Recycling method of high-concentration wine brewing wastewater

Abstract

The invention relates to a recycling method of high-concentration wine brewing wastewater, which comprises the following steps: (1) adding a fermentation substrate, a caproic acid producing inoculum and a signal molecule enhancing solution into a cathode chamber of an electric fermentation reactor, mixing, and aerating for 3-5 minutes to obtain a mixed solution; (2) adding an anode buffer solution into an anode chamber of the electric fermentation reactor; and (3) applying a cathode potential of-1.5 to-1.0 V to the cathode chamber, and carrying out anaerobic fermentation on the mixed solution in the cathode chamber at 32-36 DEG C for 10-30 days to obtain the fermentation liquor. According to the method, the caproic acid producing inoculum which can tolerate a high-concentration fermentation substrate is obtained through domestication, meanwhile, the electric fermentation condition is scientifically adjusted, synthesis of caproic acid is promoted under the synergistic interaction effect of a signal molecule enhancing solution, the yield of caproic acid is higher, byproducts are low, and cost reduction is facilitated.

Description

Technical Field

[0001] The invention relates to the field of environmental protection, and in particular to a method for recycling high-concentration brewing wastewater. Background Art

[0002] Winemaking wastewater refers to wastewater generated during the production of liquor, including yellow wine, bottom pot water of distillation or fermentation equipment, cooling water, site cleaning water, bottle washing water, etc. Direct discharge of industrial wastewater without treatment will cause huge environmental pollution and waste of resources.

[0003] Hexanoic acid is a straight-chain medium-chain acid containing 6 carbon atoms. Due to its high energy density and strong biocompatibility, it has become a precursor for many chemicals, such as catalysts, plasticizers, dyes, and flavors. In addition, the market value of hexanoic acid is about US$3,337 per ton, while acetate and butyrate are only US$600 and US$2,163 per ton. The wide range of applications and expensive economic value make hexanoic acid more attractive than short-chain acids such as acetic acid. Traditional methods of producing hexanoic acid mainly extract it from vegetable oils such as palm oil, but many unfavorable factors such as high raw material costs, toxicity inhibition, and slow microbial metabolism rate have limited the improvement of its production efficiency.

[0004] Previous studies have used electrofermentation to recover caproic acid from brewery wastewater, which is low-cost and highly efficient. However, high-concentration brewery wastewater can easily cause serious toxic inhibition on caproic acid-producing bacteria. Therefore, it is necessary to develop a caproic acid production method that can adapt to high-concentration brewery wastewater. Summary of the invention

[0005] The object of the present invention is to provide a method for recycling high-concentration brewing wastewater, comprising the following steps:

[0006] (1) adding a fermentation substrate, an acid-producing inoculant and a signal molecule enhancement solution into a cathode chamber of an electric fermentation reactor, mixing, and aerating for 3 to 5 minutes to obtain a mixed solution;

[0007] The fermentation substrate is high-concentration brewing wastewater, wherein the ethanol concentration is 1-35 g / L and the lactic acid concentration is not less than 1 g / L;

[0008] The volume ratio of the fermentation substrate to the acid-producing inoculum is (5-15):1, preferably (8-10):1;

[0009] The signal molecule enhancement solution is an organic solution containing octanoyl-homoserine lactone, wherein the final concentration of octanoyl-homoserine lactone in the mixed solution is 10-20 μM / L;

[0010] (2) adding an anode buffer to the anode chamber of the electric fermentation reactor;

[0011] (3) applying a cathode potential of -1.5 V to -1.0 V to the cathode chamber, and anaerobically fermenting the mixed solution in the cathode chamber at 32-36° C. for 10-30 days to obtain a fermentation solution.

[0012] In a preferred technical solution of the present invention, in step (1), the ethanol concentration in the fermentation substrate is 5-35 g / L.

[0013] In a preferred technical solution of the present invention, in step (1), the lactic acid concentration in the fermentation substrate is not less than 5 g / L.

[0014] In the preferred technical scheme of the present invention, in step (1), when the ethanol concentration in the fermentation substrate is higher than 35 g / L, the high-concentration brewing wastewater is diluted with cathode buffer to an ethanol concentration lower than 35 g / L.

[0015] In the preferred technical solution of the present invention, the cathode buffer contains 2-3 g / L of K 2 HPO 4 , 4-4.5g / L KH 2 PO 4 , 0.1-1g / L NH 4 Cl, 0.2-0.6 g / L MgCl 2 6H 2 O, 0.01-0.1 g / L yeast extract, 1-2 g / L sodium 2-bromoethylsulfonate, and the balance is water.

