Sulfate reduction control process based on intermittent electrical stimulation

Abstract

The invention provides a sulfate reduction control process based on intermittent electrical stimulation. The sulfate reduction control process comprises the following steps: constructing a sulfate reduction system based on a bioelectrochemical technology; providing potential for the cathode of the microbial electrolysis cell in different time periods by using an intelligent time control switch, and constructing an intermittent electric field; determining prediction parameters of the intermittent electric field based on the intelligent model; the operation parameters of the intermittent electric field are adjusted in real time according to the actual output result of the sulfate reduction system, and the growth of sulfate reducing bacteria in the system is regulated in real time through the adjusted intermittent electric field, so that the energy input in the sulfate reduction process is ensured, the SRB activity in the acid environment is improved, and the stable operation of the microbial electrolysis cell in the acid environment is maintained. According to the invention, damage to microbial cell functions and microstructures caused by continuous electrical stimulation is avoided, influence of charge transfer resistance on electron transfer is avoided, pollutants in acidic sulfate wastewater are synchronously degraded, and the method has the beneficial effects of high efficiency, energy conservation and water treatment at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of industrial wastewater treatment, and in particular to an intermittent electrical stimulation sulfate reduction control process. Background Art

[0002] Sulfate is generally considered non-toxic, but high-concentration sulfate wastewater will disrupt the balance of the natural sulfur cycle, thus inevitably producing sulfur pollution. Industrial wastewater discharged by industries such as mining and metal smelting often contains high concentrations of sulfate and strong acidity. Sulfate pollution can lead to a variety of indirect environmental problems, including ecological damage, acid mine drainage, corrosion and H2S toxicity.

[0003] Microbial Electrolysis Cell (MEC) is an electrochemical system that combines the electron transfer system of microorganisms with traditional electrochemistry, and uses microorganisms as catalysts to produce oxidation and reduction reactions on electrodes. Weak electrical stimulation significantly increases the conductivity of the electrode and accelerates the direct interspecies electron transfer (DIET) between electroactive bacteria (EAB) and sulfate-reducing bacteria (SRB).

[0004] Intermittent electrical stimulation reduces energy consumption and slows down the hydrogen evolution reaction; it gives microorganisms time to adapt and recover, avoids the permeability of microbial cells and damages the ultrastructure, thereby inhibiting the utilization of organic matrix by microorganisms and hindering the interaction between EAB and SRB. Intermittent electrical stimulation can slow down the storage of ions adsorbed by the electrode and accumulation on the electrode surface by the electric double layers (EDLs) of the biological cathode, avoiding the influence of charge transfer resistance on electron transfer, thereby maintaining a high level of metabolic activity of SRB for a long time, and the biofilm shows a compact microbial community structure and functional genes. Summary of the invention

[0005] The present invention aims to provide an intermittent electrical stimulation sulfate reduction control process to address the defects in the existing microbial electrolytic cell sulfate reduction technology.

[0006] The present invention is implemented by the following technical solutions:

[0007] An intermittent electrical stimulation sulfate reduction control process comprises the following steps:

[0008] S100. Construction of sulfate reduction system based on bioelectrochemical technology;

[0009] S200. In the sulfate reduction system, providing a potential to the cathode in time periods to construct an intermittent electric field;

[0010] S300. Determine the prediction parameters of the intermittent electric field based on the intelligent model;

[0011] S400. Adjust the intermittent electric field operating parameters in real time based on the output results of the sulfate reduction system, and regulate the growth of sulfate-reducing bacteria in the system in real time based on the adjusted intermittent electric field.

[0012] Preferably, constructing a sulfate reduction system based on bioelectrochemical technology in step S100 is specifically constructing a sulfate reduction system based on a microbial electrolytic cell module; the microbial electrolytic cell module comprises an anode region and a cathode region, wherein an anode and a cathode are respectively arranged in the anode region and the cathode region, and the anode region and the cathode region are separated by a diaphragm, and a water inlet is provided at the bottom of the microbial electrolytic cell, and a water outlet is provided at the top of the microbial electrolytic cell module.

[0013] Preferably, the specific steps of constructing the sulfate reduction system are: injecting potassium ferrocyanide nutrient solution into the anode area of ​​the microbial electrolytic cell; adding activated sludge and KH2PO4, MgCl2·6H2O, Na2SO4, CaCl2·2H2O, NH4Cl, trace element solution, vitamin solution, and C2H5OH into simulated wastewater at a volume ratio of 10-30% to the cathode area of ​​the microbial electrolytic cell; using a reference electrode to monitor the electrode potential, connecting a 10Ω resistor in the closed loop of the microbial electrolytic cell, and replacing the solution of the electrolytic cell every 24h-72h; using a DC regulated power supply to apply a voltage of 0.5-0.8V to both ends of the cathode and anode of the electrolytic cell, so that the electrolytic cell is operated at 20-30°C to achieve sulfate reduction, and each time the liquid is replaced, high-purity nitrogen is used for continuous aeration for 10 minutes to remove oxygen in the system.

[0014] Preferably, in step S200, providing electric potential to the cathode in time periods to construct an intermittent electric field includes:

[0015] S201. Determine the duty cycle of the intermittent electric field; the duty cycle includes: in the periodic experiment, the ratio of the duration of the potential to the total cycle time;

[0016] S202. Set the potential intensity and action time of the intermittent electrical stimulation; the action time includes: start time and action time; the start time is the start time of providing the potential to the cathode, and the duration time is the maintenance time of continuously providing the potential to the cathode.

