A system for adding fulvic acid to improve the pollution reduction and carbon reduction of a constructed wetland-microbial electrolysis cell and a method for operating the same

Abstract

The application discloses a system for adding fulvic acid to improve the pollution reduction and carbon reduction of a constructed wetland-microbial electrolysis cell and a running method thereof, and belongs to the field of ecological environment treatment, and comprises a water inlet system, a purification system, a water outlet system, a dosing device and an intelligent detection system. The purification system comprises one or more purification units, and different connection relationships are formed by opening and closing of valves. Wastewater input from the water inlet system is subjected to adsorption-electrolysis purification by the purification system, and is discharged from the water outlet system after reaching the standard. The intelligent detection system dynamically determines whether the fulvic acid needs to be added and the adding amount according to the water quality of the water inlet system, and simultaneously accurately adjusts the running mode, thereby significantly improving the treatment effect and reducing carbon emission. The method has the advantages of good treatment effect, stable running, convenient operation and the like, and especially realizes accurate dynamic addition according to different working conditions to improve the pollution reduction and carbon reduction effect of the constructed wetland, and is highly intelligent, low-carbon and green.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ecological environment, and particularly relates to a method for reducing pollution and carbon by adding fulvic acid to an artificial wetland-microbial electrolysis cell system. BACKGROUND

[0002] The emission of carbon and nitrogen in the water treatment process has become one of the global problems to be solved. Studies have shown that when artificial wetlands treat sewage, the emission of greenhouse gases per unit area is 2-10 times that of natural wetlands, ultimately resulting in unsatisfactory comprehensive environmental effects of artificial wetlands. Therefore, an improved method is needed to improve the ability of artificial wetlands to reduce pollution and carbon. Studies have shown that the artificial wetland-microbial electrolysis cell system has higher pollutant removal efficiency than the traditional artificial wetland, but the research on the artificial wetland-microbial electrolysis cell system is still insufficient, for example, the removal effect cannot be fully verified in the laboratory. Fulvic acid, as a major humic substance in urban sewage and artificial wetlands, has little effect on the treatment efficiency of the artificial wetland-microbial electrolysis cell system. Therefore, a method for adding fulvic acid to improve the treatment efficiency of the artificial wetland-microbial electrolysis cell system is needed.

[0003] The patent with the application number CN202210057821.3, "Device and method for decarburization and denitrification of MEC type down-flow vertical flow artificial wetland with rapid starting microbial electrolysis cell", discloses a device and method for decarburization and denitrification of MEC type down-flow vertical flow artificial wetland with rapid starting microbial electrolysis cell, which includes an artificial wetland pool body, the artificial wetland pool body is internally laid from top to bottom with a top water distribution pipe, a top non-conductive filler layer, an anode conductive filler layer, and an artificial strain introduction pipe and exhaust pipe, a non-conductive filler isolation layer, a cathode conductive filler layer and an artificial strain introduction pipe and exhaust pipe, a bottom non-conductive filler layer and a water outlet pipe, the anode conductive filler layer in the artificial wetland pool body is connected with the top non-conductive filler layer and the non-conductive filler isolation layer respectively, and the cathode conductive filler layer is connected with the bottom non-conductive filler layer and the non-conductive filler isolation layer respectively. However, this patent does not involve the addition of fulvic acid, and even less involves the dynamic addition of fulvic acid to reduce pollution and carbon in artificial wetlands.

[0004] The patent with the application number CN202111311526.8 "Water quality purification system and method of constructed wetland coupled with bioelectrochemical system" discloses a water quality purification system and method of constructed wetland coupled with bioelectrochemical system. The purification system includes a microbial electrolysis cell and a microbial fuel cell; the pool wall of the microbial electrolysis cell and the pool wall of the microbial fuel cell are both provided with a water inlet and a water outlet, the water outlet of the microbial electrolysis cell is connected with the water outlet of the microbial fuel cell through a pipeline; a cell device is arranged in the microbial electrolysis cell and the microbial fuel cell; the cathode and the anode of the cell device in the microbial electrolysis cell are both arranged in a substrate, and the anode of the cell device in the microbial fuel cell is arranged in a substrate; the anode of the cell device in the microbial electrolysis cell is connected with the cathode of the cell device in the microbial fuel cell through a conductive wire; and the cathode of the cell device in the microbial electrolysis cell is connected with the anode of the cell device in the microbial fuel cell through a conductive wire. However, the patent does not involve the addition of fulvic acid, and more does not involve the effect of dynamic addition of fulvic acid on the pollution reduction and carbon reduction of constructed wetland.

[0005] The patent with the application number CN202210315145.5 "Sewage treatment system and sewage hierarchical purification treatment method thereof" discloses a sewage treatment system and a sewage hierarchical purification treatment method thereof, and relates to the technical field of sewage treatment. The present application obtains a new sewage treatment system by coupling a constructed wetland with a bioelectrochemical system. The electrochemical microorganisms in the microbial fuel cell perform metabolism, convert the chemical energy of organic matter in the sewage into electrical energy, and then deliver the electrical energy to the microbial electrolysis cell through the electrode. The titanium mesh collects electrons in a centralized manner, improves the collection efficiency of electrons, and thus improves the efficiency of sewage treatment. However, the patent does not involve the addition of fulvic acid, and more does not involve the effect of dynamic addition of fulvic acid on the pollution reduction and carbon reduction of constructed wetland. SUMMARY

[0006] The purpose of the present application is to solve the problem of excessive greenhouse gas emissions in constructed wetlands, and to provide a system for adding fulvic acid to improve the pollution reduction and carbon reduction of constructed wetland-microbial electrolysis cell, and a method for operating the system, to reduce the emission of greenhouse gases by the constructed wetland-microbial electrolysis cell system, and to improve the removal capacity of conventional pollutants.

