Water supply nitrate treatment system and method based on dynamic sulfur cycle and fuel cell

Abstract

The invention relates to a water supply nitrate treatment system and method based on dynamic sulfur circulation and a fuel cell, the water supply nitrate treatment system comprises at least one level of standardization unit, the standardization unit is provided with an SR reactor for stage I reaction and an SRR reactor for stage II reaction which are connected in series, and at least one self-generating MFC module is arranged between the SR reactor and the SRR reactor; and the intelligent control unit is used for controlling each facility in the standardization units and centrally controlling the standardization units. According to the invention, internal circulation of sulfur elements and efficient removal of nitrate are realized through a double-stage dynamic sulfur circulation mechanism, the efficient MFC module is coupled to recover reaction chemical energy, and the intelligent control unit is utilized to realize self-adaptive operation of the system and the modular reactor group provides flexible expansion capability.

Description

Technical Field

[0001] The present invention relates to a system and method for treating nitrate in water supply based on dynamic sulfur circulation and fuel cells, a system and method for purifying and treating drinking water, and a system and method for treating excessive nitrate in rural drinking water based on dynamic sulfur circulation and microbial fuel cells. Background Art

[0002] Nitrate pollution is a major challenge facing the global water environment. According to the United Nations Environment Programme, approximately 10% of the world's groundwater has nitrate concentrations exceeding 50 mg / L, posing a serious threat to human health and ecosystem stability. Existing equipment for removing nitrate from groundwater is categorized by scale: large-scale drinking water treatment equipment for urban water plants, including specialized denitrification equipment, and smaller denitrification devices designed specifically for supplying water to small, relatively isolated villages.

[0003] Existing small-scale denitrification water supply devices mainly use sulfur autotrophic denitrification technology. This denitrification water supply device has design defects: the sulfur circulation process lacks effective regulation, resulting in sulfate accumulation; sulfur autotrophic denitrification and sulfate reduction processes are difficult to coordinate efficiently. Sulfate secondary pollution is serious: Sulfur autotrophic denitrification inevitably produces sulfate, and the lack of effective control measures leads to its large accumulation (>200mg / L). Sulfur resources are not recycled: sulfur element is not formed Ineffective closed-loop circulation leads to sulfur consumption or byproduct accumulation. High operating energy consumption or high costs: Physicochemical technologies are energy-intensive; sulfur autotrophy requires the addition of alkali; hydrogen autotrophy requires a catalyst; and heterotrophy requires a carbon source. Poor tolerance to water quality fluctuations: Existing small-scale desulfurization systems are mostly fixed structures. Due to their small overall capacity, when groundwater levels fluctuate significantly (5-100 mg / L), the system cannot absorb the changes within its own capacity. Consequently, a new system must be redesigned and rebuilt, incurring significant costs and delaying water quality treatment, causing some harm to users. This inability to adapt to large-scale water quality fluctuations is particularly prominent in remote areas, such as mountainous areas. Due to the complex and variable groundwater systems in mountainous areas, excessive human development and industrial production can cause groundwater changes. How to quickly and cost-effectively respond to large sulfate fluctuations in groundwater while effectively addressing sulfate accumulation, high energy consumption, poor shock load resistance, and sulfur resource recycling and efficient energy recovery in sulfur autotrophic denitrification is a challenge that needs to be addressed. Summary of the Invention

[0004] To overcome the challenges of existing technologies, the present invention proposes a water supply nitrate treatment system and method based on a dynamic sulfur cycle and fuel cell system. This system and method utilizes a two-stage dynamic sulfur cycle mechanism to achieve internal sulfur circulation and efficient nitrate removal. This system and method utilizes a highly efficient MFC module to recover chemical energy from the reaction. Furthermore, an intelligent control unit enables adaptive system operation and a modular reactor system provides flexible expansion capabilities.

[0005] The objectives of the present invention are achieved as follows: a water supply nitrate treatment system based on a dynamic sulfur cycle and a fuel cell, comprising: at least one level of standardized units connected in parallel or series, wherein the standardized unit is provided with an SR reactor for performing a stage I reaction and an SRR reactor for performing a stage II reaction connected in series, at least one self-generating MFC module is provided between the SR reactor and the SRR reactor, and an intelligent control unit is provided for operating various facilities within the standardized unit and for centrally controlling multiple standardized units; the SR reactor, the SRR reactor and the MFC module, as well as the standardized units, are connected via pipelines with valves and standardized interfaces;

[0006] The SR reactor is provided with a water inlet connected to a pressure water source at the bottom and a water outlet connected to an SRR water inlet at the top. The SR reactor is filled with elemental sulfur particles with a particle size of 2-5 mm, with a filling rate of 40%;

[0007] The SRR reactor is provided with a water inlet at the top and a water outlet at the bottom. The SRR reactor is filled with anaerobic sludge and zero-valent iron particles with a particle size of 1-3 mm, and the zero-valent iron filling rate is 30%;

[0008] The SR reactor and SRR reactor are independently equipped with fans and aeration plates, as well as independent reagent dosing metering pumps;

[0009] The MFC module includes an anode chamber with an anode and a cathode chamber with a cathode, a proton exchange membrane is provided between the anode chamber and the cathode chamber, the anode chamber is connected to the SR reactor through a pipeline, and the cathode chamber is connected to the SRR reactor through a pipeline;

[0010] The intelligent control unit is provided with a detector, a parameter regulator, a control operator and an alarm. The detector is connected to the sensor network, and the parameter regulator is connected to the aeration volume regulator, the sulfur dosage regulator and the iron-reducing bacteria dosage regulator.

