A method and system for synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater using MABR oxygen stratification process.

Abstract

This application relates to the field of wastewater treatment technology, specifically providing a method and system for the synergistic oxidation-reduction coupling treatment of ethylthionitrogen-C-N-S in mineral processing wastewater using a MABR oxygen stratification process. This method and system innovatively develops a time-sequential dissolved oxygen (DO) dynamic control strategy: by periodically / pulsally switching anaerobic-hypoxic-aerobic conditions, the oxidation and ammonification reactions of ethylthionitrogen are directionally enhanced, and the toxic inhibitory effects of intermediate products on functional bacteria are eliminated. Based on this strategy, the system can precisely utilize the spatial distribution of the biofilm oxygen gradient within a single MABR reactor to achieve a cascade reaction of ethylthionitrogen: "sulfur oxidation-ammonification → aerobic nitrification → anoxic denitrification"; or, for high-concentration ethylthionitrogen (>50 mg / L), it can couple a pre-anaerobic reactor to enhance ammonification detoxification and denitrification.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, specifically providing a method and system for achieving synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater using a MABR oxygen stratification process. Background Technology

[0002] In lead-zinc ore beneficiation wastewater, ethyl thiocyanate (ETH) is a typical flotation reagent, but its residue problem is particularly prominent. ETH is mainly used as a collector for Cu, Pb, Sb, and other metal sulfides, with collecting performance similar to xanthates and black reagents. However, compared to xanthates and black reagents, ETH has the advantages of stronger collecting ability, faster flotation speed, lower reagent dosage, and higher selectivity. ETH can also be used in metal smelting and purification, and as an accelerator in the rubber industry. However, its degradation products and residues readily react with heavy metal ions (such as Pb). 2+ Zn 2+ Sn 2+ (etc.) form a complex pollution, leading to COD and NH4 in wastewater. + -N (ammonia nitrogen) toxicity is significantly increased. Reusing wastewater containing ethyl thiocyanate nitrogen can also interfere with flotation, causing a decrease in concentrate grade.

[0003] Traditional physical methods use techniques such as coagulation sedimentation and adsorption to initially remove ethyl nitrogen and xanthate pollutants, but they suffer from problems such as high reagent consumption, easy saturation of adsorbents, and severe membrane fouling. Chemical methods rely on advanced oxidation processes such as Fenton oxidation and photocatalysis to degrade organic matter, but they face the risks of secondary pollution such as dependence on strong acid conditions, high energy consumption, and iron sludge / volatile toxic byproducts. Biological methods such as contact oxidation utilize microbial metabolism to achieve low-cost treatment, but the strains have long acclimatization periods and poor tolerance to ethyl nitrogen and intermediate products, resulting in low degradation efficiency and insufficient process stability.

[0004] A membrane aerated biofilm reactor (MABR) is a highly efficient wastewater treatment system integrating membrane aeration technology and biofilm technology. Its main principle is to remove organic matter and nitrogen pollutants through bubble-free oxygen supply via a hollow fiber membrane and reverse concentration gradient mass transfer via the biofilm. O2 inside the membrane chamber is precisely and quantitatively delivered to the outer surface under appropriate pressure, providing electron acceptors for microorganisms on demand. Simultaneously, wastewater pollutants permeate from the biofilm surface to the inner layer, forming a highly efficient reverse diffusion mechanism that theoretically achieves 100% oxygen utilization efficiency. Furthermore, the membrane aeration method facilitates the formation of a unique stratified structure in the biofilm: the inner layer is the aerobic zone, primarily responsible for the oxidation and decomposition of organic matter and the production of NH4+. + The nitrification reaction of -N; the outer layer is an oxygen-deficient zone, where oxygen is limited, and the nitrification products are further converted into nitrogen gas through denitrification and emitted, thereby achieving efficient removal of organic matter and nitrogen.

[0005] First, while ZL202410918712.5 and ZL202210942625.4 achieved efficient biological denitrification by controlling oxygen stratification and coupling with other processes, their research focused on municipal wastewater denitrification and did not address the conversion of highly inhibitory organic nitrogen. Second, although 202510282953.X constructed a general-purpose multi-stage MABR series combination to treat various persistent organic pollutants (POPs) and nitrogen, it did not consider the specific toxic pollutant ethyl thiocyanate and its derived ammonia nitrogen pollution in mineral processing wastewater. Furthermore, although patent ZL202410448828.7 utilizes MABR to degrade xanthate, it does not address the NH4 generated from the conversion of ethyl thiocyanate. + -N pollution, and a lack of nitrogen removal technology that simultaneously performs "ammoniation-nitrification-denitrification".

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] One of the objectives of this application is to provide a method and system for the synergistic oxidation-reduction coupling treatment of ethyl nitrogen and CNS in mineral processing wastewater based on the MABR oxygen stratification process optimization, so as to achieve deep removal of ethyl nitrogen and synergistic treatment of carbon-nitrogen-sulfur in mineral processing wastewater.