[0007] Technical solution: The purpose of the present application is achieved by the following technical solution:

[0008] A system for adding fulvic acid to improve the pollution reduction and carbon reduction of constructed wetland-microbial electrolysis cell, comprising a water inlet system (1), a purification system (2), a water outlet system (3), an adding device (4), an intelligent detection system (5),

[0009] The water inlet system (1) has water inlet pipe (1-1), peristaltic pump (1-2), water inlet flow meter (1-3) and water inlet concentration detector (1-4) from left to right; the purification system (2) is provided with supporting layer (2-1), intermediate layer A (2-2), anode layer (2-3), intermediate layer B (2-4), cathode layer (2-5), gas collecting cover (2-6), concentration detector (2-9), valve A (2-10), valve B (2-11) from bottom to top; the water outlet system (3) comprises water outlet pipe (3-1), valve (3-2), water outlet flow meter (3-3) and water outlet concentration detector (3-4); the intelligent detection system (5) has water inlet module (5-1), early warning module (5-2), dosing module (5-3), water outlet module (5-4) in sequence, wherein the anode layer (2-3) and the cathode layer (2-5) are connected with the positive and negative poles of the direct current power supply (2-8) through wires (2-7) respectively. The activated sludge enters the reactor from the water inlet pipe by the peristaltic pump from bottom to top, enters the start-up period after inoculating the sludge, and after the start-up period is over, different concentrations of fulvic acid are added in four stages, and the influence of the concentration of fulvic acid on the treatment efficiency of the constructed wetland-microbial electrolysis cell system is studied.

[0010] The supporting layer (2-1) has a thickness of 10 cm, the intermediate layer A (2-2) has a thickness of 7.5 cm, the anode layer (2-3) has a thickness of 5 cm, the intermediate layer B (2-4) and the cathode layer (2-5) have a thickness of 4.5 cm, and the filling of the anode and cathode layers is consistent, that is, 5 cm high, 3-6 mm in particle size, and the coconut activated carbon is placed in the middle of the collecting electrode.

[0011] Preferably, the activated carbon is pretreated: the coconut activated carbon is repeatedly washed with clean water until there is no obvious impurity. In order to activate the efficiency of the activated carbon and facilitate the subsequent enrichment of electroactive microorganisms, it is immersed in 1 mol / L sodium hydroxide solution and 1 mol / L hydrochloric acid for 12-14 hours, and finally washed with deionized water until the washing liquid pH is 7±0.2, and dried at 105°C for standby.

[0012] Preferably, the carbon felt is pretreated: the cut carbon felt is immersed and washed in an acetone water solution for 12-14 hours to remove lipid-soluble substances. Then it is kept in fresh boiling water, which is replaced every half hour, and after repeating 6 times, it is dried at 105°C for standby.

[0013] Preferably, the supporting layer (2-1) is filled with coarse gravel with a particle size of 10-20 mm, the intermediate layer 1 (2-2) and the intermediate layer 2 (2-5) are filled with fine gravel with a particle size of 6-9 mm, and the gravel is unpolished gravel to enhance the microbial biofilm formation.

[0014] Preferably, the cathode current collector is cut into a circular ring with an inner diameter of 10 cm and an outer diameter of 15 cm to facilitate the upper plants to root downward in the circular ring, and the anode carbon felt is uniformly punched with 9 circular holes with a diameter of about 5 mm to facilitate water passing through the anode area. The water passing test shows that the working volume of the device is 7.78 L, the effective volume is 3.10 L, and the overall porosity is 39.87%. Finally, the whole device is light-proofed by using a light-proof cloth (mainly including the outer wall of the device, the water inlet bucket and the water inlet pipe).

[0015] Preferably, the artificial wetland selects yellow flag as the artificial wetland plant, and the yellow flag with similar growth state, lush plant and full tuber is selected and transplanted to the cathode area of CW2 and ECW2.

[0016] The final wastewater contains 100 mg / L of COD, 3 mg / L of TP, 20 mg / L of NH3-N and 12 mg / L of NO3-N, so that the carbon-nitrogen ratio is about 3:1. In addition, 10 times diluted modified Hoagland nutrient solution (without carbon, nitrogen and phosphorus) is added to the wastewater as a source of trace elements for plant and microbial growth

[134] , 1 mL per liter of wastewater, and the water inlet bucket is washed every day.

[0017] A method for adding fulvic acid to improve the artificial wetland-microbial electrolysis cell system for reducing pollution and carbon, comprising the following steps:

[0018] The influent concentration detector (1-4) detects the COD, TN and TP concentrations in the influent as C Ci , C Ni and C Pi respectively, and the influent flow meter (1-3) detects the influent flow Q i . The effluent concentration detector (3-4) detects the COD, TN and TP concentrations in the effluent as C Ce , C Ne and C Pe respectively, and the effluent flow meter (3-3) detects the effluent flow Q e . The concentration detector (2-9) detects the concentrations of CO2, N2O and CH4 in the gas collection hood as C CO2 , C N2O and C CH4 respectively.

