Treatment method of Maotai-flavor liquor vinasse cellar bottom water

Abstract

The invention relates to the technical field of sewage treatment, in particular to a treatment method for distillers' grains cellar bottom water of Maotai-flavor liquor. The treatment method comprises the following steps: step one, filtering the distillers' grains cellar bottom water through a 80-100-mesh sieve to remove large-particle residues; and step 2, culturing the Leclercia adcarboxada NJ22 to prepare a bacterial suspension with OD600 (optical density 600) of 1.8-2.2. And step 3, adding the suspended bacterial liquid into vinasse cellar bottom water according to a volume ratio of (8-10): 100, and fermenting. In the first stage, the temperature is 25-35 DEG C, 0.8-1 mol / L NaOH is added to maintain the pH value to be 7 + / -0.1, ventilation is performed at 1-1.5 vvm, and stirring is performed at 200-300 rpm until the OD600 of thalli is 2.2-3; in the second stage, anaerobic fermentation is performed for 50-60 hours at the temperature of 25-35 DEG C, stirring is performed at the speed of 50-100 rpm, and N2 or CO2 is introduced to remove oxygen. And 4, heating at 80-90 DEG C for 10-20 min for inactivation, centrifuging at 5000-7000 rpm for 10-20 min, and separating thallus mud and treated vinasse cellar bottom water. According to the method, lactic acid and protein in the vinasse cellar bottom water can be synchronously and deeply degraded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a processing method of Jiangxiang Baijiu (liquor) vinasse pit bottom water. BACKGROUND

[0002] During the brewing process of Jiangxiang Baijiu (liquor), a large amount of brownish-yellow liquid, i.e., vinasse pit bottom water, also known as “yellow water”, will accumulate at the bottom of the pit. The vinasse pit bottom water is complex in composition, containing starch, residual sugar, protein, organic acid, ethanol, and various microbial metabolites. Among them, the content of lactic acid is extremely high (up to 30-80 g / L), which is the core pollutant leading to low pH value (usually 3.0-3.8) and high chemical oxygen demand (COD) (up to 25,000-75,000 mg / mL) of the vinasse pit bottom water. In addition, the soluble protein and polypeptide not fully utilized in the vinasse pit bottom water also contribute considerable pollution load and result in high viscosity, making it difficult to treat. If the vinasse pit bottom water with high acidity and COD is directly discharged, it will cause serious pollution to the environment.

[0003] There are some attempts in the prior art to treat vinasse pit bottom water, but the related processing technologies need to be further improved. For example, although physical and chemical methods (such as alkali neutralization, coagulation sedimentation, membrane filtration, etc.) can reduce COD and acidity to some extent, they have problems such as high operating cost, introduction of new chemical impurities, generation of a large amount of sludge, and inability to be resourceized, and it is difficult to completely remove lactic acid and protein. On the other hand, biological treatment methods show better application prospects. The publication CN110317762A provides a strain of Pseudomonas for degrading polylactic acid, but its target application is environmental remediation of biodegradable plastics, which is fundamentally different from the application scenario and target of the complex and variable composition of Baijiu (liquor) vinasse pit bottom water system.

[0004] The more relevant prior art is to use microorganisms to degrade lactic acid in vinasse pit bottom water. Some studies have screened so-called “lactic acid-reducing bacteria” to convert lactic acid into other organic acids (such as propionic acid and butyric acid) through microbial metabolism. However, these methods have obvious limitations: (1) single function: these strains usually only focus on the degradation of lactic acid and have no effect on protein substances in the vinasse pit bottom water, which also constitute a high pollution load, and the treatment is not complete; (2) low value of products: if the proportion of metabolically produced propionic acid and butyric acid is not appropriate, it may produce unpleasant odors (such as sweat acid smell and cheese smell), which have limited flavor value and even pose a risk.

[0005] The patent with authorized publication number “CN113186116B” discloses a non-decarboxylation Lactobacillus sp. NJ22 using lactic acid as carbon source and its application. The strain can produce lactic acid and glycerol through fermentation using lactic acid produced in the late stage of Baijiu (liquor) fermentation, which can reduce the content of lactic acid in Baijiu (liquor) and improve the quality of Baijiu (liquor). The lactic acid has the effect of adjusting and blending various aromas of the liquor, and the glycerol produced by fermentation of the strain can improve the softness and thickness of the liquor; but the content of treating the pit bottom water of the distiller's grains is not involved.