[0008] To achieve the above objectives, this application adopts the following technical solution:

[0009] A method for synergistic redox coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on MABR oxygen stratification process optimization includes the following steps:

[0010] S1 Influent: Mineral processing wastewater containing ethyl nitrogen is fed into the MABR reactor, and the following DO timing control is performed according to the hydraulic retention time T:

[0011] S2 High Dissolved Oxygen Stage: Controlling the membrane aeration pressure to 11–20 psi maintains the DO concentration in the reactor solution at 3.0–6.0 mg / L, to rapidly achieve the hydrolysis of ethyl thiocyanate into diethylamine and CS2, and the oxidation-ammoniation of diethylamine into NH4. + -N and ethanol, CS2 oxidation to CO2 and H2S, and ammonia oxidation reaction; duration T1 is 2-4h;

[0012] S3 Normal Dissolved Oxygen Stage: Reduce the membrane aeration pressure to 4-10 psi to maintain the DO in the reactor solution at 1.0-2.0 mg / L, so as to inhibit the nitrite reaction and maintain the oxidation of H2S; duration T2 is 2-4 h;

[0013] S4 Low Dissolved Oxygen Stage: The membrane aeration pressure is further reduced to 1–3 psi, maintaining the dissolved oxygen (DO) in the reactor at 0.2–0.5 mg / L. This utilizes the ethanol and H2S generated in stages S2 and S3 as endogenous electron donors to drive denitrification. + -N undergoes nitrification to produce nitrate nitrogen and / or nitrite nitrogen, which is then reduced to N2 by subsequent denitrification, thus completing nitrification-denitrification simultaneously; the duration T3 is 4–16 h;

[0014] Where T = T1 + T2 + T3, and T is 8 to 24 hours.

[0015] Furthermore, when the ethyl nitrogen concentration in the mineral processing wastewater is >50 mg / L, the anaerobic reactor unit is automatically started, and the effluent from the MABR reactor is introduced into the anaerobic reactor to enhance denitrification by combining the carbon source, endogenous H2S and ethanol in the mineral processing wastewater, forming an "anaerobic-MABR" coupling mode.

[0016] The H2S-driven denitrification process is as follows: 5H2S + 8HNO3 → 5H2SO4 +

[0017] 4N2 + 4H2O.

[0018] When the ethyl thiocyanate concentration in the mining wastewater is ≤50mg / L, the anaerobic reactor unit is shut down, and only the single MABR reactor is operated to complete the entire ethyl thiocyanate-CNS synergistic oxidation-reduction process.

[0019] Furthermore, the effluent from the MABR reactor is recycled back to the anaerobic reactor at a reflux ratio of 100% to 300%.

[0020] Furthermore, the DO setpoints of the solutions in the reactors at each stage (S2-S4) are dynamically adjusted through a real-time feedback system. The input parameters of this real-time feedback system include: the ethyl nitrogen concentration of the mineral processing wastewater and the NH4+ concentration of the effluent from the MABR reactor. + NOx - and TN concentration.

[0021] A system for implementing the above-mentioned ethylthionium nitrogen-CNS synergistic redox coupling method includes:

[0022] MABR reactor unit (1): Mineral processing wastewater is pumped into MABR reactor unit (1) through water pump (7) and a biofilm is cultivated on aeration membrane module (2). The formation of a biofilm with an oxygen concentration gradient on the aeration membrane module (2) is controlled by the gas mass flow meter (4), dissolved oxygen sensor (5) and pH sensor (6) on the aeration pump (3). The biofilm is divided into aerobic zone, anoxic zone and anaerobic zone from the inside to the outside. The control box (14) and the gas mass flow meter are connected to form a time sequence control system, which is used to execute the DO sequence of S2-S4.

[0023] Optional anaerobic reactor unit (9): mineral processing wastewater containing ethyl thionione is pumped into anaerobic reactor unit (9) through inlet pump (12). The effluent from MABR reactor (1) is returned to anaerobic reactor unit (9) through reflux pump (13). The dissolved oxygen concentration and pH are controlled by dissolved oxygen sensor (5) and pH sensor (6). The high-concentration ethyl thionione wastewater is pretreated by ammoniation and the effluent from MABR reactor (1) is enhanced by denitrification using stirrer (10) and anaerobic biofilm carrier (11).

[0024] Adaptive switching valve group (15-18) is used to automatically select the single MABR mode (valve (15), (17) and (18) open, valve (16) closed) or the "anaerobic-MABR" coupled mode (valve (15), (16) and (18) open, valve (17) closed) according to the ethyl thiocyanate concentration of the mineral processing wastewater.

[0025] Furthermore, in the anaerobic reactor unit (9), the effluent recirculation ratio of the MABR reactor (1) is 100% to 300%.

[0026] Furthermore, the anaerobic reactor unit (9) is selected from one of the following: upflow anaerobic sludge blanket (UASB), anaerobic moving bed biofilm reactor (AMBBR), or expanded granular sludge blanket (EGSB).

