Sulfur autotrophic constructed wetland-microbial fuel cell coupling system

Abstract

The utility model belongs to sewage treatment device, especially point to a kind of sulphur autotrophy artificial wetland-microbial fuel cell coupling system. Wherein water inlet tank is connected with sewage collection end, artificial wetland includes the support layer, mixed filler layer, middle layer, anode layer, isolation layer, cathode layer and plant layer distributed from bottom to top;Support layer as the material input end of artificial wetland and the pumping output end of water inlet tank are communicated, the material output end of artificial wetland is discharged through the water outlet of its side part, and anode layer and cathode layer respectively correspond to accommodate the anode and cathode of microbial fuel cell;The material output end of artificial wetland is located in the lower part of isolation layer and is communicated with outside through siphon pipe;The filler in mixed filler layer adopts uniform mixed sulphur granule and siderite.The utility model effectively solves the treatment problem of low C / N ratio wastewater in prior art, has the advantages such as good denitrification and phosphorus removal effect, no secondary pollution, optimal dissolved oxygen distribution, promote the deep removal of pollutants and the like.

Description

Technical Field

[0001] This utility model pertains to wastewater treatment devices, and specifically refers to a sulfur autotrophic constructed wetland-microbial fuel cell coupling system. Background Technology

[0002] Constructed wetlands (CWs) face significant challenges in treating wastewater with low carbon-to-nitrogen ratios (C / N). Their denitrification process primarily relies on heterotrophic denitrification, requiring organic matter as electron donors to reduce nitrates. However, when the influent C / N ratio is below 2, the carbon source is severely insufficient, limiting the activity of denitrifying bacteria and significantly reducing nitrate removal rates. To address this carbon source shortage, additional organic carbon sources such as acetic acid and methanol are typically added, which not only significantly increases operating costs but may also cause secondary pollution (e.g., residual carbon sources leading to excessive COD in the effluent or algal blooms). Furthermore, traditional constructed wetlands rely on adsorption by the packing material and absorption by plants for phosphorus removal, which is prone to failure due to packing saturation over long-term operation. Therefore, traditional constructed wetlands suffer from low denitrification efficiency, high operating costs, and the risk of secondary pollution when treating low C / N wastewater.

[0003] Microbial fuel cells (MFCs) coupled with constructed wetlands (MFC-CW) have been reported in existing literature. While they can simultaneously achieve wastewater purification and energy recovery, their power generation efficiency is limited by insufficient oxygen supply in the cathode region and low electrode reaction efficiency. On the one hand, the cathode of a microbial fuel cell relies on oxygen as an electron acceptor; however, the anoxic environment of traditional microbial fuel cells results in low dissolved oxygen concentration in the cathode region, limiting the oxygen reduction reaction rate and thus reducing the system voltage output. Traditional enhancement methods (such as plant oxygenation and artificial aeration) suffer from high cost or poor stability.

[0004] The applicant has not found any patent literature reports related to this application in domestic patent databases. Summary of the Invention

[0005] The purpose of this invention is to provide a sulfur-autotrophic constructed wetland-microbial fuel cell coupling system. This system achieves denitrification by using sulfur autotrophy as an electron donor, eliminating the need for additional carbon sources and producing minimal sludge, while also possessing phosphorus removal capabilities. Furthermore, a tidal flow operation mode driven by a siphon creates an oxygen concentration gradient through periodic or intermittent filling and emptying: during the drainage phase, atmospheric oxygen rapidly permeates to the cathode layer, while during the filling phase, the high dissolved oxygen water promotes the oxygen reduction reaction, significantly increasing the dissolved oxygen concentration in the cathode area. In addition, hydraulic shearing alleviates packing caking and enhances mass transfer efficiency. This provides a new, economical, and sustainable approach for low-carbon wastewater treatment.

[0006] The overall technical concept of this utility model is:

[0007] A sulfur-autotrophic constructed wetland-microbial fuel cell coupling system is described, in which the inlet tank is connected to the wastewater collection end. The constructed wetland includes, from bottom to top, a support layer, a mixed packing layer, an intermediate layer, an anode layer, an isolation layer, a cathode layer, and a plant layer. The support layer serves as the material input end of the constructed wetland and is connected to the pump output end of the inlet tank. The material output end of the constructed wetland is discharged through an outlet located on its side. The anode and cathode layers respectively house the anode and cathode of the microbial fuel cell.

[0008] A. The material output end of the constructed wetland is located at the bottom of the isolation layer and is connected to the outside via a siphon pipe;

[0009] B. The filler in the mixed filler layer is a uniformly mixed mixture of sulfur particles and siderite.