[0006] The inventors have made in-depth research on the non-decarboxylation Lactobacillus NJ22, so as to design a green biological treatment process based on the non-decarboxylation Lactobacillus NJ22, which can simultaneously and deeply degrade lactic acid and protein in the pit bottom water of distiller's grains, fundamentally reduce the pollution load, and directionally produce high-value flavor substances (such as acetic acid and amino acid) in the treatment process, so as to realize high-value resource utilization of the pit bottom water of distiller's grains. SUMMARY

[0007] The present application aims to provide a treatment method of the pit bottom water of distiller's grains with sauce-flavor liquor, which can simultaneously and deeply degrade lactic acid and protein in the pit bottom water of distiller's grains.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a treatment method of the pit bottom water of distiller's grains with sauce-flavor liquor, comprising the following steps: Step one, filtering the pit bottom water of distiller's grains through an 80-100 mesh sieve to remove large particle residues; Step two, culturing the non-decarboxylation Lactobacillus NJ22 and forming a bacterial suspension, the OD 600 of the bacterial suspension being 1.8-2.2; Step three, putting the bacterial suspension into the filtered pit bottom water of distiller's grains for fermentation, the volume ratio of the bacterial suspension to the pit bottom water of distiller's grains being 8-10:100; the fermentation process includes two stages, the first stage being carried out at a fermentation temperature of 25-35℃, NaOH solution being added into the pit bottom water of distiller's grains to maintain the pH of the pit bottom water of distiller's grains at 7±0.1, the air input amount being 1-1.5vvm, and the pit bottom water of distiller's grains being stirred throughout the process at a stirring speed of 200-300rpm; when the OD 600 of the non-decarboxylation Lactobacillus NJ22 in the pit bottom water of distiller's grains is 2.2-3, the first stage of fermentation ends and the second stage starts, which is an anaerobic fermentation and lasts for 50-60h, and the second stage is carried out at a fermentation temperature of 25-35℃, and the pit bottom water of distiller's grains is stirred throughout the process at a stirring speed of 50-100rpm; Step four, after the fermentation ends, the material liquid is heated to 80-90℃ and maintained for 10-20min to inactivate the bacterial cells and enzyme activity; the centrifuge is used to centrifuge at 5000-7000rpm for 10-20min to separate the bacterial sludge and the treated pit bottom water of distiller's grains.

[0009] The beneficial effects of the present scheme: the present scheme filters and pretreats the pit bottom water of distiller's grains, removes large-particle residues, provides a clean reaction matrix for subsequent biological fermentation, and reduces impurities that interfere with bacterial growth and metabolic efficiency. By inoculating and cultivating high-activity non-decarboxylation Lekti NJ22 and adding it at a ratio of 8-10:100, sufficient functional bacteria are ensured to start the degradation process. The first stage of aerobic fermentation (25-35°C, pH=7±0.1, 1-1.5vvm aeration, 200-300rpm stirring) provides optimal conditions for bacterial proliferation, allowing the biomass to rapidly reach an OD 600 =2.2-3 high density, which is the basis for efficient degradation; the second stage of anaerobic fermentation (50-60h, 25-35°C, 50-100rpm stirring) ingeniously guides the metabolic pathway of non-decarboxylation Lekti NJ22 under anaerobic conditions, synchronously degrading the carbon source (lactic acid) and nitrogen source (protein) and directing the conversion to high-value acetic acid and glycerol, which fundamentally and significantly reduces the COD and acidity of the pit bottom water of distiller's grains, while generating flavor substances that enhance the soft and sweet taste and mellow taste of the liquor, achieving waste-to-resource. Finally, through heating inactivation and centrifugal separation, the termination of the fermentation process and the effective removal of the bacteria are ensured, obtaining a treatment liquid rich in flavor substances and a bacterial slurry that can be further utilized, avoiding secondary pollution and ensuring product safety and subsequent application convenience.