[0017] Preferably, in S300, determining the prediction parameters of the intermittent electric field based on the intelligent model includes:

[0018] S301. Determine input parameters, which include: pH value, ORP value, temperature, SO42- Concentration, S 2- concentration, COD value, and growth kinetics of sulfate-reducing bacteria;

[0019] S302. Input the input parameters into the intelligent model, and the intelligent model calculates the output results according to the prediction algorithm of the model, and the output results include: the predicted potential intensity and predicted action time of the intermittent electric field;

[0020] S303. Using the predicted potential intensity and predicted action time of the intermittent electric field as prediction data of the intermittent electric field.

[0021] Preferably, the intelligent model in step S302 is a GRU neural network model;

[0022] The method of combining the GRU neural network model to predict and precisely control the potential intensity and action time of the intermittent electric field in real time to achieve intelligent operation is to set various water quality sensors in the reactor of the sulfate reduction control process, and timely collect data on the sulfate reduction reaction in the reactor. The GRU neural network model is used to analyze the obtained operation and reaction conditions, predict the potential intensity and action time of the intermittent electric field, and adjust the current operating conditions. The potential intensity, action time and related reaction operation parameter indicators are fed back to realize the sulfate reduction control process and achieve the degradation of pollutants in acidic sulfate wastewater.

[0023] Preferably, the method for constructing the GRU neural network model includes:

[0024] S3021. The pH value, ORP value, temperature, SO4 2- Concentration, S 2- Concentration, COD value, and sulfate-reducing bacteria growth dynamics are used as input parameters of the GRU neural network model, and the input parameters are normalized:

[0025]

[0026] x is the original data point, x' is the normalized data, and x max and x min are the maximum and minimum values ​​of the data set x respectively;

[0027] S3022. Determine the input parameter x according to the data obtained in step S3021. t ;

[0028] The reset gate is used to determine how to combine new input with past memory, and the formula is as follows:

[0029] r t =σ(W r ·[h t-1,x t ])

[0030] Among them, W r is the weight matrix of the reset gate, h t-1 is the previous hidden state, x t is the current input, σ is the sigmoid activation function;

[0031] Determine the update gate to control the degree of integration of the current state and the past state. The formula is as follows:

[0032] z t =σ(W z ·[h t-1 ,x t ])

[0033] Among them, W z is the weight matrix of the update gate;

[0034] Determine the candidate hidden state, the formula is as follows:

[0035]

[0036] Among them, W h is the weight matrix of the candidate state, * indicates element-by-element multiplication;

[0037] The final hidden state is determined by combining the previous hidden state and the candidate state, as follows:

[0038]

[0039] The input parameters are used as operating parameters to obtain output results; the output results include: the predicted potential intensity and predicted action time of the intermittent electric field.

[0040] Preferably, the method for constructing a GRU neural network model further includes:

[0041] Based on the preset sulfate reduction system feature extraction template, the first system feature of the sulfate reduction system is extracted, and the system features include: simulated wastewater parameters, microbial electrolysis cell configuration parameters and environmental parameters;

[0042] According to the first system characteristics, target sulfate reduction process records are screened;

[0043] Analyze the target sulfate reduction process records and obtain sensor monitoring data during the sulfate reduction process.

[0044] Preferably, according to the first system characteristic, screening the target sulfate reduction process record includes:

[0045] Obtaining the first historical sulfate reduction process record;

[0046] Analyze the first historical sulfate reduction process record to obtain reduction effect evaluation parameters, which include sulfate concentration, sulfate removal efficiency, reactor residual COD concentration, and COD removal rate;

[0047] Obtaining a restoration effect evaluation model, inputting a restoration effect evaluation parameter into the restoration effect evaluation model, and obtaining a restoration effect evaluation value;

[0048] If the reduction effect evaluation value is greater than or equal to the preset reduction effect evaluation value threshold, the corresponding first historical sulfate reduction process record is used as the second historical sulfate reduction process record;

[0049] According to the first system characteristics, construct the sulfate reduction system description factor;

[0050] Extracting the second system characteristics and constructing a reference sulfate reduction system description factor according to the second historical sulfate reduction process record and the sulfate reduction system characteristic extraction template;

[0051] Calculate the factor cosine value of the sulfate reduction system description factor and the reference sulfate reduction system description factor;

[0052] If the factor cosine value is greater than or equal to the preset factor cosine value threshold, the corresponding second historical sulfate reduction process record is used as the third historical sulfate reduction process record;

[0053] Parse the third historical sulfate reduction process records to obtain the identity information of the operator;

[0054] According to the operator's identity information, determine the operator's historical experimental irregular records;

[0055] Characterize the irregular records of historical experiments to obtain the irregular record features;

[0056] According to the irregular record features and the preset irregular feature-irregular value comparison library, the irregular value is determined, and the irregular value is spread out on the preset time axis according to the first recording time of the corresponding acquired historical experimental irregular record;

[0057] Marking the second recording time of the third historical sulfate reduction process record on the time axis;

[0058] Obtain the recording time interval between the first recording time and the second recording time, and accumulate the recording time intervals corresponding to the same operator to obtain the recording time and;

[0059] According to the recording time interval and the recording time corresponding to the first recording time, obtaining a correction weight of the irregular value corresponding to the first recording time;

[0060] Multiply the correction weight and the irregular value correspondingly to obtain the corrected irregular value corresponding to the first recording time;

[0061] Accumulate the corrected irregularity values ​​of the same operator to obtain the irregularity degree;

[0062] According to the operator identity information, the third historical sulfate reduction process record corresponding to the operation of the operator whose irregularity is less than the preset irregularity threshold is selected as the target sulfate reduction process record.