[0010] The specific technical concept of this utility model also includes:

[0011] The siphon is the core component driving the tidal flow (TF) water circulation mode. When the water level reaches the top of the siphon, the siphon effect is triggered, and purified water is discharged through the siphon. When the water level drops to the bottom of the siphon, the siphon effect is disrupted by the introduction of air, thus achieving intermittent or periodic drainage. The siphon's function is not limited to drainage; it also increases dissolved oxygen concentration and enhances oxygen reduction efficiency through periodic drainage. To facilitate better operation of the siphon, the preferred technical approach is to connect the siphon's material output to the outlet tank.

[0012] To increase the specific surface area of ​​the working medium in the intermediate layer, promote contact between wastewater and microorganisms, and improve the efficiency of sulfur autotrophic denitrification, a preferred technical approach is to use porous ceramic spheres containing Fe3O4 nanoparticles with a particle size of 10–15 mm as the working medium in the intermediate layer. In this way, the Fe3O4 nanoparticles adsorb sulfides through magnetism and surface active sites, reducing the inhibitory effect of sulfides on microorganisms.

[0013] A more preferred technical approach is to use porous ceramic spheres with a pore size of 2–5 cm.

[0014] The main purpose of using a uniformly mixed mixture of sulfur particles and siderite in the mixed packing layer is that sulfur acts as an electron donor, enabling sulfur-oxidizing bacteria (such as Thiobacillus) to reduce nitrates to nitrogen gas, eliminating the need for an external carbon source and solving the denitrification problem in wastewater with a low C / N ratio. The Fe in the siderite... 2+ Phosphate is removed through chemical precipitation (generating Fe3(PO4)2) or adsorption, inhibiting phosphorus release. Simultaneously, the oxidizing property of siderite partially converts sulfides into sulfates, reducing the accumulation of toxic substances. To achieve the above effects, a preferred technical solution is that the sulfur particles have a diameter of 2–4 cm, and the siderite particles have a diameter of 4–8 cm.

[0015] The anode and cathode are electrically connected to both ends of a resistor, which is connected to a voltage acquisition module for collecting the voltage of the microbial fuel cell. The resistor optimizes the current and voltage of the microbial fuel cell by adjusting the circuit load to match the system's internal resistance, achieving maximum power output. The voltage acquisition module monitors the voltage across the resistor in real time, guiding adjustments to operating parameters. Together, they maintain electron transfer efficiency and protect the electrode materials.

[0016] The working medium within the support layer is natural gravel with a porosity ≥40% and a particle size of 5–10 mm. The high porosity and large particle size of the gravel can disperse the incoming water flow, avoid local blockage, and ensure that the wastewater rises evenly to the subsequent functional layers.

[0017] The working medium within the anode and cathode layers is coconut shell activated carbon with a particle size of 4–8 mm. The high specific surface area of ​​the coconut shell activated carbon used for embedding the anode provides attachment sites for electrogenic bacteria, promoting their oxidation of sulfur products (such as sulfur dioxide). 0 The oxidation of residual organic matter releases electrons. Graphite felt, as the anode material, is highly conductive and corrosion-resistant. It transfers electrons to the cathode layer through an external circuit, driving the electricity generation process. Coconut shell activated carbon within the cathode layer is used to embed the graphite plate cathode, receiving electrons from the anode, combining with oxygen to generate water, completing the electricity generation cycle.

[0018] The working medium within the isolation layer is coarse sand with a particle size of 2–3 mm. This technical measure prevents the anode and cathode packings from mixing, maintaining the stability of the layered structure. Simultaneously, the coarse sand further traps small particles, preventing blockage in the cathode area.

[0019] Emergent plants are planted within the plant layer. The roots of these plants release oxygen into the cathode layer, replenishing dissolved oxygen and enhancing the cathode reaction. They also absorb ammonia nitrogen and phosphate from the water, assisting in the chemical and microbial removal processes.

[0020] The applicant needs to explain that:

[0021] In the description of this utility model, the terms "input" and "output" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] The technological advancements achieved by this utility model are as follows:

[0023] 1. The mixed packing layer of this utility model uses uniformly mixed sulfur particles and siderite as packing material. Through sulfur autotrophic denitrification technology, it effectively solves the problem of treating wastewater with low C / N ratio. The device uses elemental sulfur as an electron donor, achieving denitrification without the need for external organic carbon sources, and avoiding the problem of secondary pollution caused by carbon source addition. At the same time, the siderite packing material has the effect of removing phosphorus.

[0024] 2. This utility model adopts a siphon tube structure design, uses a tidal flow operation mode, and optimizes the dissolved oxygen distribution through periodic filling and drainage, which not only ensures the oxygen reduction reaction in the cathode area, but also promotes the deep removal of pollutants.

[0025] 3. The synergistic effect of emergent plant roots further enhances the system's purification efficiency, forming a complete pollutant removal system.

[0026] 4. Microbial fuel cell technology enables energy recovery during wastewater treatment. It directly converts the chemical energy in wastewater into electrical energy, providing supplementary energy for system operation and reducing operating costs. Attached Figure Description

[0027] The accompanying drawings of this utility model are as follows:

[0028] Figure 1 This is a schematic diagram of the structure of this utility model.

