Device and method for producing ethanol through electric fermentation of food industry wastewater based on mixed culture of lactic acid bacteria and saccharomycetes

Abstract

The invention belongs to the field of waste treatment and energy recycling, and discloses a device and method for producing ethanol through electric fermentation of food industry wastewater based on lactic acid bacteria and saccharomycetes mixed culture. The device comprises an anode chamber and a cathode chamber, the cathode chamber is arranged in an inner cavity of the anode chamber, and the tops of the anode chamber and the cathode chamber are sealed; a preset distance is reserved between the bottom of the cathode chamber and the bottom of the anode chamber, a proton exchange membrane is arranged at the bottom of the cathode chamber, a cathode electrode is arranged in an inner cavity of the cathode chamber, the top of the inner cavity of the cathode chamber is further connected with a gas collection structure, an anode electrode is arranged in the inner cavity of the anode chamber outside the cathode chamber, and the anode chamber is further provided with an anode chamber water inlet and an anode chamber water outlet. According to the invention, the metabolic pathway of microorganisms is controlled by controlling the cathode and anode potentials, and ethanol is generated for recycling; the anode loses electrons to reach a corresponding potential to control metabolism of anode microorganisms, so that removal and directional conversion of organic matters are realized; protons on the surface of the cathode are reduced into hydrogen by electrons.

Description

Technical Field

[0001] The present invention belongs to the field of waste treatment and energy recovery and utilization, and specifically relates to a device and a production method for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast. Background Art

[0002] At present, the content of organic matter in water bodies has not been effectively controlled, and organic pollution is still a hot environmental issue. Traditional ethanol production technology mostly uses saccharification fermentation or petrochemical synthesis, and traditional food wastewater organic matter removal technology cannot recycle organic matter in wastewater. If traditional biological treatment is used, additional organic matter may be required, which not only increases investment costs, but also easily causes secondary pollution and increases greenhouse gas emissions. It is of great significance to explore resource recovery technology while treating wastewater.

[0003] Lactic acid bacteria and yeast are widely used microorganisms in daily life and industrial production. They are cheap, abundant in source, and have strong electrical activity. Using electrons as a mediator to regulate microbial metabolism, microorganisms decompose organic matter in water and convert it into ethanol in a directional manner, which can not only remove pollutants from water, but also recycle and reuse organic matter resources in water.

[0004] However, the metabolic pathways of microorganisms are diverse, and the metabolic pathways of microorganisms under different environmental conditions are also different. Therefore, how to control the metabolic pathways of microorganisms so that they can achieve the directional conversion of target products is the key to the technology of producing ethanol from food wastewater by electro-fermentation of lactic acid bacteria and yeast mixed culture. Summary of the invention

[0005] In view of the current status of wastewater treatment and resource recovery, the present invention proposes a device and a production method for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast. The present invention controls the metabolic pathway of microorganisms by controlling the potential of anode and cathode to produce ethanol for recycling; the anode loses electrons to achieve the corresponding potential to control the metabolism of anode microorganisms and realize the removal and directional conversion of organic matter; the protons on the cathode surface obtain electrons and are reduced to hydrogen.

[0006] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows: A device for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast, comprising an anode chamber and a cathode chamber, wherein the cathode chamber is arranged in the inner cavity of the anode chamber, the tops of the anode chamber and the cathode chamber are sealed, a preset distance is left between the bottom of the cathode chamber and the bottom of the anode chamber, a proton exchange membrane is arranged at the bottom of the cathode chamber, a cathode electrode is arranged in the inner cavity of the cathode chamber, a gas collecting structure is also connected to the top of the inner cavity of the cathode chamber, an anode electrode is arranged in the inner cavity of the anode chamber outside the cathode chamber, and the anode chamber is also provided with an anode chamber water inlet and an anode chamber water outlet.

[0007] Preferably, the cathode electrode is suspended in the middle of the reaction zone in the inner cavity of the cathode chamber 12 through an external wire, and the external wire passes through one end of the sealing cover and extends to the outside of the cathode chamber.

[0008] Preferably, two anode electrodes and one reference electrode are provided in the anode chamber, and the two anode electrodes and one reference electrode are evenly distributed in the circumferential direction of the anode chamber.