[0010] Preferably, as an improvement, when preparing the bacterial suspension, the non-decarboxylation Lekti NJ22 strain is inoculated into the modified Lu-Ye liquid medium, cultured at a temperature of 25-35°C on a 150-200 rpm shaker for 48-72h; the bacteria are collected by centrifugation at 7500-8500 rpm for 4-6 min, the supernatant is removed, the bacteria are washed with sterile water, and the bacteria are suspended in sterile water to prepare a bacterial suspension with an OD 600 =1.8-2.2. Using the modified Lu-Ye liquid medium to culture non-decarboxylation Lekti NJ22 can specifically optimize the nutritional environment for bacterial growth, significantly improving the proliferation rate and activity of the bacteria; culturing at 25-35°C on a 150-200 rpm shaker can further promote uniform growth and biomass accumulation of the bacteria through sufficient oxygen supply and liquid disturbance; washing the bacteria with sterile water after centrifugal collection can effectively remove impurities (such as unmetabolized carbon sources, inorganic salts, etc.) remaining in the culture medium, avoiding the interference of impurities with subsequent fermentation; finally, suspending the bacteria in sterile water to prepare a bacterial suspension with an OD600=1.8-2.2 can ensure stable bacterial concentration and sufficient activity, while reducing external pollution, providing a basis for high-purity, high-activity functional bacteria for efficient degradation in the fermentation stage of pit bottom water of distiller's grains.

[0011] Preferably, as an improvement, before the suspension is put into the filtered distiller's grains pit liquid, bean cake powder is added to the filtered distiller's grains pit liquid, and the ratio of the bean cake powder to the distiller's grains pit liquid is 3-5 g:1000 ml. The bean cake powder is rich in protein, and its addition can strongly induce the non-decarboxylation Lactobacillus NJ22 to synthesize and secrete extracellular protease, thereby significantly activating and enhancing the ability of the strain to degrade the native protein pollutants in the distiller's grains pit liquid, solving the bottleneck problem that the prior art can only reduce milk but cannot remove nitrogen. Secondly, the bean cake powder has complex components, and contains vitamins, growth factors and trace elements in addition to protein, which can effectively make up for the imbalance of the nutritional components of the distiller's grains pit liquid, provide comprehensive nutritional support for the rapid aerobic proliferation of the strain in the first stage, accelerate the accumulation of biomass, and shorten the fermentation period. Thirdly, the nitrogen in the bean cake powder mainly exists in the form of organic macromolecules, forcing the strain to decompose by producing enzymes to be used, which ingeniously guides the metabolic pathway of the bacterial cells, enables them to continuously and efficiently express protease, and ensures the continuous progress of the protein degradation process. The addition ratio of 3-5 g:1000 ml is the best economic balance point of the induction and nutritional effect, and a lower ratio will not show a significant effect, and a higher ratio may cause resource waste and increase the subsequent solid-liquid separation load.

[0012] Preferably, as an improvement, the concentration of the NaOH solution is 0.8-1 mol / L. The flow addition of the NaOH solution at this concentration is easy to fine control, can realize smooth adjustment of the pH, avoids the risk of local over-alkalization and impact on the activity of the bacterial cells caused by too high a concentration, and also avoids the problems of too high flow addition frequency, complicated operation and introduction of too much water to dilute the reaction system caused by using too low a concentration of the alkali. Moreover, this concentration can effectively neutralize the acetic acid produced by the bacterial cells metabolizing lactic acid, timely maintain the pH of the fermentation system in the optimal range of 7.0±0.1, create and stabilize the best environment for the growth of the bacterial cells and the expression of enzyme activity, and is an important technical guarantee for ensuring the efficient progress of the first stage of aerobic fermentation.

[0013] Preferably, as an improvement, the fermentation process of the distiller's grains pit liquid is carried out using a fermentation tank, and N2 or CO2 is introduced to replace the air at the top of the fermentation tank during the second stage of anaerobic fermentation. The physical replacement and driving away of the air in the headspace of the fermentation tank by introducing N2 or CO2 can quickly and thoroughly establish a strict anaerobic environment. DETAILED DESCRIPTION

[0014] The following will be further described in detail through specific embodiments: The distiller's grains pit liquid is taken from a local Maotai-flavor liquor factory in Maotai Town, and the distiller's grains pit liquid in Examples 1-3 is of the same batch.

