A method for monitoring water quality and enhancing pollutant removal performance by using embedded CW-MFC

Abstract

The application discloses a method for monitoring water quality and enhancing pollutant removal performance by using embedded CW-MFC, and belongs to water environment treatment technology. The method comprises the following steps: embedding a CW-MFC system into a CW system, so that effluent of the CW system can enter the CW-MFC system from the top of the CW system; effluent of the CW system entering the CW-MFC system and effluent of the CW-MFC system itself are combined at the bottom of a cathode layer of the CW-MFC system, and then discharged from an effluent outlet of the CW-MFC system; a fitting equation of coulomb efficiency of the CW-MFC system and organic matter concentration of inlet water of the bottom of the CW-MFC system is constructed; and on the premise of obtaining the organic matter concentration of effluent of the bottom of the cathode layer of the CW-MFC system, the organic matter concentration of inlet water of the bottom of the CW-MFC system is obtained according to the fitting equation and a coulomb efficiency calculation formula. The CW-MFC system is embedded into the CW system, the pollutant removal performance of the CW system is improved, the relationship between the inlet water organic matter concentration and the coulomb efficiency of the system is utilized, and the monitoring of the organic matter concentration of inlet water of the bottom of the CW-MFC system is realized.

Description

Technical Field

[0001] This invention relates to the field of water environment management technology, and more specifically to a method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC. Background Technology

[0002] With the rapid advancement of urbanization and industrialization, the discharge of various types of domestic sewage and industrial wastewater is constantly increasing, putting enormous pressure on existing sewage treatment systems. Influenced by policy requirements and increasingly stringent demands for ecological and environmental quality, there is a need to find a sewage treatment system that aligns with the principles of systemic governance and combines natural restoration with artificial remediation to alleviate the current sewage treatment pressure. Constructed wetland (CW) sewage treatment systems are an ideal choice that meets these needs. As a type of artificially designed and constructed functional wetland that resembles a natural ecosystem, it integrates the concepts of natural restoration and artificial remediation. Through the combined effects of plants, microorganisms, and system substrates, it simulates the function of natural constructed wetlands, thereby achieving diverse ecological functions. CW systems have many advantages, including simple operation, low operating costs, and high sustainability. They are currently widely used in ecologically sensitive urban areas, serving as both sewage treatment and ecological barriers.

[0003] With the widespread application of constructed wetland (CW) systems in many cities, several problems have emerged in practice. When the influent C / N ratio is relatively low, traditional CW systems often suffer from low total nitrogen removal rates. Furthermore, as a biological treatment technology, lower temperatures not only reduce microbial activity but also significantly limit the denitrification capacity of constructed wetlands. In addition, traditional CW systems are relatively poorly resistant to pollutant shocks. When faced with significant fluctuations in water quality, the treatment effect of constructed wetlands is affected, requiring a longer recovery time. This is especially true during sudden intrusions of toxic substances, which severely threaten CW systems. Against this backdrop, a technology is needed that can both improve pollutant removal efficiency and monitor the operational status of CW systems.

[0004] Microbial fuel cells (MFCs) are an emerging clean energy technology capable of effectively treating various types of wastewater, including domestic sewage, agricultural wastewater, and industrial wastewater. Extensive research has demonstrated their potential for integration with other wastewater treatment facilities to enhance treatment efficiency. Furthermore, MFCs convert the chemical energy generated during the redox process of degrading organic matter in wastewater into electrical energy. The electrical signals output by the MFC system reflect the state of electrochemical microorganisms. Since the metabolism and electron transport processes of these microorganisms are influenced by the influent substrate, using MFCs as biosensors for influent substrate monitoring has become a major research focus in recent years. Currently, MFCs are being studied for real-time monitoring in various treatment processes.

[0005] The structure of the MFC-coupled CW system utilizes the anaerobic environment in the lower part of the CW system and the aerobic environment near the system surface, satisfying the anaerobic environment required by the MFC anode microorganisms and the aerobic environment required by the cathode. After coupling the MFC and CW systems, the electrical signal output by the CW-MFC system shows a certain correlation with the concentration of influent substrates, enabling the monitoring of pollutants in the influent. Simultaneously, the CW-MFC technology can enhance the pollutant removal performance of the CW system, meeting the expectation of increased pollution loads.

