A bioelectrochemical method for producing hydrogen using leachate from kitchen waste

Abstract

The present invention relates to a bioelectrochemical method for producing hydrogen using leachate of kitchen waste. The bioelectrochemical method for producing hydrogen using leachate of kitchen waste comprises the following steps: S1. constructing a bioelectrochemical reactor, enriching microorganisms at the anode of the bioelectrochemical reactor, and completing the start-up of the bioelectrochemical reactor; S2. adding leachate of kitchen waste with a pH of 10 to 11 to the started bioelectrochemical reactor, and operating the reactor. The bioelectrochemical method realizes the production of hydrogen using leachate of kitchen waste, and not only the purity of the produced hydrogen is high, but also the energy efficiency is high, the energy consumption is low, and the COD removal rate of the effluent is high.

Description

Technical Field

[0001] The present invention relates to the field of bioelectrochemistry, and more specifically, to a bioelectrochemical method for producing hydrogen by utilizing leachate from kitchen waste. Background Art

[0002] About 1.3 billion tons of food produced globally each year is lost in the food supply chain, which generates a large amount of food waste. Food waste is an organic solid waste that accounts for 15%-63% of the world's total urban solid waste. Untreated food waste releases odors and produces leachate during collection and transportation due to its high volatile solid and moisture content, causing serious environmental pollution. It is estimated that improper disposal of food waste in landfills will lead to an additional global greenhouse gas emission of approximately 3.2 gigatons per year. As people pay more attention to environmental protection and energy recovery, the treatment and disposal of food waste leachate has also attracted much attention.

[0003] The leachate of restaurant waste has a high organic matter content and good biodegradability, and has a high potential for hydrogen production. Hydrogen energy is considered a clean energy source because its combustion only produces water and does not generate any pollutants. Hydrogen can be produced in two ways: one is a chemical process, such as electrolysis, pyrolysis and gasification; the other is a biological process, such as biophotolysis, photofermentation and dark fermentation. At present, hydrogen is mainly produced by the chemical process of decomposing fossil fuels, but fossil fuels are non-renewable energy and emit a large amount of greenhouse gases. my country's "Medium- and Long-Term Plan for the Development of the Hydrogen Energy Industry (2021-2035)" predicts that by 2025, the amount of hydrogen produced from renewable energy will reach 100,000 to 200,000 tons / year. Therefore, the use of restaurant waste leachate to produce hydrogen is of great significance for promoting the resource utilization of organic waste and the production of hydrogen from renewable energy.

[0004] At present, the main method for energy recovery of food waste leachate is anaerobic fermentation (dark fermentation), such as an upflow anaerobic sludge blanket (UASB) reactor, in which wastewater flows upward through the sludge bed and is treated by anaerobic microorganisms to convert organic pollutants into biogas (i.e., methane and carbon dioxide). The main disadvantage of UASB treatment is that it is sensitive to toxic substances. Moreover, anaerobic fermentation can only convert organic waste into biogas but cannot produce high-purity hydrogen. Steam reforming is required to convert methane into hydrogen through pretreatment, steam conversion, CO conversion, hydrogen purification and other steps. The system and method provided by the invention patent entitled "System and method for treating food waste leachate" can achieve the recovery of biodiesel, but it does not involve hydrogen production.

[0005] The invention patent entitled "Bioelectrochemical hydrogen production device and method for producing hydrogen using the device" provides a method for bioelectrochemical hydrogen production. The bioelectrochemical hydrogen production device includes a reactor, an anode, a cathode, a first gas outlet and an external power supply. The raw material for hydrogen production is glucose. It has not been studied whether its scheme is applicable to hydrogen production from food waste leachate.

[0006] In this regard, it is of great significance to research and develop the technology of producing hydrogen using leachate from food waste. Summary of the invention

[0007] The primary purpose of the present invention is to overcome the problem that the existing technology for preparing hydrogen using leachate of kitchen waste is still relatively lacking, and to provide a bioelectrochemical method for preparing hydrogen using leachate of kitchen waste. The bioelectrochemical method realizes the production of hydrogen using leachate of kitchen waste, and not only the purity of the prepared hydrogen is high, but also the energy efficiency is high, the energy consumption is low, and the COD removal rate of the effluent is high.

