Method for domesticating electrode biofilm based on liquidambar formosana fruit biochar and application thereof

Abstract

This invention provides a method for the domestication of electrode biofilms based on Liquidambar formosana fruit biochar, comprising: burning Liquidambar formosana fruit into biochar under anaerobic conditions; pre-colonizing a dominant electroactive bacterial species on the surface of the biochar; subsequently synthesizing bio-nanomaterials in situ on the surface; and finally adding a mixed bacterial source to domesticate the electrode biofilm. This invention improves the start-up speed and efficacy of the mixed bacterial electrode biofilm by enhancing both the electroactive bacterial bio-enhancement and the electron transfer enhancement of the nanomaterials, providing a new method for the rapid domestication of highly efficient mixed bacterial electrode biofilms in bioelectrochemical systems, and has significant application prospects in environmental protection and resource utilization.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and resource utilization technology, specifically relating to an electrode biofilm domestication method based on Liquidambar formosana fruit biochar and its application. Background Technology

[0002] Bioelectrochemical systems (BES) are an emerging technology that utilizes microorganisms to catalyze anodic (oxidation) or cathodic (reduction) reactions. Its main applications include power generation in microbial fuel cells, pollutant removal, and biosensing; hydrogen production, methanogenesis, and chemical synthesis in microbial electrolyzers; and hydrogen production, methanogenesis, chemical synthesis, and pollutant removal in electrofermentation reactors.

[0003] Microbial fuel cells (MFCs) are devices that use microorganisms as catalysts to degrade organic matter and convert the released chemical energy into electrical energy during the decomposition process. They offer advantages such as a wide range of raw materials, mild reaction conditions, and clean and efficient operation. MFCs have been widely used to treat organic wastewater, heavy metal wastewater, sludge, cellulose, etc., and can remove pollutants and recover electrical energy without the need for or with only a small amount of organic carbon source, making them a promising wastewater treatment technology.

[0004] Microbial electrolyzers (MECs) are devices that combine the metabolic processes of anodic microorganisms with the potential difference provided by an external circuit power supply. They can efficiently produce hydrogen under potential conditions below the hydrolysis potential, and can also be used to reduce CO2 to produce methane or synthesize valuable chemicals. They are characterized by simple operation, high efficiency, low energy consumption, low pollution, greenness, and environmental friendliness.

[0005] Electrofermentation reactors (EFB) are a novel process that utilizes the electrochemistry of microorganisms to control their fermentation metabolism. Electrodes can provide or receive electrons, serving as a source of unbalanced fermentation and altering microbial metabolism by changing the redox balance. Therefore, electrofermentation has become a research hotspot in the field of anaerobic fermentation.

[0006] In summary, BES is widely used in the treatment of various types of wastewater (such as antibiotics, ammonia nitrogen, and organic matter removal) and the recovery of electrical energy, the synthesis of bioenergy (such as hydrogen and methane) and high-value chemicals (such as long-chain fatty acids), and as a biosensor (such as heavy metal toxicity sensing), among other fields, and has broad application prospects.

[0007] In bioelectrochemical electrochemical systems (BES), electrode biofilms play a crucial role. Mixed-bacterial electrode biofilms possess significant practical application potential due to their strong resilience, broad substrate spectrum, ease of operation, and low cost. However, obtaining highly efficient mixed-bacterial electrode biofilms remains challenging: long-term acclimatization and selection are required to enrich functional bacterial communities from diverse bacterial sources (such as sludge, wastewater, and riverbed sediments) and allow them to adhere and form a film on the electrode. This biofilm typically contains many non-electroactive bacteria in addition to electroactive bacteria, and the randomness of attachment means that many non-electroactive bacteria occupy niches on the electrode surface, affecting direct electron transfer and thus impacting the overall electron transfer efficiency of the biofilm. Especially when the biofilm is thick, electrons generated by the outer biofilm are difficult to transfer effectively to the electrode. Therefore, improving the electron transfer efficiency of mixed-bacterial electrode biofilms, thereby increasing start-up speed and effectiveness, has become a key issue affecting bioelectrochemical technology and its applications.