[0027] Furthermore, the anaerobic biofilm carrier (11) is made of polyethylene, polypropylene or modified materials thereof, or polyurethane foam, with a specific gravity of 0.95–1.05 g / cm³. -3 This ensures thorough mixing with water.

[0028] Furthermore, the aeration method of the MABR reactor unit (1) is hollow fiber membrane bubble-free aeration, and the membrane material is a hydrophobic polymer.

[0029] Furthermore, the membrane aeration pressure of the MABR reactor unit (1) is 1 to 20 psi, the hydraulic retention time is 8 to 24 h, and the pH control range is 6.5 to 8.5.

[0030] Compared with the prior art, the technical effects of this application are as follows:

[0031] This application, for the first time, provides an adaptive switching mechanism based on the influent ethyl thiocyanate concentration. It proposes a complete cascade reaction chain targeting ethyl thiocyanate, with a time sequence ratio of "short-term high-oxygen detoxification + long-term low-oxygen denitrification," significantly inhibiting nitrite accumulation. Simultaneously, it utilizes the decomposition byproducts (H2S, ethanol) of ethyl thiocyanate for denitrification, achieving carbon-sulfur-nitrogen synergy. This results in the elimination of toxicity inhibition, reduced energy consumption, improved system adaptability to fluctuating water quality, and zero additional carbon source addition to the system itself. Specifically:

[0032] 1. Enhanced Dynamic Adaptability and Broader Treatment Applicability: This application pioneers an adaptive operation mode switching mechanism based on influent ethyl thiocyanate (ET) concentration. For high-concentration ET wastewater, the system automatically activates the "anaerobic reactor + MABR" coupled mode, utilizing pre-anaerobic denitrification to remove nitrate nitrogen and reduce ET thiocyanate toxicity, while the post-MABR simultaneously and efficiently completes ammonification-nitrification. When the influent ET concentration decreases, the system seamlessly switches to a standalone MABR mode, achieving synergistic removal of ET, organic carbon, and ammonia nitrogen within a single reactor, significantly improving the system's adaptability to complex water quality fluctuations in mineral processing wastewater and its overall treatment applicability.

[0033] 2. Precise Enhancement of the Reaction Chain through Time-Sequential Dissolved Oxygen Control, Effectively Eliminating Inhibition and Improving Stability: This application innovatively drives and enhances the cascade reaction process of ethyl thiocyanate oxidation-ammoniation-nitrification-denitrification by time-sequentially controlling dissolved oxygen concentration (e.g., periodic / pulsed anaerobic-hypoxic environment). This strategy actively creates suitable hypoxic conditions at key stages (e.g., the initial reaction stage or high-load period), significantly accelerating the decomposition of ethyl thiocyanate into organic acids and releasing ammonia nitrogen, while efficiently activating the activity of ammonifying bacteria. Real-time DO control effectively inhibits nitrite accumulation, completely eliminating its toxic inhibitory effect on ethyl thiocyanate oxidizing and ammonifying bacteria. Compared to existing technologies that operate with constant DO or rely on passive modes of natural gradients, this active time-sequential DO control can dynamically respond to load changes and directionally regulate key reaction steps as needed, significantly improving the removal of ethyl thiocyanate and ammonia nitrogen.

[0034] 3. High system integration, simplified process, and significantly improved efficiency: This application, through innovation in MABR core technology and operating strategies, highly integrates complex processes such as ethyl nitrogen removal, organic matter mineralization, ammoniation, nitrification, and denitrification—which traditionally require multiple independent units (such as anaerobic units, aerobic nitrification units, anoxic denitrification units, and external carbon source systems)—into one or two (in coupled mode) reactors. This integration greatly simplifies the process flow, reduces the number of structures and floor space, and significantly improves the overall pollutant removal efficiency and system operational performance through precise utilization of spatial gradients and adaptive mode switching. Attached Figure Description

[0035] The various technical features of this application and their relationships will be further explained below with reference to the accompanying drawings. The drawings are exemplary; some technical features are not shown to scale, and some drawings may omit technical features commonly used in the art to which this application pertains that are not essential for understanding and implementing this application, or additionally show technical features that are not essential for understanding and implementing this application. In other words, the combination of various technical features shown in the drawings is not intended to limit this application. Furthermore, throughout this application, the same reference numerals refer to the same things. Specific descriptions of the drawings are as follows:

[0036] Figure 1 A simplified schematic diagram of the oxygen stratification reaction mechanism in MABR biofilms;

[0037] Figure 2 A detailed schematic diagram of the oxygen stratification reaction mechanism in MABR biofilms;

[0038] Figure 3 This is a system flow diagram of the "pre-anaerobic reactor + post-MABR" coupled mode;

[0039] Figure 4 Flowchart for a standalone MABR mode;

[0040] Figure 5 The graph shows the changes in ethyl nitrogen (A), ammonia nitrogen (B), total nitrogen (TN) (C), and COD (D) concentrations in the influent and effluent during the simultaneous ammoniation-nitrification-denitrification process of a single MABR.