[0029] The reference numerals in the attached figures are as follows:

[0030] 1. Inlet tank; 2. Peristaltic pump; 3. Inlet; 4. Support layer; 5. Mixed packing layer; 6. Intermediate layer; 7. Anode layer; 8. Anode; 9. Outlet; 10. Siphon; 11. Isolation layer; 12. Cathode layer; 13. Cathode; 14. Plant layer; 15. Resistor; 16. Voltage acquisition module; 17. Outlet tank. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments, but it should not be construed as a limitation of the present invention. The protection scope of the present invention shall be determined by the contents of the claims. Any equivalent technical means substitution made in accordance with the specification shall not depart from the protection scope of the present invention.

[0032] Example

[0033] The overall structure of this embodiment is as follows: Figure 1As shown, a sulfur-autotrophic constructed wetland-microbial fuel cell coupled system is described, wherein the inlet tank 1 is connected to the wastewater collection end, and the constructed wetland includes, from bottom to top, a support layer 4, a mixed packing layer 5, an intermediate layer 6, an anode layer 7, an isolation layer 11, a cathode layer 12, and a plant layer 14; the support layer 4 serves as the material input end of the constructed wetland and is connected to the pump output end of the inlet tank 1, and the material output end of the constructed wetland is discharged through the outlet 9 provided on its side; the anode 8 and cathode 13 of the microbial fuel cell are respectively housed in the anode layer 7 and cathode layer 12; wherein:

[0034] A. The material output end of the constructed wetland is located at the lower part of the isolation layer 11 and is connected to the water outlet tank 17 via the siphon pipe 10.

[0035] B. The filler in the mixed filler layer 5 is a mixture of uniformly mixed sulfur particles and siderite.

[0036] The working media in each functional layer of the constructed wetland are made of the following materials:

[0037] The working medium in the intermediate layer 6 is a porous ceramic ball containing Fe3O4 nanoparticles with a particle size of 10-15 mm and a pore size of 2-5 cm.

[0038] The sulfur particles in the mixed packing layer have a diameter of 2–4 cm, and the siderite particles have a diameter of 4–8 cm.

[0039] The working medium within the support layer 4 is natural gravel with a porosity ≥40% and a particle size of 5–10 mm.

[0040] The working medium in the anode layer 7 and the cathode layer 12 is coconut shell activated carbon with a particle size of 4-8 mm.

[0041] The working medium inside the isolation layer 11 is coarse sand with a particle size of 2 to 3 mm.

[0042] Emergent plants are planted in the plant layer 14.

[0043] The anode 8 and cathode 13 are electrically connected to the two ends of the resistor 15, and the two ends of the resistor 15 are connected to a voltage acquisition module 16 for acquiring the voltage of the microbial fuel cell.

Claims

1. A sulfur autotrophic constructed wetland-microbial fuel cell coupling system, wherein a water inlet tank (1) is in communication with a sewage collection end, the constructed wetland comprises, from bottom to top, a support layer (4), a mixed filler layer (5), an intermediate layer (6), an anode layer (7), an isolation layer (11), a cathode layer (12), and a plant layer (14); the support layer (4) is in communication with the pumping output end of the water inlet tank (1) as the material input end of the constructed wetland, the material output end of the constructed wetland is discharged through the water outlet (9) provided on the side thereof, and the anode layer (7) and the cathode layer (12) respectively correspondingly accommodate an anode (8) and a cathode (13) of a microbial fuel cell; characterized in that: A. The material output end of the constructed wetland is located at the lower part of the isolation layer (11) and is in communication with the outside through a siphon (10); B. The fillers in the mixed filler layer (5) are sulfur granules and siderite which are mixed uniformly.

2. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The material output of the siphon (10) is in communication with a water outlet tank (17).

3. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The working medium in the intermediate layer (6) is a porous ceramic ball with Fe3O4 nanoparticles and a particle size of 10-15 mm.

4. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 3, characterized in that The pore size of the porous ceramic ball is 2-5 cm.

5. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The particle size of the sulfur granules is 2-4 cm, and the particle size of the siderite is 4-8 cm.

6. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The anode (8) and the cathode (13) are respectively electrically connected to two ends of a resistor (15), and two ends of the resistor (15) are connected with a voltage acquisition module (16) for acquiring the voltage of the microbial fuel cell.

7. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The working medium in the support layer (4) is natural gravel with a porosity of ≥40% and a particle size of 5-10 mm.

8. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The working medium in the anode layer (7) and the cathode layer (12) is coconut shell activated carbon with a particle size of 4-8 mm.

9. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The working medium in the isolation layer (11) is coarse sand with a particle size of 2-3 mm.

10. The sulfur-autotrophic constructed wetland-microbial fuel cell coupled system according to claim 1, wherein The plant layer (14) is planted with emergent plants.

Images