[0009] Preferably, the anode electrode and the reference electrode are suspended in the middle of the anode chamber inner cavity reaction zone in the height direction through external wires, the anode chamber water inlet is located above the anode electrode and the reference electrode, and the anode chamber water outlet is located below the anode electrode and the reference electrode.

[0010] Preferably, a stirring device is provided in the anode chamber below the bottom of the cathode chamber.

[0011] Preferably, the anode chamber and the cathode chamber are both cylindrical in shape and are coaxially arranged, the cathode electrode is a carbon cloth electrode, and the anode electrode is a carbon felt electrode.

[0012] The present invention also provides a method for producing ethanol from food industry wastewater by electro-fermentation based on mixed culture of lactic acid bacteria and yeast, which is carried out using the device for producing ethanol from food industry wastewater by electro-fermentation based on mixed culture of lactic acid bacteria and yeast as described above. The method comprises: Inoculation start-up process: inoculate the lactic acid bacteria and yeast inoculum into the culture solution, then pass the culture solution into the anode chamber, adjust the pH to 7.0-7.3, add the acidic pH KCL solution to the cathode chamber, apply a voltage of 0.2-1.0V to the anode, operate the food industry wastewater electric fermentation ethanol production device based on the mixed culture of lactic acid bacteria and yeast, and complete the inoculation start-up when the concentration of each component of the fermentation solution in the supernatant no longer changes; Operation process: The anode chamber adopts batch treatment, and the food wastewater is introduced into the anode chamber from the anode chamber water inlet, so that the liquid level is higher than the top of the anode electrode, and the pH of the anode liquid is adjusted to 5.5-6.0; The cathode chamber adopts batch operation, and the acidic power-consuming matrix is ​​added into the cathode chamber so that the liquid level of the acidic power-consuming matrix is ​​higher than the top of the cathode electrode; A voltage of 0.2 to 1.0V is applied to the anode electrode and the cathode electrode to perform mixed electric fermentation. In the anode chamber, the organic matter in the food wastewater is decomposed by lactic acid bacteria, and part of it is used by lactic acid bacteria to generate pyruvic acid through the regulation of electricity, and then used by yeast to generate ethanol. The yeast also uses the remaining decomposed substances to continue fermentation to produce ethanol under the enhanced effect of electricity. The liquid after fermentation is discharged from the outlet of the anode chamber; In the cathode chamber, the cathode electrode obtains the electrons lost by the anode electrode, and uses the electrons to reduce the hydrogen ions in the cathode liquid into hydrogen gas, and the generated hydrogen gas is collected by the gas collecting structure; During the fermentation in the anode chamber and the hydrogen production in the cathode chamber, proton exchange is carried out between the anode chamber and the cathode chamber through the proton exchange membrane to maintain the charge balance between the anode chamber and the cathode chamber.

[0013] Preferably, the potential of the anode electrode is 0.44V to 1.24V.

[0014] Preferably, the pH of the acidic KCL solution is 5-6, and the concentration of KCL is 0.2-0.3 mol / L.

[0015] Preferably, during operation, the pH of the anolyte is intermittently adjusted to 5.5-6.0 with a NaOH solution; The microbial concentration in the anode chamber is 1×10 6 ~1×10 7 CFU / mL, the ratio of lactic acid bacteria to yeast is 1:(1~3).