[0006] Modifying traditional CW systems with CW-MFC sensors can not only improve the overall pollutant removal performance of the system, but also build a 3D electrochemical sensor network based on the whole system. However, there is currently no relevant technical solution to combine CW-MFC sensors with traditional CW systems. In addition, how to detect water quality at specific locations in the system is also a problem that needs to be solved. Summary of the Invention

[0007] In view of this, the present invention provides a method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC. The method embeds a CW-MFC system into a CW system, utilizing the relationship between the organic matter concentration in the influent and the coulombic efficiency exhibited by the system to enhance the pollutant removal performance of the CW system while simultaneously monitoring the influent organic matter concentration. The method provided by this invention can improve existing CW systems at a relatively low cost, not only enhancing the pollutant removal performance of the CW system but also enabling influent water quality monitoring. It also provides a way to utilize the weak output electricity, showing broad prospects in water environment management and monitoring.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] One method discloses a method for monitoring water quality and enhancing pollutant removal performance using embedded CW-MFC, comprising the following steps: The CW-MFC system is embedded inside the CW system, so that the water effluent from the CW system can enter the CW-MFC system from the top of the CW system. The water effluent from the CW system and the water effluent from the CW-MFC system enter the CW-MFC system and then merge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system. Construct fitting equations for the coulombic efficiency and bottom influent organic matter concentration of the CW-MFC system; Based on the fitting equation and the coulomb efficiency calculation formula, the organic matter concentration of the bottom influent of the CW-MFC system is obtained, provided that the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system is obtained.

[0010] Furthermore, the cathode layer comprises a shell made of titanium mesh cage, the interior of which is filled with activated carbon.

[0011] Furthermore, the CW-MFC system includes a CW-MFC shell, and within the CW-MFC shell, wetland plants, a cathode layer, a transition layer, and an anode layer are arranged sequentially from top to bottom; the cathode layer and the anode layer are interconnected by wires, and an external resistor is connected in series in the wires.

[0012] Furthermore, the CW system is configured with a concave structure, the groove of which is used to embed the CW-MFC shell of the CW-MFC system, and wetland plants and a filling medium layer are arranged sequentially from top to bottom in the space around the groove of the concave structure.

[0013] Furthermore, the transition layer includes a volcanic rock layer.

[0014] Furthermore, the filling medium layer consists of large-diameter volcanic rock and small-diameter volcanic rock from bottom to top.

[0015] Furthermore, fitting equations were constructed for the coulombic efficiency and bottom influent organic matter concentration of the CW-MFC system, specifically including the following equations:

[0016] Where CE represents the Coulomb efficiency, and a and b are both coefficients of the fitted equation. This indicates the concentration of organic matter in the bottom influent of the CW-MFC system.

[0017] Furthermore, based on the aforementioned fitting equation and coulombic efficiency calculation formula, and assuming the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system is obtained, the organic matter concentration of the influent at the bottom of the CW-MFC system is also obtained, specifically including: Obtain the formula for calculating Coulomb efficiency:

[0018] In the formula, CE represents the coulombic efficiency; M represents the molar mass of organic matter as oxygen; I represents the current value; F represents the Faraday constant; q represents the influent flow rate of the CW-MFC system; p represents the number of electrons transferred by oxidizing 1 mol of organic matter as O2; ΔCOD represents the difference between the COD concentration of the influent and the COD concentration of the effluent at the bottom of the cathode in the CW-MFC system. This indicates the concentration of organic matter in the water exiting from the bottom of the cathode layer; Substituting the fitted equation into the Coulomb efficiency calculation formula yields the equivalent formula:

[0019] Based on the equivalent formula and the organic matter concentration in the water effluent at the bottom of the cathode layer... The concentration of organic matter in the bottom influent of the CW-MFC system was obtained.

[0020] On the other hand, a device for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC is also disclosed, including a CW-MFC system and a CW system; The CW-MFC system includes a CW-MFC shell, inside which wetland plants, a cathode layer, a transition layer, and an anode layer are arranged sequentially from top to bottom; the cathode layer includes a shell made of titanium mesh cage, and the shell is filled with activated carbon; the cathode layer and the anode layer are connected to each other by wires, and an external resistor is connected in series in the wires; The CW system is configured with a concave structure. The groove of the concave structure is used to embed the CW-MFC shell of the CW-MFC system. After embedding, the water from the CW system can enter the CW-MFC system from the top of the CW system. The water from the CW system entering the CW-MFC system and the water from the CW-MFC system itself converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system. Wetland plants and a filling medium layer are arranged sequentially from top to bottom in the space around the groove of the concave structure.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for monitoring water quality and enhancing pollutant removal performance using embedded CW-MFC, which has the following beneficial effects: (1) This invention is based on the CW-MFC system. By embedding it into the CW system, the pollutant removal performance of the CW system is improved. At the same time, by utilizing the relationship between the organic matter concentration in the influent and the coulombic efficiency of the system, the organic matter concentration in the bottom influent of the CW-MFC system is monitored. This allows the organic matter concentration in the deep influent to be obtained by measuring the organic matter concentration in the shallow effluent when the CW-MFC system is at a deep depth.