[0016] In the preferred technical solution of the present invention, in step (1), the electric fermentation reactor is an H-type double-chamber electrolytic cell, which is divided into an anode chamber and a cathode chamber by a proton exchange membrane in the middle, and ruthenium iridium titanium mesh and carbon felt are used as anode and cathode respectively, and Ag / AgCl electrode is used as reference electrode.

[0017] In the preferred technical scheme of the present invention, in step (1), the method for preparing the caproic acid-producing inoculum is: inoculating wine-making cellar mud into a mixed culture medium at a solid-liquid ratio of 1-1.5:1 (g / L) to obtain a culture solution, and anaerobically culturing at pH 6.5±0.5 and 35±2°C for 1-2 weeks to obtain the culture solution, wherein an equal amount of the culture solution is replaced with a fresh mixed culture medium accounting for 5-10% of the volume of the culture solution every 5-7 days.

[0018] In the preferred technical solution of the present invention, in the preparation of the acid-producing inoculum, the mixed culture medium contains 10-15 g / L ethanol, 10-15 g / L lactic acid, 5-10 g / L acetic acid, 2-3 g / L K 2 HPO 4 , 4~4.5g / L KH 2 PO 4 , 0.1~1g / L NH 4Cl, 0.2-0.6 g / L MgCl 2 6H 2 O, 0.01-0.1 g / L yeast extract and 1-2 g / L sodium 2-bromoethylsulfonate, and the balance is water.

[0019] In a preferred technical solution of the present invention, in the mixed culture medium, the molar ratio of ethanol:lactic acid is 1.5-2.5:1, preferably 1-2:1.

[0020] In a preferred technical solution of the present invention, in the mixed culture medium, the molar ratio of (ethanol+lactic acid):acetic acid is 3-5:1, preferably 3-4:1.

[0021] In a preferred technical solution of the present invention, in the preparation of the caproic acid-producing inoculum, the wine-making mud contains caproic acid-producing bacteria, and preferably the caproic acid-producing bacteria are Clostridium sensu stricto 12 and Bacillus.

[0022] In a preferred technical solution of the present invention, in step (1), the sum of the abundances of Clostridia and Bacilli in the acid-producing inoculum is not less than 45%, preferably not less than 55%, and more preferably not less than 65%.

[0023] In the preferred technical scheme of the present invention, in step (1), the signal molecule enhancement solution is prepared by dissolving octanoyl-homoserine lactone in an organic solvent, wherein the organic solvent is a polar solvent, preferably dimethyl sulfoxide, and the mass volume ratio of the octanoyl-homoserine lactone to the organic solvent is 1:300-500 (g / mL).

[0024] In a preferred technical solution of the present invention, in step (1), the aeration gas is nitrogen or carbon dioxide.

[0025] In the preferred technical solution of the present invention, in step (1), optionally, sodium 2-bromoethylsulfonate is added to the mixed solution, and the mass volume ratio of the sodium 2-bromoethylsulfonate to the mixed solution is 0.1-0.5%.

[0026] In the preferred technical solution of the present invention, in step (2), the anode buffer contains 2 to 3 g / L of K 2 HPO 4 , 4~4.5g / L KH 2 PO 4 , the balance is water.

[0027] In a preferred technical solution of the present invention, in step (3), the fermentation is carried out on a magnetic stirrer at 100-150 rpm.

[0028] In a preferred technical solution of the present invention, in step (3), after 5-12 days of fermentation, a signal molecule enhancement solution having a volume equal to the initial added volume is added to the cathode chamber.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] The present invention adopts the following method to detect:

[0031] 1. Determination of ethanol, lactic acid and caproic acid content: The collected samples were centrifuged at low temperature (12000rpm) and filtered (0.45μm) to remove the precipitate, and then the concentrations of caproic acid and ethanol in the samples were detected by gas chromatography (Shimadzu GC-2010plus, Japan) equipped with a capillary column (HP-FFAP type) and a hydrogen flame ionization detector (FID). The lactic acid concentration was determined using a high performance liquid chromatography equipped with an SH1011 column (column temperature 60℃, flow rate 1mL / min, mobile phase 28μL / L sulfuric acid solution).

