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

Abstract

The invention discloses a method for monitoring water quality and enhancing pollutant removal performance by using an embedded CW-MFC (Carbon Wave-Microbial Fuel Cell), and belongs to a water environment treatment technology, the method comprises the following steps: embedding a CW-MFC system into a CW system, so that the effluent of the CW system can enter the CW-MFC system from the top of the CW system, and the effluent of the CW system entering the CW-MFC system and the self effluent of the CW-MFC system can be communicated with each other; after being converged at the bottom of the cathode layer of the CW-MFC system, the water is discharged from a water outlet of the CW-MFC system; constructing a fitting equation of coulombic efficiency and bottom inflow organic matter concentration of the CW-MFC system; and according to the fitting equation and the coulombic efficiency calculation formula, on the premise of obtaining the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system, obtaining the organic matter concentration of the effluent at the bottom of the CW-MFC system. On the basis of the CW-MFC system, the CW-MFC system is embedded into the CW system, so that the pollutant removal performance of the CW system is improved, and meanwhile, the concentration of the organic matters in the inlet water at the bottom of the CW-MFC system is monitored by utilizing the relationship between the concentration of the organic matters in the inlet water and the coulombic efficiency presented by the system.

Description

Technical Field

[0001] The present invention relates to the technical field of water environment treatment, and more specifically, to a method for monitoring water quality and enhancing the pollutant removal performance by using an embedded CW-MFC. Background Art

[0002] With the rapid advancement of urbanization and industrialization, the emissions of various domestic sewage and industrial wastewater are increasing continuously, resulting in a huge pressure on the existing sewage treatment systems. Under the background of increasing policy requirements and people's requirements for the quality of the ecological environment, it is necessary to find a sewage treatment system that conforms to the concept of systematic treatment and combines natural restoration and artificial repair to relieve the current sewage treatment pressure. The constructed wetland (CW) sewage treatment system is exactly an ideal choice that meets these requirements. As a functional wetland designed and constructed artificially similar to a natural ecosystem, it integrates the concept of combining natural restoration and artificial repair, and can simulate the role of a natural constructed wetland under the combined action of multiple factors such as plants, microorganisms and system substrates in the system, so as to achieve diverse ecological functions. The CW system has many advantages such as simple operation, low operating cost and high sustainability. At present, it has been widely used in the ecological sensitive areas of cities, playing the role of sewage treatment and acting as an ecological barrier.

[0003] With the wide application of the CW system in many cities, some problems have also emerged in the practical process. When the influent C / N ratio is relatively low, the traditional CW system often has the adverse effect of a relatively low total nitrogen removal rate. Moreover, as a biochemical treatment technology, the decrease in temperature will not only lead to a decrease in microbial activity, but also greatly limit the denitrification ability of the constructed wetland system. In addition, the traditional CW system has relatively poor resistance to pollutant shock. When facing large fluctuations in water quality, the treatment effect of the constructed wetland on pollutants will be affected to a certain extent, and it requires a long recovery time. Especially when sudden toxic substances invade, the CW system will be severely threatened. Under this background, the CW system needs a technology that can both improve the pollutant removal efficiency and monitor the operation status of the CW system.

[0004] Microbial fuel cell (MFC) is an emerging clean energy technology, which can effectively treat various types of wastewater such as domestic sewage, agricultural wastewater and industrial wastewater. At present, it has been proven by a large number of studies that it can be used in combination with other sewage treatment facilities to enhance the sewage treatment effect. At the same time, MFC can convert the chemical energy in the oxidation-reduction process of degrading organic matter in wastewater into electrical energy, and the electrical signal output by the MFC system can reflect the state of electrochemically active microorganisms. The metabolism and electron transfer processes of electrochemically active microorganisms are affected by the influent substrate, which makes it a research hotspot in recent years to use MFC as a biosensor for environmental monitoring to monitor the influent substrate. At present, it has also been studied for real-time monitoring as a biosensor in the treatment processes of various devices.

[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 surface of the system to meet the anaerobic environment required by the anode microorganisms of the MFC and the aerobic environment required by the cathode. After the MFC is coupled with the CW system, there is a certain correlation between the electrical signal output by the CW-MFC system and the concentration of the influent substrate, and on this basis, the monitoring of pollutants in the influent can be realized. At the same time, the CW-MFC technology can enhance the pollutant removal performance of the CW system and meet the expected increase in the pollution load.