[0022] (2) The hollow cathode design of the embedded CW-MFC system can improve the pollutant removal efficiency of the CW system and prevent the accumulation of anode electrons due to insufficient aerobic environment of the cathode, thereby improving the monitoring performance of CW-MFC as a sensor. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the device for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC, as provided by the present invention.

[0025] Figure 2 This is a schematic diagram of the fitting curve between coulombic efficiency and influent COD concentration provided in Embodiment 1 of the present invention.

[0026] In the diagram, 1. Cathode layer; 2. Anode layer; 3. Transition layer (volcanic rock); 4. Filling matrix (small-diameter volcanic rock); 5. Filling matrix (large-diameter volcanic rock); 6. Wetland plants; 7. Wires; 8. External circuit resistor; 9. Inlet; 10. Outlet; 11. CW system casing; 12. CW-MFC system casing. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] As mentioned in the background section, constructed wetlands are currently used in various cities for wastewater treatment, ecological landscape construction, and urban stormwater management. Converting a constructed wetland (CW) system into a constructed wetland-manufactured wetland (CW-MFC) system would be a time-consuming and labor-intensive undertaking. Furthermore, constructed wetlands require a technology that can both improve pollutant removal efficiency and monitor the system's operational status.

[0029] To address the aforementioned technical problems, this invention provides a method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC sensor, specifically as follows: First, a hybrid device combining the CW-MFC system and the CW system is constructed. Both the CW-MFC system and the CW system are upflow vertical flow systems, such as... Figure 1 As shown, the CW-MFC system includes a CW-MFC shell 12, inside which, from top to bottom, are arranged wetland plants 6, a cathode layer 1, a transition layer 3, and an anode layer 2. The cathode layer 1 consists of a shell made of titanium mesh cage, the interior of which is filled with activated carbon, thus creating a hollow structure in the cathode layer of the CW-MFC system. The cathode layer 1 and the anode layer 2 are interconnected by a wire 7, in which an external resistor 8 is connected in series. The CW system is configured with a concave structure, the groove of which is used to embed the CW-MFC shell of the CW-MFC system. After embedding... The top of the CW system is a certain distance (e.g., 5-10cm) higher than the top of the internal CW-MFC system. The effluent from the CW system can enter the CW-MFC system from the top of the external CW system. The effluent from the CW system and the effluent from the CW-MFC system itself converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system. Wetland plants and filling media layers are arranged in the space around the groove of the concave structure from top to bottom. The filling media layers are large-diameter volcanic rock 5 and small-diameter volcanic rock 4 from bottom to top.

[0030] Figure 1 9 represents the inlet. The pressure pump draws water through the inlet to both the external CW system and the internal CW-MFC system (the internal structure of the inlet is shown). Finally, the water from the CW system enters the CW-MFC system from the top of the CW system. The water from the CW system and the water from the CW-MFC system merge at the bottom of the cathode layer of the CW-MFC system and are then discharged from the outlet 10 of the CW-MFC system.

[0031] The CW-MFC system and the CW system hybrid device use CW-MFC as a sensor. By embedding CW-MFC into the CW system, the correlation between the organic matter concentration in the influent and the coulombic efficiency of the system is utilized to fit the organic matter concentration and coulombic efficiency, and a relationship curve between the two is constructed. This enables the monitoring and measurement of organic matter concentration in the deep bottom influent of CW-MFC and improves the pollutant removal performance of the CW system.

[0032] The specific organic matter concentration in the deep bottom influent of CW-MFC is obtained through the following methods: The fitting equations for the coulombic efficiency and bottom influent organic matter concentration of the CW-MFC system were constructed, specifically including the following equations:

[0033] Where CE represents the Coulomb efficiency, and a and b are both coefficients of the fitted equation. This indicates the concentration of organic matter in the bottom influent of the CW-MFC system.