[0016] The present invention has the following beneficial effects: The food industry wastewater electro-fermentation ethanol production device based on the mixed culture of lactic acid bacteria and yeast of the present invention is provided with an anode chamber water inlet and an anode chamber water outlet in the anode chamber, and a cathode chamber water inlet and a cathode chamber water outlet in the cathode chamber. When in use, wastewater is introduced into the anode chamber from the anode chamber water inlet, and buffer is introduced into the cathode chamber from the cathode chamber water inlet. When the anode electrode and the cathode electrode are respectively connected to a power source (such as a constant potential instrument), the microorganisms attached to the anode electrode control the potential by losing electrons to control the metabolic pathway. Under the dual effects of electrochemistry and anaerobic environment, the conversion process of pyruvate entering the TCA cycle of lactic acid bacteria is inhibited, part of the pyruvate is converted into ethanol, and part of the pyruvate is discharged and used by yeast as a carbon source, so that fermentation to produce ethanol is realized. After fermentation, The wastewater is discharged from the outlet of the anode chamber; the cathode electrode obtains the electrons lost by the anode electrode and reduces the hydrogen ions in the water to hydrogen; the generated hydrogen is collected by the gas collecting structure; during the process of producing ethanol from the wastewater by electro-fermentation, protons are exchanged between the anode chamber and the cathode chamber through a proton exchange membrane, so that the charge balance between the anode chamber and the cathode chamber is maintained; through the above, the fuel cell of the present invention (i.e., the food industry wastewater electro-fermentation ethanol production device based on the mixed culture of lactic acid bacteria and yeast) can produce ethanol from the organic matter in the food industry wastewater, and can realize the synchronous and continuous treatment of the organic matter in the industrial wastewater. The fuel cell of the present invention can produce ethanol from the wastewater with high COD and can remove the organic matter in the wastewater with high COD, and has the characteristics of economy and environmental protection. The microorganisms on the anode electrode are yeast and lactic acid bacteria, both of which are cheap and easy to obtain, and yeast and lactic acid bacteria can inhibit the growth of other microorganisms during the electro-fermentation process, which is beneficial to the purification of the product and the increase of the yield. They can also be used to work synergistically and make full use of their metabolic pathways to improve the efficiency and yield of ethanol production. Lactic acid bacteria can utilize a small portion of the lactic acid and other substrates produced by yeast, resulting in a purer product.

[0017] Through the above-mentioned effect of the electric fermentation, it can be known that the ethanol production method of the present invention can remove organic matter in food industry wastewater, convert organic matter into ethanol to achieve the removal and recovery of organic matter, and convert hydrogen in the wastewater into hydrogen gas for discharge, without polluting the air and removing it completely; the present invention can remove organic matter in food industry wastewater, and in the process of removal, it can also produce ethanol, and the produced ethanol can be exported and utilized, so it has the characteristics of economy and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to the present invention; Figure 2 It is a top view of the device for producing ethanol by electric fermentation of food industry wastewater based on mixed culture of lactic acid bacteria and yeast according to the present invention; Figure 3for Figure 2 Schematic diagram of the middle AA section; Figure 4 Result diagram of ethanol concentration in the embodiment of the present invention.

[0019] In the figure: 1- spiral stirrer, 2- anode chamber water outlet, 3- proton exchange membrane, 4- anode electrode, 5- cathode electrode, 6- anode chamber water inlet, 7- flange, 8- gas collecting pipe, 9- constant potential instrument, 10- reference electrode, 11- anode chamber, 12- cathode chamber, 13- gas collection bag. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific drawings and specific embodiments. Unless otherwise specified or conflicting, the preferred embodiments can be combined arbitrarily.

[0021] Reference Figure 1~Figure 3 The food industry wastewater electro-fermentation ethanol production device based on the mixed culture of lactic acid bacteria and yeast of the present invention comprises an anode chamber 11 and a cathode chamber 12, wherein the anode chamber 11 and the cathode chamber 12 are respectively filled with organic wastewater and a buffer solution; the anode chamber 11 and the cathode chamber 12 are both hollow structures, the anode chamber 11 and the cathode chamber 12 are coaxially arranged, the upper ends of the anode chamber 11 and the cathode chamber 12 are both provided with sealing flanges, the sealing flanges are detachably connected with sealing covers, and the sealing covers of the anode chamber 11 and the cathode chamber 12 are both provided with external wire ports; The anode chamber 11 is provided with an anode chamber water inlet 6 and an anode chamber water outlet 2 from top to bottom. In the anode chamber 11, the portion between the anode chamber water inlet 6 and the anode chamber water outlet 2 is the anode chamber reaction zone. The anode chamber reaction zone is provided with two anode electrodes 4, and the anode electrodes 4 are carbon felt electrodes. The anode electrodes 4 are suspended on the sealing cover of the anode chamber and are located in the middle of the reaction zone of the anode chamber 11. The anode electrodes 4 are connected with external wires, and the external wires connected to the anode electrodes 4 extend from the external wires to the outside of the anode chamber 1 and are finally connected to the constant potential instrument 9. A gas collecting structure is provided at the top of the cathode chamber 12, and the gas collecting structure includes an exhaust port, which is provided on a detachable sealing cover of the cathode chamber, and a gas collecting pipe 8 is inserted into the cathode chamber 12 from the exhaust port, and the lower end of the gas collecting pipe 8 is located above the cathode electrode 5, and the upper end of the gas collecting pipe 8 is connected to a gas collection bag 13, and the exhaust port, the gas collecting pipe 8 and the gas collection bag 13 together constitute the above-mentioned gas collecting structure, in the cathode chamber 12, water enters and exits through the detachable sealing cover on the top of the cathode chamber, and a cathode electrode 5 is provided in the cathode chamber 12, and the cathode electrode 5 adopts a rectangular carbon cloth, and the cathode electrode 5 is below the buffer solution level in the cathode chamber 12, and the lower end of the gas collecting pipe 8 is above the buffer solution level; the cathode electrode 5 is suspended from the sealing cover of the cathode chamber and is located in the middle of the cathode chamber 12, and an external wire is connected to the cathode electrode 5, and the external wire connected to the cathode electrode extends from the external wire port to the outside of the cathode chamber and is finally connected to the constant potential instrument 9; the anode electrode 4 and the cathode electrode 5 are fixed by platinum wire passing through the sealing cover; A proton exchange membrane 3 is fixed at the bottom of the cathode chamber, and the anode chamber matrix and the cathode chamber matrix exchange substances through the proton exchange membrane 3. The ratio of the area of ​​the proton exchange membrane 3 to the sum of the volumes of the anode chamber 11 and the cathode chamber 12 is 1: (50-70).

