, the system response was significantly delayed, the ORP trend showed a sharp deviation, and the effluent sulfide concentration rebounded periodically. This phenomenon indicates that under high fluctuation conditions, the lack of an adaptive mechanism will lead to impaired metabolic function of the microbial community, which in turn will cause the reactor's electron transfer chain to break or inhibit the process.

[0190] Furthermore, data from a 72-hour operating cycle demonstrates that the system with intelligent feedback control rapidly adjusts its operating state within each load cycle, maintaining various electrochemical parameters within the set threshold ranges. In contrast, the system without control functionality struggles to establish an effective process self-stabilization mechanism. This demonstrates that the proposed control strategy can achieve dynamic process leveling without human intervention, demonstrating significant engineering utility and system resilience.

[0191] Experiment 3:

[0192] Purpose of the experiment:

[0193] Evaluate the impact of setting up an energy recovery module and a suitable terminal filtration unit on the system's energy self-sufficiency, filtration stability, and clean water performance under low-load treatment conditions of sodium hydrosulfide high-sulfur wastewater.

[0194] Experimental conditions and device description:

[0195] Wastewater source: from the tail water section of sodium hydrosulfide production, with low daily discharge but strong persistence, sulfide concentration of 300±30mg / L, pH8.1;

[0196] Device settings:

[0197] Example 3: Configure a three-stage reaction structure of a microbial battery, with a terminal filter pore size of 5 μm and an energy recovery system;

[0198] Comparative Example 5: The energy recovery system is removed, and the rest of the structure is the same;

[0199] Comparative Example 6: The filter pore size is 10 μm and the energy recovery configuration remains unchanged;

[0200] Monitoring equipment: power meter, turbidity meter, filter pressure recorder, maintenance record sheet.

[0201] Experimental steps:

[0202] All three systems were connected to the same amount of tailwater from the same source and operated continuously for 7 days;

[0203] In Example 3, the output current of the microbial battery is recovered and converted to DC to power the sensor system; in Comparative Example 5, the current is not used and the system sensor is driven by an external power supply;

[0204] Record the total power recovery, sensor external power supply requirements, outlet water turbidity, and filter differential pressure changes every 24 hours;

[0205] Perform routine maintenance assessments every 48 hours, recording maintenance items such as whether membrane blockage occurs, backwash frequency, and cleaning time;

[0206] All systems maintained a temperature of 28°C and a constant water inlet rate (10 mL / min), and external variable interference was strictly controlled (see Table 3 for details).

[0207] Table 3

[0208]

[0209] Summarize:

[0210] This experiment evaluated the synergistic effect and system stability of the multi-stage MFC coupled constant potential control and terminal filtration module in the treatment of high-sulfur wastewater by comparing the key performance parameters of Example 3, Comparative Example 5 and Comparative Example 6 under the same operating conditions.

[0211] In terms of power recovery capability, Example 3 achieved an output of 41.2mWh / day during a stable operation period, demonstrating good energy conversion efficiency. This result indicates that constant control of the electrode potential helps maintain the electron transfer activity of the microbial community and ensures continuous energy release. In contrast, Comparative Example 5 (27.6mWh / day) has a relatively low current output due to the lack of effective potential regulation; Comparative Example 6 (21.4mWh / day) does not construct a closed-loop electron flow path, and its energy utilization efficiency is even more limited.

[0212] In terms of effluent quality, the effluent turbidity of Example 3 was controlled at 3.1 NTU, indicating good coupling between the front-end degradation and the final fine filtration of the reaction system, resulting in strong solid-liquid separation capabilities. The effluent turbidity of Comparative Example 5 was 6.5 NTU, reflecting the average treatment stability of the final filtration module. The effluent turbidity of Comparative Example 6 increased to 9.3 NTU, indicating the risk of colloid or suspended matter leakage and insufficient system control precision.

[0213] The filtration differential pressure data further reflects the operating load of each system. Example 3 maintained a pressure of 12.0 kPa throughout the experimental period, demonstrating low operating resistance and strong pollution resistance in its filtration structure. In contrast, the differential pressure in Comparative Example 5 increased to 16.7 kPa, reflecting the significant impact of accumulated contamination on the filter membrane. The final differential pressure in Comparative Example 6 reached 24.8 kPa, indicating a tendency for clogging in its filtration structure over long-term operation, short maintenance cycles, and large system pressure fluctuations.

[0214] Experiment 4:

[0215] Purpose of the experiment:

[0216] By comparing the key performance parameters of Example 1 (using activated cultured composite bacteria) with those of Comparative Example 7 (unactivated bacteria) and Comparative Example 8 (using external chemical agents) in the process of treating high sulfide wastewater, the technical advantages and environmental friendliness of using activated cultured composite bacteria proposed in the present invention are verified.