[0008] Biochar is a carbon-rich solid produced by the thermochemical transformation of biomass under anaerobic or oxygen-deficient conditions. It has a wide range of sources, including plant roots, stems, leaves, and fruits, all of which can be burned into biochar. Summary of the Invention

[0009] To address the technical problem of low electron transfer efficiency in biofilms on electrode surfaces, this invention constructs a layer of superior electroactive bacteria with stronger direct electron transfer capabilities on the electrode surface, and further enhances its electron transfer capabilities through hybrid nanoparticles. This improves the activation speed and efficacy of mixed-bacterial electrode biofilms, and has broad application prospects.

[0010] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0011] A method for domesticating electrode biofilms based on Liquidambar formosana fruit biochar includes the following steps:

[0012] (1) The fruit of the Liquidambar formosana was burned into biochar under anaerobic conditions;

[0013] (2) Pre-colonization of dominant electroactive bacterial species on the surface:

[0014] The biochar obtained in step (1) was placed in a culture medium containing dominant electroactive bacteria and cultured on a shaker to obtain biochar containing an colonization surface.

[0015] (3) In-situ synthesis of bio-nanomaterials:

[0016] The biochar containing the colonization surface layer was placed in a synthetic culture medium containing precursors for synthetic nanoparticles and electron donors for microbial reduction. The biochar was cultured in a shaker under sealed conditions, allowing the dominant electroactive bacteria to reduce the precursors and obtain biochar containing a hybrid nanoparticle surface layer.

[0017] (4) Electrode biomembrane acclimatization:

[0018] The biochar containing the nanoparticle hybrid surface was used as the anode of the MFC device, and a solution containing an organic carbon source was used as the anolyte. Mixed bacterial inoculum was added to the anode chamber of the MFC device. The MFC device was run in batches and the anolyte and catholyte were replaced periodically until the power generation of the MFC device was stable.

[0019] Preferably, step (1) further includes chemically activating the Liquidambar formosana fruit before firing or physically activating the Liquidambar formosana fruit during firing; the chemical activation includes soaking in one or more of an acid, alkali, or salt for at least 12 hours and then washing; the physical activation is the introduction of CO2 or H2O gas. Activation can further increase the porosity and specific surface area of ​​the material surface.

[0020] Preferably, the acid is H3PO4, HCl, or H2SO4; the base is KOH or NaOH; and the salt is ZnCl2, CaCl2, MgCl2, or K2CO3.

[0021] Preferably, the firing temperature in step (1) is 600 to 1000°C.

[0022] Preferably, the culture medium and the dominant electroactive bacteria mentioned in step (2) are selected from one of the following:

[0023] Shewanella and LB medium, Geobacter and Geobacter medium, Desulfovibrio and Desulfovibrio medium.

[0024] Preferably, the formulation of the Geobacterium culture medium is: 30 mM carbonate buffer, 20 mM sodium acetate, and 40 mM ferric citrate, wherein the carbonate buffer consists of: NaHCO3 2.50 g / L, NH4Cl 1.50 g / L, NaH2PO4 0.60 g / L, KCl 0.10 g / L, trace element solution 10 mL / L, and vitamin solution 10 mL / L; the trace element solution consists of: C6H9NO6 1.50 g / L. g / L, MgSO4·7H2O3.00g / L, MnSO4·H2O0.50g / L, NaCl1.00g / L, FeSO4·7H2O0.10g / L, CoSO4·7H2O0.18g / L, Ca Cl2·2H2O0.10g / L, ZnSO4·7H2O0.18g / L, CuSO4·5H2O0.01g / L, KA1(SO4)2·12H2O0.02g / L, H3BO30.01g / L, Na 2MoO4·2H2O 0.01g / L, NiCl2·6H2O 0.03g / L, Na2SeO3·5H2O 0.30mg / L, Na2WO4·2H2O 0.40mg / L; Vitamin solution composition: Biotin 2.00mg / L, Folic acid 2.00mg / L, Pyridoxine hydrochloride 10.00mg / L, Thiamine hydrochloride dihydrate 5.00mg / L, Riboflavin 5.00mg / L, Niacin 5.00mg / L, Calcium pantothenate 5.00mg / L, Vitamin B... 12 0.10 mg / L, para-aminobenzoic acid 5.00 mg / L, thioctic acid 5.00 mg / L.

