A system and method for treating nitrates in water supply based on dynamic sulfur cycle and fuel cell

Abstract

This invention relates to a water nitrate treatment system and method based on dynamic sulfur cycle and fuel cells, comprising: at least one standardized unit, each standardized unit having an SR reactor for stage I reaction and an SRR reactor for stage II reaction connected in series, at least one self-generating MFC module between the SR reactor and the SRR reactor, and an intelligent control unit for operating the various facilities within the standardized unit and for centralized control of multiple standardized units. This invention achieves internal sulfur circulation and efficient nitrate removal through a two-stage dynamic sulfur cycle mechanism, recovers reaction chemical energy through a coupled high-efficiency MFC module, and utilizes the intelligent control unit to achieve adaptive system operation and modular reactor group to provide flexible expansion capabilities.

Description

Technical Field

[0001] This invention relates to a water supply nitrate treatment system and method based on dynamic sulfur cycle and fuel cell, a system and method for drinking water purification and treatment, and a rural drinking water supply nitrate exceeding standard treatment system and method based on dynamic sulfur cycle and microbial fuel cell. Background Technology

[0002] Nitrate pollution is a major challenge facing the global water environment. According to statistics from the United Nations Environment Programme, approximately 10% of the world's groundwater has a nitrate concentration exceeding 50 mg / L, seriously threatening human health and ecosystem stability. Existing equipment for removing nitrates from groundwater can be categorized by scale into large-scale drinking water treatment facilities used in urban water plants, which include dedicated nitrate removal equipment, and smaller devices specifically designed for supplying water to relatively isolated villages with small populations.

[0003] Existing small-scale nitrate-reducing water supply systems primarily employ sulfur autotrophic denitrification technology. This type of system suffers from design flaws: the sulfur cycle lacks effective control, leading to sulfate accumulation; and sulfur autotrophic denitrification and sulfate reduction processes are difficult to coordinate efficiently. Secondary sulfate pollution is severe: sulfur autotrophic denitrification inevitably produces sulfate, and the lack of effective control measures results in its large accumulation (>200 mg / L). Sulfur resources are not recycled: sulfur element is not formed. Effective closed-loop circulation leads to sulfur consumption or byproduct accumulation. High energy consumption or cost: physicochemical technologies are energy-intensive; sulfur autotrophy requires alkali addition; hydrogen autotrophy requires catalysts; heterotrophy requires carbon sources. Poor resistance to water quality fluctuations: Existing small-scale sulfate removal units are mostly fixed structures. Due to their small overall system capacity, when groundwater levels change significantly (5-100 mg / L), the system cannot absorb the changes within its own volume, necessitating redesign and reconstruction. This not only incurs significant costs but also delays water quality treatment and causes some harm to users. Inability to adapt to large-scale water quality changes is particularly prominent in remote areas such as mountainous regions. Due to the complex and variable groundwater systems in mountainous areas, excessive human development and industrial production can alter groundwater. How to quickly and cost-effectively address significant changes in groundwater sulfate levels, while effectively solving the problems of sulfate accumulation, high energy consumption, poor resistance to shock loads, sulfur resource recycling, and efficient energy recovery in sulfur autotrophic denitrification, remains a problem that needs to be solved. Summary of the Invention

[0004] To overcome the problems of existing technologies, this invention proposes a water supply nitrate treatment system and method based on dynamic sulfur cycle and fuel cell. The system and method achieve internal sulfur circulation and efficient nitrate removal through a two-stage dynamic sulfur cycle mechanism, coupled with a high-efficiency MFC module to recover reaction chemical energy, and utilizes an intelligent control unit to achieve adaptive system operation and modular reactor groups to provide flexible expansion capabilities.

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

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

[0007] The SRR reactor is equipped with an inlet at the top and an 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 each independently equipped with a blower and aeration disc, as well as their own independent reagent dosing metering pump;

[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 pipe, and the cathode chamber is connected to the SRR reactor through a pipe.

[0010] The intelligent control unit is equipped with a detector, a parameter regulator, a control arithmetic unit, and an alarm. The detector is connected to a sensor network, and the parameter regulator is connected to an aeration rate regulator, a sulfur dosing regulator, and an iron-reducing bacteria dosing 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 pipe 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 electrogenic microorganisms are loaded on the anode. The anode chamber is either integrated into the SR reactor or set as an independent chamber to treat liquid streams containing organic matter or nitrite.