[0006] By transforming the traditional CW system with the CW-MFC sensor, not only can the overall pollutant removal performance of the system be improved, but also a 3D electrochemical sensor network based on the overall system can be constructed. However, there is currently no relevant technical solution to combine the CW-MFC sensor with the traditional CW system. In addition, how to detect the water quality at special positions 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 by using an embedded CW-MFC. The CW-MFC system is embedded in the CW system, and the relationship between the concentration of organic matter in the influent and the Coulomb efficiency exhibited by the system is used to enhance the pollutant removal performance of the CW system while realizing the monitoring function of the influent organic matter concentration. The method provided by the present invention can be improved on the existing CW system at a relatively low cost, which can not only improve the pollutant removal performance of the CW system, but also realize the monitoring of the influent water quality, and find a way to utilize the weak electrical energy output, showing broad prospects in water environment treatment and monitoring.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] On the one hand, a method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC is disclosed, including the following steps:

[0010] Embed the CW-MFC system inside the CW system so that the effluent of the CW system can enter the CW-MFC system from the top of the CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system.

[0011] Construct a fitting equation for the Coulombic efficiency and the bottom influent organic matter concentration of the CW-MFC system.

[0012] According to the fitting equation and the Coulombic efficiency calculation formula, on the premise of obtaining the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system, the organic matter concentration of the bottom influent of the CW-MFC system is obtained.

[0013] Further, the cathode layer includes a housing composed of a titanium mesh cage, and the housing is filled with activated carbon.

[0014] Further, the CW-MFC system includes a CW-MFC housing. Inside the CW-MFC housing, wetland plants, a cathode layer, a transition layer, and an anode layer are arranged in sequence from top to bottom. The cathode layer and the anode layer are connected to each other by a wire, and an external resistor is connected in series in the wire.

[0015] Further, the CW system is set as a concave structure. The groove of the concave structure is used to embed the CW-MFC housing of the CW-MFC system, and wetland plants and a filling medium layer are arranged in sequence from top to bottom in the space around the groove of the concave structure.

[0016] Further, the transition layer includes a volcanic rock layer.

[0017] Further, the filling medium layer is composed of large-sized volcanic rocks and small-sized volcanic rocks from bottom to top.

[0018] Further, constructing a fitting equation for the Coulombic efficiency and the bottom influent organic matter concentration of the CW-MFC system specifically includes the following equation:

[0019] CE = a·(COD 进 ) b [[ID=�5]]

[0020] [[ID=�6]]Wherein, CE represents the Coulombic efficiency, both a and b represent the coefficients of the fitting equation, and COD 进 represents the organic matter concentration of the bottom influent of the CW-MFC system.

[0021] Further, based on the fitting equation and the Coulombic efficiency calculation formula, on the premise of obtaining the organic matter concentration of the water outlet at the bottom of the cathode layer of the CW-MFC system, the organic matter concentration of the water inlet at the bottom of the CW-MFC system is obtained, specifically including:

[0022] Obtain the Coulombic efficiency calculation formula:

[0023]

[0024] In the formula, CE represents the Coulombic efficiency; M represents the molar mass of organic matter with oxygen as the standard; 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 for oxidizing 1 mol of organic matter with O2 as the standard; △COD represents the difference between the influent COD concentration and the COD concentration of the water outlet at the cathode bottom of the CW-MFC system; COD 出 represents the organic matter concentration of the water outlet at the bottom of the cathode layer;

[0025] Substitute the fitting equation into the Coulombic efficiency calculation formula to obtain the equivalent formula:

[0026]

[0027] According to the equivalent formula and the organic matter concentration COD of the water outlet at the bottom of the cathode layer 出 Obtain the organic matter concentration of the water inlet at the bottom of the CW-MFC system.