[0034] Based on the fitting equation and the coulomb efficiency calculation formula, and assuming the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system is obtained, the organic matter concentration of the influent at the bottom of the CW-MFC system is obtained, specifically including: Obtain the formula for calculating Coulomb efficiency:

[0035] In the formula, CE represents the coulombic efficiency; M represents the molar mass of organic matter as oxygen; I represents the current value; F represents the Faraday constant; q represents the influent flow rate of the CW-MFC system; p represents the number of electrons transferred by oxidizing 1 mol of organic matter as O2; ΔCOD represents the difference between the COD concentration of the influent and the COD concentration of the effluent at the bottom of the cathode in the CW-MFC system. This indicates the concentration of organic matter in the water exiting from the bottom of the cathode layer; Substituting the fitted equation into the Coulomb efficiency calculation formula yields the equivalent formula:

[0036] Based on the equivalent formula and the organic matter concentration in the water effluent at the bottom of the cathode layer... The concentration of organic matter in the bottom influent of the CW-MFC system was obtained.

[0037] In this invention, the coefficients in the fitting equation were obtained through numerous experiments. Specifically, after embedding the CW-MFC system into the CW system, a data acquisition device was used to monitor the system voltage. Based on this, the COD concentrations of the influent and the bottom of the cathode were measured, and the coulombic efficiency of the CW-MFC system was then measured. A fitting curve was constructed based on the relationship between the influent COD concentration and the coulombic efficiency of the CW-MFC system. The fitting equation was then obtained based on the fitting curve. (See the specific fitting curve for reference.) Figure 2 . Furthermore, the transition layer 3 is volcanic rock.

[0038] Furthermore, the wetland plant 6 is a rooted emergent aquatic plant, including but not limited to calamus and canna.

[0039] In one or more embodiments of the present invention, a CW-MFC system is embedded within a CW system. In the CW-MFC system, the cathode of the MFC is located in the surface region of the CW system. When effluent from the external CW system enters, this region constitutes a relatively aerobic and humid environment, providing an abundant oxygen supply. The anode of the MFC is located in the deep anaerobic region of the CW system to ensure stable operation of the MFC anode. The anode and cathode of the MFC are connected via an external circuit, in which an external resistor is connected.

[0040] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0041] Example 1 Build an embedded CW-MFC system and embed it into the CW system. Its structure is as follows: Figure 1 As shown, the CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer constructed of volcanic rock, and a cathode layer also made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit, which includes a resistor. Externally, the CW system has a diameter of 250 mm and a height of 500 mm. Internally, from bottom to top, it consists of a support layer of large-diameter volcanic rock and an intermediate layer of small-diameter volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system in the lower part of the cathode before being discharged. A hydraulic retention time of 24 hours and an external resistance of 1000 Ω were selected. Sweet flag was used as the wetland plant. After ten days of stable operation, the system entered the experimental phase.

[0042] By varying the influent COD concentration, different coulombic efficiencies were obtained through testing. The organic matter concentrations in the influent and at the bottom of the cathode were determined using the potassium dichromate method. Subsequently, a fitting curve between coulombic efficiency and COD concentration was constructed by analyzing the correlation between coulombic efficiency and influent COD concentration. Figure 2 As shown, after establishing the fitting curve, the corresponding influent organic matter concentration can be calculated from the curve and the coulombic efficiency of the system. The coulombic efficiency is calculated using the formula (1) as follows: (1) In the formula, CE: Coulomb efficiency (%); M: Molar mass of organic matter (32 g / mol) based on oxygen. I: current (A); F: Faraday constant (96485 C / mol); q: Inlet flow velocity (m) 3 / s); p: The number of electrons transferred when 1 mol of organic matter is oxidized, using O2 as the standard (4e). - mol / mol); △COD: The difference in COD concentration between the system influent and the effluent at the bottom of the cathode (mg / L).

[0043] Example 2 An embedded CW-MFC system was constructed and integrated into the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer made of volcanic rock, and a cathode layer made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit containing a resistor. The external CW system is 250 mm in diameter and 500 mm in height. Internally, from bottom to top, it consists of a support layer of large-particle volcanic rock and an intermediate layer of small-particle volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system in the lower part of the cathode before being discharged. A hydraulic retention time of 48 h and an external resistance of 1000 Ω were selected. Sweet flag (Acorus calamus) was used as the wetland plant. After ten days of stable operation, the experiment began.