[0011] Furthermore, a gas circulation pipeline is provided between the SR reactor and the SRR reactor to promote the transfer of sulfur oxidation products.

[0012] Furthermore, a static mixer is provided on the connecting pipes between the standardized units.

[0013] Furthermore, the anode chamber of the MFC module: uses a titanium mesh modified with nitrogen-doped carbon nanotubes as the anode substrate, and the anode is loaded with electrogenic microorganisms. The anode chamber is either integrated into the SR reactor or provided as an independent chamber to treat a liquid stream containing organic matter or nitrite;

[0014] The cathode chamber uses porous carbon cloth as a substrate, loads a platinum catalyst, and is filled with conductive biochar filler to increase the reaction area and promote electron transfer. The cathode chamber is either integrated in the SRR reactor or set as an independent chamber.

[0015] Furthermore, the intelligent control unit is provided with a human-computer interaction interface including: a real-time monitoring area, a parameter adjustment area, a control logic area, and an alarm prompt area;

[0016] The real-time monitoring area dynamically displays parameters including: pH value, ORP, sulfate concentration, and nitrate concentration;

[0017] The parameter adjustment area is provided with adjustment buttons and adjustment sliders, including: an aeration volume adjustment knob, a sulfur addition acceleration slider, and an iron-reducing bacteria addition frequency adjustment setting slider;

[0018] The control logic area is provided with a switching nitrate nitrogen concentration threshold setting program;

[0019] The alarm prompt area is provided with a sulfate concentration threshold setting program for alarm and a threshold exceeding alarm indication.

[0020] A method for treating nitrate in water supply based on dynamic sulfur circulation and fuel cells using the above system, the steps of the method are as follows:

[0021] Step 1: Set the initial operating parameters: The initial operating parameters include: the aeration rate of the SR reactor and the SRR reactor, the sulfur addition rate, the iron-reducing bacteria addition frequency, the nitrate nitrogen concentration threshold for switching, and the sulfate concentration threshold for alarm;

[0022] Step 2, start and test the raw water: start the water source, and conduct online real-time testing of the raw water at the water inlet of the SR reactor: pH value; redox potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration;

[0023] Step 3, Operation Mode Phase I: Anaerobic sulfur autotrophic denitrification in the SR reactor: Shut off the aeration of the SRR reactor and start the gas circulation between the SR and SRR reactors; Nitrate-containing raw water enters the SR reactor. Under anaerobic conditions, sulfur particles act as electron donors, and nitrate is reduced to nitrite by microorganisms. During this stage, the MFC anode chamber also generates electricity.

[0024] Step 4, circulation and switching: the intelligent control unit controls the switching between the two stages according to the monitoring parameters. When the SR outlet water NO3 - When the -N concentration is lower than 10 mg / L, the intelligent control unit triggers the stage switch;

[0025] Step 5, Operation Mode Phase II: Microaerobic sulfate reduction and sulfur regeneration in the SRR: Start aeration in the SRR reactor to maintain a microaerobic environment, start gas circulation between the SR and SRR, and the mixed solution containing nitrite and sulfate produced by the SR reactor in Phase I enters the SRR reactor; Aeration optimization control: Based on the real-time monitoring values ​​of redox potential and dissolved oxygen, the intelligent control unit dynamically adjusts the aeration rate of the SRR reactor to stabilize the dissolved oxygen within the target range;

[0026] In the SRR, sulfate-reducing bacteria use hydrogen produced by zero-valent iron corrosion or directly use zero-valent iron as an electron donor to reduce sulfate to sulfide. The generated sulfide reacts with elemental sulfur transferred through gas circulation or liquid phase to regenerate elemental sulfur particles or polysulfide. Ultimately, it precipitates or adheres to regenerate in the presence of iron. Zero-valent iron acts as an electron intermediary to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber also generates electricity.

[0027] Step 6, sulfate feedback regulation: When SO4 is detected in the SRR reactor or in the effluent 2- When the concentration exceeds the limit, the controller triggers the "iron-reducing bacteria activation program" and starts the metering pump to pulse-feed Fe to the SRR reactor. 2+ solution to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction;

[0028] Step 7, output detection: Perform online real-time detection of the SRR reactor outlet: pH value; redox potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; based on the test results, determine: either allow the water to enter the drinking water system, return to the SR reactor inlet for further treatment, or enter the next standardization unit for further treatment.

[0029] Furthermore, the MFC power generation process:

[0030] In stage I, anode microorganisms oxidize sulfur or intermediates in the anaerobic environment of SR, producing electrons and protons; electrons are transferred to the cathode through an external circuit, and protons migrate to the cathode through the proton exchange membrane; in stage II, in the microaerobic environment of SRR, oxygen accepts electrons and combines with protons to be reduced to water.