[0025] Preferably, the formula of the sulfur-reducing bacteria culture medium is: 5mM Na2SO4, 15mM Na3C6H5O7, 2mM K2HPO4, 7.5mM CaCl2, 15mM MgCl2, and 20mM NH4Cl.

[0026] Preferably, the shaking culture conditions in step (2) are 30°C and 200 rpm for 14 hours.

[0027] Preferably, the synthetic culture medium in step (3) is a mixed culture medium of M9 medium and liquid LB medium, that is, a small amount of liquid LB medium is added to M9 medium, preferably in a volume ratio of 19:1.

[0028] Preferably, the M9 culture medium has the following formulation: Na2HPO4·12H2O 17.8 g / L, KH2PO4 3.0 g / L, NaCl 0.5 g / L, NH4Cl 1.0 g / L; and the liquid LB culture medium has the following formulation: tryptone 10 g / L, yeast extract 5 g / L, NaCl 10 g / L.

[0029] Preferably, the synthetic culture medium described in step (3) is subjected to deoxygenation and sterilization treatment.

[0030] Preferably, the concentration of the electron donor in step (3) is 18 mmol / L.

[0031] Preferably, the electron donor in step (3) is sodium lactate, sodium acetate, sodium propionate or glucose.

[0032] Preferably, the conditions for shaking culture in step (3) are 30°C, 100 rpm, and culture for 24 h.

[0033] Preferably, the nanoparticles in step (3) are nano-gold, nano-iron sulfur, nano-copper sulfur, graphene, or nano-palladium.

[0034] The precursors mentioned in step (3) are determined according to the nanomaterials to be synthesized. For example, tetrachloroauric acid is added to synthesize nano-gold, iron (such as ferric chloride, ferric citrate) and sulfur (such as sodium thiosulfate, sodium sulfate) are added to synthesize nano-sulfur iron, copper (such as copper chloride, copper sulfate) and sulfur (such as sodium thiosulfate, sodium sulfate, copper sulfate) are added to synthesize nano-graphene, graphene oxide is added to synthesize nano-palladium, etc.

[0035] Preferably, the mixed bacterial inoculum source in step (4) is anaerobic activated sludge, lake bottom sediment, soil or wastewater.

[0036] Preferably, the organic carbon source in step (4) is glucose, sodium acetate, sodium lactate or sodium pyruvate, with glucose being the most preferred.

[0037] Preferably, the anolyte in step (4) is domestic wastewater or industrial wastewater.

[0038] Preferably, the MFC device is a dual-chamber MFC or a single-chamber MFC. Preferably, the catholyte of the dual-chamber MFC device is a phosphate buffer solution containing an electron acceptor, wherein the electron acceptor is preferably potassium ferricyanide; the cathode electron acceptor of the single-chamber MFC device is oxygen.

[0039] The present invention also provides an application of the electrode biofilm domestication method based on Liquidambar formosana fruit biochar, the application of which includes the construction of a bioelectrochemical system.

[0040] Preferably, the bioelectrochemical system is used for electricity generation, hydrogen production, methanogenesis, chemical synthesis, pollutant removal, or biosensing.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] This invention utilizes the fruit of the sweetgum tree, whose porous and spiny natural structure not only facilitates bacterial attachment but also endows it with a strong adsorption capacity for pollutants due to its large specific surface area, making it highly suitable for the production of biochar electrodes. Using the porous and spiny natural structure of sweetgum tree fruit to produce biochar as a BES electrode material enables the resource utilization of agricultural and forestry solid waste.