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

[0015] Furthermore, the intelligent control unit is equipped with a human-machine 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 equipped with adjustment buttons and adjustment sliders, including: an aeration volume adjustment knob, a sulfur addition acceleration rate slider, and an iron reducing bacteria addition frequency adjustment setting slider;

[0018] The control logic area is equipped with a nitrate nitrogen concentration threshold setting program for switching.

[0019] The alarm notification area is equipped with a sulfate concentration threshold setting program for alarms and an alarm indication for threshold over-limit.

[0020] A method for treating nitrates in water supply based on a dynamic sulfur cycle and a fuel cell using the above system, the method comprising the following steps:

[0021] Step 1, set initial operating parameters: Initial operating parameters include: aeration rate of SR reactor and SRR reactor, sulfur addition acceleration rate, iron reducing bacteria addition frequency, nitrate nitrogen concentration threshold for switching, and sulfate concentration threshold for alarm.

[0022] Step 2, Start and test raw water: Turn on the water source and perform online real-time testing of the raw water at the inlet of the SR reactor: pH value; oxidation-reduction potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration;

[0023] Step 3, Operation Mode Phase I: Anaerobic sulfur autotrophic denitrification in the SR reactor: Aeration in the SRR reactor is turned off, and gas circulation between the SR reactor and the SRR reactor is started; raw water containing nitrate enters the SR reactor. Under anaerobic conditions, sulfur particles act as electron donors, and nitrate is reduced to nitrite by microorganisms. During this phase, electricity is generated simultaneously in the MFC anode chamber.

[0024] Step 4, Cycling and Switching: The intelligent control unit controls the switching between the two stages based on monitoring parameters. When SR effluent NO3 - When the -N concentration is below 10 mg / L, the intelligent control unit triggers a phase switch.

[0025] Step 5, Operation Mode Phase II: Micro-aerobic sulfate reduction and sulfur regeneration in SRR: Aeration of the SRR reactor is started to maintain a micro-aerobic environment, and gas circulation between SR and SRR is initiated. The mixed liquid containing nitrite and sulfate produced in 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 keep the dissolved oxygen stable within the target range;

[0026] In SRR: Sulfate-reducing bacteria use hydrogen generated by the corrosion of zero-valent iron 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 polysulfides. Finally, iron is present and precipitates or adheres to regenerate. Zero-valent iron acts as an electron medium to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber generates electricity simultaneously.

[0027] Step 6, Sulfate Feedback Adjustment: When SO4 is detected in the SRR reactor or effluent... 2- When the concentration exceeds the limit, the controller triggers the "iron-reducing bacteria activation program," starting the metering pump to pulse-add Fe to the SRR reactor. 2+ The solution was used to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction.

[0028] Step 7, Output Detection: Perform online real-time monitoring of the SRR reactor outlet: pH value; oxidation-reduction potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; based on the detection results, determine whether the water can be allowed to enter the drinking water system, returned to the SR reactor inlet for further treatment, or sent to the next standardized unit for further processing.

[0029] Furthermore, the aforementioned MFC power generation process:

[0030] In stage I, anodic microorganisms oxidize sulfur or intermediate products in the anaerobic environment of SR, producing 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, 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 this invention are as follows: This invention achieves internal sulfur circulation and efficient nitrate removal through a two-stage dynamic sulfur cycle mechanism, coupled with a high-efficiency MFC module to recover the chemical energy of the reaction, and utilizes an intelligent control unit to achieve adaptive system operation and modular reactor groups to provide flexible expansion capabilities. The advantage of this two-stage dynamic cycle mechanism lies in its ability to utilize generator tanks with identical physical shapes, connected by pipelines to form standardized units. These standardized units can then be flexibly combined in series, parallel, and series-parallel configurations to address the challenges of large-scale changes in the desulfate treatment system, cleverly solving the difficulty of changing system capacity due to significant fluctuations in groundwater. Through flexible combinations, this system can accommodate drinking water treatment for thousands of people, as well as for dozens or even just a few dozen, making it an excellent solution. This two-stage cycle not only solves the problems of sulfate accumulation, high energy consumption, poor shock load resistance, and sulfur resource recycling in sulfur autotrophic denitrification, but also utilizes the separation of sulfur autotrophic denitrification and sulfur regeneration reactions to couple with a bio-battery, feeding back into the system's own power supply, reducing operating costs while being more environmentally friendly. This invention significantly reduces secondary sulfate pollution: through an innovative two-stage dynamic sulfur cycle mechanism, it achieves sulfur element... The system utilizes internal recycling to achieve a closed-loop sulfur production process, unlike traditional single-reaction processes. This significantly reduces net sulfate formation (by 60%-80% compared to traditional sulfur autotrophic denitrification), ultimately resulting in lower SO4 levels in the effluent. 2- The concentration remains consistently below 50 mg / L, meeting the requirements of the "Groundwater Quality Standard" (GB / T14848-2017). Simultaneously, this mechanism avoids a highly acidic environment, eliminating the need for additional alkalinity neutralization. This invention also exhibits excellent resistance to shock loads: the modular design combined with intelligent control allows the system to effectively adapt to wide fluctuations in nitrate concentration (5-100 mg / L) in the water supply source by adjusting the number of series stages (changing the total HRT hydraulic retention time) and optimizing operating parameters in real time (aeration, reagent dosing, mode switching). It also avoids secondary pollution from organic carbon sources: the core process is based on sulfur autotrophy and hydrogen autotrophy (iron corrosion hydrogen production), eliminating the need for external organic carbon sources and mitigating the risk of increased effluent COD from heterotrophic denitrification; effluent COD can be controlled at <10 mg / L. Furthermore, no high-salinity wastewater is generated: unlike reverse osmosis, ion exchange, and other physicochemical technologies, this system's biochemical process does not produce high-salinity concentrated wastewater. Attached Figure Description

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

[0033] Figure 1 This is a schematic diagram of the standardized units in parallel of the system described in Embodiment 1 of the present invention;

[0034] Figure 2This is a schematic diagram of the standardized unit series connection of the system described in Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of the standardized unit series and parallel connection of the system described in Embodiment 1 of the present invention;

[0036] Figure 4 This is a schematic diagram of the standardized unit structure of the system described in Embodiment 1 of the present invention;

[0037] Figure 5 This is a schematic diagram of the MFC module structure of the standardized unit of the system described in Embodiment 1 of the present invention;

[0038] Figure 6 This is a schematic diagram of the human-computer interaction interface of the system described in Embodiment 5 of the present invention. Detailed Implementation

[0039] Example 1:

[0040] This embodiment describes a water nitrate treatment system based on a dynamic sulfur cycle and a fuel cell, such as... Figure 1-6 As shown. This embodiment includes: at least one level of parallel connection (such as...) Figure 1 As shown, Figure 1 It consists of three standardized units connected in parallel or in series (e.g., three standardized units connected in parallel). Figure 2 As shown, Figure 2 (The system consists of four standardized units connected in series) or in parallel plus series (e.g.) Figure 3 As shown, Figure 3 The system consists of three parallel loops, each consisting of two standardized units connected in series. This series, parallel, or series-parallel connection method forms a flexible nitrate treatment system for water supply, particularly suitable for the needs of small and medium-sized drinking water treatment in rural areas. Expansion method: Multiple standardized units can be quickly connected via standardized interfaces such as flanges (e.g., DN500) or quick-connect clamps. A static mixer (velocity gradient G value approximately 300S) is installed in the inter-stage connection pipelines of each standardized unit. -1 This is to enhance the mixing and transfer of substances in the water flow.

[0041] The standardized unit (e.g.) Figure 4As shown, the system includes an SR reactor 1 for stage I reaction and an SRR reactor 2 for stage II reaction, connected in series. At least one self-generating MFC module 3 is located between the SR and SRR reactors. An intelligent control unit is also provided to operate the various facilities within the standardized unit and to centrally control multiple standardized units. The SR reactor, SRR reactor, and MFC module, as well as the standardized units, are connected via pipelines with connecting valves 4 and standardized interfaces. To achieve modularity, this embodiment emphasizes standardizing all pipeline interfaces to two or three different diameters, such as standard flange DN500. Besides flange (DN500) connections, modular reactor units at each level can be connected using clamp-type quick-connect structures (pressure rating ≥1.6MPa) for easy installation and disassembly. Valves are typically electrically controlled valves, including various types such as slide valves, butterfly valves, and rotary valves. Since the liquid being processed has a certain degree of acidity, the pipelines and valves need to be corrosion-resistant.

