Method for producing biogas by using fruit juice waste liquid

Abstract

The invention discloses a method for producing biogas by utilizing fruit juice waste liquid, and belongs to the technical field of fruit juice waste liquid treatment. The fruit juice waste liquid is subjected to solid-liquid separation to obtain liquid; the liquid enters hydrolytic acidification equipment and is subjected to hydrolytic acidification under an anoxic condition to generate volatile fatty acid; and conveying the volatile fatty acid into anaerobic equipment, carrying out anaerobic fermentation under the action of methanogens to obtain biogas, and collecting the biogas. The fruit juice waste liquid contains rich organic matters and sugar, if the fruit juice waste liquid is treated as wastewater, not only is resource waste caused, but also environmental burden is increased, the characteristic that the fruit juice waste liquid is rich in organic matters and sugar is utilized, and the fruit juice waste liquid is subjected to hydrolytic acidification and anaerobic fermentation treatment to prepare and produce biogas, so that the effect of waste utilization is realized; the utilization rate of the juice waste liquid is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fruit juice waste liquid treatment, and in particular to a method for generating biogas by utilizing fruit juice waste liquid. Background Art

[0002] In the existing juice production process, juice waste liquid is usually directly treated as wastewater. Although this treatment method solves the problem of waste liquid discharge to a certain extent, it has some significant defects and shortcomings: 1) Juice waste liquid contains a large amount of organic matter and sugar. The treatment of these waste liquids requires investment in sewage treatment equipment and operating costs; the chemical agents and energy consumption in the sewage treatment process further increase the treatment cost; 2) Direct discharge or treatment of organic matter, sugars and other nutrients in juice waste liquid leads to waste of resources. If these organic substances are not effectively utilized, it will not only waste resources, but also may cause pollution to the environment; 3) The by-products (such as sludge) that may be generated during sewage treatment also need to be further treated, which increases the environmental burden. The traditional sewage treatment method has low treatment efficiency for juice wastewater, unstable treatment effect, and it is difficult to meet the expected emission standards. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for generating biogas by utilizing fruit juice waste liquid, so as to solve the technical problem that the fruit juice waste liquid is easily wasted in resources and increases the environmental burden when treated as wastewater.

[0004] To achieve the above object, the present invention provides a method for generating biogas from fruit juice waste liquid, comprising the following steps:

[0005] Performing solid-liquid separation on the fruit juice waste liquid to obtain liquid;

[0006] The liquid enters the hydrolysis and acidification equipment and is hydrolyzed and acidified under anoxic conditions to produce volatile fatty acids;

[0007] The volatile fatty acids are transported to an anaerobic device and anaerobically fermented under the action of methanogens to obtain biogas;

[0008] The biogas is collected.

[0009] In some embodiments of the present invention, in the hydrolysis and acidification step, Bacillus is added to the hydrolysis and acidification equipment; and / or yeast and acetic acid bacteria are added to the hydrolysis and acidification equipment.

[0010] In some embodiments of the present invention, Bacillus is added to the hydrolysis and acidification equipment, and the added amount of the Bacillus is 0.2% to 1% of the total mass of the liquid.

[0011] In some embodiments of the present invention, yeast and acetic acid bacteria are added to the hydrolysis acidification equipment, the inoculation amount of the yeast is 0.2% to 1% of the total mass of the liquid, and the inoculation amount of the acetic acid bacteria is 0.2% to 1% of the total mass of the liquid.

[0012] In some embodiments of the present invention, the temperature of the hydrolysis and acidification is 35°C to 40°C.

[0013] In some embodiments of the present invention, the pH of the hydrolysis and acidification is controlled at 6.0-6.5.

[0014] In some embodiments of the present invention, the hydrolysis and acidification time is 3 to 7 days.

[0015] In some embodiments of the present invention, the temperature of the anaerobic fermentation is 37° C. to 40° C.; and / or the pH of the anaerobic fermentation is controlled at 7.0 to 7.5; and / or the time of the anaerobic fermentation is 30 to 40 days.