[0019] The intelligent detection system (5) performs the following operations:

[0020] 1) Calculate the influent pollution content W i by formula 1:

[0021]

[0022] In the formula, C Ciis the COD concentration in the influent, mg / L;

[0023] C Ni is the TN concentration in the influent, mg / L;

[0024] C Pi is the TP concentration in the influent, mg / L;

[0025] K C is the conversion coefficient of pollutant COD, dimensionless;

[0026] K N is the conversion coefficient of pollutant TN, dimensionless;

[0027] K P is the conversion coefficient of pollutant TP, dimensionless;

[0028] Q i is the water inlet flow rate.

[0029] 2) Calculate the influent carbon-nitrogen ratio CN by formula 2 i :

[0030] CN i =C Ci / C Ni Formula 2

[0031] Where C Ci is the COD concentration in the influent, mg / L;

[0032] C Ni is the TN concentration in the influent, mg / L;

[0033] 3) Calculate the water pollution content W by formula 3 e :

[0034]

[0035] Where C Ce is the COD concentration in the effluent, mg / L;

[0036] C Ne is the TN concentration in the effluent, mg / L;

[0037] C Pe is the TP concentration in the effluent, mg / L;

[0038] K C is the conversion coefficient of pollutant COD, dimensionless;

[0039] K N is the conversion coefficient of pollutant TN, dimensionless;

[0040] K PConversion factor for pollutant TP, dimensionless

[0041] Q e Effluent flow, L / s.

[0042] 4) Calculate the greenhouse gas production G by formula 4:

[0043]

[0044] In the formula, C CO2 Volume fraction of CO2 in the hood, dimensionless;

[0045] C N2O Volume fraction of N2O in the hood, dimensionless;

[0046] C CH4 Volume fraction of CH4 in the hood, dimensionless;

[0047] V is the volume of the hood, m 3 ;

[0048] K CO2 , K N2O , K CH4 Conversion factor for CO2, N2O, CH4, respectively, dimensionless.

[0049] The system operation is divided into the following three working conditions according to the above calculation results:

[0050] Working condition one:

[0051] A. The wastewater is introduced into the reactor from the bottom to the top by the peristaltic pump (1-2) through the inlet pipe (1-1), and the intelligent detection system (5) determines the pollutant content W i and the carbon-nitrogen ratio CN i of the inlet water: when W i > W i,max , or CN i <CN i,max . Through the input system (5-1) feedback to the early warning system (5-2), the purification system is adjusted through the early warning system (5-2), the valve A (2-10) is closed, the valve B (2-11) is opened, the pool body A is changed into series mode with pool bodies B, C, and D, and the pool bodies B, C, and D are in parallel mode. The dosing module (5-3) calculates the dosing amount of fulvic acid for reducing pollution as W 黄1 .

[0052] B. Then the wastewater passes through the supporting layer (2-1), the intermediate layer A (2-2), and enters the anode layer (2-3), and the oxidation reaction occurs in the anode layer (2-3).

[0053] C. After that, the wastewater flows into the intermediate layer B (2-4), which mainly functions as a separation layer between the anode layer (2-3) and the cathode layer (2-5), and the treatment of wastewater by microorganisms occurs in this layer.

[0054] D. Then the wastewater flows into the cathode layer (2-5), where a reduction reaction occurs.

[0055] E. The effluent flow meter (3-3) and the effluent concentration detector (3-4) detect the flow and concentration of the treated water. When W e <W e,max , the valve C (3-3) is opened, and the wastewater purified by the pool A flows into the pools B, C, and D through the valve B (2-11), and after treatment, it flows out through the effluent pipe (3-1).

[0056] F. The concentration detector (2-9) detects the concentration of greenhouse gases in the gas hood, and the intelligent detection system (5) determines the greenhouse gas production G: when G > G min , it is determined that the wetland greenhouse gas production is higher than the limit value, and additional fulvic acid is needed for carbon reduction, with a dosage of W 黄2 .

[0057] Case two:

[0058] A. The wastewater is introduced into the reactor from the bottom up by the peristaltic pump (1-2) through the inlet pipe (1-1), and the intelligent detection system (5) determines the influent pollutant content W i and the carbon-nitrogen ratio CN i : when W i,min < W i < W i,max , and CN i > CN i,max . Through the input module (5-1) feedback to the warning module (5-2), the purification system is adjusted through the warning system (5-2), the valve A (2-10) is opened, and the valve B (2-11) is closed, making the pools A, B, C, and D into a parallel mode, and the dosage of fulvic acid for pollution reduction calculated by the dosage module (5-3) is W 黄1 .

[0059] B. Then the wastewater passes through the supporting layer (2-1) and the intermediate layer A (2-2) into the anode layer (2-3), where an oxidation reaction occurs.

[0060] C. After that, the wastewater flows into the intermediate layer B (2-4), which mainly functions as a separation layer between the anode layer (2-3) and the cathode layer (2-5), and the treatment of wastewater by microorganisms occurs in this layer.

[0061] D. Then the wastewater flows into the cathode layer (2-5), and a reduction reaction occurs in the cathode layer (2-5).