[0043] The efficient mixed-bacterial electrode biofilm domestication method provided by this invention is time-saving and highly efficient.

[0044] In this invention, the pre-colonization of electroactive bacteria on the surface of Liquidambar formosana fruit biochar is beneficial for the selective enrichment of electroactive or symbiotic bacteria, thereby improving the speed and stability of biofilm formation.

[0045] This invention utilizes pre-colonized electroactive bacteria on a biochar electrode to synthesize and self-assemble a nanomaterial hybrid biofilm surface. This biofilm improves the electron transfer efficiency of the electrode biofilm by constructing a 3D conductive network, while the functional bacterial community is more likely to form a mutually beneficial and stable microbial ecological structure based on electromutatrophy.

[0046] This invention achieves bio-enhancement through the pre-colonization of dominant electroactive bacterial species on the surface, which can significantly improve the electrocatalytic activity of electrode biofilms.

[0047] This invention effectively improves the activity and physiological and biochemical metabolic functions of biomembrane cells by coupling nanomaterials / cell hybrid biomembranes with biochar electrodes from Liquidambar formosana fruit.

[0048] This invention introduces in-situ synthesis and self-assembly of bio-nanomaterials into electroactive biomembranes, and the presence of nanomaterials further enhances the effectiveness of the electrode biomembrane. Attached Figure Description

[0049] Figure 1 This is a schematic flowchart of the electrode biofilm domestication method based on Liquidambar formosana fruit biochar of the present invention.

[0050] Figure 2 Scanning electron microscope images (SEM) of the biochar produced from Liquidambar formosana fruit before and after (a) and (b) of the biochar produced from Liquidambar formosana fruit.

[0051] Figure 3 The voltage change (a) and maximum power density (b) of the electrode biofilms obtained by the novel biochar domestication, traditional biochar domestication, traditional carbon felt domestication and carbon felt coupled domestication methods in Examples 1 and 2 of this invention during the MFC start-up period are shown. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to specific examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0053] Example 1

[0054] (1) After washing and drying, the fruits of the Liquidambar formosana tree were placed in a tube furnace and burned at 1000℃ (heating rate of 5℃ / min) under nitrogen for 2 hours to produce biochar. The appearance of the biochar before and after burning and the resulting biochar are as follows: Figure 2 As shown.

[0055] (2) The obtained biochar was placed in LB medium containing Shewanella oneidensis MR-1 and cultured on a shaker (30℃, 200rpm) for 14h to complete the surface pre-colonization of S. oneidensis MR-1 and obtain biochar containing the colonized surface.

[0056] (3) Preparation of synthetic culture medium: 100 mL of mixed M9 and LB culture medium (M9 to LB volume ratio of 19:1) was placed into a 200 mL shake flask, aerated with nitrogen for 15 min to remove oxygen, and then sterilized to obtain synthetic culture medium. The formula of M9 culture medium is: Na2HPO4·12H2O 17.8 g / L, KH2PO4 3.0 g / L, NaCl 0.5 g / L, NH4Cl 1.0 g / L. The formula of liquid LB culture medium is: tryptone 10 g / L, yeast extract 5 g / L, NaCl 10 g / L.

[0057] (4) The biochar containing the colonization surface layer was placed in a synthesis culture medium in an anaerobic chamber, and the precursor for the synthesis of bio-nano-sulfur iron (5 mM sodium thiosulfate and 5 mM ferric chloride solution after sterile filtration) and 18 mmol / L sterile sodium lactate solution were added. After sealing, the mixture was placed in a shaker (30℃, 100 rpm) and cultured for 24 h. When the solution in the shake flask turned completely black, the synthesis of nano-sulfur iron was completed. The biochar electrode was collected to obtain biochar containing the surface layer of the nanoparticle hybrid electrode biofilm.