[0016] In some embodiments of the present invention, the biogas is collected into a high-pressure gas storage tank by a compressor, and the pressure of the compressor is 0.7MPa to 0.8MPa.

[0017] In some embodiments of the present invention, before the solid-liquid separation of the juice waste liquid, a pre-treatment is further performed, and the pre-treatment comprises the following steps:

[0018] Removing impurities: crushing and homogenizing the waste juice to obtain the waste juice with impurities removed;

[0019] Wet heat cooking: the waste liquid of the juice after removing impurities is subjected to cooking treatment.

[0020] The beneficial effects that can be achieved by the present invention are:

[0021] Juice waste liquid contains rich organic matter and sugar. If it is treated as wastewater, it will not only cause waste of resources but also increase the environmental burden. The present invention utilizes the characteristics of juice waste liquid that is rich in organic matter and sugar, and hydrolyzes and acidifies it, and performs anaerobic fermentation treatment to prepare and produce biogas, thereby achieving the effect of waste utilization and improving the utilization rate of juice waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1The present invention is a schematic diagram of a preparation process for producing biogas using fruit juice waste liquid according to an embodiment of the present invention.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] The present invention provides a method for producing biogas from fruit juice wastewater, referring to Figure 1 , including the following steps:

[0029] S20, performing solid-liquid separation on the fruit juice waste liquid to obtain a liquid;

[0030] S30, the liquid enters the hydrolysis and acidification equipment, and is hydrolyzed and acidified under anoxic conditions to produce volatile fatty acids;

[0031] S40, transporting the volatile fatty acids to an anaerobic device, and performing anaerobically fermentation under the action of methanogens to obtain biogas;

[0032] S50, collecting the biogas.

[0033] In the present invention, the fruit juice waste liquid includes waste materials generated in the production process of fruit juice beverages, and the production raw materials include fruits and / or vegetables. For example, in the production process of fruit juice beverages, the solid part remaining after filtration, as well as the waste water generated in the production process, and the waste fruit peels, vegetable residues, etc. generated by the pre-treatment of fruits and vegetables. The above waste materials usually contain a large amount of sugar and organic matter. If they are treated as ordinary wastewater, it will cause waste and also cause pollution burden to the environment. The present invention makes full use of the sugar and organic components in the fruit juice waste liquid, produces volatile fatty acids through hydrolysis and acidification, and then uses methanogens to convert volatile fatty acids into biogas, thereby achieving higher economic benefits. The entire technical solution has important economic and environmental value.

[0034] In addition to liquid, the fruit juice waste liquid also contains some solid matter, and the efficiency of preparing biogas through hydrolysis, acidification and anaerobic fermentation of solid matter is relatively low. Therefore, the present invention performs solid-liquid separation on the fruit juice waste liquid in step S20, and the separated solid matter is used for composting, which can improve the overall utilization rate of the fruit juice waste liquid.

[0035] In some embodiments, the waste juice is transported to the solid-liquid separation device through a pipeline, and the flow rate of the waste juice is set to ensure continuous and stable input of the waste juice.

[0036] In some embodiments, centrifugal separation technology can be used to separate solids and liquids in the waste liquid, and the separated liquid can be transported to the hydrolysis acidification equipment through a pipeline.

[0037] Step S30 hydrolyzes and acidifies the liquid obtained by separating the juice waste liquid. During this process, the microbial community can decompose the complex organic matter in the juice waste liquid and convert it into soluble organic matter such as fatty acids, sugars, amino acids, etc. The above is the hydrolysis process, and in the acidification stage, the soluble organic matter will be converted into volatile fatty acids (VFAs) by acidification bacteria. Volatile fatty acids include at least one of acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid. The above volatile fatty acids are precursor substances for the subsequent gas production stage and play an important role in the process of biogas production.

[0038] In some embodiments, in the hydrolysis and acidification step, Bacillus is added to the hydrolysis and acidification equipment; and / or, yeast and acetic acid bacteria are added to the hydrolysis and acidification equipment.