[0022] Reference Figure 1 The anode electrode 4 and cathode electrode 5 of the present invention are both rectangular plate structures of the same shape, wherein the anode electrode 4 is a rectangular carbon felt sheet, the aspect ratio of the anode electrode 4 is (2.5~3.5):1, the ratio of the total surface area of ​​the anode electrode 4 to the total volume of the anode chamber 11 is 1:(8~12), and the distance between the top of the anode electrode 4 and the surface of the electricity-generating matrix liquid is at least 30 mm. The cathode electrode 5 is a rectangular carbon cloth, the aspect ratio of the cathode electrode 5 is (2.5~3.5):1, and the ratio of the surface area of ​​the cathode electrode 5 to the total volume of the cathode chamber is 1:(8~12). The height-to-diameter ratio of the anode chamber 11 is (2~3):1, and the headspace accounts for 5%~10%; the height-to-diameter ratio of the cathode chamber 12 is (2.5~3.5):1, and the headspace accounts for 10%~15%; A spiral stirrer 1 is provided at the bottom of the anode chamber 11 below the cathode chamber 12. The spiral stirrer 1 is located below the water outlet 2 of the anode chamber. Anaerobic fermentation is carried out under the environmental condition of 0°C and the action of the spiral stirrer 1. The ethanol concentration in the anode chamber is monitored at all times. The rotation speed of the spiral stirrer is 150-200 rpm.

[0023] Two anode electrodes 4 and a reference electrode 10 are arranged in the anode chamber 11. The two anode electrodes 4 are evenly distributed in the circumferential direction of the anode chamber 11. The reference electrode 10 and the two working electrodes 4 of the anode are distributed in an isosceles triangle. The distance between the two anode electrodes 4 and the wall of the cathode chamber 12 is at least 1.5 cm. The reference electrode 10 is suspended in the same manner as the anode electrode 4 and at the same height. The reference electrode 10 is an Ag / AgCl electrode. The anode chamber is also connected to a pH monitor, and the cathode chamber is connected to a gas flow meter.

[0024] The ethanol production method of the present invention is carried out by the above-mentioned food industry wastewater electric fermentation ethanol production device based on mixed culture of lactic acid bacteria and yeast, and includes the following process: Inoculation start-up process: Inoculate the lactic acid bacteria and yeast inoculum into the culture medium (10g / L yeast extract, 5g / L peptone, 3g / L NaCl, 1.5g / L NaHCO 3 、0.1g / L MgCl 2 6H 2 O, 2g / L KH 2 PO 4 and 20 g / L glucose), and then the culture solution was passed into the anode chamber of the reactor, the pH was adjusted to 7.0-7.3, an acidic KCL solution with a pH of 5-6 was added to the cathode, the reactor was connected to a constant potential instrument, a voltage of 0.2-1.0 V was applied to the anode, the reactor was operated for 3 days, and the supernatant was taken every 12 hours to detect the concentration of each component of the fermentation liquid until the concentration no longer changed, that is, the inoculation start-up of the device was completed; The electro-fermentation operation process includes the following steps: Step 1, the anode is treated in batch mode, food wastewater is introduced into the anode chamber 11 through the anode chamber water inlet 6, the liquid level is higher than the top of the anode electrode 4, and the pH of the anode liquid is adjusted to 5.5-6.0.

