Method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor

Abstract

The present invention discloses a novel method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor. The method couples TiO2, a nano-semiconductor material with advantages such as stable chemical properties, non-toxicity and high photocatalytic activity, with a Thiobacillus denitrificans biofilm system to form an inorganic semiconductor-microorganism system. Under light conditions, the Thiobacillus denitrificans biofilm uses photogenerated electrons to convert NO3 ‑ This method overcomes the shortcomings of traditional inorganic semiconductor-microorganism integration, such as complex operational processes, reactive oxygen species generated by light that damage bacteria, reduce quantum efficiency, and inhibit nitrous oxide reductase (NOS), resulting in the production of large amounts of greenhouse gases (N2O). It offers the advantages of simple process, low energy consumption, environmental friendliness, economy, safety, and reliability. Furthermore, the system structure is relatively simple, making it easier to modify and improve in a modular manner, thus enabling large-scale promotion and application.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor. Background Art

[0002] With the development of science and technology and the improvement of people's living standards, environmental pollution has become increasingly serious. In recent years, due to the abuse of nitrogen fertilizers and sewage discharge, NO3 - Pollution is becoming increasingly serious, which accelerates the eutrophication process of water bodies, and the intermediate product of its reduction, NO2 - It can also easily cause hypoxia and methemoglobinemia in humans and animals, which poses a serious threat to human health and the ecological environment.

[0003] Thiobacillus denitrificans is a typical autotrophic denitrifying bacterium that can convert NO3 - It is reduced to N2 and also has the advantages of strong repair ability and fast reproduction speed. Currently, commonly used electron donors include inorganic electron sources such as reduced sulfides, hydrogen, and electrode electrons. However, these electron sources have more or less disadvantages such as easy generation of secondary pollution, low electron utilization rate, and complicated process, which are not conducive to large-scale promotion and application in practical environments.

[0004] Based on this, the present invention provides a NO3 - A new method of reduction is to couple the nano-semiconductor material TiO2, which has the advantages of stable chemical properties, non-toxicity and high photocatalytic activity, with the Thiobacillus denitrificans biofilm system to form an inorganic semiconductor-microorganism system. In this semiconductor-microorganism system, aluminum tubes are used to physically separate the nano-TiO2 film and Thiobacillus denitrificans. The excellent conductivity of aluminum is used to use the photoelectrons generated by nano-TiO2 under light as an electron source to drive Thiobacillus denitrificans to reduce NO3. - The semiconductor-microorganism system solves the following problems: (1) the complicated operation process of combining inorganic semiconductors with microorganisms; (2) the reactive oxygen species generated by light damage bacteria and have low quantum efficiency; and (3) the inhibition of nitrous oxide reductase (NOS), which produces a large amount of greenhouse gas (N2O). Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated microbial photoelectrochemical reactor for reducing NO3 to address the shortcomings of the in situ coupled inorganic semiconductor-microorganism system method, such as complex operation process, active oxygen generated by light damaging bacteria, low quantum efficiency and inhibition of nitrous oxide reductase (NOS). - A new method for N2.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor, comprising: constructing an integrated microbial photoelectrochemical reactor, injecting NO3 into the reactor, - solution and reduce NO3 under light conditions - is N2;

[0008] The method for constructing the integrated microbial photoelectrochemical reactor comprises the following steps:

[0009] 1) Cultivation of Thiobacillus denitrificans biofilm on graphite particles;

[0010] 2) Nano-TiO2 thin film was prepared by sol-gel method and coated on the surface of aluminum tube as photoanode;

[0011] 3) transferring the aluminum tube covered with the nano-TiO2 film into a transparent tube, and filling the space between the aluminum tube covered with the nano-TiO2 film and the transparent tube with a buffer solution and a sacrificial reagent;

[0012] 4) Adding graphite particles after cultivation and NO3 into the aluminum tube covered with nano-TiO2 film - solution and electron donor-free culture medium, followed by aeration and deoxygenation to remove oxygen inside the aluminum tube.