[0039] The addition of Bacillus can improve the decomposition of protein, starch and cellulose in the liquid, and easily convert them into more volatile fatty acids in the subsequent acidification process, thereby increasing the yield of biogas.

[0040] In some embodiments, the concentration of the added Bacillus is greater than or equal to 10 5 CFU / mL.

[0041] In some embodiments, Bacillus is added to the hydrolysis and acidification device, and the amount of Bacillus added is 0.2% to 1% of the total mass of the liquid.

[0042] The addition of yeast can increase the production of ethanol, while the addition of acetic acid bacteria can promote the conversion of ethanol into volatile fatty acid acetic acid, thereby increasing the production of biogas.

[0043] In some embodiments, acetic acid bacteria is added 48 hours after yeast is added. Saccharomyces cerevisiae can continuously produce ethanol 48 hours after yeast is added. At this time, adding acetic acid bacteria is beneficial to improving the efficiency and effect of acetic acid bacteria in converting ethanol into volatile fatty acid acetic acid.

[0044] In some embodiments, the concentration of the added yeast is greater than or equal to 10 5 CFU / mL.

[0045] In some embodiments, the concentration of the added acetic acid bacteria is greater than or equal to 10 5 CFU / mL.

[0046] In some embodiments, yeast is added to the hydrolysis and acidification equipment, the inoculation amount of the yeast is 0.2% to 1% of the total mass of the liquid, and the inoculation amount of the acetic acid bacteria is 0.2% to 1% of the total mass of the liquid.

[0047] In some embodiments, the temperature of hydrolysis acidification is 35°C to 40°C. Under this temperature condition, the efficiency of acidification can be improved, the acidification time can be shortened, the activity of microorganisms can be maintained, the growth and reproduction of acid-producing bacteria can be enhanced, the production of volatile fatty acids can be promoted, and the production of methane in the subsequent stage can be facilitated.

[0048] In some embodiments, the pH of the hydrolysis and acidification is controlled at 6.0 to 6.5. The above pH is the suitable pH for hydrolysis and acidification microorganisms. The microorganisms are highly active and can efficiently decompose complex organic matter into simple organic acids.

[0049] In some embodiments, the hydrolysis and acidification time is 3 to 7 days, which can increase the production of volatile fatty acids.

[0050] In step S40, volatile fatty acids are anaerobically fermented under the action of methanogens to obtain biogas.

[0051] In some embodiments, the methanogens include acetic acid bacteria and methanogens, the methanogens primarily convert acetic acid and carbon dioxide into methane and water, and the acetic acid bacteria convert other volatile fatty acids into acetic acid and part of methane.

[0052] In some embodiments, the temperature of anaerobic fermentation is 37° C. to 40° C., which is a temperature range in which methanogens are more active and can promote gas production.

[0053] In some embodiments, the pH of the anaerobic fermentation is controlled at 7.0-7.5, which is beneficial to promoting the progress of anaerobic fermentation and increasing the yield of biogas.

[0054] In some embodiments, the anaerobic fermentation time is 30 to 40 days, which can promote the complete conversion of volatile fatty acids and increase the yield of biogas.

[0055] In the present invention, the main component of the generated biogas is methane, and the secondary component is carbon dioxide.

[0056] In some embodiments, the biogas may be piped to a periodic collection system for collection and storage.

[0057] In some embodiments, the biogas can be collected and transported to a high-pressure gas storage tank by a compressor, and the pressure of the compressor is 0.7 MPa to 0.8 MPa.

[0058] In some embodiments, before the solid-liquid separation of the juice waste liquid, a pre-treatment step S10 is further included, and the pre-treatment includes the following steps:

[0059] S11, removing impurities: crushing and homogenizing the waste juice to obtain waste juice with impurities removed;

[0060] S13, wet heat cooking: the waste liquid of the juice after the impurities are removed is cooked.