[0028] On the other hand, a device for monitoring water quality and enhancing the pollutant removal performance by using an embedded CW-MFC is also disclosed, including a CW-MFC system and a CW system;

[0029] The CW-MFC system includes a CW-MFC housing, and wetland plants, a cathode layer, a transition layer, and an anode layer are sequentially arranged in the CW-MFC housing from top to bottom; the cathode layer includes a housing composed of a titanium mesh cage, and activated carbon is filled inside the housing; the cathode layer and the anode layer are connected to each other through a wire, and an external resistor is connected in series in the wire;

[0030] The CW system is set as a concave structure, and the groove of the concave structure is used to embed the CW-MFC housing of the CW-MFC system. After embedding, the effluent of the CW system can enter the CW-MFC system from the top of the CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the water outlet of the CW-MFC system; wetland plants and a filling medium layer are sequentially arranged from top to bottom in the space around the groove of the concave structure.

[0031] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for monitoring water quality and enhancing the pollutant removal performance by using an embedded CW-MFC, which has the following beneficial effects:

[0032] (1) Based on the CW-MFC system, the present invention embeds it into the CW system to improve the pollutant removal performance of the CW system. At the same time, by using the relationship between the influent organic matter concentration and the Coulombic efficiency presented by the system, the organic matter concentration in the bottom influent of the CW-MFC system is monitored, so that when the depth of the CW-MFC system is relatively deep, the organic matter concentration of the deep influent can be obtained by measuring the organic matter concentration of the effluent in the shallow layer.

[0033] (2) The hollow cathode design of the embedded CW-MFC system can improve the pollutant removal efficiency of the CW system, and can also prevent the anode electron accumulation phenomenon caused by insufficient aerobic environment at the cathode, and improve the monitoring performance of the CW-MFC as a sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0035] Figure 1 It is a schematic diagram of the overall structure of the device for monitoring water quality and enhancing the pollutant removal performance by using an embedded CW-MFC provided by the present invention.

[0036] Figure 2 It is a schematic diagram of the fitting curve between the Coulombic efficiency and the influent COD concentration provided in Embodiment 1 of the present invention.

[0037] In the figure, 1, cathode layer; 2, anode layer; 3, transition layer (volcanic stone); 4, filling matrix (small particle size volcanic stone); 5, filling matrix (large particle size volcanic stone); 6, wetland plants; 7, wire; 8, external circuit resistance; 9, water inlet; 10, water outlet; 11, CW system housing; 12, CW-MFC system housing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] As introduced in the background art, at present, constructed wetlands have been applied in various cities for various sewage treatments, ecological landscape construction, urban rainwater management, etc. Converting the CW system into a CW-MFC system would be a huge project that is time-consuming and laborious. Moreover, the CW system requires a technology that can not only improve the pollutant removal efficiency but also monitor the operation status of the CW system.

[0040] To solve the above technical problems, the present invention provides a method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC sensor, specifically as follows:

[0041] First, construct a hybrid device of the CW-MFC system and the CW system. Both the CW-MFC system and the CW system are upflow vertical flow systems. As Figure 1 shown, the CW-MFC system includes a CW-MFC housing 12. Inside the CW-MFC housing 12, wetland plants 6, a cathode layer 1, a transition layer 3, and an anode layer 2 are sequentially arranged from top to bottom; the cathode layer 2 includes a housing formed by a titanium mesh cage, and the inside of the housing formed by the titanium mesh cage is filled with activated carbon, so that the cathode layer in the CW-MFC system forms a hollow structure; the cathode layer 1 and the anode layer 2 are connected to each other through a wire 7, and an external resistor 8 is connected in series in the wire 7; the CW system is arranged in a concave structure, and the groove of the concave structure is used to embed the CW-MFC housing of the CW-MFC system. After embedding, the top of the CW system is higher than the top of the internal CW-MFC system by a certain distance (such as 5 - 10 cm). The effluent of the CW system can enter the CW-MFC system from the top of the external CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system 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 sequentially arranged from top to bottom in the space around the groove of the concave structure; the filling medium layer is large-sized volcanic stones 5 and small-sized volcanic stones 4 from bottom to top.

[0042] Figure 1 In [Figure], 9 represents the water inlet. The influent is respectively input into the external CW system and the internal CW-MFC system through the water inlet by a pressure pump (the internal structure of the water inlet is shown). Finally, the effluent of the CW system can enter the CW-MFC system from the top of the CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet 10 of the CW-MFC system.