[0013] As a possible implementation, further, step 1) specifically includes:

[0014] Using an electrochemical workstation to apply voltage, the Thiobacillus denitrificans bacterial solution was centrifuged / filtered to obtain the precipitate, which was then transferred to the cathode of a dual-chamber battery and co-cultured with graphite particles.

[0015] As a possible implementation method, further, the applied voltage of the electrochemical workstation is -500mV to -740mV;

[0016] The anode of the dual-chamber battery is a graphite plate, and the anode solution is a PBS buffer solution; the cathode of the dual-chamber battery is a titanium wire and graphite particles, the cathode serves as a working electrode, and the cathode solution is a cathode culture medium without an electron donor.

[0017] As a possible embodiment, further, the Thiobacillus denitrificans bacterial solution is a bacterial solution of Thiobacillus denitrificans cultured in a sodium thiosulfate medium, wherein the pH value of the medium is 6.5 to 7.5; the OD value of the Thiobacillus denitrificans bacterial solution is 600 nm The value is 0.1 to 0.3, or the Thiobacillus denitrificans bacterial solution is in the logarithmic growth phase;

[0018] Thiobacillus denitrificans is selected from at least one of Thiobacillus denitrificans ATCC 25259, Thiobacillus denitrificans DSM 12475, and Thiobacillus denitrificans JCM:3870.

[0019] As a possible embodiment, further, the compositions of the sodium thiosulfate medium, the cathode medium without electron donor, and the medium without electron donor are as shown in the following table:

[0020]

[0021] Each liter of trace element solution SL-4 contains 0.4-0.6 g EDTA, 0.1-0.3 g FeSO4·4H2O, 100 mL trace element solution SL-6, and the balance is water;

[0022] Each liter of trace element solution SL-6 contains 0.08-0.12g ZnSO4·7H2O, 0.002-0.004g MnCl2·4H2O, 0.2-0.4g H3BO3, 0.1-0.3g CoCl2·6H2O, 0.008-0.012g CuCl2·2H2O, 0.01-0.03g NiCl2·6H2O, 0.02-0.04g Na2MoO4·4H2O, and the balance is water;

[0023] Each liter of ferrous sulfate solution contains 2 mg FeSO4·7H2O and 2.7 mL H2SO4.

[0024] As a preferred embodiment, preferably, the centrifugal speed is 5000-8000 r / min, and the centrifugal time is 5-10 min.

[0025] As a possible implementation, further, step 2) specifically includes:

[0026] a) Cleaning the aluminum tube in an ultrasonic machine and an ozone UV cleaner;

[0027] b) TiO2 prepared by the sol-gel method is spin-coated on the outside of the aluminum tube using a coating pulling machine, and then annealed in a muffle furnace.

[0028] As a possible implementation, further, step b) specifically includes the following steps:

[0029] Solution A was added dropwise to solution B, and then HNO3 was added to the mixed solution to adjust the pH to 1-2;

[0030] The solution was then kept at room temperature for 24 h for sol-gel aging;

[0031] Subsequently, the prepared sol-gel was spin-coated on the outside of the aluminum tube using a coating puller and calcined in a muffle furnace at 500 °C for 2 h;

[0032] The solution A consists of 76% C2H5OH, 9% H2O and 15% CH3COOH;

[0033] The solution B consists of 54% Ti(OC4H9)4 and 46% C2H5OH;

[0034] The volume ratio of solution A to solution B is 19:31.

[0035] As a possible embodiment, further, in step 3), the buffer solution is selected from PBS buffer solution; the concentration of the sacrificial reagent is 0.1-1 wt %, and the sacrificial reagent is selected from a mixed solution of anhydrous sodium sulfite and sodium sulfide nonahydrate;

[0036] The mixed solution consists of 3% to 5% of anhydrous sodium sulfite, 8% to 10% of sodium sulfide nonahydrate, and 85% to 89% of deionized water.