[0008] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0009] A bioelectrochemical method for producing hydrogen using leachate from kitchen waste comprises the following steps:

[0010] S1. constructing a bioelectrochemical reactor, enriching microorganisms at the anode of the bioelectrochemical reactor, and completing the startup of the bioelectrochemical reactor;

[0011] S2. Add food waste leachate with a pH of 10 to 11 to the bioelectrochemical reactor after startup and run it;

[0012] The dominant bacterial species at the genus level in the anode-enriched microorganisms include Aminivibrio and Acetoanaerobium, and the relative abundances of Aminivibrio and Acetoanaerobium are both 5-15%; the bacterial species at the genus level in the anode-enriched microorganisms also include Desulfovibrio, and its relative abundance is 0.5-5%.

[0013] The inventors of the present invention have found through multiple studies that Aminivibrio and Acetoanaerboium can be enriched at the anode. Aminivibrio is Aminivibrio, which is an anaerobic fermentation bacterium and can decompose macromolecular organic matter (such as starch, fat, oil, etc.) in the leachate of food waste into small molecular organic acids; Acetoanaerboium is an anaerobic acetic bacteria and can ferment small molecular organic acids to produce acetic acid; Desulfovibrio is a typical electrogenic bacteria genus, and acetic acid can be directly used by Desulfovibrio to produce electricity, releasing electrons and protons (H +); the electrons reach the cathode through the external circuit of the bioelectrochemical reactor, H + They migrate through the solution in the bioelectrochemical reactor to the cathode, where they react to generate hydrogen.

[0014] Further regulation of the relative abundance of Aminivibrio and Acetoanaerboium and control of the pH of the food waste leachate within the range of 10-11 can achieve efficient synergy between Aminivibrio and Acetoanaerboium, and then achieve efficient and stable hydrogen production with food waste leachate as the matrix under the action of Desulfovibrio electrogenic microorganisms and electrochemistry.

[0015] Specifically, the bioelectrochemical method of the present invention can utilize restaurant kitchen waste leachate to efficiently produce hydrogen, and the purity of the produced hydrogen can reach more than 70% for a long time. At the same time, the energy efficiency of the bioelectrochemical method based on the input electrical energy is ≥100%, which is much higher than the energy efficiency of the traditional alkaline water electrolysis hydrogen production technology (60-75%). Under the action of the anode electricity-producing microorganisms, the electrical energy consumed is greatly reduced, which is only 1 / 10-1 / 2 of the energy consumption of the traditional alkaline water electrolysis hydrogen production method. In addition, the bioelectrochemical method can also effectively reduce the COD content of restaurant kitchen waste leachate, and the COD removal rate of the effluent is more than 80%.

[0016] That is, the bioelectrochemical method of the present invention utilizes food waste leachate to produce hydrogen, which not only has high purity of the produced hydrogen, but also has high energy efficiency, low energy consumption, and high COD removal rate of effluent water.

[0017] Preferably, the relative abundance of Aminivibrio is 13.6-15%, the relative abundance of Acetoanaerobium is 12.1-15%, and the relative abundance of Desulfovibrio is 0.7-1.0%.

[0018] Preferably, the bioelectrochemical reactor in step S1 is a single-chamber electrolytic cell.

[0019] Any anode commonly used in the art can be used in the present invention.

[0020] Preferably, the anode in step S1 is a carbon brush material anode.

[0021] More preferably, the anode is a carbon brush.

[0022] Preferably, the specific process of enriching microorganisms in step S1 is: adding the substrate and the effluent from the primary sedimentation tank of the sewage treatment plant into the bioelectrochemical reactor, mixing them, and then applying an external voltage to the bioelectrochemical reactor.

[0023] More preferably, the matrix is ​​an aqueous solution containing 1-10 g / L sodium acetate, with a pH of 6-9 and a conductivity of 7-10 mS / cm.

[0024] More preferably, the volatile solid suspended matter of the effluent from the primary sedimentation tank of the sewage treatment plant is 0.1-0.3 g / L, and the pH is 6-9.

[0025] More preferably, the external voltage is 0.6-0.8V.

[0026] Preferably, in step S1, when the maximum current density output by the bioelectrochemical reactor is not less than 50.0 A / m 3 And when it runs stably for at least 3 cycles, the startup is considered successful.

[0027] The cathode of the bioelectrochemical reactor does not need to be specifically limited, and cathodes commonly used in the art can be used in the present invention.

[0028] Preferably, the cathode of the bioelectrochemical reactor in step S1 is a carbon material cathode.

[0029] More preferably, the cathode is a carbon material cathode with a platinum content of ≥0.5 mg / g.