[0031] The advantages and beneficial effects of the present invention include: It utilizes a two-stage dynamic sulfur circulation mechanism to achieve internal sulfur circulation and efficient nitrate removal, coupled with a high-efficiency MFC module to recover reaction chemical energy, and utilizing an intelligent control unit to enable adaptive system operation and flexible expansion capabilities for modular reactor groups. This two-stage dynamic circulation mechanism offers the advantage of utilizing generator tanks of identical physical shape, connected by piping to form standardized units. These standardized units can then be flexibly combined in series, parallel, or other combinations to accommodate a wide range of fluctuations in the desulfurization system, cleverly resolving the difficulty of adjusting system capacity due to significant groundwater fluctuations. Through this flexible combination, the system can accommodate drinking water treatment for both thousands of people and tens or even dozens of people, providing an excellent solution. This two-stage circulation approach not only addresses the problems of sulfate accumulation, high energy consumption, poor shock load resistance, and sulfur resource recycling in sulfur autotrophic denitrification, but also leverages the separation of sulfur autotrophic denitrification and sulfur regeneration reactions to couple with biobatteries, feeding back into the system's own power supply, reducing operating costs while being more environmentally friendly. The present invention significantly reduces sulfate secondary pollution: through the innovative two-stage dynamic sulfur cycle mechanism, the sulfur element is The recycling within the system realizes the closed loop of sulfur, which is different from the traditional single reaction and greatly reduces the net generation of sulfate (60%-80% lower than the traditional sulfur autotrophic denitrification). 2- The concentration is stably lower than 50 mg / L, which meets the requirements of the "Groundwater Quality Standard" (GB / T14848-2017). At the same time, this mechanism avoids a strongly acidic environment and does not require additional alkalinity neutralization. The present invention also has excellent shock load resistance: modular design combined with intelligent control enables the system to effectively adapt to the wide range of fluctuations in nitrate concentration in the water supply source (5-100 mg / L) by adjusting the number of series stages (changing the total HRT hydraulic retention time) and real-time optimization of operating parameters (aeration, agent addition, mode switching). At the same time, it avoids secondary pollution from organic carbon sources: the core process is based on sulfur autotrophic and hydrogen autotrophic (iron corrosion hydrogen production) processes, and there is no need to add exogenous organic carbon sources, eliminating the risk of increased effluent COD caused by heterotrophic denitrification. The effluent COD can be controlled at <10 mg / L. And no high-salinity wastewater is produced: Unlike physical and chemical technologies such as reverse osmosis and ion exchange, the biochemical process of this system does not produce high-salinity concentrated wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the accompanying drawings and examples.

[0033] Figure 1 This is a schematic diagram of the standardized units in parallel of the system according to the first embodiment of the present invention;

[0034] Figure 2This is a schematic diagram of the standardized units connected in series in the system according to the first embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the standardized series and parallel connection of units of the system according to the first embodiment of the present invention;

[0036] Figure 4 is a schematic structural diagram of a standardized unit of the system according to the first embodiment of the present invention;

[0037] Figure 5 Schematic diagram of the MFC module structure of the standardized unit of the system according to the first embodiment of the present invention;

[0038] Figure 6 Schematic diagram of the human-computer interaction interface of the system according to the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0039] Example 1:

[0040] This embodiment is a water supply nitrate treatment system based on dynamic sulfur cycle and fuel cell, such as Figure 1-6 This embodiment includes: at least one parallel connection (such as Figure 1 As shown, Figure 1 In the example, three standardized units are connected in parallel) or in series (e.g. Figure 2 As shown, Figure 2 In the example, four standardized units are connected in series) or in parallel and in series (e.g. Figure 3 As shown, Figure 3 There are three parallel circuits in the system, and each circuit consists of two standardized units connected in series). This series, parallel or series-parallel method forms a flexible water supply nitrate treatment system, which is particularly suitable for the needs of medium and small drinking water treatment in rural areas. Expansion method: Multiple standardized units are quickly connected through standardized interfaces such as flanges (such as DN500) or quick-release clamps. Static mixers (velocity gradient G value is about 300S) are set in the inter-stage connecting pipes of each standardized unit. -1 ) to enhance the mixing and transfer of substances in the water flow.

[0041] The standardized unit (such as Figure 4(as shown) is provided with an SR reactor 1 for carrying out stage I reaction and an SRR reactor 2 for carrying out stage II reaction, which are connected in series. At least one self-generating MFC module 3 is provided between the SR reactor and the SRR reactor, as well as an intelligent control unit for manipulating various facilities in the standardized unit and centrally controlling multiple standardized units; the SR reactor, SRR reactor and MFC module, as well as the standardized units are connected by pipelines with connecting valves 4 and standardized interfaces. In order to achieve modularization, this embodiment particularly emphasizes unifying the interfaces of all pipelines into standardized interfaces of two or three calibers, such as the standard flange DN500. In addition to the flange (DN500) connection, the modular reactor units at each level can be connected with a clamp-type quick-connect structure (pressure rating ≥1.6MPa) to facilitate quick installation and disassembly. Valves usually use electrically controlled valves, which can be various forms of valves such as slide valves, butterfly valves, and rotary core valves. Since the liquid being treated has a certain acidity, the pipelines and valves need to be corrosion-resistant devices.

[0042] The three main parts of the standardized unit described in this embodiment are: an SR reactor, an SRR reactor, and a self-generated MFC module. The shape, internal structure, position and standard of the connection ports of the reaction tanks of the SR reactor and the SRR reactor can be exactly the same, and the SR reactor and the SRR reactor are formed only by connecting pipes and filling the reaction materials inside. Since it is a non-pressure tank, more connection ports can be reserved to facilitate more forms of pipe connection and provide more combination forms. The reference size of the tank is Φ500mm in diameter × 2000mm in height, and it is made of corrosion-resistant materials such as stainless steel or carbon fiber.