[0042] The three main components of the standardized unit described in this embodiment are: an SR reactor, an SRR reactor, and a self-generating MFC module. The SR and SRR reactors can have identical external shapes, internal structures, and connection port locations and standards; they are formed solely through pipe connections and the internal reaction materials. Because they are non-pressure tanks, more connection ports can be provided to facilitate various pipe connection methods, thus offering more combination options. The reference tank dimensions are a diameter of Φ500mm × a height of 2000mm, constructed from corrosion-resistant materials such as stainless steel or carbon fiber.

[0043] The SR reactor (Sulfur Reduction Reactor) has an inlet 101 at the bottom connected to a pressurized water source, equipped with an inlet valve 102. The pressurized water source can be a booster pump or a previous standardized unit. The top of the SR reactor has an outlet 103 connected to the SRR inlet 201, equipped with a connecting valve and a static mixer. Because the inlet and outlet are at the bottom, the water flow in the SR reactor is from bottom to top, which allows for better contact between the water and the reactants, forming a favorable reaction process. The SR reactor is filled with elemental sulfur particles with a particle size of 2-5 mm, with a filling rate of 40%. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 0 In addition, 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 then it still needs to enter the sulfur recycling stage.

[0044] The SRR reactor (Sulfur Reduction and Regeneration Reactor) is equipped with an inlet at the top and an outlet 202 at the bottom, along with an outlet valve 203. The SRR reactor is filled with anaerobic sludge (MLSS concentration of 8-12 g / L) and zero-valent iron particles with a particle size of 1-3 mm, with a zero-valent iron filling rate of 30%. (The text also mentions the removal of zero-valent iron particles, but this seems unrelated to the main topic of the SRR reactor.) 0 In addition, ferrous sulfate (FeSO4) or ferrous chloride (FeCl2) solutions can be continuously or intermittently added to the SRR reactor as electron donors for sulfate reduction or activators for iron-reducing bacteria. However, the addition strategy needs to be optimized to avoid excessive introduction of iron ions.

[0045] The single-stage unit has a nitrate removal rate of ≥85% and a sulfur regeneration rate of ≥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 independently equipped with a blower and aeration discs, as well as their own independent reagent dosing system. The blower can be a Roots blower with a pressure of 30 kPa. The reagent dosing system 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 an SR reactor via a pipe, and the cathode chamber is connected to an SRR reactor via a pipe. Figure 5 As shown.

[0051] This embodiment presents an integrated structure for energy recovery coupled with a high-efficiency microbial fuel cell (MFC). The MFC anode is integrated with a sulfur cycle unit (particularly SR reactor stage I) to generate electricity using the chemical energy from sulfur / sulfide oxidation. The MFC cathode is integrated with a sulfur cycle unit (particularly SRR reactor stage II) to generate electricity using the oxygen reduction reaction.

[0052] Microbial fuel cells (MFCs) utilize electrode materials with high specific surface area and high catalytic activity (nitrogen-doped carbon nanotube-modified titanium mesh anode and platinum / carbon cloth cathode) and conductive biochar filler. Multi-stage (e.g., three-stage) series designs can significantly improve the output voltage (0.9-1.2V) and power density (5-8W / m³) of the MFC module. 3 This allows it to effectively recover energy.

[0053] The intelligent control unit centrally controls the operation within all standardized units and coordinates the operation between them. The intelligent control unit is equipped with detectors for monitoring various parameters during operation, regulators for adjusting and setting parameters, a control calculator, and alarms for triggering adjustments when thresholds are exceeded. The detectors are connected to a sensor network distributed throughout the system, and the parameter regulators—aeration rate regulator, sulfur dosing regulator, and iron-reducing bacteria dosing regulator—are also connected. The intelligent control unit has a human-machine interface (HMI) for real-time monitoring, parameter adjustment, operation control, and alarm functions. The HMI can be an electronic display screen with virtual buttons, knobs, sliders, and calculation dialog boxes, or it can consist of physical buttons, knobs, and sliders, along with a threshold setting program displayed on the electronic screen.

[0054] 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: connecting pipes are installed at the top of the SR reactor and the SRR reactor.