[0032] 2. Determination of microbial abundance in the acid-producing inoculum: First, use Soil DNA kit was used to extract DNA from the acid-producing inoculum. Then, primers 338F and 806R were used to amplify the V3-V4 region of the bacterial 16S rRNA gene by PCR. The amplification program was as follows: 95°C pre-denaturation for 3 min, 27 cycles (95°C denaturation for 30 s, 55°C annealing for 30 s, 72°C extension for 30 s), then 72°C stable extension for 10 min, and finally stored at 4°C. PCR products were recovered using 2% agarose gel and purified using the AxyPrep DNA gel extraction kit. The purified amplicons were sequenced on the MiSeq PE300 platform and the microbial abundance was calculated.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention domesticates a caproic acid-producing inoculum that can tolerate high-concentration brewing wastewater, and scientifically adjusts the electrofermentation conditions. Under the synergistic effect of the signal molecule enhancement solution, the enrichment of caproic acid-producing bacteria can be promoted, and their substrate metabolism capacity can be improved, thereby promoting the synthesis of caproic acid. The caproic acid yield is high and the by-products are low, which is beneficial to reducing the caproic acid production cost and downstream separation cost.

[0035] 2. The invention has simple process, convenient operation, low cost, no waste discharge, and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the electric fermentation reactor of the present invention;

[0037] Figure 2 Comparison of caproic acid concentration in the fermentation broth of Examples 1-3 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0038] The following is a detailed description of the embodiments of the present invention in conjunction with examples, but these examples are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0039] For details on the electrofermentation reactor, see Figure 1 . A double-chamber reactor was constructed with a ruthenium-iridium-titanium mesh (3cm×4cm×0.1cm) as the anode, a carbon felt (3cm×4cm) as the working electrode, and an Ag / AgCl electrode as the reference electrode. The anode chamber and the cathode chamber were separated by a proton exchange membrane. The cathode chamber is the main reaction chamber, and its total volume / effective working volume are 150ml / 130ml respectively. The cathode potential is provided by a constant potential power supply system, and the potential of the Ag / AgCl reference electrode is used as a reference. The potential difference between the working electrode and the Ag / AgCl reference electrode is the size of the cathode potential. The anode chamber is mainly used to form a closed current loop with the cathode chamber. The cathode chamber is sealed to ensure an anaerobic environment, and the anode chamber is not sealed.

[0040] The brewing yellow water in the embodiment was taken from a winery in Anhui. The brewing yellow water was diluted with cathode buffer to obtain a fermentation substrate, wherein the ethanol concentration in the fermentation substrate was 31 g / L and the lactic acid concentration was 34 g / L. The formula of the cathode buffer was: 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract, 1 g / L sodium 2-bromoethylsulfonate, and the balance is water.

[0041] The wine-making cellar mud is taken from Anhui Wenwang Gongjiu Winery, and the wine-making cellar mud contains caproic acid-producing bacteria Clostridium sensu stricto 12 and Bacillus.

[0042] Signal molecule enhancement solution: weigh 2.7 mg of octanoyl-homoserine lactone and dissolve it in 1 mL of dimethyl sulfoxide, and mix well to obtain the solution.

[0043] Anode buffer: 2.6 g / L K2 HPO 4 , 4.4g / L KH 2 PO 4 , the balance is water.

[0044] Example 1

[0045] (1) adding 120 mL of fermentation substrate and 10 mL of caproic acid-producing inoculum to the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, and simultaneously adding 200 μL of a signal molecule enhancement solution, adjusting the pH to 6.45 with a sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0046] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of wine-making pit mud is inoculated into 250 ml of mixed culture medium to obtain a solution to be acclimated. The pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions. Subsequently, an equal amount of acclimation solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5. The solution is cultured in an incubator at 35±2°C for 1 month to obtain a caproic acid-producing inoculum, wherein the sum of the microbial abundances of the classes Clostridia and Bacilli is not less than 65%;

[0047] The formula of the mixed culture medium is: 10.22 g / L ethanol, 10 g / L lactic acid, 6.67 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0048] (2) Add 130 ml of anode buffer into the anode chamber;

[0049] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0050] Example 2

[0051] (1) adding 120 mL of fermentation substrate and 10 mL of hexanoic acid-producing inoculum to the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, and simultaneously adding 200 μL of a signal molecule enhancement solution, adjusting the pH to 6.45 with a sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0052] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of wine-making pit mud is inoculated into 250 ml of mixed culture medium to obtain a solution to be acclimated. The pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions. Subsequently, an equal amount of acclimation solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5. The solution is cultured in an incubator at 35±2°C for 1 month to obtain a caproic acid-producing inoculum, wherein the sum of the microbial abundances of the classes Clostridia and Bacilli is not less than 65%;