[0043] The SR reactor (Sulfur Reduction Reactor is a sulfur autotrophic denitrification reactor) is provided with a water inlet 101 connected to a pressure water source at the bottom, and is equipped with a water inlet valve 102. The pressure water source is either a booster water pump or a standard unit of the upper level. The top of the SR reactor is provided with a water outlet 103 connected to the SRR water inlet 201, and is equipped with a connecting valve and a static mixer. Since the water inlet is at the bottom and the water outlet is at the bottom, the water flow in the SR reactor is from bottom to top, which can better enable the water flow to fully contact the reactants and form a good reaction process. The SR reactor is filled with elemental sulfur granules with a particle size of 2-5mm, and the filling rate is 40%. In addition to elemental sulfur particles (S 0 ), sodium thiosulfate (Na2S2O3) crystals with a particle size of 1-3 mm can also be used as a sulfur source to achieve sulfur autotrophic denitrification (producing sulfate and sulfur) in the SR reactor, and the subsequent sulfur cycle regeneration stage still needs to be entered.

[0044] The SRR reactor (Sulfur Reduction and Regeneration Reactor) is provided with a water inlet at the top and a water outlet 202 at the bottom, and is equipped with a water outlet valve 203. The SRR reactor is filled with anaerobic sludge (mixed liquid suspended solids concentration MLSS is 8-12g / L) and zero-valent iron particles with a particle size of 1-3mm, with a zero-valent iron filling rate of 30%. In addition to the zero-valent iron particles (Fe 0 ), it is also possible to consider using ferrous sulfate (FeSO4) or ferrous chloride (FeCl2) solution to be continuously or intermittently added to the SRR reactor as an electron donor for sulfate reduction or an activator of iron-reducing bacteria, but the dosing strategy needs to be optimized to avoid excessive introduction of iron ions.

[0045] The nitrate removal rate of the single-stage unit is ≥85%, and the sulfur regeneration rate is ≥70%.

[0046] The reaction equation is:

[0047] SO4 2- +8e - +10H + →H2S+4H2O (sulfate reduction)

[0048] 3H2S+2Fe 0 →2FeS+S 0 +3H2(sulfur regeneration precipitation)

[0049] The SR reactor and SRR reactor are each equipped with a blower and aeration tray, as well as independent reagent dosing facilities. The blower can be a Roots blower with a pressure of 30 kPa. The reagent dosing facility can be a metering pump with an accuracy of ±1%.

[0050] The MFC (Microbial Fuel Cell) module includes an anode chamber 302 with an anode 301 and a cathode chamber 304 with a cathode 303. A proton exchange membrane 305 is provided between the anode chamber and the cathode chamber. The anode chamber is connected to the SR reactor through a pipeline, and the cathode chamber is connected to the SRR reactor through a pipeline. Figure 5 shown.

[0051] This embodiment integrates a high-efficiency microbial fuel cell (MFC) with an integrated structure for energy recovery. The MFC anode is integrated with a sulfur recycling unit (specifically, SR reactor stage I), utilizing the chemical energy of sulfur / sulfide oxidation to generate electricity. The MFC cathode is integrated with a sulfur recycling unit (specifically, SRR reactor stage II), utilizing the oxygen reduction reaction to generate electricity.

[0052] Microbial fuel cells use electrode materials with high specific surface area and high catalytic activity (nitrogen-doped carbon nanotubes modified titanium mesh anode, platinum / carbon cloth cathode) and conductive biochar filler. Microbial fuel cells can use a multi-stage (such as three-stage) series design to significantly improve the output voltage (0.9-1.2V) and power density (5-8W / m 3 ), so that it can effectively recover energy.

[0053] The intelligent control unit centrally controls the operation within all standardized units and coordinates the operation between the various standardized units. The intelligent control unit is provided with a detector for monitoring various parameters during operation, a regulator for adjusting and setting various parameters, a control operator, and an alarm for exceeding the threshold and requiring adjustment. The detector is connected to the sensor network distributed in various parts of the system, and the parameter regulator, aeration volume regulator, sulfur dosage regulator, and iron-reducing bacteria dosage regulator are connected. The intelligent control unit is provided with a human-computer interaction interface, through which the entire system is monitored in real time, parameters are adjusted, operation is controlled, and alarms are given. The human-computer interaction interface can be an electronic display screen, as well as virtual buttons, knobs, sliders, and operation dialog boxes on the electronic display screen, or physical buttons, knobs, sliders, in conjunction with the threshold setting program on the electronic display screen.

[0054] In order to form a closed gas circulation channel and promote the transfer of sulfur oxidation products (SO2, etc.) between reactors, a gas circulation pipeline can be set up: a connecting pipe is set at the top of the SR reactor and the SRR reactor.

[0055] The working principle of this embodiment is: two-stage intermittent operation mode:

[0056] Phase I, anaerobic sulfur autotrophic denitrification - carried out in SR: turn off the aeration of the SRR reactor to maintain an anaerobic environment. Start the gas circulation between the SR reactor and the SRR reactor. Let the raw water containing nitrates enter the SR reactor. Under anaerobic conditions, sulfur particles (S 0 ) as electron donor, nitrate (NO3 - ) is reduced to nitrite (NO2 - ). During this stage, the anode chamber of the MFC module generates electricity synchronously.