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

[0056] Stage I, Anaerobic Sulfotrophic Denitrification – Conducted in the SR reactor: Aeration in the SRR reactor is shut off to maintain an anaerobic environment. Gas circulation between the SR and SRR reactors is initiated. Nitrate-containing raw water is introduced into the SR reactor. Under anaerobic conditions, sulfur particles (S…)… 0 ) as an electron donor, nitrate (NO3) - ) is reduced to nitrite (NO2) by microorganisms - During this stage, the anode chamber of the MFC module generates electricity synchronously.

[0057] Phase II, Microaerobic Sulfate Reduction and Sulfur Regeneration – Conducted in the SRR: Aeration in the SRR reactor is initiated (air flow rate adjustable range: 0.8-1.2 L / min) to maintain a microaerobic environment, such as dissolved oxygen (DO) controlled at 0.5-2.0 mg / L. Gas circulation between the SR and SRR reactors is started. 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 direct utilization of Fe 0 As an electron donor, sulfate (SO4) 2- ) Reduced to sulfide (S 2- The generated S 2- With elemental sulfur (S) transferred through gas circulation or liquid phase 0 (Possibly from an SR reactor or externally added) reaction, regenerating to form elemental sulfur particles (S 0 (or polysulfides) eventually precipitate or adhere and regenerate in the presence of iron. Zero-valent iron (Fe) 0 It acts as an electron intermediary to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber can generate electricity simultaneously.

[0059] Circulation and switching: The intelligent control unit adjusts the switching based on monitored parameters (such as SR effluent NO3). - The switching between the two stages is controlled by the concentration of nitrogen (N-N) (through controlling aeration start / stop, valve switching, etc.).

[0060] The core of this embodiment lies in separating the nitrate removal process into two physically or logically distinct stages: Stage I: anaerobic sulfur autotrophic denitrification within the SR (Self-Rating Regulator); Stage II: microaerobic iron-mediated sulfate reduction and sulfur regeneration within the SRR (Self-Rating Regulator). Intermittent aeration control (maintaining microaerobic aeration during Stage II) is used as the key means to switch and maintain different reaction conditions (anaerobic vs. microaerobic). Zero-valent iron (Fe2+) is utilized. 0 As an electron mediator, it accelerates sulfate reduction and promotes the formation of S. 2- Regenerated into S by reacting with a sulfur source (from stage I or supplement). 0 Sulfur element is formed The internal closed-loop circulation is the core of solving the problem of sulfate accumulation.

[0061] This embodiment is based on an adaptive intelligent control strategy using multi-parameter feedback. The core lies in basing the control strategy on key water quality parameters (NO3). - -N,SO4 2- Real-time feedback of pH, ORP, DO, etc., and automatic control of operating mode switching (Stage I / II). Triggering Fe when sulfate concentration exceeds the limit (>50 mg / L). 2+ A pulse dosing program is used to activate sulfate-reducing bacteria. Aeration rate is dynamically optimized based on ORP / DO. A fast-response (≤3 minutes) control algorithm (such as multidimensional PID) is employed to achieve the precise control described above.

[0062] The modular reactor design and expansion method of this embodiment: Standardized reactor unit design (Φ500×2000mm). 1-5 stages are connected in series laterally via flanges or clamps. Static mixers (G≈300S) are installed between stages. -1 Enhanced mass transfer. This design directly supports the system's ability to withstand water quality fluctuations (5-100 mg / L) and its flexible scalability.

[0063] Example 2:

[0064] This embodiment is an improvement upon Embodiment 1, detailing 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 As shown.

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

[0066] Example 3:

[0067] This embodiment is an improvement on the above embodiment, and is a refinement of the standardization unit in the above embodiment. In this embodiment, a static mixer is provided on the connecting pipe between the standardization units.

[0068] The static mixer can be selected with a velocity gradient G value of approximately 300S. -1 This is to enhance the mixing and transfer of substances in the water flow.

[0069] Example 4:

[0070] This embodiment is an improvement upon the above embodiment, a refinement of the MFC module. In this embodiment, the anode chamber of the MFC module uses a titanium mesh modified with nitrogen-doped carbon nanotubes as the anode substrate (specific surface area ≥ 120 m²). 2 / g), with electrogenic microorganisms (such as Geobacter Spp.) loaded on the anode. The anode chamber is either integrated into the SR reactor (corresponding to stage I) or a separate chamber is set up to treat liquid streams containing organic matter or nitrite. The anode material can also be replaced: graphene-modified nickel foam (specific surface area ≥200m²) can be used. 2 / g) replaces nitrogen-doped carbon nanotube-modified titanium mesh as the MFC anode substrate.