[0030] Preferably, the COD concentration of the kitchen waste leachate in step S2 is 1-2 g / L, and the conductivity is 8.25-8.83 mS / cm.

[0031] Preferably, the external voltage of the operation in step S2 is 0.8-2.0V.

[0032] More preferably, the external voltage of the operation in step S2 is 0.8-1.0V.

[0033] Preferably, the pH of the food waste leachate is adjusted by adding a carbonate buffer.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This bioelectrochemical method realizes hydrogen production from food waste leachate, which not only has high purity of hydrogen, but also has high energy efficiency, low energy consumption and high COD removal rate of effluent water. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a graph showing the hydrogen production results of the bioelectrochemical method of Example 1 under the conditions of an applied voltage of 0.8 V and pH = 10.5.

[0037] Figure 2 This is a diagram showing the COD removal effect of the bioelectrochemical method of Example 1 under the conditions of an applied voltage of 0.8V and pH=10.5.

[0038] Figure 3 This is a graph showing the electricity generation curve of the bioelectrochemical method of Example 1 under the conditions of an applied voltage of 0.8 V and pH = 10.5.

[0039] Figure 4 This is a diagram showing the energy efficiency calculation results of the bioelectrochemical method of Example 1 under the conditions of an applied voltage of 0.8 V and pH = 10.5.

[0040] Figure 5 This is a diagram showing the results of colony structure analysis of the anode of the bioelectrochemical reactor of the bioelectrochemical method of Example 1.

[0041] Figure 6 This is a diagram showing the hydrogen production effect of the bioelectrochemical method of Example 2.

[0042] Figure 7 This is a diagram showing the hydrogen production effect of the bioelectrochemical method of Example 3.

[0043] Figure 8 This is a diagram showing the hydrogen production effect of the bioelectrochemical method of Example 4.

[0044] Fig. 9 This is a graph showing the electricity generation of the bioelectrochemical method of Example 4.

[0045] Fig.10 This is a diagram showing the effect of hydrogen production by the comparative bioelectrochemical method of Comparative Example 1. DETAILED DESCRIPTION

[0046] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0047] Example 1

[0048] This embodiment provides a bioelectrochemical method for producing hydrogen using kitchen waste leachate, comprising the following steps:

[0049] 1. Construction of bioelectrochemical reactor

[0050] The single-chamber electrolytic cell is used as a bioelectrochemical reactor. The effective volume of the bioelectrochemical reactor is about 120mL. The distance between the cathode and the anode is controlled at about 3cm. A 10Ω resistor is connected externally, and a gas collection bag is installed on the top of the bioelectrochemical reactor to collect the gas generated during the reaction and measure the components. The anode of the bioelectrochemical reactor is a carbon brush, which is made of carbon fiber and titanium wire. The main steps of preparation are: cut 48 sections of carbon fiber with a length of 3cm, and each two sections are wound on the titanium wire to form a section, and a total of 24 sections are woven. The fixed position is tightened clockwise with pliers to make the carbon fiber and the titanium wire fully contact. The total length of the carbon brush is about 8cm. Then the woven carbon brush is wrapped with tin foil, placed in a box-type resistance furnace and heated at 450℃ for 30min. After cooling, the surface of the titanium wire is polished clean with sandpaper for use. The cathode is a carbon cloth, which is made of platinum-carbon catalyst and conductive carbon black. The main steps of preparation are: cut a circular carbon cloth with a diameter of 4cm, weigh a Pt loading of 0.5mg / cm 2 Add appropriate amount of 5wt% Nafion solution and isopropanol to the carbon black and conductive carbon black, stir evenly and apply them on the front and back sides of the carbon cloth, and leave it at room temperature for 24 hours before use.

[0051] 2. Enrichment of microorganisms and start-up of bioelectrochemical reactors

[0052] The inoculated microorganisms come from the effluent of a sewage treatment plant's primary sedimentation tank. The basic physical and chemical properties of the effluent are: pH = 6.62, volatile suspended solids are 0.2g / L. The matrix contains an aqueous solution of 1g / L sodium acetate, pH = 6.93, and conductivity = 7.05mS / cm. The effluent of the primary sedimentation tank and the matrix are mixed in a bioelectrochemical reactor at a ratio of 1:1, and then a voltage is applied across the bioelectrochemical reactor, with an external voltage of 0.8V.