[0062] E. The effluent flow meter (3-3) and the effluent concentration detector (3-4) detect the flow and concentration of the treated water. When W e <W e,max , the valve C (3-3) opens, and the wastewater enters the pool bodies A, B, C, and D through the inlet pipe via the peristaltic pump. After evolution in the pool bodies, it flows out through the outlet pipe (3-1).

[0063] F. The concentration detector (2-9) detects the concentration of greenhouse gases in the gas collection hood, and the intelligent detection system (5) determines the greenhouse gas production G: when G > G min , it is determined that the wetland greenhouse gas production is higher than the limit value, and additional fulvic acid is needed for carbon reduction, with a dosage of W 黄2 .

[0064] Case three:

[0065] A. The wastewater enters the reactor from the bottom up through the inlet pipe (1-1) via the peristaltic pump (1-2), and the intelligent detection system (5) determines the influent pollutant content W i and the influent carbon-nitrogen ratio CN i : when W i < W i,min , and CN i > CN i,max , feedback is given to the warning system (5-2) through the input system (5-1), and the purification system is adjusted through the warning system (5-2), opening valve A (2-10) and closing valve B (2-11), so that the pool bodies A, B, C, and D become parallel mode, and the dosage module (5-3) calculates the dosage of fulvic acid for pollution reduction as W 1 .

[0066] B. Then the wastewater passes through the supporting layer (2-1), the intermediate layer A (2-2), and enters the anode layer (2-3), where an oxidation reaction occurs.

[0067] C. After that, the wastewater flows into the intermediate layer B (2-4), which mainly serves as a separation layer between the anode layer (2-3) and the cathode layer (2-5), and microbial treatment of the wastewater occurs in this layer.

[0068] D. Then the wastewater flows into the cathode layer (2-5), and a reduction reaction occurs in the cathode layer (2-5).

[0069] E. Then the concentration detector (3-3) detects the concentration, and the effluent flow meter (3-3) and the effluent concentration detector (3-4) detect the flow and concentration of the treated water. When W e<W e,max When valve C (3-2) is opened, the wastewater enters the pool bodies A, B, C, and D through the inlet pipe and the peristaltic pump, and after evolving through the pool body, it flows out through the outlet pipe (3-1).

[0070] F. The concentration detector (2-9) detects the concentration of greenhouse gases in the gas hood, and the intelligent detection system (5) determines the amount of greenhouse gases produced G: when G>G min When the greenhouse gas production in the wetland is judged to be higher than the limit, additional fulvic acid is needed for carbon reduction, and the dosage is W 黄2 .

[0071] Determine the dosage of fulvic acid according to formula 5

[0072] W 黄 =W 黄1 +W 黄2 Formula 5

[0073] in,

[0074]

[0075] Where W 黄1 is the dosage of fulvic acid used for pollution reduction, mg;

[0076] W 黄2 is the dosage of fulvic acid for carbon reduction, mg;

[0077] W i is the pollutant content of the influent, mg;

[0078] W i,max is the upper limit of the influent pollution content, mg;

[0079] W i,min is the lower limit of the influent pollution content, mg;

[0080] G is the amount of greenhouse gas produced, m 3 ;

[0081] G min is the lower limit of greenhouse gas production, m 3 ;

[0082] K1 is the conversion coefficient, dimensionless.

[0083] K2 is the conversion coefficient, mg / m 3 .

[0084] Compared with the prior art, the advantages of the present invention are:

[0085] (1) The application adopts fulvic acid as the dosing material of the constructed wetland-microbial electrolysis cell system, which is a kind of humus organic matter existing in urban sewage and the constructed wetland. By adding fulvic acid, the emission of greenhouse gases in the constructed wetland-microbial electrolysis cell system is reduced, and the removal capacity of conventional pollutants is improved.

[0086] (2) The application adopts the series-parallel connection mode of four devices to improve the wastewater treatment effect and efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0087] Figure 1 It is a schematic diagram of the connection relationship of the constructed wetland-microbial electrolysis cell system of the application;

[0088] Figure 2 It is a flowchart of working condition one;

[0089] Figure 3 It is a flowchart of working condition two;

[0090] Figure 4 It is a flowchart of working condition three.

[0091] Among them, the water inlet system-1, the purification system-2, the water outlet system-3, the dosing device-4, the intelligent detection system-5; the water inlet pipe-1-1, the peristaltic pump-1-2;

[0092] The water inlet flowmeter-1-3, the water outlet pipe-3-1, the valve 3-2, the water outlet flowmeter-3-3, the water outlet concentration detector 3-4;

[0093] The supporting layer-2-1, the intermediate layer A-2-2, the anode layer-2-3, the intermediate layer B-2-4, the cathode layer-2-5, the gas collection cover-2-6, the concentration detector-2-9, the direct current power supply-2-8. DETAILED DESCRIPTION

[0094] The technical solution of the application will be specifically described below in combination with specific embodiments:

[0095] A constructed wetland-microbial electrolysis cell system for improving pollution reduction and carbon reduction by adding fulvic acid, comprising a water inlet system 1, a purification system 2, a water outlet system 3, a dosing device 4, and an intelligent detection system 5; wherein the water inlet system 1, the purification system 2, and the water outlet system 3 are connected in sequence, and the intelligent detection system 5 is connected to the water inlet system, the purification system, the water outlet system, and the dosing device at the same time; the dosing device is connected to the purification system. The wastewater is input into the purification unit of the purification system from bottom to top through the water inlet system 1, and after adsorption-microbial electrolysis purification, it is discharged through the water outlet system after meeting the purification standard; during the purification process, the intelligent detection system determines the opening and closing of the valves between the purification units according to the pollutant concentration in the wastewater to be treated, thereby constructing the connection relationship of the purification units, and simultaneously judging whether fulvic acid needs to be added and the addition amount.