[0053] The formula of the mixed culture medium is: 7.68 g / L ethanol, 10 g / L lactic acid, 5.56 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0054] (2) Add 130 ml of anode buffer into the anode chamber;

[0055] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0056] Example 3

[0057] (1) adding 120 mL of fermentation substrate and 10 mL of hexanoic acid-producing inoculum to the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, and simultaneously adding 200 μL of a signal molecule enhancement solution, adjusting the pH to 6.45 with a sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0058] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of wine-making pit mud is inoculated into 250 ml of mixed culture medium to obtain a solution to be acclimated; the pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions, and then an equal amount of acclimation solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5, and the mixture is cultured in an incubator at 35±2° C. for 1 month to obtain a caproic acid-producing inoculum, wherein the sum of the abundance of microorganisms of the classes Clostridia and Bacilli is not less than 65%;

[0059] The formula of the mixed culture medium is: 12.79 g / L ethanol, 10 g / L lactic acid, 7.78 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0060] (2) Add 130 ml of anode buffer into the anode chamber;

[0061] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0062] Comparative Example 1

[0063] (1) adding 120 mL of fermentation substrate and 10 mL of hexanoic acid-producing inoculum to the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, and simultaneously adding 200 μL of a signal molecule enhancement solution, adjusting the pH to 6.45 with a sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0064] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of the original pit mud is inoculated into 250 ml of the mixed culture medium to obtain the acclimated solution. The pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions. Subsequently, an equal amount of the acclimated solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5, and the mixture is cultured in an incubator at 35±2° C. for 1 month to obtain the caproic acid-producing inoculum;

[0065] The formula of the mixed culture medium is: 5.11 g / L ethanol, 10 g / L lactic acid, 4.44 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0066] (2) Add 130 ml of anode buffer into the anode chamber;

[0067] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0068] Comparative Example 2

[0069] (1) adding 120 mL of fermentation substrate and 10 mL of hexanoic acid-producing inoculum to the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, and simultaneously adding 200 μL of a signal molecule enhancement solution, adjusting the pH to 6.45 with a sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0070] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of the original pit mud is inoculated into 250 ml of the mixed culture medium to obtain the acclimated solution. The pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions. Subsequently, an equal amount of the acclimated solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5, and the mixture is cultured in an incubator at 35±2° C. for 1 month to obtain the caproic acid-producing inoculum;

[0071] The formula of the mixed culture medium is: 15.34 g / L ethanol, 10 g / L lactic acid, 8.89 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0072] (2) Add 130 ml of anode buffer into the anode chamber;

[0073] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0074] Comparative Example 3

[0075] (1) adding 120 mL of fermentation substrate and 10 mL of caproic acid-producing inoculum into the cathode chamber of the electric fermentation reactor to obtain a mixed solution; adding 0.13 g of sodium 2-bromoethylsulfonate to the mixed solution, adjusting the pH to 6.45 with sodium hydroxide solution, placing a magnetic stirring rotor, and aerating with nitrogen for 5 minutes;

[0076] The preparation method of the caproic acid-producing inoculum is as follows: 142.8 g of the original pit mud is inoculated into 250 ml of the mixed culture medium to obtain the acclimated solution. The pH value is adjusted to 6.5±0.5 with sodium hydroxide, and then nitrogen is aerated for 5 minutes to maintain anaerobic conditions. Subsequently, an equal amount of the acclimated solution is replaced with 20 ml of fresh culture medium every 7 days, and the pH is maintained at 6.5±0.5, and the mixture is cultured in an incubator at 35±2° C. for 1 month to obtain the caproic acid-producing inoculum;

[0077] The formula of the mixed culture medium is: 10.22 g / L ethanol, 10 g / L lactic acid, 6.67 g / L acetic acid, 2.6 g / L K 2 HPO 4 , 4.4g / L KH 2 PO 4 , 0.31 g / L NH 4 Cl, 0.2 g / L MgCl 2 6H 2 O, 0.05 g / L yeast extract and 1 g / L sodium 2-bromoethylsulfonate, the balance being water;

[0078] (2) Add 130 ml of anode buffer into the anode chamber;

[0079] (3) The magnetic stirring speed of the cathode chamber was set to 150 rpm, the constant cathode potential was set to -1.0 V, anaerobic fermentation was performed, and the fermentation temperature was set to 36°C. After 11 days of fermentation, 200 μL of the signal molecule enhancement solution was added to the cathode chamber. The fermentation was continued until the 25th day to obtain the fermentation broth. The caproic acid concentration in the fermentation broth was detected by the method of the present invention. Figure 2 .