[0044] By changing the COD concentration of different influents, different values ​​of coulombic efficiency were obtained through detection. The organic matter concentrations of the influent and the bottom of the cathode were determined by the potassium dichromate method. Then, by analyzing the correlation between coulombic efficiency and influent COD concentration, a fitting curve between coulombic efficiency and COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration can be calculated from the curve and the detected coulombic efficiency of the system.

[0045] Example 3 An embedded CW-MFC system was constructed and integrated into the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer made of volcanic rock, and a cathode layer made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit containing a resistor. The external CW system is 250 mm in diameter and 500 mm in height. Internally, from bottom to top, it consists of a support layer of large-diameter volcanic rock and an intermediate layer of small-diameter volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system at the lower part of the cathode before being discharged. A hydraulic retention time of 60 h and an external resistance of 1000 Ω were selected. Sweet flag (Acorus calamus) was used as the wetland plant. After ten days of stable operation, the experiment began.

[0046] By changing the COD concentration of different influents, different values ​​of coulombic efficiency were obtained through detection. The organic matter concentrations of the influent and the bottom of the cathode were determined by the potassium dichromate method. Then, by analyzing the correlation between coulombic efficiency and influent COD concentration, a fitting curve between coulombic efficiency and COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration can be calculated from the curve and the detected coulombic efficiency of the system.

[0047] Example 4 An embedded CW-MFC system was constructed and integrated into the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer made of volcanic rock, and a cathode layer made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit containing a resistor. The external CW system is 250 mm in diameter and 500 mm in height. Internally, from bottom to top, it consists of a support layer of large-diameter volcanic rock and an intermediate layer of small-diameter volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system in the lower part of the cathode before being discharged. A hydraulic retention time of 24 h, an external resistance of 500 Ω, and calamus as the wetland plant were selected. After ten days of stable operation, the experiment began.

[0048] By changing the COD concentration of different influents, different values ​​of coulombic efficiency were obtained through detection. The organic matter concentrations of the influent and the bottom of the cathode were determined by the potassium dichromate method. Then, by analyzing the correlation between coulombic efficiency and influent COD concentration, a fitting curve between coulombic efficiency and COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration can be calculated from the curve and the detected coulombic efficiency of the system.

[0049] Comparative Example 1 An embedded CW-MFC system was constructed and embedded within the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer made of volcanic rock, and a cathode layer made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit containing a resistor. The external CW system is 250 mm in diameter and 500 mm in height. Internally, from bottom to top, it consists of a support layer of large-diameter volcanic rock and an intermediate layer of small-diameter volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system at the lower part of the cathode before being discharged. A hydraulic retention time of 12 hours and an external resistance of 1000 Ω were selected. Sweet flag (Acorus calamus) was used as the wetland plant. After ten days of stable operation, the experiment began.

[0050] By varying the influent COD concentration, different coulombic efficiencies were obtained through testing. The organic matter concentrations in the influent and at the bottom of the cathode were determined using the potassium dichromate method. Subsequently, a fitting curve was constructed between coulombic efficiency and influent COD concentration based on the correlation between the two. The results showed that the fitted curve did not accurately reflect the relationship between the system coulombic efficiency and the influent COD concentration. This indicates that the relatively fast influent flow rate makes it difficult for microorganisms to fully contact and utilize organic matter. As the influent COD concentration increases, microorganisms are exposed to higher organic matter concentrations, exceeding the optimal organic matter concentration range for microbial metabolism. This affects the intracellular metabolic pathways of the relevant microorganisms, resulting in a poorly fitted curve between the system coulombic efficiency and the influent COD concentration. In other words, the corresponding influent organic matter concentration cannot be calculated from the curve and the detected system coulombic efficiency.

[0051] Comparative Example 2 An embedded CW-MFC system was constructed and embedded within the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. Internally, from bottom to top, it consists of an anode layer made of titanium mesh cage filled with activated carbon, a transition layer made of volcanic rock, and a cathode layer made of titanium mesh cage filled with activated carbon. The cathode and anode are connected via an external circuit containing a resistor. The external CW system is 250 mm in diameter and 500 mm in height. Internally, from bottom to top, it consists of a support layer of large-diameter volcanic rock and an intermediate layer of small-diameter volcanic rock. The effluent from the CW system flows from top to bottom through the cathode of the CW-MFC system and then merges with the effluent from the CW-MFC system in the lower part of the cathode before being discharged. A hydraulic retention time of 24 hours and an external resistance of 2000 Ω were selected. Sweet flag (Acorus calamus) was used as the wetland plant. After ten days of stable operation, the experiment began.