[0041] Figure 6 The graph shows the changes in the concentrations of ethyl nitrogen (A), ammonia nitrogen (B), TN (C), and COD (D) in the influent and effluent during the ammoniation-nitrification-denitrification process in the coupled system of "pre-anaerobic reactor + post-MABR". Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions described in this application will be further described in detail below with reference to specific embodiments.

[0043] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0044] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0045] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0046] Unlike domestic sewage, mineral processing wastewater typically contains high concentrations of heavy metals, high salinity, high suspended solids, low pH, and residual mineral processing reagents. These factors have a strong inhibitory or even toxic effect on microbial activity. In order to solve the ecological harm caused by the residual ethyl thiocyanate collector in mineral processing wastewater, a specific strategy was developed to achieve a cascade reaction of "sulfur oxidation-ammoniation-nitrification-denitrification", thereby driving the simultaneous degradation of ethyl thiocyanate and ammonia nitrogen.

[0047] Based on this, this application provides a method and system for the synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on the optimized MABR oxygen stratification process, such as... Figure 1 This system simultaneously achieves nitrogen removal through ethyl thiocyanate oxidation, ammoniation, nitrification, and denitrification within a single reaction system. Furthermore, it is also applicable to other various organic nitrogen water pollution treatment scenarios.

[0048] In this application, "ethyl thionitrogen-CNS synergistic redox coupling" refers to the process within the same reaction system, such as... Figure 2 This method utilizes the redox reaction of ethyl thiocyanate (an organic collector containing C, N, and S) as its core removal mechanism, simultaneously achieving the following redox electron transfer equilibrium: 1. Ethyl thiocyanate and its cracking products (diethylamine, ethanol, etc.) are oxidized to CO2, simultaneously serving as electrons required for denitrification; 2. Organic nitrogen in ethyl thiocyanate is converted to N2 via a hydrolysis-ammoniation-nitrification-denitrification pathway; 3. Sulfur in ethyl thiocyanate is hydrolyzed and oxidized to generate H2S / HS-, which is further converted to SO42- via denitrification or aerobic respiration. This coupled process achieves a synergistic effect of simultaneous removal and detoxification of carbon, nitrogen, and sulfur in mineral processing wastewater in one step, with zero external carbon source, low energy consumption, and through periodic DO timing control, oxygen gradient stratification, and recycling of endogenous electron donors.

[0049] A system for synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on MABR oxygen stratification process optimization includes:

[0050] In the MABR unit (1), wastewater is pumped into the unit by the water pump (7) and a biofilm is cultivated on the aeration membrane module (2). The biofilm with an oxygen concentration gradient is formed on the aeration membrane module (2) by the gas mass flow meter (4) on the aeration pump (3), as well as the dissolved oxygen sensor (5) and pH sensor (6). It is divided into aerobic zone, anoxic zone and anaerobic zone from the inside to the outside. The control box (14) and the gas mass flow meter are connected to form a time sequence control system, which is used to execute the DO sequence of S2-S4. The outlet (8) is the discharge port of the treated water.

[0051] The optional anaerobic reactor unit (9) is used to transport mineral processing wastewater into the anaerobic reactor unit (9) via the inlet pump (12). The dissolved oxygen concentration and pH are controlled by the dissolved oxygen sensor (5) and pH sensor (6) for ammoniation pretreatment of high-concentration ethyl thiocyanate mineral processing wastewater. The stirrer (10) is used for uniform stirring within the anaerobic reactor unit. The anaerobic biofilm carrier (11) can be fully mixed with water during aeration to provide a suitable three-phase (gas, liquid, and solid) growth environment for microorganisms, which is conducive to the cultivation of anaerobic biofilm.

[0052] When an anaerobic reactor unit (9) is present, the effluent from the anaerobic reactor (9) is circulated to the MABR unit (1), and the nitrified liquid (effluent) produced by the MABR unit (1) is returned to the anaerobic reactor through a return pump (13). The nitrified liquid return ratio is 100% to 300%.

[0053] When there is no anaerobic reactor unit (9), the mineral processing wastewater directly enters the MABR unit (1) to complete the entire process treatment.

[0054] The two modes mentioned above are achieved through adaptive switching valve groups (15-18). Based on the ethyl thiocyanate concentration in the mineral processing wastewater, the single MABR mode (valve (15), (17) and (18) open, valve (16) closed) or the "anaerobic-MABR" coupled mode (valve (15), (16) and (18) open, valve (17) closed) is automatically selected.

[0055] In some implementations, the membrane aeration pressure of the MABR unit is 1–20 psi, the hydraulic retention time is 8–24 h, and the pH control range is 6.5–8.5.

[0056] In some embodiments, the aeration method of the MABR unit (1) is bubble-free aeration using a hollow fiber membrane, and the membrane material is a hydrophobic polymer.

[0057] In some embodiments, the anaerobic reactor unit (9) can be any reactor that provides an anaerobic environment for ammoniation and denitrification, including upflow anaerobic sludge blanket (UASB), anaerobic moving bed biofilm reactor (MBBR), or expanded granular sludge blanket (EGSB).