[0053] During the startup period, when the current density output by the bioelectrochemical reactor is lower than 15A / m 3 When the number of substrate changes increases, 50% of the substrate is replaced with a new substrate. As the number of substrate changes increases, the microorganisms inoculated in the bioelectrochemical reactor gradually stabilize. When the maximum current density output by the bioelectrochemical reactor is greater than 50.0 A / m 3 When the bioelectrochemical reactor runs stably for 3 cycles, it is considered that it has been successfully started and the start-up phase is over (there is no strict regulation on the number of times the substrate can be replaced, as long as the bioelectrochemical reactor can meet the conditions for successful start-up).

[0054] 3. Add kitchen waste leachate and run

[0055] The leachate of food waste was taken from a canteen. After it was taken back, the garbage residue, sediment and surface grease were simply filtered out with gauze. The basic physical and chemical properties of the leachate of food waste were: COD = 40-80g / L, pH = 3-6, and conductivity = 20-25mS / cm. The leachate of food waste was diluted (diluted 80 times) and carbonate buffer was added. The basic physical and chemical properties of the diluted leachate of food waste were: COD = about 1g / L, pH = 10.5, and conductivity = 8.25mS / cm. The diluted leachate of food waste was added to the bioelectrochemical reactor, and the bioelectrochemical reactor was operated to react to degrade the organic matter in the diluted leachate of food waste and produce hydrogen. During the operation, the external voltage remained unchanged and was always 0.8V. Whenever the current density output by the bioelectrochemical reactor was less than 15A / m 3 When the bio-electrochemical reactor is used, the diluted food waste leachate is replaced to continue degrading organic matter and producing hydrogen.

[0056] Using the method of this embodiment, the effect of hydrogen production is as follows: Figure 1 As shown in the figure, after the first cycle, the total gas production (total gas volume) of the bioelectrochemical reactor was 85 mL, of which hydrogen accounted for 89% and methane accounted for 11%. As the number of reaction cycles increased, the total gas production per cycle fluctuated between 80 and 97 mL, and the proportion of hydrogen could be stabilized at around 85%. Since the reaction environment was under alkaline conditions, almost no CO2 was generated.

[0057] The COD removal rate of the method of this embodiment is as follows Figure 2 As shown, the COD removal rate in each cycle is above 88%, and the effluent COD is less than 100 mg / L.

[0058] The power generation curve of the bioelectrochemical reactor of the method of this embodiment is as follows Figure 3 As shown in Figure 2, the maximum current density reached within a cycle of 29 hours is 123A / m 3 .

[0059] The energy efficiency of each operation cycle of the method of this embodiment is calculated according to the following formula:

[0060] The energy efficiency calculated based on the electric energy of external voltage input is:

[0061]

[0062] The energy efficiency calculated based on the sum of the electrical energy consumed by the external voltage and the chemical energy conversion of organic matter in the leachate of food waste is:

[0063]

[0064] Where: η E(H2) is the energy efficiency (%) calculated based on the electric energy input from the external voltage, η E+S (H2) is the energy efficiency calculated based on the sum of the electrical energy consumed by the external voltage and the chemical energy conversion of organic matter in the leachate of food waste, is the number of moles of H2 (mol), is the combustion heat of hydrogen 285.8 (kJ / mol), I is the current in the circuit (A), U is the applied voltage (V), R ex is the resistance of the external circuit (Ω), n s is the COD mass removed from the leachate of food waste (g), ΔH s is the calorific value of the kitchen waste leachate calculated by COD, 14.7 (kJ / g), and t is the operating time (s).

[0065] like Figure 4 As shown in the figure, based on the calculation of the electric energy input by the external voltage, the energy efficiency of hydrogen energy generation reaches an average of 150-170%, which is much higher than the energy efficiency of traditional alkaline water electrolysis hydrogen production technology (60-75%); even if calculated based on the sum of the electric energy consumed by the external voltage and the chemical energy conversion of organic matter in the leachate of food waste, the energy efficiency of hydrogen energy generation can still reach an average of 60-80%.