[0052] By varying the influent COD concentration, different coulombic efficiencies were obtained through testing. The organic matter concentrations in the influent and at the bottom of the cathode were determined using the potassium dichromate method. Subsequently, a fitting curve between coulombic efficiency and COD concentration was constructed by analyzing the correlation between coulombic efficiency and COD concentration. The results showed that the fitted curve did not accurately reflect the relationship between the system coulombic efficiency and the influent COD concentration. This indicates that an excessively large external resistance hinders electron transport, making it difficult for the system coulombic efficiency to exhibit a curve with a high degree of fit with the influent COD concentration. In other words, the corresponding influent organic matter concentration could not be calculated from the curve and the detected system coulombic efficiency.

[0053] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0054] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for monitoring water quality and enhancing pollutant removal performance using embedded CW-MFC, characterized in that, Includes the following steps: The CW-MFC system is embedded inside the CW system, so that the water effluent from the CW system can enter the CW-MFC system from the top of the CW system. The water effluent from the CW system and the water effluent from the CW-MFC system enter the CW-MFC system and then merge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system. The CW-MFC system includes a CW-MFC shell, inside which wetland plants, a cathode layer, a transition layer, and an anode layer are arranged sequentially from top to bottom. The cathode layer and the anode layer are interconnected by wires, and an external resistor is connected in series in the wires. The cathode layer includes a shell made of titanium mesh, and the shell is filled with activated carbon. The CW system is configured with a concave structure, and the groove of the concave structure is used to embed the CW-MFC shell of the CW-MFC system. In the space around the groove of the concave structure, wetland plants and a filling medium layer are arranged sequentially from top to bottom. Construct fitting equations for the coulombic efficiency and bottom influent organic matter concentration of the CW-MFC system; specifically... Including the following equations: Where CE represents the Coulomb efficiency, and a and b are both coefficients of the fitted equation. This indicates the concentration of organic matter in the bottom influent of the CW-MFC system; Based on the fitting equation and the coulomb efficiency calculation formula, the organic matter concentration of the bottom influent of the CW-MFC system is obtained, provided that the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system is obtained; wherein, the hydraulic retention time is 24h-60h and the external resistance is 500Ω-1000Ω.

2. The method for monitoring water quality and enhancing pollutant removal performance using embedded CW-MFC according to claim 1, characterized in that, The transition layer includes a volcanic rock layer.

3. The method for monitoring water quality and enhancing pollutant removal performance using embedded CW-MFC according to claim 1, characterized in that, The filling medium layer consists of large-diameter volcanic rock and small-diameter volcanic rock from bottom to top.

4. The method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 1, based on the fitting equation and coulombic efficiency calculation formula, obtains the organic matter concentration of the influent at the bottom of the CW-MFC system, assuming the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system is obtained, specifically including: Obtain the formula for calculating Coulomb efficiency: In the formula, CE represents the coulombic efficiency; M represents the molar mass of organic matter as oxygen; I represents the current value; F represents the Faraday constant; q represents the influent flow rate of the CW-MFC system; p represents the number of electrons transferred by oxidizing 1 mol of organic matter as O2; ΔCOD represents the difference between the COD concentration of the influent and the COD concentration of the effluent at the bottom of the cathode in the CW-MFC system. This indicates the concentration of organic matter in the water exiting from the bottom of the cathode layer; Substituting the fitted equation into the Coulomb efficiency calculation formula yields the equivalent formula: Based on the equivalent formula and the organic matter concentration in the water effluent at the bottom of the cathode layer... The concentration of organic matter in the bottom influent of the CW-MFC system was obtained.

5. A device for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC, characterized in that, The method for implementing any one of claims 1-4 includes a CW-MFC system and a CW system; The CW-MFC system includes a CW-MFC shell, inside which wetland plants, a cathode layer, a transition layer, and an anode layer are arranged sequentially from top to bottom; the cathode layer includes a shell made of titanium mesh cage, and the shell is filled with activated carbon; the cathode layer and the anode layer are connected to each other by wires, and an external resistor is connected in series in the wires; The CW system is configured with a concave structure. The groove of the concave structure is used to embed the CW-MFC shell of the CW-MFC system. After embedding, the water from the CW system can enter the CW-MFC system from the top of the CW system. The water from the CW system entering the CW-MFC system and the water from the CW-MFC system itself converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system. Wetland plants and a filling medium layer are arranged sequentially from top to bottom in the space around the groove of the concave structure.

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