[0058] In some implementations, the anaerobic biofilm carrier is typically made of lightweight materials such as polyethylene, polypropylene and their modified forms, and polyurethane foam, with a specific gravity close to that of water.

[0059] In some embodiments, the MABR oxygen stratification method for simultaneous ammoniation-nitrification-denitrification of ethyl nitrogen in mineral processing wastewater is not only implemented using hollow permeable fiber membranes as carriers, but also includes technologies such as aerobic granular sludge reactors and moving bed biofilm reactors, which can achieve complete synergistic degradation of ethyl nitrogen and intermediate product ammonia nitrogen in a single system through similar methods.

[0060] This application provides a method for achieving synergistic redox coupling treatment of ethyl thionitrogen-CNS in mineral processing wastewater based on the above system and optimized MABR oxygen stratification process, comprising the following steps:

[0061] S1: The mineral processing wastewater containing ethyl nitrogen is fed into the MABR reactor, and the membrane aeration pressure is controlled to make the biofilm circulate in sequence with different dissolved oxygen concentrations, so as to achieve efficient enrichment of functional bacteria.

[0062] Within this MABR reactor, the following DO timing control is performed cyclically according to the hydraulic retention time T:

[0063] S2: High Dissolved Oxygen Stage (Duration T1 hours): The membrane aeration pressure is controlled (11–20 psi) to maintain the DO concentration in the reactor solution at 3.0–6.0 mg / L, enhancing the hydrolysis of ethyl thiocyanate, the diethylamine oxidation-ammoniation reaction, the ammonia oxidation reaction, and the rapid oxidation of CS2. During this process, ethyl thiocyanate is hydrolyzed into diethylamine and carbon disulfide, and then diethylamine is oxidized and ammonified to convert into NH4. + -N and ethanol, CS2 is converted into CO2 and H2S gas;

[0064] S3: Normal Dissolved Oxygen Stage (Duration T2 hours): Control the membrane aeration pressure (4-10 psi) to maintain the DO concentration in the reactor solution at 1.0-2.0 mg / L, inhibit the nitrite reaction, and maintain the oxidation of H2S.

[0065] S4: Low Dissolved Oxygen Stage (Duration T3 hours): Controlling the membrane aeration pressure (1–3 psi) maintains the DO concentration in the reactor solution at 0.2–0.5 mg / L, promoting the growth of H2S and ethanol-driven denitrifying bacteria, and maintaining the synchronous nitrification-denitrification balance to minimize aeration energy consumption; NH4 + -N undergoes nitrification during this process to generate nitrate nitrogen / nitrite nitrogen, which is then reduced to N2 through subsequent denitrification.

[0066] Where T = T1 + T2 + T3, and T1 = 2 to 4 hours; T2 = 2 to 4 hours; T3 = 4 to 16 hours.

[0067] In one embodiment, when the ethyl thiocyanate concentration in the wastewater is ≤50 mg / L, the entire process of simultaneous oxidation-ammoniation-nitrification-denitrification of ethyl thiocyanate is completed in a single MABR reactor by controlling the air pressure (5-20 psi), hydraulic retention time (8-24 h), and pH (6.5-8.5) of the MABR.

[0068] In one embodiment, when the concentration of ethyl thiocyanate in the influent is >50 mg / L, the treated mineral processing wastewater is fed into an anaerobic reactor to enhance denitrification. Specifically, the remaining nitrate / nitrite nitrogen in the MABR effluent is returned to the anaerobic reactor, and denitrification is carried out using the anaerobic environment in the anaerobic reactor and the carbon source in the influent.

[0069] In one implementation, the DO setpoints for each stage are dynamically adjusted via a real-time feedback system. Input parameters include: influent ethyl nitrogen concentration and effluent NH4 concentration. + and NO x - Concentration, total nitrogen (TN) in effluent.

[0070] The DO timing control, CNS three-phase synergistic reaction path and adaptive operation strategy of this application are not only applicable to hollow fiber membrane MABR, but also to any aerobic granular sludge reactor, moving bed biofilm reactor MBBR or other biofilm system that can form oxygen stratification in a single reactor, without changing the DO timing, reflux ratio and control logic.

[0071] This application addresses the core challenge of low nitrogen removal efficiency caused by the inhibition of nitrification-denitrification bacteria by ethyl thiocyanate in traditional technologies. It innovatively develops a time-sequential dissolved oxygen (DO) dynamic regulation strategy: by periodically / pulsally switching anaerobic-hypoxic-aerobic conditions, the oxidative decomposition and ammonification reactions of ethyl thiocyanate are directionally enhanced, and the toxic inhibitory effects of intermediate products on functional bacteria are eliminated. Based on this strategy, the system can precisely utilize the spatial distribution of the biofilm oxygen gradient within a single MABR reactor to achieve a cascade reaction of ethyl thiocyanate: "sulfur oxidation-ammonification → aerobic nitrification → anoxic denitrification"; or, for high concentrations of ethyl thiocyanate (>50 mg / L), it can couple a pre-anaerobic reactor to enhance ammonification detoxification and denitrification.