[0096] The purification system 2 comprises more than one purification unit, and different connection relationships are constructed by opening and closing of valves; the wastewater input from the water inlet system is purified by adsorption-electrolysis of the purification system 2, and discharged from the water outlet system after reaching the standard; the intelligent detection system 5 judges whether it is necessary to add fulvic acid and the amount of addition according to the water body condition.

[0097] The purification unit is provided with a supporting layer 2-1, an intermediate layer A 2-2, an anode layer 2-3, an intermediate layer B 2-4, a cathode layer 2-5, a gas collection cover 2-6 and a concentration detector 2-9 from bottom to top; the anode layer 2-3 and the cathode layer 2-5 are connected to the positive and negative poles of a direct current power supply 2-8 through wires respectively; after the start-up period ends, different concentrations of fulvic acid are put in according to different water body conditions.

[0098] The water inlet system 1 is sequentially provided with a water inlet pipe 1-1, a peristaltic pump 1-2, a flow meter 1-3 and a concentration detector from left to right; the water outlet system 3 comprises a water outlet pipe 3-1, a concentration detector B 3-2 and a valve C 3-3. The intelligent detection system 5 is sequentially provided with a water inlet module 5-1, a warning module 5-2, an adding module 5-3 and a water outlet module 5-4; wherein the water inlet module and the warning module are connected to the water inlet system 1, the adding module 5-3 is connected to an adding device, the adding device is connected to the purification system, and the water outlet module is connected to the water outlet system.

[0099] In this embodiment, the thickness of the supporting layer 2-1 is 10 cm, the thickness of the intermediate layer 2-2 is 7.5 cm, the intermediate layer 2-4; the filling material of the anode and cathode layers is coconut activated carbon, 5 cm high, particle size 3-6 mm, and a current collector is placed in the middle.

[0100] The filling material of the anode and cathode is pretreated before use, wherein: the pretreatment of the coconut activated carbon is to wash and dry the coconut activated carbon, then immerse it in 1 mol / L sodium hydroxide solution and 1 mol / L hydrochloric acid for 12-14 h for activation, finally wash it with deionized water until the washing liquid pH is 7±0.2, and dry it at 105℃ for standby. The pretreatment of the carbon felt used as the anode current collector is to immerse and wash the cut carbon felt in an acetone aqueous solution to remove fat-soluble substances; then immerse it in fresh boiling water, replace the boiling water every half hour, repeat 6 times, and dry it at 105℃ for standby.

[0101] Example 1

[0102] In this embodiment, the number of purification units is four, and the connection relationship between the first purification unit and the fourth purification unit is constructed by opening and closing of the valve A 2-10 and the valve B 2-11.

[0103] The specific operation process is: take four organic glass columns with an inner diameter of 15 cm and a height of 44.5 cm, and mark them as purification units 1 to 4.

[0104] Artificially synthesized simulated secondary water was selected as the experimental wastewater (carbon-nitrogen ratio of 3:1), and 10-fold diluted Hoagland nutrient solution (removed carbon, nitrogen and phosphorus) was added to the wastewater as a source of trace elements for plant and microbial growth, with an addition amount of 1 mL per liter of wastewater.

[0105] The retrieved activated sludge was passed through a 2mm sieve to remove large particles of impurities. After repeated washing and sedimentation with clean water three times, the sludge was cultured in an anaerobic environment in the laboratory for one week, during which the nutrient solution was replaced every three days. Finally, the activated sludge and experimental simulated wastewater were mixed in a volume ratio of 1:9 and introduced into the artificial wetland from bottom to top using a peristaltic pump.

[0106] After inoculation with sludge, the constructed wetland officially entered its startup phase. On the first day, the reactor was not drained. From the second to the seventh day, half of the reactor effluent was mixed with half of fresh wastewater and returned to the reactor. From the eighth day onward, the reactor officially operated with continuous upward flow, maintaining a constant hydraulic load rate. Furthermore, the potential difference between the anode and cathode was maintained at 0.8 to 0.9 V. To achieve this, a voltmeter was frequently used for measurement and calibration. The entire startup phase lasted two months.

[0107] After the start-up period, the COD, TN and TP concentrations in the influent are detected by the influent concentration detector and are C Ci，1 、C Ni,1 、C Pi,1 , the water inlet flow meter detects the water inlet flow Q i The effluent concentration detector detected the COD, TN and TP concentrations in the effluent water, which were C Ce，1 、C Ne,1 、C Pe,1 The intelligent detection system calculates the influent pollution content W according to formula 1. i,1 Calculate the influent carbon-nitrogen ratio CN according to formula 2 i，1 .

[0108] Intelligent detection system for water pollution content W i,1 and the influent carbon-nitrogen ratio CN i，1 Make a judgment: Since W is satisfied i,1 >W i,max , determine the operating condition 1. The water inlet module feeds back to the early warning system, which adjusts the connection relationship of the purification units of the purification system so that the first purification unit and the second to Nth purification units are in series mode, and the second to Nth purification units are in parallel mode; the dosage of fulvic acid for pollution reduction is W 黄1 In addition, the intelligent detection system calculates the water pollution content W according to formula 3e，1 , determine that W e , 1 < W e,max . Open the valve, the wastewater purified by the first purification unit flows into the parallel second to N through the valve after reprocessing, and flows out through the effluent pipe.