[0025] The cathode adopts batch operation, and the acidic KCL solution with a pH of 5-6 is introduced into the cathode chamber from the sealing cover on the top of the cathode chamber so that the liquid level is higher than the top of the cathode electrode. The concentration of the KCL solution used in the cathode is 0.2-0.3 mol / L.

[0026] Step 2, the anode electrode 4 and the cathode electrode 5 are connected to the constant potential meter 9 respectively, and a voltage of 0.2 to 1.0V is applied to the anode through the constant potential meter 9 to perform mixed electric fermentation. In the anode chamber 11, the organic matter (such as starch) in the wastewater is decomposed by lactic acid bacteria, and part of it is used by lactic acid bacteria to generate pyruvic acid through the regulation of electricity, and then used by yeast to generate ethanol. The yeast can also continue to ferment and produce ethanol by using the remaining decomposed substances under the enhanced effect of electricity. The liquid after the fermentation is completed is discharged from the anode chamber outlet 2; In the cathode chamber 12, the cathode electrode 5 obtains the electrons lost by the anode electrode 4, and the cathode electrode 5 uses the electrons to reduce the hydrogen ions in the cathode liquid into hydrogen gas. The generated hydrogen gas is discharged from the gas collecting pipe 8 and collected by the gas collection bag 13, and the cathode liquid is discharged through the sealing cover at the top of the cathode chamber; During the fermentation in the anode chamber and the hydrogen production in the cathode chamber, proton exchange is carried out between the anode chamber and the cathode chamber through the proton exchange membrane to maintain the charge balance between the anode chamber and the cathode chamber.

[0027] During the electrofermentation process, the pH is adjusted intermittently, preferably using NaOH solution to adjust the pH of the anolyte to 5.5-6.0 every 12-24 hours. The microbial concentration in the anode chamber is 1×10 6 ~1×10 7 CFU / mL, the ratio of lactic acid bacteria to yeast is 1:(1~3). The potential of the working electrode (i.e., the anode electrode 4) is set to 0.44V to 1.24V.

[0028] Example like Figure 1-Figure 3 As shown, the anode electrode 4 in the anode chamber and the cathode electrode 5 in the cathode chamber are connected to a constant potential instrument 9 through external wires.

[0029] In the electric fermentation device of the present invention, the size and proportion of each component can be set according to the actual situation. In this embodiment, the height-to-diameter ratio of the anode chamber and the cathode chamber is 3:1, the distance from the anode chamber water outlet 2, the anode chamber water inlet 6 to the lower end surface of the sealing flange is 1 / 10 of the total height of the anode chamber, the headspace of the anode chamber accounts for 10%; the headspace of the cathode chamber accounts for 12.5%. The anode electrode material is carbon felt, the anode electrode 4 is rectangular, the height-to-width ratio is 2.5:1, and the ratio of the total surface area of ​​the anode electrode 4 to the total volume of the anode chamber is 1cm 2 : 10cm 3 The Ag / AgCl reference electrode 10 is used as the reference electrode of the anode chamber. The cathode electrode 5 is a rectangular carbon cloth; the aspect ratio of the cathode electrode 14 is 3:1, and the ratio of its surface area to the total volume of the cathode chamber is 1 cm 2 : 20cm 3 The ratio of the membrane area of ​​the proton exchange membrane 3 to the sum of the volumes of the cathode chamber and the anode chamber is 1 cm 2 : 60cm 3 A spiral stirrer is provided at the bottom of the anode chamber, and continuous reaction is achieved by stirring with the stirrer. Through experiments, the above dimensions and proportions can better achieve the experimental purpose of the present invention.

[0030] In this embodiment, the food wastewater electro-fermentation ethanol production device using a mixed culture of lactic acid bacteria and yeast is made of organic glass, and its working process is as follows: Carbon cloth pretreatment: Cut the carbon cloth of appropriate size (7.5 cm long and 2.5 cm wide), soak it in 60% PTFE emulsion for 5 minutes to fix the carbon cloth, then place the carbon cloth on tin foil and put it in a muffle furnace, set the temperature to 350°C, and burn it for 10 minutes.