[0057] Phase II, microaerobic sulfate reduction and sulfur regeneration, is performed in the SRR: Aeration is initiated in the SRR reactor (the air volume can be set within a range of 0.8-1.2 L / min) to maintain a microaerobic environment, such as maintaining a dissolved oxygen (DO) level between 0.5-2.0 mg / L. Gas circulation is initiated between the SR and SRR reactors. The effluent / mixed liquor containing nitrite and sulfate produced in Phase I by the SR reactor enters the SRR reactor.

[0058] In SRR, sulfate-reducing bacteria utilize zero-valent iron (Fe 0 ) Hydrogen produced by corrosion or directly using Fe 0 As an electron donor, sulfate (SO4 2- ) is reduced to sulfide (S 2- ). The generated S 2- The elemental sulfur (S 0 , which may come from the SR reactor or externally) to regenerate elemental sulfur particles (S 0 ) or polysulfide, and finally precipitates or adheres to regenerate in the presence of iron. 0 ) acts as an electron intermediary to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber can also generate electricity.

[0059] Cycle and switch: The intelligent control unit will detect and control the water according to the monitoring parameters (such as SR outlet NO3 - -N concentration) controls the switching between the two stages (by controlling aeration start and stop, valve switching, etc.).

[0060] The core of this embodiment is to separate the nitrate removal process into two physically or logically distinct stages: Stage I: anaerobic sulfur autotrophic denitrification in the SR; Stage II: microaerobic iron-mediated sulfate reduction and sulfur regeneration in the SRR. Intermittent aeration control (aeration is turned on in Stage II to maintain microaerobic conditions) is used as a key means to switch and maintain different reaction conditions (anaerobic vs. microaerobic). Zero-valent iron (Fe 0 ) acts as an electron mediator to accelerate sulfate reduction and promote the generation of S 2- Regeneration of S with sulfur source (from stage I or supplement) 0 , forming sulfur The internal circulation closed loop is the core of solving the problem of sulfate accumulation.

[0061] This embodiment is based on the adaptive intelligent control strategy of multi-parameter feedback. The core is to - -N,SO4 2- , pH, ORP, DO) real-time feedback, automatic control of the operation mode switch (stage I / II). When the sulfate concentration exceeds the limit (> 50mg / L), the Fe 2+ A pulse dosing program activates sulfate-reducing bacteria. Dynamically optimizes aeration based on ORP / DO. Fast-response (≤ 3 minutes) control algorithms (such as multi-dimensional PID) are used to achieve this precise control.

[0062] The design and expansion of the modular reactor group of this embodiment can be standardized. The reactor unit (Φ500×2000mm) can be designed. 1-5 stages are connected in series horizontally through flanges or clamps. Static mixers (G≈300S -1 ) to enhance mass transfer. This design directly supports the system's ability to withstand water quality fluctuations (5-100mg / L) and its flexible scalability.

[0063] Example 2:

[0064] This embodiment is an improvement of the first embodiment and a refinement of the first embodiment regarding the gas circulation pipeline. In this embodiment, a gas circulation pipeline 5 and a gas valve 501 are provided between the SR reactor and the SRR reactor to promote the transfer of sulfur oxidation products. Figure 4 shown.

[0065] Gas circulation pipeline: inner diameter 50mm, connecting the top space of SR and SRR reactors to form a closed gas circulation channel, and sulfur-containing gases such as sulfide are transferred between the reactors.

[0066] Example 3:

[0067] This embodiment is an improvement of the above embodiment and a refinement of the above embodiment regarding the standardized units. Static mixers are provided on the connecting pipes between the standardized units described in this embodiment.

[0068] The static mixer can use a velocity gradient G value of about 300S -1 , to enhance the mixing and transfer of substances in the water flow.

[0069] Example 4:

[0070] This embodiment is an improvement of the above embodiment and a refinement of the above embodiment regarding the MFC module. The anode chamber of the MFC module described in this embodiment uses a titanium mesh modified with nitrogen-doped carbon nanotubes as the anode substrate (specific surface area ≥ 120 m 2 / g), the anode is loaded with electrogenic microorganisms (such as Geobacter spp.), and the anode chamber is either integrated into the SR reactor (corresponding to stage I) or set up as an independent chamber to treat the liquid flow containing organic matter or nitrite. The anode material can also be replaced: graphene-modified nickel foam (specific surface area ≥ 200m 2 / g) instead of nitrogen-doped carbon nanotube-modified titanium mesh as the MFC anode substrate.

[0071] The cathode chamber is a porous carbon cloth substrate loaded with platinum (Pt) catalyst (load 0.5 mg / cm 2) is filled with conductive biochar (particle size 2-5 mm) to increase the reaction area and promote electron transfer. The cathode chamber can be integrated into the SRR reactor (corresponding to Phase II, utilizing oxygen reduction) or set up as a separate chamber. Non-precious metal catalysts (such as Fe-NC catalysts) can also be used in place of platinum (Pt) catalysts in MFC cathodes to reduce costs, but electrode structure optimization may be required to maintain adequate performance.