[0037] As a possible implementation manner, further, the light source of the illumination is selected from at least one of sunlight, a xenon lamp, or a 365nm light strip;

[0038] The light intensity is 1~100mW / cm 2 The temperature during illumination is 25-35℃.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention uses abundant and cheap light energy as the driving force to excite the photogenerated electrons of TiO2 inorganic semiconductor, and then the Thiobacillus denitrificans bacteria can selectively convert NO3- Reduction to N2 not only significantly reduces process costs, but also avoids the inhibition of nitrous oxide reductase (NOS) in Thiobacillus denitrificans, which leads to the massive production of greenhouse gas N2O.

[0041] The present invention overcomes the shortcomings of the in-situ coupled inorganic semiconductor-microorganism system method, such as complex operating process, active oxygen damage to bacteria generated by light, low quantum efficiency and inhibition of nitrous oxide reductase (NOS); it has the advantages of simple process, low energy consumption, environmental protection, economy, safety and stability, and the system structure is relatively simple, making it easier to modify and improve in a modular manner, so it can be promoted and applied on a large scale in actual systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly describes the accompanying drawings required for describing the embodiments. It should be understood that the embodiments described below are only a portion of the embodiments of the present invention, and not all of them. Any other embodiments derived from these embodiments by a person of ordinary skill in the art without inventive effort are also within the scope of protection of the present invention.

[0043] Figure 1 Schematic diagram of the principle of the Thiobacillus denitrificans-TiO2 hybrid system.

[0044] Figure 2 NO3 degradation of Thiobacillus denitrificans-TiO2 hybrid system for different nano-TiO2 film thicknesses - The impact of restoration.

[0045] Figure 3 is a characterization diagram of the prepared nano-TiO2; wherein, Figure 3 -A is the energy band structure diagram of TiO2; Figure 3 -B is the XRD pattern of TiO2; Figure 3 -C is the XPS pattern of TiO2; Figure 3 -D is the SEM image of TiO2.

[0046] Figure 4 Schematic diagram of a dual-chamber battery. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] Refer to the attached Figure 1 As shown, this embodiment provides a method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor, comprising: constructing an integrated microbial photoelectrochemical reactor, injecting NO3 into the reactor - solution and reduce NO3 under light conditions - The light source is selected from at least one of sunlight, xenon lamp or 365nm light strip; the light intensity is 1-100mW / cm 2 The temperature during illumination is 25-35℃.

[0049] The method for constructing an integrated microbial photoelectrochemical reactor comprises the following steps:

[0050] 1) Cultivating a Thiobacillus denitrificans biofilm on graphite particles, specifically comprising the following steps:

[0051] Using an electrochemical workstation with an applied voltage of -500mV to -740mV, the Thiobacillus denitrificans bacterial solution was centrifuged at 5000-8000 rpm for 5-10 minutes, filtered, and the precipitate was transferred to the cathode of a dual-chamber battery and co-cultured with graphite particles. In this embodiment, the graphite particles had a diameter of 4mm and a height of 4mm.

[0052] The anode of the double-chamber battery is a graphite plate, and the anode solution is a PBS buffer solution; the cathode of the double-chamber battery is a titanium wire and graphite particles, and the cathode solution is a cathode medium without an electron donor (such as a Figure 4 shown).

[0053] The Thiobacillus denitrificans bacterial solution is a bacterial solution cultured in a sodium thiosulfate medium, wherein the pH value of the medium is 6.5 to 7.5; the OD value of the Thiobacillus denitrificans bacterial solution is 0. 600nm The value is 0.1 to 0.3, or the Thiobacillus denitrificans bacterial solution is in the logarithmic growth phase;

[0054] Wherein, the Thiobacillus denitrificans is selected from at least one of Thiobacillus denitrificans ATCC25259, Thiobacillus denitrificans DSM 12475, and Thiobacillus denitrificans JCM:3870.

[0055] The specific steps of step 1) are as follows:

[0056] First, assemble the dual-chamber battery, with the two cells separated by a proton exchange membrane. Then, place the anode components (titanium wire, carbon plate) and cathode components (graphite particles, titanium wire bent into a ring) in their respective chambers. Then, fill the two chambers with deionized water, plug the top rubber stopper, cover with a yellow lid, and place in an autoclave for sterilization at 120°C (the air pressure needs to be balanced during sterilization to prevent explosion).