[0109] The concentration detector detects the concentrations of CO2, N2O and CH4 in the gas hood as C CO2，1 , C N2O,1 and C CH4,1 , respectively. The greenhouse gas generation G1 is calculated by formula 4, and it is determined that G1 < G min , the amount of fulvic acid added for carbon reduction is 0.

[0110] Example 2

[0111] In this example, after the start-up period, the influent concentration detector detects the COD, TN and TP concentrations in the influent as C Ci，2 , C Ni,2 and C Pi,2 , respectively. The influent flow meter detects the influent flow Q i . The effluent concentration detector detects the COD, TN and TP concentrations in the effluent as C Ce，2 , C Ne,2 and C Pe,2 , respectively. The intelligent detection system calculates the influent pollution content W i,2 according to formula 1, and the influent carbon-nitrogen ratio CN i，2 according to formula 2.

[0112] The intelligent detection system determines the influent pollution content W i,2 and the influent carbon-nitrogen ratio CN i，2 : since W i,min < W i , 2 < W i,max , and CN i,2 > CN i,max , it is determined that the operating condition two is running. The influent module feeds back to the early warning system, and the connection relationship of the purification units of the purification system is adjusted through the early warning system, so that the first to N purification units are in parallel mode. Open valve A and close valve B to adopt purification units 1-4 in parallel to meet the effluent standard and improve the treatment efficiency. The amount of fulvic acid added for pollution reduction is:

[0113]

[0114] The concentration detector detects the concentrations of CO2, N2O and CH4 in the gas hood as C CO2，2 , C N2O,2 and C CH4,2, the greenhouse gas production G2 is calculated by formula 4, and it is determined that G2 < G min , the yellow humic acid dosage for carbon reduction is 0.

[0115] Example 3

[0116] In this example, after the start-up period, the influent concentration detector detects the COD, TN and TP concentrations in the influent as C Ci，3 , C Ni,3 , C Pi,3 , and the influent flow meter detects the influent flow Q i . The effluent concentration detector detects the COD, TN and TP concentrations in the effluent as C Ce，3 , C Ne,3 , C Pe,3 . The intelligent detection system calculates the influent pollutant content W i,3 according to formula 1, and calculates the influent carbon-nitrogen ratio CN i，3 according to formula 2.

[0117] The intelligent detection system determines the influent pollutant content W i,1 and the influent carbon-nitrogen ratio CN i,3 : since the following conditions are met:

[0118] W i,3 < W i,min , and CN i,3 > CN i,max

[0119] , it is determined that the operating condition three is running, and the feedback is fed back to the early warning system (5-2) through the influent module (5-1), and the connection relationship of the purification units of the purification system is adjusted through the early warning system (5-2), so that the first purification unit and the second to Nth purification units are in parallel mode. The dosage of yellow humic acid for reducing pollution is W 黄1 , which is 10 mg.

[0120] The concentration detector detects the concentrations of CO2, N2O and CH4 in the gas hood as C CO2，3 , C N2O,3 , C CH4,3 , and the greenhouse gas production G3 is calculated by formula 4, and it is determined that G3 > G min . The dosage of yellow humic acid for carbon reduction is:

[0121]

[0122] The total dosage of yellow humic acid W 黄 = W 黄1 + W 黄2

[0123] Therefore, the application provides a method for reducing pollution, reducing carbon and improving the system of constructed wetland-microbial electrolysis cell by adding fulvic acid, which applies fulvic acid to reduce greenhouse gas emission of the constructed wetland, and connects different purification units in series and in parallel according to different wastewater to be treated, and good effects are achieved.