[0063] Preferably, in S400, the intermittent electric field operating parameters are adjusted in real time according to the output result of the sulfate reduction system, including:

[0064] S401. Real-time monitoring of operating parameters of the intermittent electrical stimulation sulfate reduction system;

[0065] S402. If the monitored output parameters are different from the predicted parameters, the operating parameters are adjusted to the predicted parameters; if the monitored output parameters are the same as the predicted parameters, an intermittent electric field is formed according to the current operating parameters; according to the growth of the adjusted sulfate-reducing bacteria, the operating cycle is adjusted, and the predicted cycle is determined according to the multiple value of the adjusted cycle and the cycle data.

[0066] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings are used to provide further explanation of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0068] Figure 1 This is a process flow chart of sulfate reduction control by intermittent electrical stimulation in an embodiment of the present invention;

[0069] Figure 2 (a) is the pH change trend; (b) is the ORP change trend; (c) is the sulfate concentration change and reduction rate; (d) is the initial and final sulfate removal effect under intermittent and continuous electric fields. DETAILED DESCRIPTION

[0070] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The preferred implementations described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0071] The present invention provides an intermittent electrical stimulation sulfate reduction control process, please refer to Figure 1The process method includes: constructing a sulfate reduction system based on bioelectrochemical technology; in the sulfate reduction system, providing a periodic potential to the MEC to construct an intermittent electric field.

[0072] The microbial electrolysis cell provided by the present invention comprises an electrolysis cell; the electrolysis cell may be a single-chamber electrolysis cell or a double-chamber electrolysis cell; when the electrolysis cell is a double-chamber electrolysis cell, it preferably further comprises an ion exchange membrane, and the two chambers are separated by the ion exchange membrane; the ion exchange membrane is preferably a proton exchange membrane, an anion exchange membrane or a cation exchange membrane; in the embodiment provided by the present invention, the ion exchange membrane is specifically a proton exchange membrane.

[0073] The electrolytic cell is provided with nutrient solution and SO4 2- , which is the place where the electrochemical reduction reaction of microorganisms occurs; when the electrolytic cell is a double-chamber electrolytic cell, the sulfur-containing wastewater is arranged in the electrolytic cell of the biological cathode, and the anode nutrient solution preferably includes inorganic salts; the cathode nutrient solution preferably includes nutrient salts, vitamins, trace elements and carbon sources; the inorganic salts preferably include potassium ferrocyanide and potassium ferrocyanide, and the concentration of inorganic salts in the nutrient solution is preferably 42.2g / L; the nutrient salts preferably include ammonium chloride and potassium dihydrogen phosphate, and the concentration of nutrient salts in the nutrient solution is preferably 0.3-1.0 g / L, more preferably 0.4-0.8g / L, and more preferably including 1.0g / L ammonium chloride and 0.65g / L potassium dihydrogen phosphate; the trace elements preferably include calcium chloride, magnesium sulfate, sodium chloride, manganese sulfate, sodium molybdate, boric acid and zinc chloride; the carbon source is one or more of glucose, sodium acetate, starch and anhydrous ethanol, and specifically ethanol in the embodiment provided by the present invention; the amount of the carbon source added is preferably such that the concentration of the carbon source in the nutrient solution is 1-1.5ml / L, more preferably 1.2mL / L.

[0074] The electrolytic cell is provided with an electrochemical anode and a biological cathode, and the electrochemical anode and the biological cathode are immersed in a nutrient solution in SO4 2-In which, the electrode is preferably a carbon material, more preferably a carbon brush; the carbon brush has a large surface area that is conducive to full contact with the mixed bacteria, and is not easy to fall off after the film is formed. The microbial film is preferably formed by electroactive bacteria and sulfate-reducing bacteria; the bacterial community is preferably derived from the anaerobic sludge of the Chengdong Sewage Treatment Plant in Yancheng City, and then domesticated. The electrochemical anode is connected to the biological cathode through an external circuit; the external circuit includes a power supply and a fixed resistor; the power supply is preferably a DC regulated power supply; the fixed resistor is preferably connected in series between the positive electrode of the power supply and the biological cathode; the resistance value of the fixed resistor is preferably 10Ω. The microbial electrolysis cell provided by the present invention preferably also includes a data acquisition device; the data acquisition device is connected to both ends of the fixed resistor to record the response changes of the voltage / current at both ends of the fixed circuit. The cathode area of ​​the microbial electrolysis cell provided by the present invention is preferably also provided with a reference electrode; the reference electrode is preferably Ag / AgCl. The present invention has no special restrictions on the sources of all raw materials, which can be commercially available.

[0075] The biocathode is preferably prepared according to the following steps: immersing the cathode carbon brush in an acetone solution for 24 hours, washing with deionized water, and drying in a muffle furnace to obtain anode and cathode electrodes; the drying temperature is preferably 450° C.; the drying time is preferably 30 minutes. Under an applied voltage condition, the cathode is acclimated in a nutrient solution containing SRB and a carbon source to obtain a biocathode.