[0058] (5) The biochar with a surface nano-sulfur-iron / cell hybrid biofilm was placed in a two-chamber MFC device as the anode, and anaerobic activated sludge (taken from Nanjing Qiaobei Wastewater Treatment Plant) was added for electrode biofilm acclimation. The inoculation ratio was 1:13 (anaerobic dry sludge: anode solution). The anode solution was simulated glucose wastewater with COD = 1000 mg / L (0.31 g / L NH4Cl; 2.452 g / L NaH2PO4; 4.576 g / L Na2HPO4; 0.13 g / L KCl; 1 g / L C6H4PO4). 12 O6·H2O; pH=7.0), the catholyte was a phosphate buffer solution containing 50mM potassium ferricyanide. The cathode electrode was a carbon felt, and the intermediate septum was a Nafion 117 proton exchange membrane. All anode and cathode chambers of the MFC were strictly sealed during the experiment, with an external resistance of 1000Ω. The assembled MFC with connected circuits was run in batches in a 30℃ constant temperature biochemical incubator (dark room). The anode and cathode solutions were changed every 3-4 days to allow electrochemically active microorganisms to accumulate on the anode electrode. When the battery produced electricity stably for two consecutive cycles, it was considered that the electrodeophilic microorganisms had been successfully accumulated, and the mixed-bacterial electrode biofilm acclimation was completed.

[0059] (6) The biofilm electrode obtained in step (5) is a novel domesticated biochar group;

[0060] The biochar traditional domestication group was obtained by the following method: only steps (1) and (5) above were used, in which step (5) the sycamore fruit biochar obtained in step (1) was directly used for subsequent operations.

[0061] The carbon felt traditional domestication group was obtained by the following method: only step (5) above was used, wherein step (5) used carbon felt electrodes instead of biochar for subsequent operations.

[0062] The carbon felt coupled acclimatization group was obtained by the following method: using the MFC anode electrode as carbon felt, anaerobic activated sludge and nano-sulfur iron synthesis precursor were added together to the MFC anode chamber to synthesize nano-sulfur iron. The synthesis medium was a mixed medium of M9 and LB (volume ratio of 19:1), and the synthesis cycle was 24h. After the synthesis cycle was completed, anaerobic activated sludge and concentrated S. oneidensis MR-1 bacterial solution (concentration was the same as the S. oneidensis MR-1 biomass attached in the new acclimatization method based on the biochar electrode of Liquidambar formosana fruit) were added to the MFC anode to continue the acclimatization of the mixed bacterial electrode biofilm. Other conditions were the same as described in (5).

[0063] Power generation test: The power generation of MFC after starting up using the above four acclimatization methods is as follows: Figure 3As shown. In terms of power generation, the highest voltage of the anode electrode of the novel biochar-acclimated MFC reached 0.5753V in the first cycle, which is 2.87 times that of the traditional biochar acclimation group (0.2005V), 2.49 times that of the traditional carbon felt acclimation group (0.2309V), and 1.27 times that of the carbon felt coupled acclimation group (0.4526V). From the perspective of the acclimatization cycle, the maximum voltage of the novel biochar acclimatization group was 0.6506V and 0.6632V in the second and third cycles, respectively, indicating that power generation was basically stable, acclimatization was complete, and the start-up period ended. The maximum voltage of the traditional biochar acclimatization group was 0.4778V and 0.6056V in the second and third cycles, respectively, while the maximum voltage of the traditional carbon felt acclimatization group was 0.3842V and 0.4219V in the second and third cycles, respectively. The maximum voltage of both experimental groups using the traditional acclimatization method remained unstable in each cycle, with significant fluctuations within the cycle, indicating that acclimatization was not yet complete. The maximum voltage of the carbon felt coupled acclimatization group was 0.5246V and 0.5391V in the second and third cycles, respectively. Although the maximum voltage of the carbon felt coupled acclimatization group was similar, the large fluctuations within the cycle indicated that its system was still unstable and required further acclimatization. Correspondingly, the maximum power density of the novel biochar acclimatization group in the third cycle was 689.10 mW / m³. 2 Compared with the traditional biochar domestication group (432.85 mW / m), respectively 2 The efficiency was increased by 59.20%, compared to the traditional carbon felt acclimatization group (270.45 mW / m). 2 The efficiency was increased by 154.80%, compared to the carbon felt coupled acclimatization group (473.93 mW / m). 2 The efficiency was increased by 45.40%. Furthermore, compared to traditional carbon felt acclimatization, the novel biochar acclimatization method shortened MFC start-up time by at least 50%, demonstrating a significant advantage. Therefore, considering both MFC power generation and start-up speed, the novel acclimatization method based on Liquidambar formosana fruit biochar electrodes of this invention is more effective.