[0031] Carbon brush pretreatment: The carbon brush is first soaked in acetone for 12 hours, then burned at 37°C for 30 minutes. After cooling to room temperature, the carbon brush is soaked in deionized water for 24 hours before use.

[0032] Assemble the reactor: The reactor is a double-chamber reactor with a reactor volume of 250 mL. The reactor material is organic glass, and the entire device is a sealed anaerobic environment. Start-up of the reactor: Inoculate the inoculum of lactic acid bacteria and yeast into the culture medium (10 g / L yeast extract, 5 g / L peptone, 3 g / L NaCl, 1.5 g / L NaHCO 3 、0.1g / L MgCl 2 6H 2 O, 2g / L KH 2 PO 4 and 20 g / L glucose), and then the culture solution was passed into the anode chamber of the reactor, the pH was adjusted to 7.0-7.3, an acidic KCL solution with a pH of 5 was added to the cathode, the reactor was connected to a constant potential instrument, a voltage of 0.8 V was applied to the anode, the reactor was operated for 3 days, and the supernatant was taken every 12 hours to detect the concentration of each component of the fermentation liquid until the concentration no longer changed, that is, the inoculation start-up of the device was completed.

[0033] The anode chamber adopts batch operation. The simulated wastewater containing organic matter such as starch (4g / L starch, 2g / L ammonium sulfate, 1g / L magnesium sulfate, 2g / L potassium dihydrogen phosphate, pH adjusted to 6.5) enters the anode chamber reaction zone from the anode chamber water inlet 6 to form a fermentation matrix in the anode chamber reaction zone; the fermentation reaction potential is controlled by applying a certain voltage to the lactic acid bacteria and yeast attached to the carbon felt sheet of the anode electrode 4 to control the microbial metabolic pathway; the directional conversion of organic matter is achieved; the treated wastewater is discharged from the anode chamber water outlet 2. The electrons lost by the microorganisms attached to the anode electrode 4 are transmitted to the cathode electrode 5 via an external wire, and the voltage is controlled within a certain range by controlling the voltage through a constant potential meter. The acidic KCL solution with a pH of 5 is passed into the cathode chamber from the top sealing cover of the cathode chamber; the cathode electrode 5 obtains electrons from the anode electrode 5 of the anode chamber, and the cathode electrode 5 uses the electrons to reduce the hydrogen ions in the KCL solution to hydrogen gas; the generated hydrogen gas is discharged from the gas collecting pipe 8 and collected by the gas collection bag 13; the reacted buffer solution is extracted from the top of the cathode chamber. To maintain the charge balance between the anode chamber and the cathode chamber, proton exchange was performed through the proton exchange membrane 3. Gas chromatography and ultraviolet spectrophotometry were used to determine the ethanol and starch contents in the fermentation broth, respectively. The anode potential was set to 0.80 V, and the fermentation was carried out at 27 ° C and 300 rpm stirring speed. The fermentation time was 4 days. The results are as follows: Figure 4 As shown, the ethanol production can reach 1.27 g / L and the yield can reach 0.45 g / g.

[0034] In summary, the present invention can deal with the current situation of difficult resource recovery in industrial wastewater treatment in my country, realize the recovery of wastewater organic resources, and has multiple advantages such as economy, environmental protection and resource recycling.

[0035] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A device for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast, characterized in that: The invention comprises an anode chamber (11) and a cathode chamber (12), wherein the cathode chamber (12) is arranged in the inner cavity of the anode chamber (11), the tops of the anode chamber (11) and the cathode chamber (12) are sealed, a preset distance is left between the bottom of the cathode chamber (12) and the bottom of the anode chamber (11), a proton exchange membrane (3) is arranged at the bottom of the cathode chamber (12), a cathode electrode (5) is arranged in the inner cavity of the cathode chamber (12), a gas collecting structure is further connected to the top of the inner cavity of the cathode chamber (12), an anode electrode (4) is arranged in the inner cavity of the anode chamber (11) outside the cathode chamber (12), and the anode chamber (11) is further provided with an anode chamber water inlet (6) and an anode chamber water outlet (2).