[0061] In step S11, the pulp and other solid impurities in the juice waste liquid are mainly broken into fine particles to increase the surface area, so that the juice waste liquid is more easily utilized by microorganisms in the subsequent hydrolysis and fermentation process, producing more volatile fatty acids, thereby increasing the yield of biogas.

[0062] In some embodiments, the method of removing impurities includes mechanical crushing and high-pressure homogenization crushing.

[0063] In step S13, wet heat cooking can increase the release of fermentable substances in the fruit juice waste liquid, destroy the cell walls of various components in the fruit juice waste liquid, and release more soluble sugars and other fermentable components. In addition, during the thermal treatment process of wet heat cooking, competitive microorganisms can be reduced and the activity of target microorganisms can be increased.

[0064] In some embodiments, the temperature of moist heat cooking is 70°C to 80°C.

[0065] In some embodiments, the pre-treatment of step S10 further includes a discharge and sand removal treatment of step S12. The discharge and sand removal treatment mainly removes sand particles and sediments with low utilization rate in the fruit juice waste liquid to ensure the smooth progress of subsequent hydrolysis, acidification and anaerobic fermentation.

[0066] In some embodiments, after completing the impurity removal in step S11, the discharge and sand removal treatment in step S12 is performed. This is because after the impurities in the juice waste liquid are broken, the solid part with high utilization rate can be crushed and dissolved in the liquid, releasing a large amount of available fermentable substances. The discharge and sand removal treatment is then performed, which can reduce the waste of the available part, greatly improve the utilization rate of the juice waste liquid, and increase the yield of biogas.

[0067] The biogas stored in the present invention can be used as clean energy, for example, for power generation or as fuel. The liquid discharged from the anaerobic tank is transported to a liquid fertilizer processing device through a pipeline, and the device includes a mixing tank, a regulating tank, and a filtering device. The liquid passes through the filtering device to remove suspended matter and impurities, and obtains liquid fertilizer that meets the standards.

[0068] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0069] Example 1

[0070] The steps of the method for generating biogas from fruit juice wastewater in this embodiment are as follows:

[0071] S20, the waste liquid generated in the juice production process is transported to the solid-liquid separation device through a pipeline, and the flow rate of the waste liquid is set to ensure continuous and stable waste liquid input. In the solid-liquid separation device, the solid and liquid in the waste liquid are separated by centrifugal separation technology to obtain liquid and solid parts. The solid part (mainly pomace) is collected and transported to a composting site for composting treatment, and the separated liquid (liquid phase of the juice waste liquid) is transported to a hydrolysis acidification tank through a pipeline.

[0072] S30, the liquid enters the hydrolysis acidification tank, and the liquid is subjected to the action of microbial hydrolysis bacteria and acidification bacteria under anoxic conditions, decomposing the complex organic matter into simple organic acids, namely volatile fatty acids (VFA). The temperature of the hydrolysis acidification tank is maintained at 35°C, and the pH value is controlled between 6.0-6.5 to optimize the activity of microorganisms and the generation of VFA. The residence time of the liquid in the hydrolysis acidification tank is 3 to 7 days to ensure that the organic matter is fully converted into VFA.

[0073] S40. The generated volatile fatty acids are transported to the anaerobic tank through a pipeline. In the anaerobic tank, VFA is converted into biogas by the action of methanogens. The temperature of the anaerobic tank is maintained at 37-40°C and the pH value is controlled between 7.0-7.5 to optimize the activity of methanogens. The residence time of the liquid in the anaerobic tank is 30 days to ensure that VFA is fully converted into biogas. The main components of the generated biogas are methane (about 60%) and carbon dioxide (about 40%).

[0074] S50, biogas is transported to the biogas collection system through pipelines for collection and storage, with a daily biogas output of about 500 cubic meters. The collected biogas is compressed to 0.8MPa by a compressor and then stored in a high-pressure gas storage tank.