[0064] Example 2

[0065] This embodiment illustrates the application efficiency verification of the four groups of biofilm electrodes obtained in Example 1 for MFC treatment of organic wastewater, antibiotic wastewater, and heavy metal wastewater. The effects of anode COD, anode chloramphenicol (CAP), and cathode Cr(VI) removal rates are also investigated.

[0066] (1) The electrode biofilms obtained by the above four acclimation methods were placed in the organic wastewater treated by the MFC anode for 72 hours, with all other conditions being the same as the MFC operating conditions described in Example 1. The organic wastewater was the same as the glucose simulated wastewater with COD = 1000 mg / L described in Example 1.

[0067] (2) The electrode biofilms obtained by the above four acclimation methods were placed in MFC anode-treated antibiotic wastewater for 72 hours, with all other conditions being the same as the MFC operating conditions described in Example 1. The antibiotic wastewater was the glucose simulated wastewater described in Example 1 with 30 mg / L chloramphenicol (CAP) added.

[0068] (3) The electrode biofilms obtained by the above four acclimation methods were reversed and used in the MFC cathode treatment of heavy metal wastewater for 10 hours. The anode electrode biofilm was the electrode biofilm obtained by traditional carbon felt acclimation. All other conditions were the same as the MFC operating conditions described in Example 1. The cathode heavy metal wastewater was simulated chromium-containing wastewater containing 40 mg / L Cr(VI) (0.28 g / L NH4Cl, 2.132 g / L NaH2PO4, 4.576 g / L Na2HPO4, 0.78 g / L KCl, 0.2 g / L NaHCO3; pH = 7).

[0069] The treatment performance of electrode biofilms obtained by the four acclimation methods for MFC treatment of wastewater with different pollutants is shown in Table 1. For simulated glucose wastewater with an initial COD of 1000 mg / L, the COD removal rate of the novel biochar acclimation group reached 97.21%, which was 10.28%, 15.97%, and 7.14% higher than that of the traditional biochar acclimation group, the traditional carbon felt acclimation group, and the carbon felt coupled acclimation group, respectively. For simulated CAP wastewater with an initial concentration of 30 mg / L, the CAP removal rate of the novel biochar acclimation group was 93.86%, which was higher than that of the traditional biochar acclimation group. The CAP removal rates of the novel biochar domestication group, the traditional carbon felt domestication group, and the carbon felt coupled domestication group were increased by 42.69%, 71.68%, and 31.07%, respectively. For Cr(VI)-containing wastewater with an initial concentration of 40 mg / L, the Cr(VI) removal rate of the novel biochar domestication group was 100%, which was 57.41%, 109.82%, and 53.54% higher than that of the traditional biochar domestication group, the traditional carbon felt domestication group, and the carbon felt coupled domestication group, respectively. The results show that the electrode biofilm obtained by the novel domestication method based on Liquidambar formosana fruit biochar electrode of this invention has significant effects on the treatment of organic wastewater, antibiotic wastewater, and heavy metal wastewater.

[0070] Table 1. Comparison of the performance of electrode biofilms obtained by novel biochar domestication, traditional biochar domestication, traditional carbon felt domestication, and carbon felt coupled domestication in MFC for treating wastewater with different pollutants.