[0124] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for operating a system for reducing pollution and carbon by adding fulvic acid to an artificial wetland-microbial electrolysis cell, characterized in that: The wastewater is input into the purification unit of the purification system (2) from bottom to top through the water inlet system (1), and is discharged through the water outlet system (3) after purification. During the purification process, the intelligent detection system (5) determines the opening and closing of the valves between the purification units according to the concentration of pollutants in the wastewater to be treated, thereby constructing the connection relationship of the purification units, and determining whether to add fulvic acid and the amount of addition. The amount of fulvic acid addition is determined according to formula 5: W 黄 = W 黄1 + W 黄2 wherein, In the formula, W 黄1 is the yellow ferment acid dosage for reducing pollutants, mg; W 黄2 is the yellow ferment acid dosage for reducing carbon, mg; W i is the influent pollutant content, mg; W i,max is the upper limit of the influent pollutant content, mg; W i,min is the lower limit of the influent pollutant content, mg; G is the greenhouse gas production, m 3 ; G min is the lower limit of the greenhouse gas production, m 3 ; K1 is a conversion coefficient, dimensionless; K2 is a conversion coefficient, mg / m 3 ; The influent concentration detector (1-4) detects the COD, TN, and TP concentrations in the influent as C Ci , C Ni , and C Pi , respectively, the influent flow meter (1-3) detects the influent flow rate Q i ; the effluent concentration detector (3-4) detects the COD, TN, and TP concentrations in the effluent as C Ce , C Ne , and C Pe , respectively, the effluent flow meter (3-3) detects the effluent flow rate Q e ; the concentration detector (2-9) detects the CO2, N2O, and CH4 concentrations in the gas collection hood as C CO2 , C N2O , and C CH4 , respectively. The intelligent detection system (5) performs the following operations according to the above detection data: 1) Calculate the incoming wastewater pollutant content W by equation 1 i : In the formula, C Ci is the COD concentration in the influent, mg / L; C Ni is the TN concentration in the influent, mg / L; C Pi is the TP concentration in the influent, mg / L; K C is the conversion coefficient of the pollutant COD, dimensionless; K N is the conversion coefficient of the pollutant TN, dimensionless; K P is the conversion coefficient of the pollutant TP, dimensionless; Q i is the influent flow rate; 2) Calculate the influent carbon to nitrogen ratio CN by equation 2 i : CN i =C Ci / C Ni Formula 2 In the formula, C Ci is the COD concentration in the influent, mg / L; C Ni is the TN concentration in the influent, mg / L; 3) Calculate the water contamination W by equation 3 e : In the formula, C Ce COD concentration in effluent, mg / L; C Ne TN concentration in effluent, mg / L; C Pe TP concentration in effluent, mg / L; K C Conversion coefficient of pollutant COD, dimensionless; K N Conversion coefficient of pollutant TN, dimensionless; K P Conversion coefficient of pollutant TP, dimensionless; Q e Effluent flow, L / s; 4) Calculate the greenhouse gas generation G by formula 4: where C CO2 is the volume fraction of CO2in the hood, dimensionless; C N2O is the volume fraction of N2O in the hood, dimensionless; C CH4 is the volume fraction of CH4in the hood, dimensionless; V is the volume of the hood, m 3 ; K CO2 , K N2O , K CH4 are the conversion factors for CO2, N2O, CH4, respectively, dimensionless.

2. The operation method of the system for reducing pollution and carbon by adding fulvic acid to improve the constructed wetland-microbial electrolysis cell according to claim 1, characterized in that: There are three working conditions as follows: Working condition one: (1) The wastewater is introduced into the water inlet system by a peristaltic pump (1-2) through a water inlet pipe (1-1), and the intelligent detection system (5) determines the pollution content W i and the carbon-nitrogen ratio CN i of the water inlet, and determines: When W i >W i,max , or CN i <CN i,max Then, the feedback to the early warning module (5-2) through the water inlet module (5-1) adjusts the connection relationship of the purification units of the purification system through the early warning module (5-2), so that the first purification unit and the second to Nth purification units are in series mode, and the second to Nth purification units are in parallel mode; the dosing module (5-3) calculates the dosing amount of fulvic acid for pollution reduction as W 黄1 ; (2) In the first purification unit, wastewater flows from bottom to top through the support layer (2-1), the intermediate layer A (2-2), and enters the anode layer (2-3), where oxidation reaction occurs; the intermediate layer B (2-4) is used for microbial treatment of wastewater, which is a separation layer between the anode layer (2-3) and the cathode layer (2-5); and the cathode layer (2-5) is flowed into, where reduction reaction occurs; (3) The water flow meter (3-3) and the water concentration detector (3-4) detect the flow and concentration of the treated water. When W e <W e,max the valve (3-2) is opened, the wastewater purified by the first purification unit flows into the parallel 2nd to Nth through the valve and after being treated again, it flows out through the water outlet pipe (3-1) to meet the standards, wherein; (4) The concentration detector (2-9) detects the concentration of the greenhouse gas in the gas collecting hood, and the intelligent detection system (5) determines the greenhouse gas production G: when G>G min , it is determined that the wetland greenhouse gas production is higher than the limit value, and additional fulvic acid is needed for carbon reduction, and the dosage is W 黄2 ; Working condition two: (1) The intelligent detection system (5) determines the pollution content W of the influent i and the carbon-nitrogen ratio CN of the influent i : when W i,min < W i < W i,max , and CN i < CN i,max , the feedback is fed back to the early warning module (5-2) through the influent module (5-1), the connection relationship of the purification units of the purification system is adjusted through the early warning module (5-2), the first to the Nth purification units are in parallel mode, and the dosing module (5-3) calculates the dosing amount of fulvic acid for reducing pollution as W 黄1 . (2) In the first to Nth purification units, wastewater flows from bottom to top through the support layer (2-1), the intermediate layer A (2-2), and enters the anode layer (2-3), where oxidation reaction occurs; the intermediate layer B (2-4) is used for microbial treatment of wastewater, which is a separation layer between the anode layer (2-3) and the cathode layer (2-5); and the cathode layer (2-5) is flowed into, where reduction reaction occurs; (3) The water flow meter (3-3) and the water concentration detector (3-4) detect the flow and concentration of the treated water. When W e <W e,max , the valve (3-2) is opened, and the water that meets the standards flows out. (4) The concentration detector (2-9) detects the concentration of the greenhouse gas in the gas collecting hood, and the intelligent detection system (5) determines the greenhouse gas production G: when G>G min , it is determined that the wetland greenhouse gas production is higher than the limit value, and additional fulvic acid is needed for carbon reduction, and the dosage is W 黄2 ; Working condition three: (1) The intelligent detection system (5) determines the pollutant content W of the incoming water i and the carbon-nitrogen ratio CN of the incoming water i ​ When W i <W i,min , and CN i >CN i,max Then, the feedback from the water inlet module (5-1) to the early warning module (5-2) is adjusted by the early warning module (5-2) to connect the purification units of the purification system, so that the first purification unit and the second to Nth purification units are in parallel mode; the dosing module (5-3) calculates the dosage of fulvic acid for pollution reduction as W 黄1 ; (2) In the first to Nth purification units, wastewater flows from bottom to top through the support layer (2-1), the intermediate layer A (2-2), and enters the anode layer (2-3), where oxidation reaction occurs; the intermediate layer B (2-4) is used for microbial treatment of wastewater, which is a separation layer between the anode layer (2-3) and the cathode layer (2-5); and the cathode layer (2-5) is flowed into, where reduction reaction occurs; (3) The water flow meter (3-3) and the water concentration detector (3-4) detect the flow and concentration of the treated water. When W e <W e,max , the valve (3-2) is opened and the water that meets the standards is discharged. (4) The concentration detector (2-9) detects the concentration of the greenhouse gas in the gas collecting hood, and the intelligent detection system (5) determines the greenhouse gas production G: when G>G min , it is determined that the wetland greenhouse gas production is higher than the limit value, and additional fulvic acid is needed for carbon reduction, and the dosage is W 黄2 .