[0072] Proton exchange membrane: Nafion117 membrane (thickness about 50 μm) is used to separate the anode chamber and the cathode chamber.

[0073] Circuit connection: The anode and cathode are connected through an external circuit, and can be single-stage or multi-stage (usually 2-5 stages) connected in series to increase the output voltage.

[0074] Embodiment 5:

[0075] This embodiment is an improvement of the above embodiment and a refinement of the above embodiment regarding the intelligent control unit. Figure 6 As shown, the intelligent control unit is provided with a human-computer interaction interface including: a real-time monitoring area, a parameter adjustment area, a control logic area, and an alarm prompt area;

[0076] The real-time monitoring area dynamically displays parameters including pH value, ORP (oxidation-reduction potential), sulfate concentration, and nitrate concentration.

[0077] These parameters are monitored in real time through a sensor network consisting of pH sensors, ORP (oxidation-reduction potential) sensors, sulfate concentration sensors, and nitrate concentration sensors installed at key locations of the system, such as the water inlet and outlet, and displayed on the human-computer interaction interface for the operator's reference.

[0078] The parameter adjustment area features adjustment buttons and sliders, including an aeration volume adjustment knob, a sulfur dosing rate slider, and an iron-reducing bacteria dosing frequency adjustment slider. These knobs and sliders are primarily set during system initialization or manually adjusted during system operation. During normal operation, the system automatically adjusts to achieve optimal operating conditions.

[0079] The control logic area includes an algorithm setup program and a nitrate nitrogen concentration threshold setting program for switching. The control core utilizes a multi-dimensional PID control algorithm (e.g., proportional coefficient Kp = 0.8, integral coefficient Ki = 0.2, and differential coefficient Kd = 0.1) to achieve real-time adjustment of the aforementioned parameters, with a control response time of ≤ 3 minutes. In addition to PID control, advanced control algorithms such as fuzzy control and model predictive control (MPC) can also be used to achieve adaptive optimization of the system.

[0080] The alarm prompt area includes a sulfate concentration threshold setting program for alarm and an alarm indication for threshold over-limit. The threshold can be calculated manually or through a system-installed program that displays the corresponding calculation process through a dedicated dialog box on the interface.

[0081] Example 6:

[0082] The present embodiment is a method for treating nitrate in water supply based on dynamic sulfur circulation and fuel cells using the system described in the above embodiment. The nitrate treatment method described in this embodiment is a two-stage intermittent operation mode, namely: the raw water first enters the SR reactor for anaerobic sulfur autotrophic denitrification, and then undergoes reduction reaction in the SRR reactor alternately and intermittently. This staged reaction can effectively improve the efficiency of anaerobic sulfur autotrophic denitrification and reduction reaction, reduce secondary sulfur pollution of sulfuric acid and avoid secondary pollution of organic carbon sources. What is more clever is that the two-stage different microbial biochemical reactions can be used to form a microbial fuel cell to achieve partial self-sufficiency in energy: the coupled high-efficiency MFC module (using nitrogen-doped carbon nanotube anode, platinum / carbon cloth cathode, conductive biochar filler and multi-stage series structure) significantly improves the electron transfer efficiency and output voltage (0.9-1.2V) and power density (5-8W / m 3 ), which can recycle the chemical energy in the nitrate-sulfide oxidation process, covering 30%-50% of the system's own energy consumption (fans, pumps, controls, etc.). The entire power system has been carefully designed to reduce energy consumption to a minimum. Equipped with solar cells, it can achieve complete self-energy, which is particularly suitable for use in remote rural areas.

[0083] The method described in this embodiment is centered around one standardized unit. If necessary, multiple standardized units can be set up in series to treat raw water, or in order to increase the processing capacity, multiple standardized units can be connected in parallel to treat raw water.

[0084] The specific steps of the method are as follows:

[0085] Step 1, set the initial operating parameters: The initial operating parameters include: the aeration volume of the SR reactor and the SRR reactor, the sulfur addition rate, the iron-reducing bacteria addition frequency, the nitrate nitrogen concentration threshold for switching, and the sulfate concentration threshold for alarm.

[0086] System startup requires setting some parameters based on the raw water quality parameters and past experience.

[0087] Step 2: Turn on and test the raw water: Turn on the water source and conduct real-time online testing of the raw water at the water inlet of the SR reactor (also a standardized unit): pH value (accuracy ±0.1); oxidation-reduction potential (ORP) (accuracy ±10mV); dissolved oxygen (DO) (range 0-20mg / L); nitrate nitrogen (NO3) --N concentration (range 0-100mg / L); sulfate SO4 2- Concentration (range 0-200 mg / L);

[0088] Step 3, Operation Mode Phase I: Anaerobic sulfur autotrophic denitrification in the SR reactor: turn off the aeration of the SRR reactor (to maintain an anaerobic environment), and start the gas circulation between the SR reactor and the SRR reactor (optional); the raw water containing nitrate enters the SR reactor, and under anaerobic conditions, sulfur particles (S 0 ) as electron donor, nitrate (NO3 - ) is reduced to nitrite (NO2 - ), during this stage, the MFC anode chamber generates electricity synchronously;

[0089] Operational performance: The hydraulic retention time (HRT) of a single-stage unit is designed to be 1-2 hours. By adjusting the total HRT by the number of series stages, the system can effectively handle fluctuations in influent nitrate concentration within the range of 5-100 mg / L.