[0066] A sterile scalpel was used to shear the anode of the bioelectrochemical reactor after 5 cycles of stable operation. The mass (wet weight) of the sample was about 0.5 g. After rinsing the sample surface with sterile saline, the sample DNA was extracted. The amplification region was V3-V4, and the primers were 338F (5'-ACTCCTACGGGAGGCAGCAG-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3'). After extracting the total DNA of the sample, the bacterial polymerase chain reaction (PCR) was started, with an initial denaturation at 98°C for 30 s, a total of 30 cycles (each cycle included 98°C for 15 s, 58°C for 15 s, and 72°C for 15 s), and a final extension step of 1 min at 72°C. The amplicon was purified using the AxyPrep DNA gel extraction kit and quantified using QuantiFluor. The qualified library was sequenced and analyzed using IlluminahiSeq 2500 (Cui W., Lu Y., Zeng C., Yao J., Liu G., Luo H., Zhang R. Hydrogen production in single-chamber microbial electrolysis cell under high applied voltages [J]. Science of The Total Environment, 2021, 780 (22): 146597.). The colony structure of the anode biofilm is as follows Figure 5 As shown, Figure 5 (a) Distribution of biofilm colony structure at the phylum level, among which the relative abundance of Firmicutes was 38.4%, the relative abundance of Synergistota was 21.9%, and the relative abundance of Bacteroidota was 18.9%; Figure 5 (b) is the distribution of biofilm community structure at the genus level, where the dominant species include Aminivibrio and Acetoanaerobium, with a relative abundance of 13.6% for Aminivibrio and 12.1% for Acetoanaerobium; Desulfovibrio is also included, which is a typical electrogenic genus with a relative abundance of 0.7%. Aminivibrio and Acetoanaerboium at this relative abundance, combined with food waste leachate of appropriate pH, can achieve efficient synergy of Aminivibrio and Acetoanaerboium, and then achieve efficient and stable hydrogen production with food waste leachate as the matrix under the action of Desulfovibrio electrogenic microorganisms and electrochemistry.

[0067] Example 2

[0068] This embodiment provides a bioelectrochemical method for producing hydrogen using leachate from kitchen waste. The method is basically the same as that in Example 1, except that after the bioelectrochemical reactor in Example 1 runs for 8 cycles, the cathode is replaced with a brand new carbon cloth (the main steps for preparing the carbon cloth are the same as those in Example 1), and the anode remains unchanged.

[0069] Using the method of this embodiment, the hydrogen production result is as follows Figure 6 As shown, after the first cycle, the total gas production was 105 mL, of which H2 accounted for 91%. After 12 cycles of reaction, the total gas production was stabilized at about 80 mL, and the proportion of hydrogen was stabilized at about 85%. This shows that replacing a new cathode will not improve the effect of using kitchen waste leachate to produce hydrogen in the bioelectrochemical reactor, but it will not affect it either. This also shows that the dominant bacteria at the specific genus level enriched on the anode are the key to the efficient and stable hydrogen production of the present invention.

[0070] The COD removal rate, power generation curve and energy efficiency of this embodiment are similar to those of embodiment 1.

[0071] Example 3

[0072] This embodiment provides a bioelectrochemical method for producing hydrogen using food waste leachate. The method is basically the same as Example 1, except that: in step 3, the food waste leachate is diluted 40 times, and the basic physical and chemical properties of the diluted food waste leachate are: COD = about 2 g / L, pH = 10.5, and conductivity = 8.63±0.20 mS / cm.

[0073] Using the method of this embodiment, the effect of hydrogen production is as follows: Figure 7 As shown. After the first cycle, the reactor gas production was as high as 164mL, of which hydrogen accounted for 87%, that is, the hydrogen volume was 142mL. By the fifth cycle, the total gas production was stable at 120mL, of which the hydrogen volume was 84mL, and the hydrogen accounted for 70%. This shows that reducing the dilution multiple of the food waste leachate and then adding it to the bioelectrochemical reactor (that is, when the concentration of the food waste leachate added to the bioelectrochemical reactor is high), can effectively increase the hydrogen production. Although the hydrogen purity has decreased, it is still at a high level.

[0074] The COD removal rate, power generation curve and energy efficiency of this embodiment are similar to those of embodiment 1.

[0075] Example 4

[0076] This embodiment provides a bioelectrochemical method for producing hydrogen using leachate from kitchen waste. The method is basically the same as that in Embodiment 1, except that the external voltage applied in the second and third steps is 1.0V.

[0077] Using the method of this embodiment, the effect of hydrogen production is as follows: Figure 8 As shown in Figure 1, similar to Example 1, the final hydrogen content is stabilized at about 85%. The power generation curve of the bioelectrochemical reactor is shown in Figure 2. Fig. 9 As shown, the maximum current density reached during the cycle is 140A / m 3 , compared with the maximum current density of Example 1 at an external voltage of 0.8V, there is a significant improvement, an increase of about 13%.