[0072] Compared with existing technologies, this application achieves two major innovative breakthroughs: First, it precisely enhances the reaction chain through time-series controlled dissolved oxygen, realizing short-range spatial coupling and efficient transfer of "sulfur oxidation-ammoniation → nitrification → denitrification"; second, it develops an adaptive dual-mode operation system: through precise utilization of spatial gradients and adaptive switching of modes, it significantly improves the overall removal efficiency of pollutants and the operational efficiency of the system. This solution, through the synergistic control of time-series DO and spatial gradients, effectively eliminates the inhibition of ethyl thiocyanate toxicity, reduces energy consumption and sludge production, and provides a revolutionary solution for highly toxic mineral processing wastewater.

[0073] The present application is further described below with reference to specific embodiments. The advantages and features of the present application will become clear from the description. The embodiments described are merely exemplary and do not constitute any limitation on the scope of the present application. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present application without departing from the spirit and scope of the present application, but such modifications and substitutions all fall within the protection scope of the present application.

[0074] Example 1: Pre-anaerobic reactor + Post-MABR

[0075] This embodiment presents a method and system for the synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on the optimized MABR oxygen stratification process.

[0076] Pre-anaerobic reactor + post-MABR system (see Figure 3 ):

[0077] In the MABR unit (1), wastewater is pumped into the unit by the water pump (7) and a biofilm is cultivated on the aeration membrane assembly (2). The biofilm with an oxygen concentration gradient is formed on the surface of the biofilm by the gas mass flow meter (4) on the aeration pump (3), the dissolved oxygen sensor (5), and the pH sensor (6), and is divided into aerobic zone, anoxic zone and anaerobic zone from the inside out.

[0078] The anaerobic reactor unit (9) is where wastewater is pumped into the unit by the inlet pump (12). The dissolved oxygen (DO) concentration and pH are controlled by the dissolved oxygen sensor (5) and pH sensor (6) for ammoniation pretreatment of high-concentration ethyl nitrogen wastewater.

[0079] A stirrer (10) is used for uniform stirring within the anaerobic reaction unit;

[0080] The anaerobic biofilm carrier (11) can be fully mixed with water during aeration, providing a suitable growth environment for microorganisms in a gas, liquid and solid three phases, which helps anaerobic biofilm cultivation.

[0081] After the ore wastewater is treated in the anaerobic reactor unit (9), the effluent is transported to the MABR unit (1), and the nitrate nitrogen (nitrified liquid) generated by the MABR unit is returned to the anaerobic reactor for denitrification via the return pump (13). The nitrified liquid return ratio is 100%.

[0082] The method is carried out according to the following steps:

[0083] S1: The mineral processing wastewater containing ethyl nitrogen is fed into the MABR reactor, and the membrane aeration pressure is controlled to make the biofilm circulate in sequence with different dissolved oxygen concentrations, so as to achieve efficient enrichment of functional bacteria.

[0084] Within the MABR reactor, the following DO timing control is performed cyclically according to the hydraulic retention time T:

[0085] S2: High Dissolved Oxygen Stage (Duration T1 hours): The membrane aeration pressure is controlled (11–20 psi) to maintain the DO concentration in the reactor solution at 3.0–6.0 mg / L, enhancing the hydrolysis of ethyl thiocyanate, the diethylamine oxidation-ammoniation reaction, the ammonia oxidation reaction, and the rapid oxidation of CS2. During this process, ethyl thiocyanate is hydrolyzed into diethylamine and carbon disulfide, and then diethylamine is oxidized and ammonified to convert into NH4. + -N and ethanol, CS2 is converted into CO2 and H2S gas.

[0086] S3: Normal Dissolved Oxygen Stage (Duration T2 hours): Control the membrane aeration pressure (4-10 psi) to maintain the DO concentration in the reactor liquid at 1.0-2.0 mg / L, inhibit the nitrite nitration reaction, and maintain the oxidation of H2S.

[0087] S4: Low Dissolved Oxygen Stage (Duration T3 hours): Controlling the membrane aeration pressure (1–3 psi) maintains the DO concentration in the reactor liquid at 0.2–0.5 mg / L, promoting the growth of H2S and ethanol-driven denitrifying bacteria, and maintaining the balance between simultaneous nitrification and denitrification, thus minimizing aeration energy consumption; NH4 + -N undergoes nitrification during this process to generate nitrate nitrogen / nitrite nitrogen, which is then reduced to N2 through subsequent denitrification.

[0088] Where T = T1 + T2 + T3, and T1 = 2 - 4 hours; T2 = 2 - 4 hours; T3 = 4 - 16 hours.

[0089] S5: The treated wastewater is fed into an anaerobic reactor to enhance denitrification and nitrogen removal. Specifically, the remaining nitrate nitrogen / nitrite nitrogen in the MABR effluent is returned to the anaerobic reactor, where the anaerobic environment and the carbon source in the influent are used for denitrification.