[0015] Example 1 A method for treating distiller's grains pit liquid of Maotai-flavor liquor, comprising the following steps: Step one, the distiller's grains pit bottom water is filtered through a 100 mesh screen to remove large particle residues, and the pH, viscosity, lactic acid, total protein / polypeptide, COD, acetic acid, glycerol, amino acid nitrogen, and total ester content of the distiller's grains pit bottom water are detected.

[0016] Step two, the non-decarboxylation Lekti bacteria NJ22 is cultured and a bacterial suspension is formed, and when the bacterial suspension is prepared, the non-decarboxylation Lekti bacteria NJ22 strain is inoculated in a modified Lu-Ye liquid medium (lactic acid 1 g / L; (NH4)2SO4 2 g / L; Na2HPO4·12H2O 14.3 g / L; KH2PO4 3 g / L; MnSO4·H2O 0.28 mg / L; FeSO4·7H2O 0.3 mg / L; MgSO4·7H2O 0.06 mg / L; CaCl2 1 mg / L; CuSO4 0.05 mg / L; H3BO3 0.05 mg / L) and cultured at a temperature of 30°C on a 180 rpm shaker for 60 h; the bacterial cells are collected by centrifugation at 8000 rpm for 5 min, the supernatant is removed, the bacterial cells are washed with sterile water, and the bacterial cells are suspended in sterile water to form a bacterial suspension with an OD 600 =1.9~2.0. The non-decarboxylation Lekti bacteria NJ22 strain was deposited with the China Industrial Microbial Culture Collection Center (CICC) in Beijing, China on November 30, 2020, and the deposit number is CICC25025.

[0017] Step three, the distiller's grains pit bottom water is pumped into the fermentation tank, and then the bacterial suspension is added to the filtered distiller's grains pit bottom water for fermentation, and the volume ratio of the bacterial suspension to the distiller's grains pit bottom water is 1:10; the fermentation process includes two stages, the first stage is carried out at a fermentation temperature of 30°C, 1 mol / L NaOH solution is added to the distiller's grains pit bottom water to maintain the pH of the distiller's grains pit bottom water at 7±0.1, the air input amount is 1.2vvm, and the distiller's grains pit bottom water is stirred throughout the process at a stirring speed of 250 rpm; when the OD 600 =2.2~2.5 of the non-decarboxylation Lekti bacteria NJ22 in the distiller's grains pit bottom water, the first stage of fermentation ends and enters the second stage, CO2 is introduced to replace the air at the top of the fermentation tank, the second stage is anaerobic fermentation and lasts for 60 h, and the second stage is carried out at a fermentation temperature of 30°C, and the distiller's grains pit bottom water is stirred throughout the process at a stirring speed of 80 rpm. Step four, after the fermentation is completed, the liquid is heated to 85°C and maintained for 15 min to inactivate the bacterial cells and enzyme activity; the bacterial cells and the treated distiller's grains pit bottom water are separated by centrifugation at 6000 rpm for 15 min.

[0018] Example 2 differs from Example 1 only in step three. Step three of Example 3 is as follows: The bottom water of the fermentation pit is pumped into the fermentation tank, and then the suspended bacterial solution is added to the filtered bottom water for fermentation. The volume ratio of the suspended bacterial solution to the bottom water is 1:10. The fermentation process includes two stages. The fermentation temperature in the first stage is 30℃. A 1mol / L NaOH solution is added to the bottom water to maintain the pH of the bottom water at 7±0.1. The air flow rate is 1.2vvm. The bottom water is stirred throughout the process at a stirring speed of 250rpm. When the OD of the non-decarboxylated Lactobacillus NJ22 in the bottom water reaches a certain value... 600 When the temperature reaches 2.2~2.5, the first stage of fermentation ends and the second stage begins. The second stage is also aerobic fermentation and lasts for 60 hours. The fermentation temperature in the second stage is 30℃, the air flow rate is 1.2vvm, and the water at the bottom of the fermentation pit is stirred throughout the process at a stirring speed of 250rpm.