[0043] The hybrid device of the CW-MFC system and the CW system uses the CW-MFC as a sensor. By embedding the CW-MFC into the CW system and utilizing the correlation between the organic matter concentration in the influent water and the Coulombic efficiency presented by the system, the organic matter concentration and the Coulombic efficiency are fitted to construct a relationship curve between the two, thereby realizing the monitoring and measurement of the organic matter concentration at the deep bottom inlet of the CW-MFC and improving the pollutant removal performance of the CW system.

[0044] Specifically, the organic matter concentration at the deep bottom inlet of the CW-MFC is obtained through the following methods:

[0045] Construct the fitting equation of the Coulombic efficiency and the organic matter concentration at the bottom inlet of the CW-MFC system, specifically including the following equations:

[0046] CE = a·(COD 进 ) b

[0047] where CE represents the Coulombic efficiency, both a and b represent the coefficients of the fitting equation, and COD 进 represents the organic matter concentration at the bottom inlet of the CW-MFC system.

[0048] According to the fitting equation and the Coulombic efficiency calculation formula, on the premise of obtaining the organic matter concentration of the effluent water at the bottom of the cathode layer of the CW-MFC system, the organic matter concentration at the bottom inlet of the CW-MFC system is obtained, specifically including:

[0049] Obtain the Coulombic efficiency calculation formula:

[0050]

[0051] In the formula, CE represents the Coulombic efficiency; M represents the molar mass of organic matter with oxygen as the standard; 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 for oxidizing 1 mol of organic matter with O2 as the standard; △COD represents the difference between the influent COD concentration and the effluent COD concentration at the cathode bottom of the CW-MFC system; COD 出 represents the organic matter concentration of the effluent water at the bottom of the cathode layer;

[0052] Substitute the fitting equation into the Coulombic efficiency calculation formula to obtain the equivalent formula:

[0053]

[0054] According to the equivalent formula and the organic matter concentration COD of the effluent water at the bottom of the cathode layer 出 Obtain the organic matter concentration at the bottom inlet of the CW-MFC system.

[0055] In the present invention, the coefficients in the fitting equation are obtained through a large number of experiments. In the specific experimental process, after embedding the CW-MFC system into the CW system, a data collector is used to monitor the system voltage. On this basis, the COD concentrations of the influent and the bottom of the cathode are measured. Subsequently, the Coulombic efficiency of the CW-MFC system is measured. Through the relationship between the influent COD concentration of the CW-MFC system and the presented Coulombic efficiency, a fitting curve between the influent COD concentration and the Coulombic efficiency is constructed, and then the fitting equation is obtained according to the fitting curve. For the specific fitting curve, refer to Figure 2 .

[0056] Further, the transition layer 3 is volcanic stone.

[0057] Further, the wetland plant 6 is a rooted emergent plant, including but not limited to calamus and canna indica.

[0058] In one or more embodiments of the present invention, the CW-MFC system is embedded in the CW system. In the CW-MFC system, the cathode of the MFC is located in the surface area of the CW system. In the case where the effluent of the external CW system enters, this area constitutes a relatively aerobic and humid environment, which can provide rich oxygen supply, while the anode of the MFC is located in the deep anaerobic area of the CW system to ensure the stable operation of the MFC anode. The anode and cathode of the MFC are connected through an external circuit, and an external resistor is connected in the external circuit.

[0059] In order 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 in conjunction with specific embodiments.

[0060] Example 1

[0061] Construct an embedded CW-MFC system and embed it into the CW system. Its structure is as Figure 1 shown, where the CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. From top to bottom inside, there are an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed of volcanic stone, and a cathode layer constructed of a titanium mesh cage filled with activated carbon. The cathode and the anode are connected through an external circuit, and a resistor is connected in the external circuit. The external CW system has a diameter of 250 mm and a height of 500 mm. From top to bottom inside, there are large-particle-size volcanic stones as the support layer and small-particle-size volcanic stones as the intermediate layer in sequence. The effluent of the CW system passes through the cathode of the CW-MFC system from top to bottom and converges with the effluent of the CW-MFC system in the lower middle part of the cathode of the CW-MFC system and then is discharged. The hydraulic retention time of 24 h, an external resistor of 1000 Ω, and calamus as the wetland plant are selected. After stable operation for ten days, it enters the test stage.