[0071] The cathode chamber uses porous carbon cloth as a substrate and supports a platinum (Pt) catalyst (loading 0.5 mg / cm³). 2The cathode is filled with conductive biochar packing material (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 stage II, utilizing oxygen reduction) or set up as a separate chamber. For MFC cathodes, non-precious metal catalysts (such as Fe-NC catalysts) can also be used to replace platinum (Pt) catalysts to reduce costs, but the electrode structure may need to be optimized to maintain sufficient performance.

[0072] Proton exchange membrane: Nafion 117 membrane (approximately 50 μm thick) 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 connected in series in single or multiple stages (usually 2-5 stages) to increase the output voltage.

[0074] Example 5:

[0075] This embodiment is an improvement upon the above embodiments, and is a refinement of the intelligent control unit in the above embodiments. In this embodiment, as... Figure 6 As shown, the intelligent control unit is equipped with a human-machine 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 by a sensor network consisting of pH sensors, ORP (oxidation-reduction potential) sensors, sulfate concentration sensors, and nitrate concentration sensors installed in key parts of the system, such as the inlet and outlet, and are displayed on the human-machine interface for operators to refer to.

[0078] The parameter adjustment area is equipped with adjustment buttons and sliders, including: an aeration rate adjustment knob, a sulfur dosing acceleration rate slider, and an iron-reducing bacteria dosing frequency adjustment slider. These adjustment knobs and sliders are mainly set during system initialization or manually adjusted during system operation. However, the system can automatically adjust during normal operation to obtain the optimal operating state.

[0079] The control logic area includes an algorithm setting program and a nitrate nitrogen concentration threshold setting program for switching. The control core can achieve real-time adjustment of the above parameters based on a multi-dimensional PID control algorithm (e.g., proportional coefficient Kp = 0.8, integral coefficient Ki = 0.2, derivative coefficient Kd = 0.1), with a control response time ≤ 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 display area includes a sulfate concentration threshold setting program and an alarm indication for threshold exceeding the limit. The threshold can be calculated manually or through a program set in the system, with the calculation process displayed in a dedicated dialog box on the interface.

[0081] Example 6:

[0082] This embodiment describes a method for treating nitrates in water supply based on dynamic sulfur cycle and fuel cells, using the system described in the previous embodiment. The nitrate treatment method in this embodiment employs a two-stage intermittent operation mode: raw water first enters the SR reactor for anaerobic sulfur autotrophic denitrification, and then undergoes an alternating intermittent reduction reaction in the SRR reactor. This staged reaction effectively improves the efficiency of anaerobic sulfur autotrophic denitrification and reduction reactions, reduces secondary sulfur pollution from sulfur hydrochloric acid, and avoids secondary pollution from organic carbon sources. More ingeniously, the two different microbial biochemical reactions can be utilized to construct a microbial fuel cell, achieving partial energy self-sufficiency: the coupled high-efficiency MFC module (using nitrogen-doped carbon nanotube anodes, platinum / carbon cloth cathodes, conductive biochar fillers, and a multi-stage series structure) significantly improves electron transfer efficiency, output voltage (0.9-1.2V), and power density (5-8W / m³). 3 It can recover 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 is carefully designed to minimize energy consumption. With solar cells, it can achieve complete energy self-sufficiency and is particularly suitable for use in remote rural areas.

[0083] The method described in this embodiment focuses on a single standardized unit. If necessary, multiple standardized units can be connected in series to treat raw water, or multiple standardized units can be connected in parallel to treat raw water to increase the treatment capacity.

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

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

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

[0087] Step 2, Start and test raw water: Turn on the water source and perform online real-time testing of the raw water at the 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 0-100 mg / 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: Aeration in the SRR reactor is shut off (to maintain an anaerobic environment), and gas circulation between the SR and SRR reactors is initiated (optional); raw water containing nitrates enters the SR reactor, and under anaerobic conditions, sulfur particles (S… 0 ) as an electron donor, nitrate (NO3) - ) is reduced to nitrite (NO2) by microorganisms - During this stage, the MFC anode chamber generates electricity simultaneously.

[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 through series stages, the system can effectively handle fluctuations in influent nitrate concentration within the range of 5-100 mg / L.