[0071] experimental group COD removal rate CAP removal rate Cr(VI) removal rate Novel Biochar Domestication 97.21％ 93.86％ 100％ Traditional domestication of biochar 88.15％ 65.78％ 63.53％ Traditional domestication of carbon felt 83.82％ 54.67％ 47.66％ Carbon felt coupling domestication 90.73％ 71.61％ 65.13％

[0072] Example 3

[0073] After being washed and dried, the fruit of the Liquidambar formosana was soaked in NaOH solution for 12 hours, then washed with water until neutral and dried. It was then placed in a tube furnace and calcined at 1000℃ (heating rate of 5℃ / min) with nitrogen for 2 hours to produce biochar.

[0074] Biochar was added to a Geobacter culture medium containing Geobacter and cultured at 30°C and 200 rpm for 14 h to obtain biochar containing a colonization surface. The culture medium for *Geobacterium* was prepared as follows: 30 mM carbonate buffer, 20 mM sodium acetate, and 40 mM ferric citrate. The carbonate buffer consisted of: NaHCO3 2.50 g / L, NH4Cl 1.50 g / L, NaH2PO4 0.60 g / L, KCl 0.10 g / L, trace element solution 10 mL / L, and vitamin solution 10 mL / L. The trace element solution consisted of: C6H9NO6 1.50 g / L, MgSO4·7H2O 3.00 g / L, MnSO4·H2O 0.50 g / L, NaCl 1.00 g / L, FeSO4·7H2O 0.10 g / L, CoSO4·7H2O 0.18 g / L, CaCl2·2H2O 0.10 g / L, and ZnSO4·7H2O. 0.18 g / L, CuSO4·5H2O 0.01 g / L, KAl(SO4)2·12H2O 0.02 g / L, H3BO3 0.01 g / L, Na2MoO4·2H2O 0.01 g / L, NiCl2·6H2O 0.03 g / L, Na2SeO3·5H2O 0.30 mg / L, Na2WO4·2H2O 0.40 mg / L; Vitamin solution composition: Biotin 2.00 mg / L, Folic Acid 2.00 mg / L, Pyridoxine Hydrochloride 10.00 mg / L, Thiamine Hydrochloride Dihydrate 5.00 mg / L, Riboflavin 5.00 mg / L, Niacin 5.00 mg / L, Calcium Pantothenate 5.00 mg / L, Vitamin B 12 0.10 mg / L, para-aminobenzoic acid 5.00 mg / L, thioctic acid 5.00 mg / L.

[0075] The biochar containing the colonization surface was placed in a synthetic culture medium in an anaerobic chamber, and a precursor for the synthesis of nano-gold (0.15 mM tetrachloroauric acid solution after sterile filtration) and 18 mmol / L sterile sodium acetate solution were added. After sealing, the biochar was placed in a shaker (30℃, 100 rpm) and cultured for 24 h. The biochar electrode was then collected to obtain biochar containing the biofilm surface of the nano-gold hybrid electrode.

[0076] The mixed-bacterial electrode biofilm was acclimatized using the method in step (5) of Example 1. After completion, the simulated chromium-containing wastewater containing 40 mg / L Cr(VI) was treated using the method in (3) of Example 2, and the removal rate was 100%.

[0077] Example 4

[0078] After being washed and dried, the fruits of the sweetgum tree were placed in a tube furnace and burned with CO2 at 1000℃ (heating rate of 5℃ / min) for 2 hours to produce biochar.

[0079] Biochar was added to a sulfur-reducing bacteria culture medium containing sulfur-reducing bacteria (Desulfovibrio) and cultured at 30°C and 200 rpm for 14 h to obtain biochar with a colonizing surface. The sulfur-reducing bacteria culture medium was formulated as follows: 5 mM Na₂SO₄, 15 mM Na₃C₆H₅O₇, 2 mM K₂HPO₄, 7.5 mM CaCl₂, 15 mM MgCl₂, and 20 mM NH₄Cl.