3. The operation method of the system for reducing pollution and carbon by adding fulvic acid to improve the constructed wetland-microbial electrolysis cell according to claim 1, characterized in that: The system for improving the artificial wetland-microbial electrolysis cell pollution reduction and carbon reduction by adding fulvic acid comprises a water inlet system (1), a purification system (2), a water outlet system (3), an adding device (4), and an intelligent detection system (5). The water inlet system (1), the purification system (2), and the water outlet system (3) are connected in sequence, and the intelligent detection system (5) is connected to the water inlet system, the purification system, the water outlet system, and the adding device. The adding device is connected to the purification system. The purification system (2) comprises one or more purification units, and different connection relationships are constructed by opening and closing the valves. The wastewater input from the water inlet system is purified by the adsorption-electrolysis of the purification system (2), and is discharged from the water outlet system after reaching the standard. The intelligent detection system (5) determines whether to add fulvic acid and the amount of addition according to the water condition.

4. The operation method of the system for reducing pollution and carbon by adding fulvic acid to improve the constructed wetland-microbial electrolysis cell according to claim 3, characterized in that: The water inlet system (1) has, from left to right, a water inlet pipe (1-1), a peristaltic pump (1-2), a water inlet flow meter (1-3), and a water inlet concentration detector (1-4); the water outlet system (3) includes a water outlet pipe (3-1), a valve (3-2), a water outlet flow meter (3-3), and a water outlet concentration detector (3-4); The number of the purification units is more than one, two valves are arranged between the first purification unit and the other purification units, and the first purification unit and the other purification units are connected in series or in parallel by opening the valves respectively; the purification unit of the purification system (2) is provided, from bottom to top, with a supporting layer (2-1), an intermediate layer A (2-2), an anode layer (2-3), an intermediate layer B (2-4), a cathode layer (2-5), a gas collection cover (2-6), and a concentration detector (2-9); the anode layer (2-3) and the cathode layer (2-5) are connected to the positive and negative poles of a direct-current power supply (2-8) through wires respectively; the activated sludge enters the purification system (2) from the water inlet pipe from bottom to top by the peristaltic pump (1-2), enters the start-up period after being inoculated with sludge, and after the start-up period ends, different concentrations of fulvic acid are added according to different water conditions; The intelligent detection system (5) is provided, from left to right, with a water inlet module (5-1), a warning module (5-2), an adding module (5-3), and a water outlet module (5-4); the water inlet module (5-1) and the warning module (5-2) are connected to the water inlet system (1), the adding module (5-3) is connected to the adding device (4), the adding device (4) is connected to the purification system (2), and the water outlet module (5-4) is connected to the water outlet system (3).

5. The operation method of the system for adding fulvic acid to improve the pollution reduction and carbon reduction of the constructed wetland-microbial electrolysis cell according to claim 4, characterized in that: The supporting layer (2-1) has a thickness of 10 cm and is filled with coarse gravel with a particle size of 10-20 mm; The intermediate layer (2-2) has a thickness of 7.5 cm and is filled with fine gravel with a particle size of 6-9 mm; The filling material of the intermediate layer (2-4) and the anode and cathode layers is coconut activated carbon with a height of 5 cm and a particle size of 3-6 mm, and a current collector is placed in the middle; the anode current collector is carbon felt, and the cathode current collector is a ring; The purification unit as a whole is light-proof, and plants are planted on the upper part.

6. The operation method of the system for reducing pollution and carbon by adding fulvic acid to improve the constructed wetland-microbial electrolysis cell according to claim 5, characterized in that: The filling material of the anode and cathode layers is pretreated before use, wherein: the pretreatment of the coconut activated carbon is to wash and dry the coconut activated carbon, then immerse it in 1 mol / L sodium hydroxide solution and 1 mol / L hydrochloric acid for 12-14 h for activation, finally wash it with deionized water until the pH of the washing liquid is 7±0.2, and then dry it at 105℃ for standby; the pretreatment of the carbon felt is to immerse and wash the cut carbon felt in an acetone aqueous solution to remove lipid-soluble substances, then immerse it in fresh boiling water, replace the boiling water every half hour, repeat for 6 times, and then dry it at 105℃ for standby.

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