[0076] In the acclimation stage, the applied voltage is preferably 0.5-0.8V, more preferably 0.5V; the SRB is derived from the anaerobic sludge of the Chengdong Sewage Treatment Plant in Yancheng City; the volume of the sludge added to the nutrient solution is preferably 1: (5-10), more preferably 1: 9; the carbon source is preferably one or more of glucose, sodium acetate, starch and anhydrous ethanol, and in the embodiment provided by the present invention, it is specifically ethanol; the carbon source addition amount is preferably such that the concentration of the carbon source in the nutrient solution is 1-1.5mL / L, more preferably 1.2mL / L. Before acclimation, it is preferred to introduce protective gas to exclude the oxygen contained in the nutrient solution and maintain the operation under anaerobic environment; the protective gas is preferably at least one of nitrogen, argon and helium with a purity of not less than 99.999%, and in the embodiment provided by the present invention, it is specifically nitrogen. According to the present invention, microbial nutrient elements are preferably added to the nutrient solution to provide minerals and nutrient elements required for microbial growth; the microbial nutrient elements are preferably C6H9NO6, MgSO4·7H2O, MnSO4·H2O, NaCl, FeSO4·7H2O, CoCl2·6H2O, CaCl2, ZnSO4·7H2O, CuSO4·5H2O, AlK(SO4)·12H2O, H3BO3, Na2MoO4·2H2O, NiCl 2·6H2O, Na2WO4 or one or more thereof; the domestication is specifically to use a data acquisition device to monitor the voltage value of the fixed resistor in real time, replace 70% to 80% of the nutrient solution when the COD concentration trend is stable in a cycle, and add appropriate bacterial sources at the same time, when the voltage curve of the reactor is stable for 3 consecutive cycles in the feeding cycle, and the COD removal rate in the reactor reaches more than 90% in each cycle, it means that the electrode biofilm is successful; the amount of bacterial source added is preferably such that its volume ratio with the electrolyte is maintained at 1: (5 to 10), more preferably 1: 9. The pH value of the sulfur-containing nutrient solution in the cathode chamber of the electrolytic cell during the electrochemical reduction of the microorganism is preferably 3.5 to 5.5. In the embodiment provided by the present invention, the pH value of the sulfur-containing nutrient solution is specifically 3.5; the voltage of the electrochemical reduction of the microorganism is preferably 0.4 to 1.0V. In the embodiment provided by the present invention, the voltage of the electrochemical reduction of the microorganism is specifically 0.8V; the electrochemical reduction time of the microorganism is preferably 24h to 48h, more preferably 24h.

[0077] The working principle of the above technical solution is: the solution adopted in this embodiment is to first construct a sulfate reduction system based on bioelectrochemical technology; then, in the sulfate reduction system, provide a periodic electric potential to the MEC to construct an intermittent electric field; secondly, determine the operating parameters of the intermittent electric field based on the monitoring results, and adjust the performance of the biological cathode in the sulfate reduction system in real time through the adjusted intermittent electric field.

[0078] Combining anaerobic bioreduction technology with microbial electrolysis cell (MEC) and providing intermittent potential can effectively alleviate H2S accumulation and improve sulfate removal rate. Sulfate-reducing bacteria attached to the cathode surface will expand the electron transport chain and accelerate growth under the action of electricity. However, the optimal growth potential range of sulfate-reducing bacteria is V = -0.4 ~ -0.2 vs. SHE, which continuously provides SO4 2- The reduction potential (V = -0.8V vs. SHE) affects the growth of SRB. Long-term external voltage stimulation will reduce the reaction activity of SRB, causing the electric double layers (EDL) to store the ions electrically adsorbed by the electrode and accumulate on the electrode surface over time, eventually forming salt crystals on the electrode, increasing the charge transfer resistance and affecting electron transfer. At the same time, it damages the morphology and ultrastructure of microbial cells, changes the permeability and stability of the cell membrane, and causes a strong inhibition of SRB activity. Although the addition of neutralizers and anti-crystallization agents can provide substrates for the biocathode and alleviate accumulation, this method will increase the operating cost.

[0079] Intermittent electric field (Alternating Electric Field) means that within a certain area, the electric field strength shows periodic changes in time, rather than remaining constant like a constant electric field. Due to the sudden change in the electrode surface potential, the dynamic potential difference ΔE is generated on the cathode surface, and the electrode current / potential response change characteristics are observed. The intermittent electric field can provide different potentials for MEC through periodic potential changes, oxidize potassium ferrocyanide in the anode chamber to potassium ferrocyanide under electrical stimulation conditions, and provide electrons and protons for the cathode chamber to promote anaerobic sulfate reduction reactions. Under open circuit conditions, the strength of EDL is weakened, the internal resistance is reduced, and time for microorganisms to adapt and recover is given, reducing the risk of cell membrane structure damage. By measuring the reaction kinetic parameters on the electrode surface, the rate constant of the charge transfer reaction, and the charge transfer coefficient and other parameters, combined with biological analysis, the effect of intermittent electric field on sulfate removal and the changes in the electron transfer path are studied. Therefore, the intermittent electric field can further improve the desulfurization effect of MEC, with superior performance and stability.

[0080] Relying on the DC regulated power supply and intelligent time-controlled switch, the potential intensity and action time of the intermittent electric field can be directly controlled, and the duty cycle and number of cycles, potential intensity, potential action time, pH value, temperature, SO4 2- Concentration, ORP value, COD value and S 2- The intermittent electric field is adjusted according to the growth kinetics of sulfate-reducing bacteria and the desulfurization effect.

[0081] To further illustrate the present invention, the following is a detailed description of an intermittent electrical stimulation sulfate reduction control process provided by the present invention in conjunction with an embodiment. The reagents used in the following embodiments are all commercially available.