[0090] Step 4, Cycling and Switching: The intelligent control unit adjusts the cycle and switch based on monitoring parameters (such as SR effluent NO3). - -N concentration) controls the switching between two stages; (through controlling aeration start / stop, valve switching, etc.) mode switching control: when nitrate nitrogen (NO3) is detected in the SR reactor effluent. - When the nitrate nitrogen (NO3) concentration is below a set threshold (e.g., 10 mg / L), the intelligent control unit issues a command to shut down the SRR aeration (preparing to enter stage I) and switch relevant valves to direct the SRR effluent to subsequent treatment or reuse, while simultaneously filling the SR with fresh water or starting a new cycle; when the nitrate nitrogen (NO3) concentration in the SR reactor influent is detected... - When the -N concentration increases or based on the running time, the controller switches back to Stage II.

[0091] Step 5, Operation Mode Phase II: Micro-aerobic sulfate reduction and sulfur regeneration in SRR: Start aeration in the SRR reactor (air flow rate 0.8-1.2 L / min) to maintain a micro-aerobic environment (dissolved oxygen DO controlled at 0.5-2.0 mg / L), start gas circulation between 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 oxidation-reduction potential (ORP) and dissolved oxygen DO, the intelligent control unit dynamically adjusts the aeration rate 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 (Fe)0 As an electron donor, sulfate (SO4) 2- ) Reduced to sulfide (S 2- The resulting sulfide S 2- With elemental sulfur (S) transferred through gas circulation or liquid phase 0 (Possibly from an SR reactor or externally added) reaction, regenerating to form elemental sulfur particles (S 0 ) or polysulfides, ultimately iron exists in the precipitate or adhering regeneration, zero-valent iron (Fe) 0 As an electronic intermediary, the sulfate reduction process is accelerated, and the MFC cathode chamber generates electricity simultaneously during this stage.

[0093] Step 6, Sulfate Feedback Adjustment: When SO4 is detected in the SRR reactor or effluent... 2- When the concentration exceeds the limit (e.g., 50 mg / L), the controller triggers the "iron-reducing bacteria activation program," starting the metering pump to pulse-add Fe to the SRR reactor. 2+ Solution (e.g., FeSO4 solution, with an acceleration rate of 20-100 mg Fe) 2+ ( / h) to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction.

[0094] Step 7, Output Monitoring: Perform online real-time monitoring of the following at 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 0-100 mg / L); sulfate SO4 2- Concentration (range 0-200 mg / L); determined based on test results: either allow the water to enter the drinking water system (i.e., meet drinking standards and is safe to drink), or return it to the SR reactor inlet for further treatment (if the treatment effect does not meet drinking standards, and there is no next-level standardization unit, return it to the SR reactor inlet for further treatment), or enter the next standardization unit for further treatment (if there is a next-level standardization unit, further treatment is carried out if the first treatment does not meet the requirements).

[0095] MFC power generation process:

[0096] In stage I, anodic microorganisms oxidize sulfur or intermediate products (such as sulfur dioxide) under the anaerobic environment of SR. 2- In stage II, oxygen at the cathode in the micro-aerobic environment of SRR receives electrons and combines with protons to reduce to water.

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

[0098] Comparison of application examples of the method described in this embodiment with existing technologies: The table lists application examples of the method described in this embodiment. Compared with traditional technologies, the technical performance has been greatly improved.

[0099]