[0078] The COD removal rate, energy efficiency and total gas volume of this embodiment are similar to those of Embodiment 1.

[0079] Example 5

[0080] This embodiment provides a bioelectrochemical method for producing hydrogen using food waste leachate. The method is basically the same as that in Example 1, except that: in step 3, the pH of the diluted food waste leachate is adjusted to 10.

[0081] The total gas production volume, hydrogen concentration, COD removal rate, power generation curve and energy efficiency of this embodiment are similar to those of Example 1.

[0082] Example 6

[0083] This embodiment provides a bioelectrochemical method for producing hydrogen using food waste leachate. The method is basically the same as that in Example 1, except that: in step 3, the pH of the diluted food waste leachate is adjusted to 11.

[0084] The total gas production volume, hydrogen concentration, COD removal rate, power generation curve and energy efficiency of this embodiment are similar to those of Example 1.

[0085] Comparative Example 1

[0086] This comparative example provides a comparative bioelectrochemical method, which is different from Example 1 in that: the pH of the diluted food waste leachate in step 3 is adjusted to 9.5, and the bioelectrochemical reactor is operated to compare the effect of pH value on the hydrogen production effect of the bioelectrochemical reactor in treating food waste leachate.

[0087] The effect of hydrogen production from kitchen waste leachate in this comparative example is as follows: Fig.10 As shown in the figure, the total gas production per cycle is stable at about 40 mL, of which hydrogen accounts for 11% and methane accounts for 89%. The total gas production and hydrogen concentration are very low. This shows that pH = 9.5 has an adverse effect on hydrogen production from kitchen waste leachate.

[0088] Comparative Example 2

[0089] This comparative example provides a comparative bioelectrochemical method, which is different from Example 1 in that: the pH of the diluted food waste leachate in step 3 is adjusted to 11.5. When the diluted food waste leachate is added to the bioelectrochemical reactor, the bioelectrochemical reactor cannot operate normally, hydrogen production is almost zero, and electricity production almost disappears. This shows that when pH=11.5, it is not conducive to the operation of the bioelectrochemical reactor and it is difficult to use food waste leachate to produce hydrogen.

[0090] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A bioelectrochemical method for producing hydrogen using leachate from kitchen waste, characterized in that: The steps include: S1. constructing a bioelectrochemical reactor, enriching microorganisms at the anode of the bioelectrochemical reactor, and completing the startup of the bioelectrochemical reactor; S2. Add food waste leachate with a pH of 10 to 11 to the activated bioelectrochemical reactor and run it; The dominant bacterial species at the genus level in the anode-enriched microorganisms include Aminivibrio and Acetoanaerobium, and the relative abundances of Aminivibrio and Acetoanaerobium are both 5-15%; the bacterial species at the genus level in the anode-enriched microorganisms also include Desulfovibrio, and its relative abundance is 0.5-5%; The bioelectrochemical reactor in step S1 is a single-chamber electrolytic cell; The specific process of enriching microorganisms in step S1 is: adding the substrate and the effluent from the primary sedimentation tank of the sewage treatment plant into the bioelectrochemical reactor, mixing, and then applying an external voltage to the bioelectrochemical reactor; The COD concentration of the kitchen waste leachate in step S2 is 1-2 g / L, and the conductivity is 8.25-8.83 mS / cm.

2. The bioelectrochemical method according to claim 1, characterized in that: The anode in step S1 is a carbon brush material anode.

3. The bioelectrochemical method according to claim 1, characterized in that: The matrix is ​​an aqueous solution containing 1-10 g / L sodium acetate, with a pH value of 6-9 and an electrical conductivity of 7-10 mS / cm.

4. The bioelectrochemical method according to claim 1, characterized in that: The volatile solid suspended matter of the effluent from the primary sedimentation tank of the sewage treatment plant is 0.1-0.3 g / L, and the pH value is 6-9.

5. The bioelectrochemical method according to claim 1, characterized in that: The external voltage is 0.6-0.8V.

6. The bioelectrochemical method according to claim 1, characterized in that: In step S1, when the maximum current density output by the bioelectrochemical reactor is not less than 50.0 A / m 3 And when it runs stably for at least 3 cycles, the startup is considered successful.

7. The bioelectrochemical method according to claim 1, characterized in that: The external voltage of the operation in step S2 is 0.8-2.0V.

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