[0057] After sterilization is completed and cooled to room temperature, it is placed in a clean bench together with the cathode culture medium without electron donors, PBS buffer solution, and the centrifuged Thiobacillus denitrificans bacterial solution. The deionized water in the cathode and anode chambers is sucked out by a vacuum pump, and then the sterilized PBS buffer solution is injected into the anode, and the sterilized cathode culture medium without electron donors and the centrifuged Thiobacillus denitrificans bacterial solution are injected into the cathode. Finally, nitrogen aeration is performed for deoxygenation.

[0058] After the above steps are completed, the dual-chamber battery is placed in a 30°C constant temperature incubator, connected to an external electrochemical workstation, and an external voltage of -500mV to -740mV is applied to continuously culture the cathode biofilm on the graphite particles.

[0059] 2) Using the sol-gel method to prepare a nano-TiO2 film as a photoanode coated on the surface of the aluminum tube; specifically comprising the following steps:

[0060] a) Clean the aluminum tube in an ultrasonic machine and an ozone UV cleaner to enhance its hydrophilicity;

[0061] b) using a coating machine to spin-coat TiO2 prepared by the sol-gel method onto the outside of the aluminum tube, and then annealing it in a muffle furnace; the specific steps are as follows:

[0062] Solution A was added dropwise to solution B, and then HNO3 was added to the mixed solution to adjust the pH to 1-2;

[0063] The solution was then kept at room temperature for 24 h for sol-gel aging;

[0064] Subsequently, the prepared sol-gel was spin-coated on the outside of the aluminum tube using a coating puller and calcined in a muffle furnace at 500 °C for 2 h;

[0065] Solution A consists of 76% C2H5OH, 9% H2O, and 15% CH3COOH;

[0066] Solution B consists of 54% Ti(OC4H9)4 and 46% C2H5OH;

[0067] The volume ratio of solution A to solution B is 19:31.

[0068] 3) The aluminum tube covered with the TiO2 film is transferred into a transparent tube, and a PBS buffer solution and a sacrificial reagent are filled between the aluminum tube covered with the TiO2 film and the transparent tube; wherein the concentration of the sacrificial reagent is 0.1 to 1 wt%, and the sacrificial reagent is a mixed solution of anhydrous sodium sulfite and sodium sulfide nonahydrate;

[0069] The mixed solution is composed of 3% to 5% anhydrous sodium sulfite, 8% to 10% sodium sulfide nonahydrate, and 85% to 89% deionized water.

[0070] 4) Add the graphite particles after cultivation and the NO3 - The solution and the electron donor-free culture medium were then aerated with nitrogen to remove oxygen from the inside of the aluminum tube.

[0071] The compositions of the sodium thiosulfate medium, the cathode medium without electron donor, and the medium without electron donor in the embodiment of the present invention are shown in the following table:

[0072]

[0073]

[0074] Each liter of trace element solution SL-4 contains 0.4-0.6 g EDTA, 0.1-0.3 g FeSO4·4H2O, 100 mL trace element solution SL-6, and the balance is water;

[0075] Each liter of trace element solution SL-6 contains 0.08-0.12g ZnSO4·7H2O, 0.002-0.004g MnCl2·4H2O, 0.2-0.4g H3BO3, 0.1-0.3g CoCl2·6H2O, 0.008-0.012g CuCl2·2H2O, 0.01-0.03g NiCl2·6H2O, 0.02-0.04g Na2MoO4·4H2O, and the balance is water;

[0076] Each liter of ferrous sulfate solution contains 2 mg FeSO4·7H2O and 2.7 mL H2SO4.

[0077] Example 1

[0078] (1) Thiobacillus denitrificans was inoculated into a sodium thiosulfate medium with a pH of 7.0 at a volume ratio of 1% and cultured at 30°C;

[0079] (2) Graphite particles with a diameter of 4 mm and a height of 4 mm were ultrasonically cleaned with HCl, NaOH, and acetone solutions for 30 min, followed by three ultrasonic cleanings with deionized water, once every 30 min, with the deionized water replaced midway. After thorough cleaning, the particles were dried in a 70°C oven and then sterilized in a 120°C autoclave for later use.