[0090] S6: Through long-term stable operation (hydraulic retention time T = 24 hours), the effluent ethyl nitrogen is <1.0 mg / L (removal rate > 99%), the effluent ammonia nitrogen is <1.5 mg / L (removal rate > 90%), the effluent total nitrogen is <6.0 mg / L (removal rate > 80%), and the effluent COD is <30 mg / L (removal rate > 90%). Figure 6 As shown in the figure, the aeration energy consumption is reduced by 30% compared to constant DO operation. The oxidation of two molecules of hydrogen sulfide and two molecules of ethanol can produce 40 electrons, which is much greater than the 5 electrons required for denitrification. Therefore, controlling the oxygen flux can avoid the need for additional carbon sources.

[0091] The influent ethyl thiocyanate concentration in the above-mentioned mineral processing wastewater containing high concentrations of ethyl thiocyanate is 160–180 mg / L, ammonia nitrogen concentration is 12–15 mg / L, total nitrogen concentration is 28–30 mg / L, and COD concentration is 260–300 mg / L.

[0092] Example 2: Monomer MABR

[0093] This embodiment presents a method and system for the synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on the optimized MABR oxygen stratification process.

[0094] Monolithic MABR system (see) Figure 4 ):

[0095] In the MABR unit (1), wastewater is pumped into the unit by the water pump (7) and a biofilm is cultivated on the aeration membrane assembly (2). The biofilm with an oxygen concentration gradient is formed on the surface of the biofilm by the gas mass flow meter (4) on the aeration pump (3), the dissolved oxygen sensor (5), and the pH sensor (6), and is divided into aerobic zone, anoxic zone and anaerobic zone from the inside out.

[0096] The method is carried out according to the following steps:

[0097] S1: The mineral processing wastewater containing ethyl nitrogen is fed into the MABR reactor, and the membrane aeration pressure is controlled to make the biofilm circulate in sequence with different dissolved oxygen concentrations, so as to achieve efficient enrichment of functional bacteria.

[0098] Within the MABR reactor, the following DO timing control is performed cyclically according to the hydraulic retention time T:

[0099] S2: High Dissolved Oxygen Stage (Duration T1 hours): The membrane aeration pressure is controlled (11–20 psi) to maintain the DO concentration in the reactor liquid at 3.0–6.0 mg / L, enhancing the hydrolysis of ethyl thiocyanate, the diethylamine oxidation-ammoniation reaction, the ammonia oxidation reaction, and the rapid oxidation of CS2. During this process, ethyl thiocyanate is hydrolyzed into diethylamine and carbon disulfide, and then diethylamine is oxidized and ammonified to convert into NH4. + -N and ethanol, CS2 is converted into CO2 and H2S gas.

[0100] S3: Normal Dissolved Oxygen Stage (Duration T2 hours): Control the membrane aeration pressure (4-10 psi) to maintain the DO concentration in the reactor liquid at 1.0-2.0 mg / L, inhibit the nitrite nitration reaction, and maintain the oxidation of H2S.

[0101] S4: Low Dissolved Oxygen Stage (Duration T3 hours): Controlling the membrane aeration pressure (1–3 psi) maintains the DO concentration in the reactor liquid at 0.2–0.5 mg / L, promoting the growth of H2S and ethanol-driven denitrifying bacteria, and maintaining the balance between simultaneous nitrification and denitrification, thus minimizing aeration energy consumption; NH4 + -N undergoes nitrification during this process to generate nitrate nitrogen / nitrite nitrogen, which is then reduced to N2 through subsequent denitrification.

[0102] Where T = T1 + T2 + T3, and T1 = 2 - 4 hours; T2 = 2 - 4 hours; T3 = 4 - 16 hours.

[0103] S5: Through long-term stable operation (hydraulic retention time is 8 hours), the effluent ethyl nitrogen is <1 mg / L (removal rate >99%), the effluent ammonia nitrogen is <1 mg / L (removal rate >99%), the effluent total nitrogen is <4 mg / L (removal rate >70%), and the effluent COD is <20 mg / L (removal rate >78%). Figure 5 As shown in the figure, the aeration energy consumption is reduced by 20% compared with constant DO operation, and no external carbon source needs to be added.

[0104] The influent ethyl nitrogen concentration in the above-mentioned mineral processing wastewater containing ethyl nitrogen is 45-50 mg / L, the ammonia nitrogen concentration is 4-5 mg / L, the total nitrogen concentration is 10-13 mg / L, and the COD concentration is 90-110 mg / L.

[0105] Unless otherwise defined, all technical and scientific terms used throughout this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning as stated in this application or derived from the content described herein shall prevail. Furthermore, the terminology used in this description is for the purpose of describing embodiments of this application only and is not intended to limit this application.