[0080] The above description of the specific embodiments of the present invention does not limit the present invention. Those skilled in the art may make various changes or modifications based on the present invention. As long as they do not depart from the spirit of the present invention, they should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for recycling high-concentration brewing wastewater, comprising the following steps: (1) adding a fermentation substrate, an acid-producing inoculant and a signal molecule enhancement solution into a cathode chamber of an electric fermentation reactor, mixing, and aerating for 3 to 5 minutes to obtain a mixed solution; The fermentation substrate is high-concentration brewing wastewater, wherein the ethanol concentration is 1-35 g / L and the lactic acid concentration is not less than 1 g / L; The volume ratio of the fermentation substrate to the acid-producing inoculum is (5-15):1, preferably (8-10):1; The signal molecule enhancement solution is an organic solution containing octanoyl-homoserine lactone, wherein The final concentration of octanoyl-homoserine lactone in the fermentation broth was 10-20 μM / L; (2) adding an anode buffer to the anode chamber of the electric fermentation reactor; (3) applying a cathode potential of -1.5 to -1.0 V to the cathode chamber, and anaerobically fermenting the mixed solution in the cathode chamber at 32 to 36° C. for 10 to 30 days to obtain a fermentation solution.

2. The method according to claim 1, in step (1), when the ethanol concentration in the fermentation substrate is higher than 35 g / L, the high-concentration brewing wastewater is diluted with cathode buffer to an ethanol concentration lower than 35 g / L.

3. The method according to any one of claims 1 to 2, wherein in step (1), the cathode buffer comprises 2-3 g / L K2HPO4, 4-4.5 g / L KH2PO4, 0.1-1 g / L NH4Cl, 0.2-0.6 g / L MgCl2·6H2O, 0.01-0.1 g / L yeast extract, 1-2 g / L sodium 2-bromoethylsulfonate, and the balance is water.

4. The method according to any one of claims 1 to 3, wherein in step (1), the electric fermentation reactor is an H-type double-chamber electrolytic cell, which is divided into an anode chamber and a cathode chamber by a proton exchange membrane in the middle, and a ruthenium iridium titanium mesh and a carbon felt are used as the anode and cathode, respectively, and an Ag / AgCl electrode is used as a reference electrode.

5. The method according to any one of claims 1 to 4, wherein in step (1), the preparation method of the caproic acid-producing inoculum is: inoculating winemaking pit mud into a mixed culture medium at a solid-liquid ratio of 1-1.5:1 (g / L) to obtain a culture solution, and anaerobic culture at pH 6.5±0.5 and 35±2°C for 1-2 weeks to obtain, wherein, Every 5-7 days, an equal amount of culture medium was replaced with fresh mixed medium accounting for 5-10% of the culture medium volume.

6. The method according to any one of claims 1 to 5, wherein in the preparation of the caproic acid-producing inoculum, the mixed culture medium contains 10 to 15 g / L ethanol, 10 to 15 g / L lactic acid, 5 to 10 g / L acetic acid, 2 to 3 g / L K2HPO4, 4 to 4.5 g / L KH2PO4, 0.1 to 1 g / L NH4Cl, 0.2 to 0.6 g / L MgCl2·6H2O, 0.01 to 0.1 g / L yeast extract and 1 to 2 g / L sodium 2-bromoethylsulfonate, with the remainder being water.

7. The method according to any one of claims 1 to 6, wherein in the preparation of the caproic acid-producing inoculum, the molar ratio of ethanol to lactic acid is 1.5-2.5:1, preferably 1:

1.

8. The method according to any one of claims 1 to 7, wherein in the preparation of the acetate-producing inoculum, the molar ratio of (ethanol+lactic acid):acetic acid is 3-4:1, preferably 3:

1.

9. The method according to any one of claims 1 to 8, wherein in step (1), the sum of the abundances of Clostridia and Bacilli microorganisms in the acid-producing inoculum is not less than 45%, preferably not less than 55%, and more preferably not less than 65%.

10. The method according to any one of claims 1 to 9, wherein in step (1), the signal molecule enhancement solution is prepared by dissolving octanoyl-homoserine lactone in an organic solvent, wherein the organic solvent is a polar solvent, preferably dimethyl sulfoxide, and the mass volume ratio of the octanoyl-homoserine lactone to the organic solvent is 1:300-500 (g / mL).

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