[0062] By changing the influent COD concentration, different values of Coulombic efficiency were obtained through detection. The influent and the organic matter concentration at the bottom of the cathode were measured by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration was constructed. As Figure 2 shown, after establishing the fitting curve, the corresponding influent organic matter concentration can be calculated through the curve and the detected Coulombic efficiency of the system. The Coulombic efficiency is calculated by the formula, and the calculation formula (1) is as follows:

[0063]

[0064] In the formula, CE: Coulombic efficiency (%);

[0065] M: Molar mass of organic matter with oxygen as the standard (32 g / mol);

[0066] I: Current (A);

[0067] F: Faraday constant (96485 C / mol);

[0068] q: Influent flow rate (m 3 / s);

[0069] p: Number of electrons transferred for oxidizing 1 mol of organic matter with O2 as the standard (4e - mol / mol);

[0070] △COD: Difference between the influent COD concentration and the effluent COD concentration at the bottom of the cathode of the system (mg / L).

[0071] Example 2

[0072] An embedded CW-MFC system was constructed and embedded into the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. From top to bottom inside, it is an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed of volcanic stones, and a cathode layer constructed of a titanium mesh cage filled with activated carbon. The cathode and the anode are connected through an external circuit, and a resistor is connected in the external circuit. The external CW system has a diameter of 250 mm and a height of 500 mm. From top to bottom inside, it is a large-particle-size volcanic stone as the support layer and a small-particle-size volcanic stone as the intermediate layer. The effluent of the CW system passes through the cathode of the CW-MFC system from top to bottom and converges with the effluent of the CW-MFC system in the lower-middle part of the cathode of the CW-MFC system and then is discharged. A hydraulic retention time of 48 h, an external resistance of 1000 Ω, and calamus as the wetland plant were selected. After stable operation for ten days, it entered the test stage.

[0073] By changing the influent COD concentrations, different values of Coulombic efficiency were obtained through detection. The influent and the organic matter concentration at the bottom of the cathode were measured by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration could be calculated through the curve and the detected Coulombic efficiency of the system.

[0074] Example 3

[0075] An embedded CW-MFC system was constructed and embedded into the CW system. The CW-MFC system was cylindrical, with a diameter of 125 mm and a height of 420 mm. Inside, from top to bottom, there were an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed from volcanic stones, and a cathode layer constructed from a titanium mesh cage filled with activated carbon. The cathode and the anode were connected through an external circuit, and a resistor was connected in the external circuit. The external CW system had a diameter of 250 mm and a height of 500 mm. Inside, from top to bottom, there were large-sized volcanic stones as the support layer and small-sized volcanic stones as the intermediate layer. The effluent of the CW system passed through the cathode of the CW-MFC system from top to bottom and then converged with the effluent of the CW-MFC system in the middle and lower part of the cathode of the CW-MFC system and was discharged. A hydraulic retention time of 60 h, an external resistance of 1000 Ω, and Acorus calamus as the wetland plant were selected. After stable operation for ten days, it entered the experimental stage.

[0076] By changing the influent COD concentrations, different values of Coulombic efficiency were obtained through detection. The influent and the organic matter concentration at the bottom of the cathode were measured by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration could be calculated through the curve and the detected Coulombic efficiency of the system.

[0077] Example 4

[0078] An embedded CW-MFC system was constructed and embedded into the CW system. The CW-MFC system was cylindrical, with a diameter of 125 mm and a height of 420 mm. Inside, from top to bottom, there were an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed from volcanic stones, and a cathode layer constructed from a titanium mesh cage filled with activated carbon. The cathode and the anode were connected through an external circuit, and a resistor was connected in the external circuit. The external CW system had a diameter of 250 mm and a height of 500 mm. Inside, from top to bottom, there were large-sized volcanic stones as the support layer and small-sized volcanic stones as the intermediate layer. The effluent of the CW system passed through the cathode of the CW-MFC system from top to bottom and then converged with the effluent of the CW-MFC system in the middle and lower part of the cathode of the CW-MFC system and was discharged. A hydraulic retention time of 24 h, an external resistance of 500 Ω, and Acorus calamus as the wetland plant were selected. After stable operation for ten days, it entered the experimental stage.