[0090] Step 4, circulation and switching: the intelligent control unit is based on the monitoring parameters (such as SR water NO3 - -N concentration) controls the switching between the two stages; (by controlling aeration start and stop, valve switching, etc.) Mode switching control: When the nitrate nitrogen NO3 in the SR reactor effluent is monitored - When the -N concentration is lower than the set threshold (such as 10 mg / L), the intelligent control unit issues a command to shut down the SRR aeration (preparing to enter Phase I) and switch the relevant valves to direct the SRR effluent to subsequent treatment or reuse, and at the same time fill the SR with new water or start a new cycle; when the nitrate nitrogen NO3 in the SR reactor inlet is monitored - If the -N concentration increases or based on the running time, the controller switches back to Phase II.

[0091] Step 5, Operation Mode Phase II: Microaerobic sulfate reduction and sulfur regeneration in the SRR: Start the aeration of the SRR reactor (gas volume 0.8-1.2 L / min), maintain a microaerobic environment (dissolved oxygen DO is controlled at 0.5-2.0 mg / L), start the gas circulation between the SR and SRR, and the effluent or mixed liquid containing nitrite and sulfate produced by the SR reactor in Phase I enters the SRR reactor; Aeration optimization control: Based on the real-time monitoring values ​​of the redox potential ORP and dissolved oxygen DO, the intelligent control unit dynamically adjusts the aeration volume of the SRR reactor by adjusting the fan frequency or valve opening to stabilize the dissolved oxygen DO within the target range (0.5-2.0 mg / L).

[0092] In SRR, sulfate-reducing bacteria utilize zero-valent iron (Fe 0 ) Hydrogen produced by corrosion or direct use of zero-valent iron Fe0 As an electron donor, sulfate (SO4 2- ) is reduced to sulfide (S 2- ), the sulfide S produced 2- The elemental sulfur (S 0 , which may come from the SR reactor or externally) to regenerate elemental sulfur particles (S 0 ) or polysulfide, and finally precipitated or attached in the presence of iron, zero-valent iron (Fe 0 ) acts as an electron intermediary to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber generates electricity simultaneously.

[0093] Step 6, sulfate feedback regulation: When SO4 is detected in the SRR reactor or in the effluent 2- When the concentration exceeds the limit (e.g. 50 mg / L), the controller triggers the "iron-reducing bacteria activation program" and starts the metering pump to pulse-feed Fe to the SRR reactor. 2+ Solution (such as FeSO4 solution, with a dosing rate of 20-100mgFe 2+ / h) to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction.

[0094] Step 7, output detection: conduct online real-time detection of the outlet of the SRR reactor (also a standardized unit): pH value (accuracy ±0.1); oxidation-reduction potential ORP (accuracy ±10mV); dissolved oxygen DO (range 0-20mg / L); nitrate nitrogen NO3 - -N concentration (range 0-100mg / L); sulfate SO4 2- Concentration (range 0-200mg / L); determined according to the test results: either allow the water to enter the drinking water system (i.e. meet the drinking water standards and can be drunk), or return to the SR reactor water inlet for re-treatment (if the treatment effect does not meet the drinking water standards, if there is no next-level standardization unit, then return to the SR reactor water inlet for re-treatment), or enter the next standardization unit for further treatment (this is when there is a next-level standardization unit, and further treatment is performed when the first treatment does not meet the requirements).

[0095] MFC power generation process:

[0096] In stage I, anode microorganisms oxidize sulfur or intermediates (such as S 2- ), generating electrons and protons; electrons are transferred to the cathode through the external circuit, and protons migrate to the cathode through the proton exchange membrane; in stage II, the cathode is in the microaerobic environment of SRR, and oxygen accepts electrons and combines with protons to be reduced to water.

[0097] The multi-stage series design can increase the output voltage to 0.9-1.2V, and the system output power density can reach 5-8W / m 3 (reactor volume), which can cover 30%-50% of the system's own energy consumption (such as fans, pumps, and control units).

[0098] Comparison between the application examples of the method described in this embodiment and the prior art: The table lists the application examples of the method described in this embodiment. Compared with the conventional technology, the technical performance has been greatly improved.

[0099]

[0100] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and is not limiting. Although the present invention is described in detail with reference to the preferred arrangement scheme, ordinary technicians in this field should understand that the technical solution of the present invention (such as the form of the reactor, controller, sensor, system connection method, sequence of steps, etc.) can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A water supply nitrate treatment system based on dynamic sulfur cycle and fuel cell, characterized in that: include: At least one level of standardized units connected in parallel or series, wherein the standardized unit is provided with an SR reactor for performing a stage I reaction and an SRR reactor for performing a stage II reaction connected in series, at least one self-generating MFC module is provided between the SR reactor and the SRR reactor, and an intelligent control unit is provided for operating various facilities within the standardized unit and for centrally controlling multiple standardized units; the SR reactor, SRR reactor and MFC module, as well as the standardized units, are connected via pipelines with valves and standardized interfaces; The SR reactor is provided with a water inlet connected to a pressure water source at the bottom and a water outlet connected to an SRR water inlet at the top. The SR reactor is filled with elemental sulfur particles with a particle size of 2-5 mm, with a filling rate of 40%; The SRR reactor is provided with a water inlet at the top and a water outlet at the bottom. The SRR reactor is filled with anaerobic sludge and zero-valent iron particles with a particle size of 1-3 mm, and the zero-valent iron filling rate is 30%; The SR reactor and SRR reactor are independently equipped with fans and aeration plates, as well as independent reagent dosing metering pumps; The MFC module includes an anode chamber with an anode and a cathode chamber with a cathode, a proton exchange membrane is provided between the anode chamber and the cathode chamber, the anode chamber is connected to the SR reactor through a pipeline, and the cathode chamber is connected to the SRR reactor through a pipeline; The intelligent control unit is provided with a detector, a parameter regulator, a control operator and an alarm. The detector is connected to the sensor network, and the parameter regulator is connected to the aeration volume regulator, the sulfur dosage regulator and the iron-reducing bacteria dosage regulator.