[0082] Example 1: Treatment of acidic sulfate wastewater by dual-chamber MECs

[0083] The anode chamber and cathode chamber of the double-chamber MECs are both 118mL, that is, the total volume of the MECs is 236mL. The anode and cathode are separated by a diaphragm to form two chambers, and the diaphragm is a proton exchange membrane. The cathode electrode is the biological cathode domesticated in the above steps. A solution containing 42.2g / L potassium ferrocyanide is injected into the anode water inlet; the domesticated sludge (the volume ratio of the added amount to the cathode nutrient solution is 1:9), 1.2mL / L C2H6O, 1.0g / LNH4Cl, 0.65g / L KH2PO4, and 700mg / L SO4 2- , 1mL / L trace elements (the trace element formula is: 1.5g / L C6H9NO6, 3.0g / LMgSO4·7H2O, 0.5g / LMnSO4·H2O, 1.0g / LNaCl, 0.1g / L FeSO4·7H2O, 0.1g / L CoCl2·6H2O, 0.1g / L CaCl2, 0.1g / LZnSO4·7H2O, 0.01g / L CuSO4·5H2O, 0.01g / L AlK(SO4)·12H2O, 0.01g / L H3BO3, 0.01g / LNa2MoO4·2H2O, 0.024g / LNiCl2·6H2O, 0.025g / LNa2WO4) and 1mL / L vitamins (vitamin formula: 0.002g / L Biotin, 0.002g / L 19 H 19 N7O6, 0.01g / L C8H 11 NO3, 0.005g / LC 12 H 17 ClN4OS·HCl, 0.005g / LC 17 H 20 N4O6, 0.005g / L C6H5NO2, 0.005g / LC 18 H 32 CaN2O 10 , 0.001g / LC 63 H 88 CoN 14 O 14 P、0.005g / LC7H7NO2、0.005g / LC8H 14O2S2), pH is about 3.5, high-purity nitrogen is exposed to expel dissolved oxygen in the nutrient solution, and then added to the cathode chamber of the MECs after the startup is completed. The potassium ferrocyanide solution in the anode chamber is oxidized to release electrons and protons, where electrons are transferred to the cathode chamber through the external circuit under the action of the potential difference provided by the external voltage, and protons reach the cathode chamber through the ion exchange membrane. The microorganisms attached to the cathode act as catalysts to accelerate the reduction of sulfate to sulfide. The cathode and anode are connected by titanium wire, and the external circuit is connected. The external resistance is 10Ω, and the applied voltage is maintained at 0.8V (vs. SHE). After 24 hours of microbial electroreduction at normal temperature and pressure, the sulfate concentration in the water body dropped to 98mg / L, and the sulfate removal efficiency was 87.2%. The residual COD of the reactor was 108mg / L, and the COD removal rate was 91%.

[0084] Example 2: Treatment of acidic sulfate wastewater by dual-chamber MECs under intermittent electric field

[0085] S100. Construction of sulfate reduction system based on bioelectrochemical technology;

[0086] The anode chamber and cathode chamber of the double-chamber MECs are both 118mL, that is, the total volume of the MECs is 236mL. The anode and cathode are separated by a diaphragm to form two chambers, and the diaphragm is a proton exchange membrane. The cathode electrode is the biological cathode obtained by the above steps. A solution containing 42.20g / L potassium ferrocyanide is injected into the anode water inlet; the domesticated sludge (the volume ratio of the added amount to the cathode nutrient solution is 1:9), 1.20mL / LC2H6O, 1.00g / LNH4Cl, 0.65g / LKH2PO4, and 700mg / L SO4 2- , 1.00mL / L trace elements (trace element formula: 1.50g / L C6H9NO6, 3.00g / L MgSO4·7H2O, 0.50g / LMnSO4·H2O, 1.00g / LNaCl, 0.10g / LFeSO4·7H2O, 0.10g / L CoCl2·6H2O, 0.10g / L CaCl2, 0.10g / L ZnSO4·7H2O, 0.01g / L CuSO4·5H2O, 0.01g / L AlK(SO4)·12H2O, 0.01g / L H3BO3, 0.01g / LNa2MoO4·2H2O, 0.024g / LNiCl2·6H2O, 0.025g / LNa2WO4) and 1mL / L vitamins (vitamin formula: 0.002g / L Biotin, 0.002g / L 19 H 19 N7O6, 0.01g / L C8H 11 NO3, 0.005g / LC 12H 17 ClN4OS·HCl, 0.005g / LC 17 H 20 N4O6, 0.005g / L C6H5NO2, 0.005g / LC 18 H 32 CaN2O 10 , 0.005g / LC 63 H 88 CoN 14 O 14 P、0.005g / L C7H7NO2、0.005g / L C8H 14 O2S2), pH is about 3.50, high purity nitrogen is exposed to drive out dissolved oxygen in the nutrient solution, and then added to the cathode chamber of MECs after the start-up is completed. The potassium ferrocyanide solution in the anode chamber is oxidized to release electrons and protons, where electrons are transferred to the cathode chamber through the external circuit under the potential difference provided by the external voltage, and protons reach the cathode chamber through the ion exchange membrane. The microorganisms attached to the cathode act as catalysts to accelerate the reduction of sulfate to sulfide.

[0087] S200. In the sulfate reduction system, providing a potential to the cathode in time periods to construct an intermittent electric field;

[0088] The cathode and anode are connected by titanium wire, connected to the external circuit, the external resistance is 10Ω, the external voltage is maintained at 0.8V (vs. SHE), the duty cycle is 0.5, and the action time is 6 hours on / off (6h-on / off). Long-term potential accumulation and maintenance of reduction potential will waste energy and lead to excessive hydrogen release, which will reduce the SRB reaction activity and destroy the cathode biofilm structure. Intermittent electric field is a study of the effects of periodic changes on microbial communities and bioelectrochemical processes in electrochemistry. Due to the sudden change in the potential on the electrode surface, a potential step phenomenon occurs on the cathode surface, and the electrode current / potential change characteristics are observed. The intermittent electric field can provide SRB with time to adapt and recover by controlling the potential duty cycle and action time, slowing down substrate consumption, maintaining high activity reactions during power-on, and providing different potentials for sulfate-reducing bacteria (SRB). During the power supply stage, maintaining high activity of SRB promotes sulfate reduction. During the power-off phase, the closure of the electric field helps maintain the stability of the sulfate reduction reaction. At the same time, the generated sulfate provides a substrate for the next power supply phase, maintains the flow of electrons, and realizes partial electron circulation. By measuring the reaction kinetic parameters, charge transfer and charge transfer coefficients on the electrode surface, combined with the SRB reaction kinetics, the effect of intermittent electric field duty cycle and action time on sulfate removal is studied. Through this periodic potential change, the intermittent electric field can effectively improve the efficiency of the sulfate reduction process and enhance the treatment effect of acidic wastewater.