[0079] By changing the influent COD concentrations at different levels, Coulombic efficiencies with different values were obtained through detection. The influent and the organic matter concentrations at the bottom of the cathode were determined by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration was constructed. After establishing the fitting curve, the corresponding influent organic matter concentration can be calculated through the curve and the detected Coulombic efficiency of the system.

[0080] Comparative Example 1

[0081] An embedded CW-MFC system was constructed and embedded into the CW system. The CW-MFC system was cylindrical, with a diameter of 125 mm and a height of 420 mm. Inside, from top to bottom, there were an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed from volcanic stones, and a cathode layer composed of a titanium mesh cage filled with activated carbon. The cathode and the anode were connected through an external circuit, and a resistor was connected in the external circuit. The external CW system had a diameter of 250 mm and a height of 500 mm. Inside, from top to bottom, there was a large-particle-size volcanic stone layer as the support layer and a small-particle-size volcanic stone layer as the intermediate layer. The effluent of the CW system passed through the cathode of the CW-MFC system from top to bottom and then merged with the effluent of the CW-MFC system in the lower-middle part of the cathode of the CW-MFC system before being discharged. A hydraulic retention time of 12 h, an external resistance of 1000 Ω, and Acorus calamus as the wetland plant were selected. After stable operation for ten days, the system entered the experimental stage.

[0082] By changing the influent COD concentrations at different levels, Coulombic efficiencies with different values were obtained through detection. The influent and the organic matter concentrations at the bottom of the cathode were determined by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration was constructed. It was found that the fitted relationship curve could not accurately reflect the relationship between the Coulombic efficiency of the system and the influent COD concentration. This indicated that a relatively fast influent flow rate made it difficult for microorganisms to fully contact and utilize organic matter. As the influent COD concentration increased, the microorganisms were in a higher organic matter concentration, exceeding the optimal metabolic organic matter concentration range for the microorganisms. The metabolic pathways within the cells of the relevant microorganisms were affected, resulting in difficulty in presenting a highly fitted curve between the Coulombic efficiency of the system and the influent COD concentration. That is, the corresponding influent organic matter concentration could not be calculated through the curve and the detected Coulombic efficiency of the system.

[0083] Comparative Example 2

[0084] Construct an embedded CW-MFC system and embed it into the CW system. The CW-MFC system is cylindrical, with a diameter of 125 mm and a height of 420 mm. From top to bottom inside, there are an anode layer composed of a titanium mesh cage filled with activated carbon, a transition layer constructed from volcanic stones, and a cathode layer composed of a titanium mesh cage filled with activated carbon. The cathode and the anode are connected through an external circuit, and a resistor is connected in the external circuit. The external CW system has a diameter of 250 mm and a height of 500 mm. From top to bottom inside, there is a large-particle-size volcanic stone as a support layer and a small-particle-size volcanic stone as an intermediate layer. The effluent of the CW system passes through the cathode of the CW-MFC system from top to bottom and converges with the effluent of the CW-MFC system in the lower-middle part of the cathode of the CW-MFC system and then is discharged. A hydraulic retention time of 24 h and an external resistance of 2000 Ω are selected, and calamus is used as a wetland plant. After stable operation for ten days, it enters the test stage.

[0085] By changing the COD concentration of different influents, different values of Coulombic efficiency are obtained through detection. The influent and the organic matter concentration at the bottom of the cathode are measured by the potassium dichromate method. Subsequently, based on the correlation between the Coulombic efficiency and the influent COD concentration, a fitting curve between the Coulombic efficiency and the COD concentration is constructed. It is found that the fitted relationship curve cannot accurately reflect the relationship between the Coulombic efficiency of the system and the influent COD concentration, indicating that the resistance value of the external resistor is too large and the electron transfer is blocked, which will make it difficult to present a curve with a high degree of fitting between the Coulombic efficiency of the system and the influent COD concentration. That is, the corresponding influent organic matter concentration cannot be calculated through the curve and the detected Coulombic efficiency of the system.