[0075] Example 2

[0076] Example 2 Referring to the production method of Example 1, biogas is produced by using fruit juice waste liquid, but the difference is that before step S20, the pre-treatment of step S10 is also performed, including the following steps:

[0077] S11, removing impurities: crushing and homogenizing the waste juice to obtain waste juice with impurities removed;

[0078] S12, discharge and sand removal: the waste juice after impurities are removed is subjected to discharge and sand removal treatment to remove sand particles and sediments with low utilization rate in the waste juice to ensure the smooth progress of subsequent hydrolysis, acidification and anaerobic fermentation;

[0079] S13, wet heat cooking: the fruit juice waste liquid after the impurities are broken and the sand is removed is cooked at a temperature of 70°C to 80°C.

[0080] Example 3

[0081] Example 3 refers to the production method of Example 1 to produce biogas using fruit juice waste liquid, but the difference is that in step S30 of Example 3, 1% of the total mass of the liquid is added to the liquid at a concentration of 10 5 CFU / mL of Bacillus.

[0082] Example 4

[0083] Example 4 refers to the production method of Example 3 to produce biogas using fruit juice waste liquid, but the difference is that in step S30 of Example 4, 1% of the total mass of the liquid is added to the liquid at a concentration of 10 5 CFU / mL of yeast, and 1% of the total mass of the liquid added 48 hours after the addition of yeast. 5 CFU / mL of acetic acid bacteria.

[0084] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for generating biogas from fruit juice waste liquid, characterized in that: The following steps are involved: Performing solid-liquid separation on the fruit juice waste liquid to obtain liquid; The liquid enters the hydrolysis and acidification equipment and is hydrolyzed and acidified under anoxic conditions to produce volatile fatty acids; The volatile fatty acids are transported to an anaerobic device and anaerobically fermented under the action of methanogens to obtain biogas; The biogas is collected.

2. The method for producing biogas from fruit juice waste liquid according to claim 1, characterized in that: In the hydrolysis and acidification step, Bacillus is added to the hydrolysis and acidification equipment; and / or yeast and acetic acid bacteria are added to the hydrolysis and acidification equipment.

3. The method for producing biogas from fruit juice waste liquid according to claim 2, characterized in that: Bacillus is added to the hydrolysis and acidification equipment, and the addition amount of the Bacillus is 0.2% to 1% of the total mass of the liquid.

4. The method for generating biogas from fruit juice waste liquid according to claim 2, characterized in that: Yeast and acetic acid bacteria are added to the hydrolysis and acidification equipment, wherein the inoculation amount of the yeast is 0.2% to 1% of the total mass of the liquid, and the inoculation amount of the acetic acid bacteria is 0.2% to 1% of the total mass of the liquid.

5. The method for generating biogas from fruit juice waste liquid according to claim 1, characterized in that: The temperature of the hydrolysis and acidification is 35°C to 40°C.

6. The method for generating biogas from fruit juice waste liquid according to claim 1, characterized in that: The pH of the hydrolysis and acidification is controlled at 6.0-6.

5.

7. The method for generating biogas from fruit juice waste liquid according to claim 1, characterized in that: The time of the hydrolysis and acidification is 3 to 7 days.

8. The method for generating biogas from fruit juice waste liquid according to claim 1, characterized in that: The temperature of the anaerobic fermentation is 37° C. to 40° C.; and / or the pH of the anaerobic fermentation is controlled at 7.0 to 7.5; and / or the time of the anaerobic fermentation is 30 to 40 days.

9. The method for generating biogas from fruit juice waste liquid according to claim 1, characterized in that: The biogas is collected into a high-pressure gas storage tank by a compressor, and the pressure of the compressor is 0.7MPa to 0.8MPa.

10. The method for generating biogas from fruit juice wastewater according to any one of claims 1 to 9, characterized in that: Before the solid-liquid separation of the juice waste liquid, a pre-treatment is also included, and the pre-treatment includes the following steps: Removing impurities: crushing and homogenizing the waste juice to obtain the waste juice with impurities removed; Wet heat cooking: the waste liquid of the juice after removing impurities is subjected to cooking treatment.

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