[0100] Finally, it should be noted that the above description is only used to illustrate the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention (such as the form of the reactor, controller, and sensor, the system connection method, the order of steps, etc.) without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A water nitrate treatment system based on dynamic sulfur cycle and fuel cell, characterized in that, include: The system comprises at least one standardized unit connected in parallel or series. Each standardized unit includes a series-connected SR reactor for Stage I reaction and an SRR reactor for Stage II reaction. At least one self-generating MFC module is located between the SR and SRR reactors. An intelligent control unit is also included to operate the various facilities within the standardized unit and to centrally control 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, or Sulfur Reduction Reactor, is a sulfur autotrophic denitrification reactor. The SRR reactor, or Sulfur Reduction and Regeneration Reactor, is a sulfur reduction and regeneration reactor. The MFC, or Microbial Fuel Cell, is a microbial fuel cell. The SR reactor is equipped with an inlet at the bottom connected to a pressurized water source and an outlet at the top connected to the SRR inlet. The SR reactor is filled with elemental sulfur particles with a particle size of 2-5 mm, and the filling rate is 40%. The SRR reactor is equipped with an inlet at the top and an 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 each independently equipped with a blower and aeration disc, as well as their own independent reagent dosing metering pump; 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 pipe, and the cathode chamber is connected to the SRR reactor through a pipe. The intelligent control unit is equipped with a detector, a parameter regulator, a control arithmetic unit, and an alarm. The detector is connected to a sensor network, and the parameter regulator is connected to an aeration rate regulator, a sulfur dosing regulator, and an iron-reducing bacteria dosing regulator. The anode chamber of the MFC module uses a titanium mesh modified with nitrogen-doped carbon nanotubes as the anode substrate, and electrogenic microorganisms are loaded on the anode. The anode chamber is equipped with an independent chamber to treat liquid flow containing organic matter or nitrite. The cathode chamber uses porous carbon cloth as a substrate, supports a platinum catalyst, and is filled with conductive biochar filler to increase the reaction area and promote electron transfer. The cathode chamber is set up with an independent chamber.

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

3. The system according to claim 2, characterized in that, A static mixer is provided on the connecting pipe between the standardized units.

4. The system according to any one of claims 1-3, characterized in that, The intelligent control unit is equipped with a human-machine 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 equipped with adjustment buttons and adjustment sliders, including: an aeration volume adjustment knob, a sulfur addition acceleration rate slider, and an iron reducing bacteria addition frequency adjustment setting slider; The control logic area is equipped with a nitrate nitrogen concentration threshold setting program for switching. The alarm notification area is equipped with a sulfate concentration threshold setting program for alarms and a threshold over-limit alarm indication.

5. A method for treating nitrates in water supply based on a 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 initial operating parameters: Initial operating parameters include: aeration rate of SR reactor and SRR reactor, sulfur addition acceleration rate, iron reducing bacteria addition frequency, nitrate nitrogen concentration threshold for switching, and sulfate concentration threshold for alarm. Step 2, Start and test raw water: Turn on the water source and perform online real-time testing of the raw water at the inlet of the SR reactor: pH value; oxidation-reduction potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; Step 3, Operation Mode Phase I: Anaerobic sulfur autotrophic denitrification in the SR reactor: Aeration in the SRR reactor is turned off, and gas circulation between the SR reactor and the SRR reactor is started; raw water containing nitrate enters the SR reactor. Under anaerobic conditions, sulfur particles act as electron donors, and nitrate is reduced to nitrite by microorganisms. During this phase, electricity is generated simultaneously in the MFC anode chamber. Step 4, Cycling and Switching: The intelligent control unit controls the switching between the two stages based on the monitored parameters; Step 5, Operation Mode Phase II: Micro-aerobic sulfate reduction and sulfur regeneration in SRR: Aeration of the SRR reactor is started to maintain a micro-aerobic environment, and gas circulation between SR and SRR is initiated. The mixed liquid containing nitrite and sulfate produced in 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 keep the dissolved oxygen stable within the target range; In SRR: Sulfate-reducing bacteria use hydrogen generated by the corrosion of zero-valent iron 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 polysulfides. Finally, iron is present and precipitates or adheres to regenerate. Zero-valent iron acts as an electron medium to accelerate the sulfate reduction process. During this stage, the MFC cathode chamber generates electricity simultaneously. Step 6, Sulfate Feedback Adjustment: When SO4 is detected in the SRR reactor or effluent... 2- When the concentration exceeds the limit, the controller triggers the "iron-reducing bacteria activation program," starting the metering pump to pulse-add Fe to the SRR reactor. 2+ The solution was used to stimulate the activity of sulfate-reducing bacteria and accelerate sulfate reduction. Step 7, Output Detection: Perform online real-time monitoring of the SRR reactor outlet: pH value; oxidation-reduction potential; dissolved oxygen; nitrate nitrogen concentration; sulfate concentration; based on the detection results, determine whether the water can be allowed to enter the drinking water system, returned to the SR reactor inlet for further treatment, or sent to the next standardized unit for further processing.

6. The method according to claim 5, characterized in that, The MFC power generation process described above: In stage I, anodic microorganisms oxidize sulfur or intermediate products in the anaerobic environment of SR, producing 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, in the microaerobic environment of SRR, oxygen accepts electrons and combines with protons to be reduced to water.

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