[0086] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description in the method section.

[0087] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for monitoring water quality and enhancing the performance of pollutant removal by using an embedded CW-MFC, characterized in that, It includes the following steps: Embed the CW-MFC system inside the CW system so that the effluent of the CW system can enter the CW-MFC system from the top of the CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system converge at the bottom of the cathode layer of the CW-MFC system and are discharged from the outlet of the CW-MFC system; Construct a fitting equation for the Coulomb efficiency of the CW-MFC system and the organic matter concentration of the bottom influent; According to the fitting equation and the Coulomb efficiency calculation formula, on the premise of obtaining the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system, obtain the organic matter concentration of the bottom influent of the CW-MFC system.

2. A method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 1, characterized in that The cathode layer includes a housing composed of a titanium mesh cage, and the housing is filled with activated carbon.

3. A method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 1, characterized in that The CW-MFC system includes a CW-MFC housing, and wetland plants, a cathode layer, a transition layer, and an anode layer are sequentially arranged in the CW-MFC housing from top to bottom; the cathode layer and the anode layer are connected to each other by a wire, and an external resistor is connected in series in the wire.

4. A method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 3, characterized in that The CW system is set as a concave structure, and the groove of the concave structure is used to embed the CW-MFC housing of the CW-MFC system. Wetland plants and a filler medium layer are sequentially arranged from top to bottom in the space around the groove of the concave structure.

5. A method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 3, characterized in that The transition layer includes a volcanic rock layer.

6. The method for monitoring water quality and enhancing the performance of pollutant removal by using an embedded CW-MFC according to claim 4, characterized in that The filler medium layer is large-particle-size volcanic rock and small-particle-size volcanic rock from bottom to top.

7. A method for monitoring water quality and enhancing the performance of pollutant removal by using an embedded CW-MFC according to claim 1, characterized in that Construct a fitting equation for the Coulomb efficiency of the CW-MFC system and the organic matter concentration of the bottom influent, specifically including the following equations: Among them, CE represents the Coulombic efficiency, and both a and b represent the coefficients of the fitting equation. COD 进 represents the influent organic matter concentration at the bottom of the CW-MFC system.

8. A method for monitoring water quality and enhancing pollutant removal performance using an embedded CW-MFC according to claim 7. According to the fitting equation and the Coulomb efficiency calculation formula, on the premise of obtaining the organic matter concentration of the effluent at the bottom of the cathode layer of the CW-MFC system, obtain the organic matter concentration of the bottom influent of the CW-MFC system, specifically including: Obtain the Coulomb efficiency calculation formula: Wherein, CE represents the Coulombic efficiency; M represents the molar mass of the organic matter with oxygen as the standard; 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 for oxidizing 1 mol of organic matter with O2 as the standard; △COD represents the difference between the influent COD concentration and the effluent COD concentration at the bottom of the cathode in the CW-MFC system; COD 出 represents the concentration of organic matter in the effluent at the bottom of the cathode layer; Substitute the fitting equation into the Coulomb efficiency calculation formula to obtain an equivalent formula: According to the equivalent formula and the organic matter concentration COD of the water discharged from the bottom of the cathode layer 出 the organic matter concentration of the water entering the bottom of the CW-MFC system is obtained.

9. A device for monitoring water quality and enhancing the performance of pollutant removal by using an embedded CW-MFC, characterized in that, It includes a CW-MFC system and a CW system; The CW-MFC system includes a CW-MFC housing, and wetland plants, a cathode layer, a transition layer, and an anode layer are sequentially arranged in the CW-MFC housing from top to bottom; the cathode layer includes a housing composed of a titanium mesh cage, and the housing is filled with activated carbon; the cathode layer and the anode layer are connected to each other by a wire, and an external resistor is connected in series in the wire; The CW system is set as a concave structure. The groove of the concave structure is used to embed the CW-MFC housing of the CW-MFC system. After embedding, the effluent of the CW system can enter the CW-MFC system from the top of the CW system. The effluent of the CW system entering the CW-MFC system and the self-effluent of the CW-MFC system 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 filler medium layer are sequentially arranged from top to bottom in the space around the groove of the concave structure.

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