2. The system according to claim 1, wherein: The SR reactor and the SRR reactor are connected via a gas circulation pipeline to achieve cross-reactor transfer of sulfur oxidation products.

3. The system according to claim 2, characterized in that The connecting pipes between the standardized units are provided with static mixers.

4. The system according to claim 3, characterized in that The anode chamber of the MFC module uses a titanium mesh modified with nitrogen-doped carbon nanotubes as the anode substrate, and the anode is loaded with electrogenic microorganisms. The anode chamber is either integrated into the SR reactor or provided as an independent chamber to treat liquid streams containing organic matter or nitrite. The cathode chamber uses porous carbon cloth as a substrate, loads a platinum catalyst, and is filled with conductive biochar filler to increase the reaction area and promote electron transfer. The cathode chamber is either integrated in the SRR reactor or set as an independent chamber.

5. The system according to any one of claims 1 to 4, characterized in that: The intelligent control unit is provided with a human-computer interaction interface including: a real-time monitoring area, a parameter adjustment area, a control logic area, and an alarm prompt area; The real-time monitoring area dynamically displays parameters including: pH value, ORP, sulfate concentration, and nitrate concentration; The parameter adjustment area is provided with adjustment buttons and adjustment sliders, including: an aeration volume adjustment knob, a sulfur addition acceleration slider, and an iron-reducing bacteria addition frequency adjustment setting slider; The control logic area is provided with a switching nitrate nitrogen concentration threshold setting program; The alarm prompt area is provided with a sulfate concentration threshold setting program for alarm and a threshold exceeding alarm indication.

6. A method for treating nitrate in water supply based on dynamic sulfur cycle and fuel cell using the system of claim 1, characterized in that: The steps of the method are as follows: Step 1: Set the initial operating parameters: The initial operating parameters include: the aeration rate of the SR reactor and the SRR reactor, the sulfur addition rate, the iron-reducing bacteria addition frequency, the nitrate nitrogen concentration threshold for switching, and the sulfate concentration threshold for alarm; Step 2, start and test the raw water: start the water source, and conduct online real-time testing of the raw water at the water inlet of the SR reactor: pH value; redox potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; Step 3, Operation Mode Phase I: Anaerobic sulfur autotrophic denitrification in the SR reactor: Shut off the aeration of the SRR reactor and start the gas circulation between the SR and SRR reactors; Nitrate-containing raw water enters the SR reactor. Under anaerobic conditions, sulfur particles act as electron donors, and nitrate is reduced to nitrite by microorganisms. During this stage, the MFC anode chamber also generates electricity. Step 4, cycle and switch: the intelligent control unit controls the switch between the two stages according to the monitoring parameters; Step 5, Operation Mode Phase II: Microaerobic sulfate reduction and sulfur regeneration in the SRR: Start aeration in the SRR reactor to maintain a microaerobic environment, start gas circulation between the SR and SRR, and the mixed solution containing nitrite and sulfate produced by the SR reactor in Phase I enters the SRR reactor; Aeration optimization control: Based on the real-time monitoring values ​​of redox potential and dissolved oxygen, the intelligent control unit dynamically adjusts the aeration rate of the SRR reactor to stabilize the dissolved oxygen within the target range; In the SRR, sulfate-reducing bacteria use hydrogen produced by zero-valent iron corrosion or directly use zero-valent iron as an electron donor to reduce sulfate to sulfide. The generated sulfide reacts with elemental sulfur transferred through gas circulation or liquid phase to regenerate elemental sulfur particles or polysulfide. Ultimately, it precipitates or adheres to regenerate in the presence of iron. Zero-valent iron acts as an electron intermediary to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber also generates electricity. Step 6, sulfate feedback regulation: When SO4 is detected in the SRR reactor or in the effluent 2- When the concentration exceeds the limit, the controller triggers the "iron-reducing bacteria activation program" and starts the metering pump to pulse-feed Fe to the SRR reactor. 2+ solution to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction; Step 7, output detection: Perform online real-time detection of the SRR reactor outlet: pH value; redox potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; based on the test results, determine: either allow the water to enter the drinking water system, return to the SR reactor inlet for further treatment, or enter the next standardization unit for further treatment.

7. The method according to claim 6, characterized in that The MFC power generation process described: In stage I, anode microorganisms oxidize sulfur or intermediates in the anaerobic environment of SR, producing electrons and protons; electrons are transferred to the cathode through an external circuit, and protons migrate to the cathode through the proton exchange membrane; in stage II, in the microaerobic environment of SRR, oxygen accepts electrons and combines with protons to be reduced to water.

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