[0080] The biochar containing the colonization surface was placed in a synthetic culture medium in an anaerobic chamber, and a nano-palladium synthesis precursor (5 mM sodium tetrachloropalladium solution after sterile filtration) and 18 mmol / L sterile sodium propionate solution were added. After sealing, the biochar was placed in a shaker (30℃, 100 rpm) and cultured for 24 h. The biochar electrode was then collected to obtain biochar containing the nano-palladium hybrid electrode biofilm surface.

[0081] The mixed-bacterial electrode biofilm was acclimatized using the method in step (5) of Example 1. After completion, the simulated chromium-containing wastewater containing 40 mg / L Cr(VI) was treated using the method in (3) of Example 2, and the removal rate was 100%.

Claims

1. A method for domestication of electrode biofilm based on sugar maple fruit biochar, characterized by, The application comprises the following steps: (1) burning Liquidambar formosana fruits under anaerobic conditions to obtain biochar; (2) pre-colonizing the surface layer of the biochar with dominant electroactive bacteria: placing the biochar obtained in step (1) in a culture medium containing dominant electroactive bacteria, and performing shaking culture to obtain biochar with a colonized surface layer; (3) in-situ synthesis of biological nanomaterials: placing the biochar with a colonized surface layer in a synthesis culture medium containing precursors of nanoparticles and a microbial-reduced electron donor, and performing shaking culture under a sealed condition to allow the dominant electroactive bacteria to reduce the precursors, thereby obtaining biochar with a nanoparticle hybrid surface layer; (4) domesticating the electrode biofilm: using the biochar with a nanoparticle hybrid surface layer as the anode of an MFC device, using a solution containing an organic carbon source as the anode liquid, and adding a mixed bacterial source inoculum to the anode chamber of the MFC device, and performing batch operation of the MFC device and periodically replacing the anode liquid and the cathode liquid until the MFC device stably generates electricity.

2. The electrode biofilm domestication method of claim 1, wherein, Step (1) further comprises the step of chemically activating the Liquidambar formosana fruits before burning or physically activating the Liquidambar formosana fruits during burning; the chemical activation comprises soaking in one or more of an acid, a base or a salt for at least 12 h and washing; and the physical activation is the introduction of CO2 or H2O gas.

3. The electrode biofilm domestication method of claim 1, wherein, The temperature of the burning in step (1) is 600-1000 ℃.

4. The electrode biofilm domestication method of claim 1, wherein, The culture medium and the dominant electroactive bacteria in step (2) are selected from one of the following: Shewanella Shewanella and LB medium, Geobacter Geobacter and Geobacter medium, Sulfate Reducing Bacteria Desulfovibrio and Sulfate Reducing Bacteria medium.

5. The electrode biofilm domestication method of claim 1, wherein, The synthesis culture medium in step (3) is a mixed culture medium of M9 culture medium and liquid LB culture medium.

6. The electrode biofilm domestication method of claim 5, wherein, The volume ratio of the M9 culture medium to the liquid LB culture medium is 19:

1.

7. The electrode biofilm domestication method of claim 1, wherein, The electron donor in step (3) is sodium lactate, sodium acetate, sodium propionate or glucose.

8. The electrode biofilm domestication method of claim 1, wherein, The nanoparticles in step (3) are nano-gold, nano-iron sulfide, nano-copper sulfide, graphene or nano-palladium.

9. The electrode biofilm domestication method of claim 1, wherein, The mixed bacterial source inoculum in step (4) is anaerobic activated sludge, lake sediment, soil or wastewater.

10. The electrode biofilm domestication method of claim 1, wherein, The organic carbon source in step (4) is glucose, sodium acetate, sodium lactate or sodium pyruvate.

11. Use of the method for domestication of electrode biofilm based on sugar maple fruit biochar according to any one of claims 1 to 10, characterized in that, The application includes constructing a bioelectrochemical system.

12. Use according to claim 11, characterized in that, The bioelectrochemical system is used for electricity generation, chemical synthesis, pollutant removal or biosensing.

Images