[0089] This embodiment sets up an intelligent model, and adjusts the operating parameters of the intermittent potential in real time based on the intelligent model to ensure that the desulfurization effect is improved according to the growth of SRB.

[0090] S300. Determine prediction parameters of the intermittent electric field based on the intelligent model, including:

[0091] S301. Determine input parameters, which include: pH value, ORP value, temperature, SO4 2- Concentration, S 2- concentration, COD value, and growth kinetics of sulfate-reducing bacteria;

[0092] S302. Input the input parameters into the intelligent model, and the intelligent model calculates the output results according to the prediction algorithm of the model, and the output results include: the predicted potential intensity and predicted action time of the intermittent electric field;

[0093] S303. Using the predicted potential intensity and predicted action time of the intermittent electric field as prediction data of the intermittent electric field.

[0094] In step S302, the intelligent model is a GRU neural network model;

[0095] The construction method of the GRU neural network model includes:

[0096] S3021. The pH value, ORP value, temperature, SO4 2- Concentration, S 2- Concentration, COD value, and sulfate-reducing bacteria growth dynamics are used as input parameters of the GRU neural network model, and the input parameters are normalized:

[0097]

[0098] x is the original data point, x' is the normalized data, and x max and x min are the maximum and minimum values ​​of the data set x respectively;

[0099] S3022. Determine the input parameter x according to the data obtained in step S3021. t ;

[0100] The reset gate is used to determine how to combine new input with past memory, and the formula is as follows:

[0101] r t =σ(W r ·[h t-1 ,x t ])

[0102] Among them, Wr is the weight matrix of the reset gate, h t-1 is the previous hidden state, x t is the current input, σ is the sigmoid activation function;

[0103] Determine the update gate to control the degree of integration of the current state and the past state. The formula is as follows:

[0104] z t =σ(W z ·[h t-1 ,x t ])

[0105] Among them, W z is the weight matrix of the update gate;

[0106] Determine the candidate hidden state, the formula is as follows:

[0107]

[0108] Among them, W h is the weight matrix of the candidate state, * indicates element-by-element multiplication;

[0109] The final hidden state is determined by combining the previous hidden state and the candidate state, as follows:

[0110]

[0111] The input parameters are used as operating parameters to obtain output results; the output results include: the predicted potential intensity and predicted action time of the intermittent electric field.

[0112] S400. The intermittent electric field operation parameters are adjusted in real time based on the output results of the sulfate reduction system, and the growth of sulfate-reducing bacteria in the system is regulated in real time through the adjusted intermittent electric field to improve the desulfurization effect.

[0113] Using the above intermittent electrical stimulation sulfate reduction control process, after 24 hours of microbial electroreduction at normal temperature and pressure, the sulfate concentration in the water body dropped to 32 mg / L, and the sulfate removal efficiency was 95.4%. The residual COD in the reactor was 154 mg / L, and the COD removal rate was 87%.

[0114] Figure 2 (a) is the pH change trend; (b) is the ORP change trend; (c) is the sulfate concentration change and reduction rate; (d) is the initial and final sulfate removal effect under intermittent and continuous electric fields; where IG: intermittent electric field (6h-on / off); CG: continuous electric field; BG: open circuit; SRR: sulfate reduction rate; SRE: sulfate reduction efficiency.

[0115] The working principle of the above technical solution is as follows: the solution adopted in this embodiment is to form a cycle through two stages of facilities, further monitor the performance of the biological cathode according to the two-stage cycle cycle, and make a more suitable adjustment plan for the experimental parameters according to the monitoring data results. The performance of the biological cathode is used as feedback, and the operating parameters are adjusted according to the experimental results to ensure the growth of sulfate-reducing bacteria and improve the reduction effect in an acidic environment and a low-carbon environment.

[0116] In one embodiment, the method for constructing a GRU neural network model further includes:

[0117] Based on the preset sulfate reduction system feature extraction template, the first system feature of the sulfate reduction system is extracted, and the system features include: simulated wastewater parameters, microbial electrolysis cell configuration parameters and environmental parameters; wherein the sulfate reduction system feature extraction template is: a template for extracting sulfate reduction system features by comparing sulfate reduction system information, for example: a template for extracting simulated wastewater components by comparing sulfate reduction system information;

[0118] According to the first system feature, the target sulfate reduction process record is screened; wherein the target sulfate reduction process record is: an extracted record of the sulfate reduction process sensor monitoring data learned by the subsequent GRU neural network model;

[0119] Analyze the target sulfate reduction process records and obtain sensor monitoring data during the sulfate reduction process;

[0120] Based on sensor detection data, the GRU neural network model is trained.

[0121] The working principle and beneficial effects of the above technical solution are:

[0122] The quality of the learning samples of the GRU neural network model greatly affects the learning efficiency of the model, so the learning samples need to be screened. The sulfate reduction system feature extraction template is introduced to extract the first system features of the sulfate reduction system (simulated wastewater parameters, microbial electrolysis cell configuration parameters, and environmental parameters). According to the first system features, the target sulfate reduction process records are screened, which greatly improves the suitability of the target sulfate reduction process records for subsequent learning.