[0080] (3) When the OD of Thiobacillus denitrificans in step (1) 600nm When the value is approximately 0.15, centrifuge Thiobacillus denitrificans at 6500 rpm for 7 minutes, resuspend in saline, and repeat three times. Transfer the precipitate to the cathode medium without electron donors at the cathode of the dual-chamber battery, and then add the graphite particles from step (2). Apply a -740 mV bias using an electrochemical workstation, replace the cathode medium every 10 days, and continuously culture the cathode biofilm.

[0081] (4) The aluminum tube was cleaned in an ultrasonic machine and an ozone UV cleaner to enhance its hydrophilicity, and then 38 mL of solution A (76% C2H5OH, 9% H2O, and 15% CH3COOH) was added dropwise to 62 mL of solution B (54% Ti(OC4H9)4 and 46% C2H5OH). HNO3 was then added to the mixture to adjust the pH to 1-2. The solution was further kept at room temperature for 24 hours for sol-gel aging. Subsequently, the prepared TiO2 sol was spin-coated on the outside of the aluminum tube using a coating puller and calcined at 500°C in a muffle furnace for 2 hours.

[0082] (5) Silicone rubber was used to bond a glass tube, an aluminum tube covered with a nano-TiO2 film, and a rubber stopper to construct an integrated microbial photoelectrochemical reactor. PBS buffer solution and 1 wt% sacrificial reagent (sodium sulfide and anhydrous sodium sulfite) were added between the glass tube and the aluminum tube. Graphite particles and NO3-containing - The solution and the electron donor-free culture medium are then aerated with nitrogen to remove oxygen and packaged; the combination is used to construct an integrated microbial photoelectrochemical reactor.- The concentration is 80mg / L.

[0083] (6) Under constant temperature of 30℃, a 365nm LED UV lamp (2.0mW / cm 2 ) Illuminate the integrated microbial photoelectrochemical reactor of step (5) to achieve NO3 - Reduced to N2.

[0084] In order to analyze the Thiobacillus denitrificans, the thickness of the nano-TiO2 film on the outside of the aluminum tube and the light source in NO3 - The effect of different nano-TiO2 film thicknesses on the NO3 reduction of the Thiobacillus denitrificans-TiO2 integrated microbial photoelectrochemical reactor was studied. - The impact of reduction performance, such as Figure 2 As shown, with the increase of the thickness of nano-TiO2 film, NO3 - The reduction rate also increases. When the aluminum tube is covered with three layers of nano-TiO2 film, the nitrate reduction rate is 2.17 times higher than that of the two-layer membrane reactor and 3.06 times higher than that of the one-layer membrane reactor. This shows that the Thiobacillus denitrificans-TiO2 integrated microbial photoelectrochemical reactor of the present invention has excellent NO3 reduction under light conditions. - Restore performance.

[0085] In summary, the present invention includes three core elements: the autotrophic denitrifying bacteria Thiobacillus denitrificans, an integrated microbial photoelectrochemical reactor with a nano-TiO2 film coated on the outside of an aluminum tube, and a light source. This method (semi-artificial photosynthetic system) effectively overcomes the limitations of natural and artificial photosynthetic systems, effectively combines the advantages of the two, and innovatively develops a NO3 - The new reactor with reduced performance. The reactor system is relatively simple in construction, making it easier to modify and improve in a modular manner.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor, characterized in that: include: Construct an integrated microbial photoelectrochemical reactor and inject NO3 into the reactor - solution and reduce NO3 under light conditions - is N2; The method for constructing the integrated microbial photoelectrochemical reactor comprises the following steps: 1) Cultivation of Thiobacillus denitrificans biofilm on graphite particles; 2) Nano-TiO2 thin film was prepared by sol-gel method and coated on the surface of aluminum tube as photoanode; 3) transferring the aluminum tube covered with the nano-TiO2 film into a transparent tube, and filling the space between the aluminum tube covered with the nano-TiO2 film and the transparent tube with a buffer solution and a sacrificial reagent; 4) Adding graphite particles after cultivation and NO3 into the aluminum tube covered with nano-TiO2 film - solution and electron donor-free culture medium, followed by aeration and deoxygenation to remove oxygen inside the aluminum tube.

2. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 1, characterized in that: Step 1) specifically includes: Using an electrochemical workstation to apply voltage, the Thiobacillus denitrificans bacterial solution was centrifuged / filtered to obtain the precipitate, which was then transferred to the cathode of a dual-chamber battery and co-cultured with graphite particles.

3. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 2, characterized in that: The applied voltage of the electrochemical workstation is -500mV to -740mV; The anode of the double-chamber battery is a graphite plate, and the anode solution is a PBS buffer solution; the cathode of the double-chamber battery is titanium wire and graphite particles, and the cathode solution is a cathode culture medium without an electron donor.

4. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 3, characterized in that: The Thiobacillus denitrificans bacterial solution is a bacterial solution cultured in a sodium thiosulfate medium, wherein the pH value of the medium is 6.5 to 7.5; the OD value of the Thiobacillus denitrificans bacterial solution is 0.

05. 600nm The value is 0.1 to 0.3, or the Thiobacillus denitrificans bacterial solution is in the logarithmic growth phase; The Thiobacillus denitrificans is selected from at least one of Thiobacillus denitrificans ATCC 25259, Thiobacillus denitrificans DSM 12475, and Thiobacillus denitrificans JCM 3870.

5. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 4, characterized in that: The compositions of the sodium thiosulfate medium, the cathode medium without electron donors, and the medium without electron donors are shown in the following table: Each liter of trace element solution SL-4 contains 0.4-0.6 g EDTA, 0.1-0.3 g FeSO4·4H2O, 100 mL trace element solution SL-6, and the balance is water; Each liter of trace element solution SL-6 contains 0.08-0.12g ZnSO4·7H2O, 0.002-0.004g MnCl2·4H2O, 0.2-0.4g H3BO3, 0.1-0.3g CoCl2·6H2O, 0.008-0.012g CuCl2·2H2O, 0.01-0.03g NiCl2·6H2O, 0.02-0.04g Na2MoO4·4H2O, and the balance is water; Each liter of ferrous sulfate solution contains 2 mg FeSO4·7H2O and 2.7 mL H2SO4.

6. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 2, characterized in that: The centrifugal speed is 5000-8000 r / min, and the centrifugal time is 5-10 min.

7. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 1, characterized in that: Step 2) specifically includes: a) Cleaning the aluminum tube in an ultrasonic machine and an ozone UV cleaner; b) TiO2 prepared by the sol-gel method is spin-coated on the outside of the aluminum tube using a coating pulling machine, and then annealed in a muffle furnace.

8. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 7, characterized in that: Step b) specifically comprises the following steps: Solution A was added dropwise to solution B, and then HNO3 was added to the mixed solution to adjust the pH to 1-2; The solution was then kept at room temperature for 24 h for sol-gel aging; Subsequently, the prepared sol-gel was spin-coated on the outside of the aluminum tube using a coating puller and calcined in a muffle furnace at 500 °C for 2 h; The solution A consists of 76% C2H5OH, 9% H2O and 15% CH3COOH; The solution B consists of 54% Ti(OC4H9)4 and 46% C2H5OH; The volume ratio of solution A to solution B is 19:

31.

9. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 1, characterized in that: The buffer solution in step 3) is a PBS buffer solution; the concentration of the sacrificial reagent is 0.1-1 wt %, and the sacrificial reagent is a mixed solution of anhydrous sodium sulfite and sodium sulfide nonahydrate; The mixed solution consists of 3% to 5% of anhydrous sodium sulfite, 8% to 10% of sodium sulfide nonahydrate, and 85% to 89% of deionized water.

10. The method for treating nitrate in carbon-deficient wastewater using an integrated microbial photoelectrochemical reactor according to claim 1, characterized in that: The light source of the illumination is selected from at least one of sunlight, a xenon lamp or a 365nm light strip; The light intensity is 1~100mW / cm 2 The temperature during illumination is 25-35℃.

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