[0217] Experimental materials and equipment:

[0218] High sulfide simulated wastewater (H2S: 120 mg / L, Na2S: 80 mg / L);

[0219] Sodium hydrosulfide exclusive compound bacterial agent (containing Bacillus, yeast, and Bacillus subtilis);

[0220] Bacteria expansion tank (10L) and aeration device;

[0221] Three groups of microbial battery reactors of equal configuration;

[0222] pH meter, DO meter, portable sulfide concentration detector, COD determination kit;

[0223] Plate culture counting tool (for bacterial concentration detection);

[0224] H2O2 (hydrogen peroxide) solution;

[0225] General laboratory equipment and record sheets.

[0226] Experimental design and grouping:

[0227] Example 1: The composite bacteria were activated using step S1 and inoculated into the reaction system without adding any chemical agents.

[0228] Comparative Example 7: Direct addition of unactivated commercially available microbial agents without culture and activation treatment

[0229] Comparative Example 8: Unactivated bacterial agent + adding H2O2 (20 mg / L) to the reaction system every 24 hours for synergistic treatment.

[0230] Experimental steps:

[0231] Activation culture (only for Example 1):

[0232] In a 10L expansion tank, add a composite bacterial agent (0.5‰), 1.2g / L glucose, and tap water, adjust the pH to 7.5, and culture at 28°C for 48 hours with aeration and DO maintained at 3mg / L. After 48 hours, use the plate spread counting method to confirm that the bacterial concentration reaches 1×10 9 CFU / mL and then put into the reaction system.

[0233] Start the reactor system:

[0234] The corresponding bacterial strains were added to the three groups of reactors and started continuous operation. Water quality, including sulfide concentration, COD, pH, and total colony count (CFU / mL), was sampled and analyzed daily.

[0235] Data recording and evaluation:

[0236] The changing trends of various indicators were recorded daily to evaluate the degradation rate, the maintenance level of the bacterial flora, and whether external intervention was needed (see Table 4 for details).

[0237] Table 4

[0238]

[0239]

[0240] Experimental summary:

[0241] Under the conditions of activating and cultivating the exclusive composite bacteria for sodium hydrosulfide, the microbial community has formed an adaptive dominant population dominated by Bacillus before the addition of sodium hydrosulfide, and cooperated with yeast, Bacillus subtilis, etc. to build a stable bacterial community network, which quickly established its dominance in the wastewater and started the metabolic process. Due to the sufficient carbon source and dissolved oxygen environment provided in the pre-culture stage, the bacterial community showed high sulfur metabolic activity in the reactor, achieving efficient H2S and S 2- The degradation of sulfides and the enhancement of the power generation efficiency of the microbial battery are achieved through the electron transfer process. The overall system starts quickly and responds stably.

[0242] In contrast, Comparative Example 7 did not perform bacterial activation culture, and the bacterial community in the reactor needed to undergo an environmental stress adaptation period, which manifested as sluggish reaction and low metabolic activity, resulting in prolonged system startup time and slow sulfide removal rate. At the same time, additional nutrient solution was required to maintain bacterial activity, which not only increased operational complexity but also easily led to bacterial imbalance. Although Comparative Example 8 improved the initial reaction efficiency by adding chemical oxidants, it essentially relied on external strong oxidation reactions to destroy sulfides, thereby inhibiting the stable growth of the original bacterial community in the reactor, resulting in a decrease in the activity of the microbial system in the later stage, disorder of the electrobiofilm structure, and the formation of a certain amount of byproducts, affecting the effluent water quality.

[0243] The present invention clearly sets up the activation culture of sodium hydrosulfide-specific composite bacteria, so that the bacterial community is in the optimal metabolic state before the reaction, while avoiding the use of any chemical agents, and realizes the self-driven decomposition and conversion process of high-sulfide wastewater by composite bacteria throughout the entire process. Under this mechanism, sulfur is converted into non-toxic forms such as sulfite and sulfate through biological oxidation, while the electrode interface reaction prompts electrons to migrate to the anode, forming a stable current output. The system not only has both desulfurization and energy recovery capabilities, but also has no chemical residues and side reaction pollution in the process, reflecting the concept of green, efficient and sustainable wastewater biological treatment.