[0123] In one embodiment, according to the first system feature, screening the target sulfate reduction process record includes:

[0124] Obtaining a first historical sulfate reduction process record; wherein the first historical sulfate reduction process record is: a data record of the sulfate reduction process collected in the past;

[0125] Analyze the first historical sulfate reduction process record to obtain reduction effect evaluation parameters, which include sulfate concentration, sulfate removal efficiency, reactor residual COD concentration, and COD removal rate;

[0126] Obtain a reduction effect evaluation model, input the reduction effect evaluation parameters into the reduction effect evaluation model, and obtain a reduction effect evaluation value; wherein the reduction effect evaluation model is an AI model obtained by manually training the evaluation records of sulfate reduction effect evaluation based on historical reduction effect evaluation parameters;

[0127] If the reduction effect evaluation value is greater than or equal to a preset reduction effect evaluation value threshold, the corresponding first historical sulfate reduction process record is used as the second historical sulfate reduction process record; wherein the preset reduction effect evaluation value threshold is manually preset;

[0128] According to the first system characteristic, construct a sulfate reduction system description factor; wherein the sulfate reduction system description factor is a description vector of the sulfate reduction system, and constructing a vector based on a characteristic value belongs to the prior art;

[0129] According to the second historical sulfate reduction process record and the sulfate reduction system feature extraction template, the second system feature is extracted and a reference sulfate reduction system description factor is constructed; wherein the construction method of the reference sulfate reduction system description factor is the same as that of the sulfate reduction system description factor;

[0130] Calculate the factor cosine value of the sulfate reduction system description factor and the reference sulfate reduction system description factor; wherein the factor cosine value is: the cosine value of the vector angle;

[0131] If the factor cosine value is greater than or equal to a preset factor cosine value threshold, the corresponding second historical sulfate reduction process record is used as the third historical sulfate reduction process record; wherein the preset factor cosine value threshold is manually preset, such as: 0.95;

[0132] Parse the third historical sulfate reduction process record to obtain the operator identity information; wherein the operator identity information is: the identity ID of the experimenter who conducts the sulfate reduction experiment;

[0133] According to the operator's identity information, determine the operator's historical experimental irregularity record; wherein the historical experimental irregularity record is: the operator's experimental operation irregularity record before the recording time of the third historical sulfate reduction process record;

[0134] Characterize the irregular records of historical experiments to obtain irregular record features; the irregular record features are: the characteristic representation of irregular behaviors in the irregular records of historical experiments, such as: taking off gloves during the wastewater mixing process;

[0135] According to the irregular record features and the preset irregular feature-irregular value comparison library, the irregular value is determined, and the irregular value is expanded on the preset time axis according to the first recording time of the corresponding acquired historical experimental irregular record; wherein the irregular feature-irregular value comparison library includes: one-to-one corresponding irregular features to be matched and the quantitative value of the corresponding irregular degree; the first recording time is: the occurrence time of the irregular event in the historical experimental irregular record;

[0136] Marking the second recording time of the third historical sulfate reduction process record on the time axis; wherein the second recording time is the occurrence time of the historical sulfate reduction process corresponding to the third historical sulfate reduction process record;

[0137] Obtaining a recording time interval between a first recording time and a second recording time, and accumulating the recording time intervals corresponding to the same operator to obtain the recording time and; wherein the recording time interval is the time difference between the first recording time and the second recording time;

[0138] According to the recording time interval and the recording time corresponding to the first recording time, a correction weight of the non-standard value corresponding to the first recording time is obtained; wherein the correction weight is obtained by dividing the recording time interval and the recording time to obtain a target ratio, and subtracting the target ratio from 1 to obtain the correction weight;

[0139] The correction weight and the irregularity value are multiplied correspondingly to obtain the correction irregularity value corresponding to the first recording time; the correction irregularity values ​​of the same operator are accumulated to obtain the irregularity degree;

[0140] According to the operator identity information, the third historical sulfate reduction process record corresponding to the operation of the operator whose irregularity is less than the preset irregularity threshold is selected as the target sulfate reduction process record. The preset irregularity threshold is manually preset.

[0141] The working principle and beneficial effects of the above technical solution are:

[0142] The present invention parses and obtains the first historical sulfate reduction process record to determine reduction effect evaluation parameters such as sulfate concentration, sulfate removal efficiency, reactor residual COD concentration, and COD removal rate, introduces a reduction effect evaluation model trained by artificial evaluation records for sulfate reduction effect evaluation based on the historical reduction effect evaluation parameters, inputs the reduction effect evaluation parameters into the reduction effect evaluation model to obtain a reduction effect evaluation value, and screens a second historical sulfate reduction process record whose reduction effect evaluation value is greater than a reduction effect evaluation value threshold;

[0143] Quantifying the first system feature vector to obtain the sulfate reduction system description factor, based on the same construction rule, obtaining the reference sulfate reduction system description factor of the reference sulfate reduction system in the second historical sulfate reduction process record, calculating the factor cosine value of the sulfate reduction system description factor and the reference sulfate reduction system description factor, and screening the third historical sulfate reduction process record with a similar system;

[0144] The identity information of the operator who performed the reduction experiment in the third historical sulfate reduction process record is extracted. The standardization of the operator's operation also affects the accuracy of the recorded data. Therefore, according to the operator's identity information, the historical experiment irregular records in which the operator's experimental operation was irregular before the recording time of the third historical sulfate reduction process record are obtained, the irregular behavior in the historical experiment irregular records is characterized to obtain the irregular record features, and the irregular feature-irregular value comparison library is introduced to determine the irregular value corresponding to the irregular record feature, and the first recording time and the irregular value corresponding to each other on the time axis are determined. The second recording time of the third historical sulfate reduction process record is marked on the time axis, and the recording time interval between the first recording time and the second recording time is calculated. The larger the recording time interval, the weaker the corresponding irregular value represents the irregularity of the operator at the second recording time (that is, the larger the recording time interval, the smaller the correction weight). The correction weight and the irregular value are correspondingly multiplied and then summed to obtain the irregularity of the operator, and the third historical sulfate reduction process record corresponding to the operator whose irregularity is less than the preset irregularity threshold and recorded is selected as the target sulfate reduction process record. The rationality of the learning sample screening process is improved, and the subsequent predictions of the model are more accurate.