2. The device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to claim 1, characterized in that: The cathode electrode (5) is suspended in the middle of the reaction zone in the inner cavity of the cathode chamber 12 via an external wire, and the external wire passes through one end of the sealing cover and extends to the outside of the cathode chamber (12).

3. The device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to claim 1, characterized in that: Two anode electrodes (4) and a reference electrode (10) are arranged in the anode chamber (11); the two anode electrodes (4) and the reference electrode (10) are evenly distributed in the circumferential direction of the anode chamber (11).

4. The device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to claim 3, characterized in that: The anode electrode (4) and the reference electrode (10) are suspended in the middle of the reaction zone in the inner cavity of the anode chamber (11) in the height direction via external wires; the anode chamber water inlet (6) is located above the anode electrode (4) and the reference electrode (10); and the anode chamber water outlet (2) is located below the anode electrode (4) and the reference electrode (10).

5. The device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to claim 1, characterized in that: A stirring device is provided in the anode chamber (11) below the bottom of the cathode chamber (12).

6. The device for producing ethanol from food industry wastewater by electric fermentation based on mixed culture of lactic acid bacteria and yeast according to claim 1, characterized in that: The anode chamber (11) and the cathode chamber (12) are both cylindrical in shape and are coaxially arranged; the cathode electrode (5) is a carbon cloth electrode, and the anode electrode (4) is a carbon felt electrode.

7. A method for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast, characterized in that: The method is carried out by using the food industry wastewater electric fermentation ethanol production device based on mixed culture of lactic acid bacteria and yeast as described in any one of claims 1 to 6, and the method comprises: Inoculation start-up process: inoculate the lactic acid bacteria and yeast inoculum into the culture solution, then pass the culture solution into the anode chamber (11), adjust the pH to 7.0-7.3, add a KCL solution with an acidic pH to the cathode chamber (12), apply a voltage of 0.2-1.0V to the anode, operate the food industry wastewater electric fermentation ethanol production device based on the mixed culture of lactic acid bacteria and yeast, and complete the inoculation start-up when the concentration of each component of the fermentation solution in the supernatant no longer changes; Operation process: The anode chamber (11) adopts batch processing, and the food wastewater is introduced into the anode chamber (11) through the anode chamber water inlet (6), so that the liquid level is higher than the top of the anode electrode (4), and the pH of the anode liquid is adjusted to 5.5-6.0; The cathode chamber (12) is operated in a batch mode, and an acidic power-consuming matrix is ​​added into the cathode chamber (12) so that the liquid level of the acidic power-consuming matrix is ​​higher than the top of the cathode electrode (5); A voltage of 0.2 to 1.0 V is applied to the anode electrode (4) and the cathode electrode (5) to perform mixed electro-fermentation. In the anode chamber (11), organic matter in the food wastewater is decomposed by lactic acid bacteria, part of which is used by the lactic acid bacteria to generate pyruvic acid under the regulation of electricity, and then used by yeast to generate ethanol. The yeast also uses the remaining decomposed matter to continue fermentation to produce ethanol under the enhanced effect of electricity. After the fermentation is completed, the liquid is discharged from the anode chamber outlet (2); In the cathode chamber (12), the cathode electrode (5) obtains the electrons lost by the anode electrode (4), and the cathode electrode (5) uses the electrons to reduce the hydrogen ions in the cathode liquid into hydrogen gas, and the generated hydrogen gas is collected by the gas collecting structure; During the fermentation process in the anode chamber (11) and the hydrogen production process in the cathode chamber (12), proton exchange is performed between the anode chamber (11) and the cathode chamber (12) via the proton exchange membrane (3), thereby maintaining a charge balance between the anode chamber (11) and the cathode chamber (12).

8. The method for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast according to claim 7, characterized in that: The potential of the anode electrode (4) is 0.44V to 1.24V.

9. The method for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast according to claim 7, characterized in that: The pH of the acidic KCL solution is 5-6, and the concentration of KCL is 0.2-0.3 mol / L.

10. The method for producing ethanol from food industry wastewater by electrofermentation based on mixed culture of lactic acid bacteria and yeast according to claim 7, characterized in that: During operation, the pH of the anolyte was intermittently adjusted to 5.5-6.0 with NaOH solution; The microbial concentration in the anode chamber is 1×10 6 ~1×10 7 CFU / mL, the ratio of lactic acid bacteria to yeast is 1:(1~3).

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