[0244] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide, characterized in that: The following steps are involved: S1. Activate and culture the sodium hydrosulfide-specific composite bacteria to activate the strains, and then add the activated strains to the reactors at all levels of the microbial reaction system; S2. Pre-treat the high-sulfur wastewater generated during the sodium hydrosulfide production process by removing large particle impurities through filtration and precipitation, and adjust the pH value to 6.5-8.5 to create a reaction environment suitable for microbial reaction; S3. Introducing the pretreated wastewater into a multi-stage microbial battery reaction system, wherein the system includes at least three stages of reactors, and sequentially degrading sulfides of different concentrations, wherein: The first-stage reactor is used to oxidize high-concentration hydrogen sulfide to sulfate; The second stage reactor is used to further degrade the medium concentration sulfide; The third-stage reactor is used to completely remove low-concentration residual sulfides; S4. Dynamically regulate the microbial metabolic pathways in the multi-stage reaction system by setting up an intelligent biofilm reactor; S5. Remove byproducts and precipitates that may be generated during the reaction through the dual-electrode system and terminal filtration device of the byproduct control system; S6. The electrical energy generated in the microbial battery reaction system is recovered through the energy recovery system to provide energy for the monitoring system and auxiliary devices in the entire wastewater treatment process.

2. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the step S1, the activation culture comprises: Add 0.3-1% sodium hydrosulfide exclusive compound bacteria, 1-1.5g / L glucose and tap water to the culture tank, adjust the pH to 7-8, and culture under aeration at 25-35℃ for 48 hours. Control the DO at 2-4mg / L. After activation, the bacterial density was tested and the microscopic examination showed that it reached 1×10 9 CFU / ml means the activation culture is complete; The desulfurizing bacteria agent is a composite bacterial community, mainly including Bacillus, yeast and Bacillus subtilis.

3. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the step S2, wastewater pretreatment includes: A two-stage filtration method of coarse filtration + fine filtration is used to remove particulate matter. The fine filtration uses a fiber filter with a pore size of less than 10μm. Use a sedimentation tank to allow the water to settle for no less than 2 hours to remove inorganic suspended matter and some heavy metals; The pH of the wastewater is adjusted to 6.8-7.5 by adding sodium hydroxide or sulfuric acid to adapt to the subsequent microbial reaction environment.

4. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the S3 step, the configuration of the first-stage reactor includes: The sulfur-oxidizing bacteria group, mainly composed of Thiobacillus denitrificans, is used to achieve biological oxidation of high-concentration hydrogen sulfide; Maintain a current density of 10-100 mA / m in the anode region of the reactor. 2 , to enhance the metabolic rate of microorganisms; The reactor temperature was controlled between 25 and 35°C.

5. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the S3 step, the second stage reactor comprises: Setting up facultative anaerobic bacteria to adapt to the gradual conversion of medium concentration of sulfide; The microbial battery system provides 50-200 mA / m 2 A stable current to maintain biochemical reactions; Increase the dissolved oxygen concentration through intermittent aeration.

6. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the S3 step, the third-stage reactor comprises: The microbial population selected was the Paracoccus pantotrophus species which has a high affinity for low concentrations of sulfide; Maintain 100~500mA / m in the electrode system 2 The current density; Set the reaction time to no less than 8 hours to allow the sulfide to be completely degraded.

7. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that, In the step S4, the intelligent biofilm reactor comprises: Output includes redaction, encryption, and response execution of blocking operations; The sensor is connected to the central control system and transmits data to the cloud server in real time through the wireless data module; The control system dynamically adjusts reaction conditions based on historical operating data to control the microbial metabolic pathway; The intelligent biofilm reactor automatically adjusts system temperature, pH and current parameters based on real-time collected sensor data.

8. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that: In the step S4, the dynamic control includes: A multivariable prediction model was constructed to determine treatment trends, and a fuzzy control algorithm was used to adjust ventilation volume, current density, and liquid level control; For abnormal parameter fluctuations, the system automatically triggers the dynamic control safety bypass and backwash functions to ensure stable process operation.

9. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that: In the step S5, the dual-electrode system in the by-product control system includes: The anode is made of conductive graphite felt material to promote efficient oxidation of hydrogen sulfide; The cathode uses titanium-based platinum coating material to improve the electron conduction rate; The system maintains the optimal reaction potential through a constant potential control device to inhibit the formation of by-products; The terminal filtering device comprises: Multi-stage ceramic membrane components, with pore sizes ranging from 0.5 to 5 μm, filter reaction residues and microbial sludge step by step; The matching backwash system is backwashed regularly to maintain filtration efficiency; The effluent quality meets the first-level discharge standard.

10. A biological treatment process for high-sulfur wastewater produced by sodium hydrosulfide according to claim 1, characterized in that: In step S6, the energy recovery system includes: The current generated by the microbial battery is stably output through the DC-DC conversion module and supplied to the monitoring sensors, control systems and dosing equipment; An electric energy storage unit is provided for peak load regulation or off-grid emergency operation; The energy conversion efficiency is greater than 50%, achieving closed-loop operation with partial self-sufficiency of energy for the system.

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