[0145] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the spirit and scope of the present invention are included in the scope of protection of the present invention.

Claims

1. A sulfate reduction control process with intermittent electrical stimulation, characterized in that: The following steps are involved: S100. Construction of sulfate reduction system based on bioelectrochemical technology; S200. In the sulfate reduction system, providing a potential to the cathode in time periods to construct an intermittent electric field; S300. Determine the prediction parameters of the intermittent electric field based on the intelligent model; S400. Adjust the intermittent electric field operating parameters in real time based on the output results of the sulfate reduction system, and regulate the growth of sulfate-reducing bacteria in the system in real time based on the adjusted intermittent electric field.

2. The intermittent electrical stimulation sulfate reduction control process according to claim 1, characterized in that: In step S100, constructing a sulfate reduction system based on bioelectrochemical technology is specifically constructing a sulfate reduction system based on a microbial electrolytic cell module; the microbial electrolytic cell module includes an anode area and a cathode area, wherein an anode and a cathode are arranged in the anode area and the cathode area respectively, and the anode area and the cathode area are separated by a diaphragm, and a water inlet is provided at the bottom of the microbial electrolytic cell, and a water outlet is provided at the top of the microbial electrolytic cell module.

3. The intermittent electrical stimulation sulfate reduction control process according to claim 2, characterized in that: The specific steps of constructing the sulfate reduction system are as follows: potassium ferrocyanide nutrient solution is injected into the anode area of ​​the microbial electrolytic cell; activated sludge and KH2PO4, MgCl2·6H2O, Na2SO4, CaCl2·2H2O, NH4Cl, trace element solution, vitamin solution, and C2H5OH are added to the cathode area of ​​the microbial electrolytic cell in a volume ratio of 10-30% to form simulated wastewater; a reference electrode is used to monitor the electrode potential, a 10Ω resistor is connected to the closed loop of the microbial electrolytic cell, and the solution of the electrolytic cell is replaced every 24h to 72h; a DC regulated power supply is used to apply a voltage of 0.5-0.8V to both ends of the cathode and anode of the electrolytic cell, and the electrolytic cell is operated at 20-30°C to achieve sulfate reduction, and high-purity nitrogen is used for continuous aeration for 10 minutes each time the solution is replaced to remove oxygen in the system.

4. The intermittent electrical stimulation sulfate reduction control process according to claim 1, characterized in that: In step S200, the cathode is provided with electric potential in time periods to construct an intermittent electric field, including: S201. Determine the duty cycle of the intermittent electric field; the duty cycle includes: in the periodic experiment, the ratio of the duration of the potential to the total cycle time; S202. Set the potential intensity and action time of the intermittent electrical stimulation; the action time includes: start time and action time; the start time is the start time of providing the potential to the cathode, and the duration time is the maintenance time of continuously providing the potential to the cathode.

5. The intermittent electrical stimulation sulfate reduction control process according to claim 1, characterized in that: In S300, the prediction parameters of the intermittent electric field are determined based on the intelligent model, including: S301. Determine input parameters, which include: pH value, ORP value, temperature, SO4 2- Concentration, S 2- concentration, COD value, and growth kinetics of sulfate-reducing bacteria; S302. Input the input parameters into the intelligent model, and the intelligent model calculates the output results according to the prediction algorithm of the model, and the output results include: the predicted potential intensity and predicted action time of the intermittent electric field; S303. Using the predicted potential intensity and predicted action time of the intermittent electric field as prediction data of the intermittent electric field.

6. The intermittent electrical stimulation sulfate reduction control process according to claim 5, characterized in that: In step S302, the intelligent model is a GRU neural network model; The construction method of the GRU neural network model includes: S3021. The pH value, ORP value, temperature, SO4 2- Concentration, S 2- Concentration, COD value, and sulfate-reducing bacteria growth dynamics are used as input parameters of the GRU neural network model, and the input parameters are normalized: x is the original data point, x' is the normalized data, and x max and x min are the maximum and minimum values ​​of the data set x respectively; S3022. Determine the input parameter x according to the data obtained in step S3021. t ; The reset gate is used to determine how to combine new input with past memory, and the formula is as follows: r t =σ(W r ·[h t-1 ,x t ]) Among them, W r is the weight matrix of the reset gate, h t-1 is the previous hidden state, x t is the current input, σ is the sigmoid activation function; Determine the update gate to control the degree of integration of the current state and the past state. The formula is as follows: z t =σ(W z ·[h t-1 ,x t ]) Among them, W z is the weight matrix of the update gate; Determine the candidate hidden state, the formula is as follows: Among them, W h is the weight matrix of the candidate state, * indicates element-by-element multiplication; The final hidden state is determined by combining the previous hidden state and the candidate state, as follows: The input parameters are used as operating parameters to obtain output results; the output results include: the predicted potential intensity and predicted action time of the intermittent electric field.

7. The intermittent electrical stimulation sulfate reduction control process according to claim 1, characterized in that: In S400, the intermittent electric field operating parameters are adjusted in real time based on the output results of the sulfate reduction system, including: S401. Real-time monitoring of operating parameters of the intermittent electrical stimulation sulfate reduction system; S402. If the monitored output parameters are different from the predicted parameters, the operating parameters are adjusted to the predicted parameters; if the monitored output parameters are the same as the predicted parameters, an intermittent electric field is formed according to the current operating parameters; according to the growth of the adjusted sulfate-reducing bacteria, the operating cycle is adjusted, and the predicted cycle is determined according to the multiple value of the adjusted cycle and the cycle data.

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