[0019] The only difference between Example 3 and Example 1 is that: before adding the suspension liquid, soybean cake powder is added to the filtered bottom water of the distillery lees, and the ratio of soybean cake powder to bottom water of the distillery lees is 1g:200ml.

[0020] Samples of the fermentation pit water treated in Examples 1-3 were taken and tested. The test items included pH, viscosity, lactic acid, protein, COD, acetic acid, amino acid nitrogen, and total ester content. The comparison data of the fermentation pit water before and after treatment are shown in the table below:

[0021] As shown in the table above, Example 1 achieved the goal of simultaneous and deep degradation of lactic acid and protein, significantly reducing COD and viscosity, and producing high-value acetic acid and amino acids, demonstrating excellent overall treatment results. Example 2, with its entirely aerobic fermentation, resulted in incomplete degradation of lactic acid and protein, low yield of the target product, and a relatively poor treatment effect compared to Example 1, indicating that a fully aerobic environment cannot effectively guide NJ22 to perform the target fermentation metabolism. Example 3, by adding soybean meal, outperformed Example 1 in almost all indicators, especially in protein degradation, viscosity reduction, and amino acid generation.

[0022] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for treating the bottom water of fermentation pits for soy sauce-flavored baijiu, characterized in that: Includes the following steps: Step 1: Filter the water at the bottom of the fermentation pit through an 80-100 mesh sieve to remove large particles of residue; Step 2: Cultivate non-decarboxylated Leucobacterium NJ22 and form a bacterial suspension. The OD of the bacterial suspension... 600 =1.8~2.2; Step 3: Add the bacterial suspension to the filtered fermentation water at the bottom of the fermentation pit for fermentation. The volume ratio of the bacterial suspension to the fermentation water is 8-10:

100. The fermentation process includes two stages. In the first stage, the fermentation temperature is 25-35℃. NaOH solution is added to the fermentation water to maintain the pH at 7±0.

1. The air flow rate is 1-1.5 vvm. The fermentation water is stirred throughout the process at a speed of 200-300 rpm. When the OD of the non-decarboxylated bacteria NJ22 in the fermentation water reaches a certain level... 600 When the temperature reaches 2.2~3, the first stage of fermentation ends and the second stage begins. The second stage is anaerobic fermentation and lasts for 50~60 hours. The fermentation temperature in the second stage is 25~35℃. Throughout the process, the water at the bottom of the fermentation pit is stirred at a speed of 50~100 rpm. Step 4: After fermentation, heat the liquid to 80-90℃ and maintain for 10-20 minutes to inactivate the bacteria and enzymes; centrifuge at 5000-7000 rpm for 10-20 minutes to separate the bacterial sludge and the treated lees bottom water.

2. The method for treating the bottom water of the fermentation pit for soy sauce-flavored baijiu according to claim 1, characterized in that: In preparing the bacterial suspension, non-decarboxylated Leucobacterium NJ22 strain was inoculated into modified Lu-Ye liquid medium and cultured at 25–35°C on a shaker at 150–200 rpm for 48–72 h. The bacterial cells were collected by centrifugation at 7500–8500 rpm for 4–6 min, the supernatant was discarded, the bacterial cells were washed with sterile water, and then the bacterial cells were resuspended in sterile water to prepare OD. 600 =1.8~2.2 bacterial suspension.

3. The method for treating the bottom water of a fermentation pit for soy sauce-flavored baijiu according to claim 2, characterized in that: Before adding the suspension solution, add soybean cake powder to the filtered water at the bottom of the fermentation pit. The ratio of soybean cake powder to water at the bottom of the fermentation pit is 3-5g:1000ml.

4. The method for treating the bottom water of a fermentation pit for soy sauce-flavored liquor according to claim 3, characterized in that: The concentration of the NaOH solution is 0.8–1 mol / L.

5. The method for treating the bottom water of a fermentation pit for soy sauce-flavored baijiu according to claim 4, characterized in that: The fermentation process of the water at the bottom of the fermentation pit is carried out in a fermentation tank. During the second stage of anaerobic fermentation, N2 or CO2 is introduced to replace the air at the top of the fermentation tank.

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