Claims

1. A method for synergistic oxidation-reduction coupling treatment of ethyl thiocyanate-CNS in mineral processing wastewater based on MABR oxygen stratification process optimization, characterized in that, Includes the following steps: S1 Influent: Mineral processing wastewater containing ethyl nitrogen is fed into the MABR reactor, and the following DO timing control is performed according to the hydraulic retention time T: S2 High Dissolved Oxygen Stage: Controlling the membrane aeration pressure to 11~20 psi maintains the DO concentration in the reactor solution at 3.0~6.0 mg / L, to rapidly achieve the hydrolysis of ethyl thiocyanate into diethylamine and CS2, and the oxidation-ammoniation of diethylamine into NH4. + -N and ethanol, CS2 oxidation to CO2 and H2S, and ammonia oxidation reaction; duration T1 is 2~4 h; S3 Normal Dissolved Oxygen Stage: Reduce the membrane aeration pressure to 4~10 psi to maintain the DO in the reactor solution at 1.0~2.0 mg / L, so as to inhibit the nitrite nitrification reaction and maintain the oxidation of CS2; the duration T2 is 2~4 h; S4 Low Dissolved Oxygen Stage: The membrane aeration pressure is further reduced to 1-3 psi, maintaining the dissolved oxygen (DO) in the reactor at 0.2-0.5 mg / L. This utilizes the ethanol and H2S generated in stages S2 and S3 as endogenous electron donors to drive denitrification. + -N undergoes nitrification to produce nitrate nitrogen and / or nitrite nitrogen, which are subsequently reduced to N2 by denitrification, thus completing nitrification-denitrification simultaneously; Duration T3 is 4~16 hours; Where T = T1 + T2 + T3, and T is 8~24 h; When the ethyl nitrogen concentration in the mineral processing wastewater is >50 mg / L, the anaerobic reactor is automatically started, and the effluent from the MABR reactor is introduced into the anaerobic reactor to enhance denitrification and nitrogen removal by combining the carbon source, endogenous H2S and ethanol in the mineral processing wastewater, forming an "anaerobic-MABR" coupling mode. When the ethyl nitrogen concentration in the ore wastewater is ≤50 mg / L, the anaerobic reactor is shut down, and only the single MABR reactor is operated to complete the entire ethyl nitrogen-CNS synergistic oxidation-reduction process, forming a single MABR mode.

2. The method according to claim 1, characterized in that, The effluent from the MABR reactor is recycled back to the anaerobic reactor at a reflux ratio of 100% to 300%.

3. The method according to claim 1 or 2, characterized in that, The DO setpoints of the solutions in the reactors at each stage (S2-S4) are dynamically adjusted via a real-time feedback system. The input parameters of this real-time feedback system include: the ethyl nitrogen concentration in the mineral processing wastewater and the NH4+ concentration in the effluent from the MABR reactor. + NO x - and TN concentration.

4. A system for implementing the method of ethyl thiocyanate-CNS synergistic redox coupling treatment according to any one of claims 1 to 3, characterized in that, include: M ABR reactor (1): Mineral processing wastewater is pumped into MABR reactor (1) through water pump (7) and a biofilm is cultivated on aeration membrane module (2). The formation of a biofilm with an oxygen concentration gradient on the aeration membrane module (2) is controlled by the gas mass flow meter (4), dissolved oxygen sensor (5) and pH sensor (6) on the aeration pump (3). The biofilm is divided into aerobic zone, anoxic zone and anaerobic zone from the inside to the outside. The control box (14) and the gas mass flow meter (4) form a timing control system to execute the DO timing of S2-S4. Anaerobic reactor (9): The mineral processing wastewater containing ethyl thionione is pumped into the anaerobic reactor (9) through the inlet pump (12). The effluent from the MABR reactor (1) is returned to the anaerobic reactor (9) through the return pump (13). The dissolved oxygen concentration and pH are controlled by the dissolved oxygen sensor (5) and the pH sensor (6). The high-concentration ethyl thionione wastewater is pretreated by ammoniation and the effluent from the MABR reactor (1) is enhanced by denitrification using the stirrer (10) and the anaerobic biofilm carrier (11). An adaptive switching valve assembly is used to automatically select either the standalone MABR mode or the "anaerobic-MABR" coupled mode based on the ethyl thiocyanate concentration in the mineral processing wastewater.

5. The system according to claim 4, characterized in that, In the anaerobic reactor (9), the effluent recirculation ratio of the MABR reactor (1) is 100%~300%.

6. The system according to claim 4, characterized in that, The anaerobic reactor (9) is selected from one of the following: upflow anaerobic sludge blanket (UASB), anaerobic moving bed biofilm reactor (AMBBR), or expanded granular sludge blanket (EGSB).

7. The system according to claim 4, characterized in that, The anaerobic biofilm carrier (11) is made of polyethylene, polypropylene, modified polyethylene material, modified polypropylene material, or polyurethane foam, with a specific gravity of 0.95~1.05 g cm⁻¹. -3 This ensures thorough mixing with water.

8. The system according to claim 4, characterized in that, The aeration method of the MABR reactor (1) is bubble-free aeration using hollow fiber membrane, and the membrane material is a hydrophobic polymer.

9. The system according to claim 4, characterized in that, The membrane aeration pressure of the MABR reactor (1) is 1~20 psi, the hydraulic retention time is 8~24 h, and the pH control range is 6.5~8.5.

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