Organic waste acidification fermentation and grease preparation method and fermentation system thereof

Abstract

The invention provides an organic waste acidification fermentation and grease preparation method and a fermentation system thereof. The system comprises an acidification fermentation system, a filter membrane device and an oil-producing microbial fermentation system which are connected in sequence, the acidification fermentation system is used for placing fermentation raw materials and inoculation bacteria liquid and is provided with a solid-liquid separation screen; the filter membrane device is used for removing impurity components in the volatile organic acid mixed solution; the oleaginous microbial fermentation system is used for placing volatile organic acid mixed liquor and oleaginous microbial cells. According to the acidification fermentation and grease preparation method and system, effective conversion from multi-element organic waste to microbial grease is achieved, and the technical cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the field of organic waste treatment and microbial grease preparation, and in particular to an organic waste acidification fermentation and grease preparation method and a fermentation system thereof. Background Art

[0002] As a typical clean energy liquid fuel, biodiesel has many advantages in physical and chemical properties, including good lubricity, low sulfide emissions, low particulate matter emissions, low greenhouse gas emissions, good combustion performance, and superior transportation and storage safety. However, the key bottleneck problem that restricts the rapid development of my country's biodiesel industry is the lack of raw oils and fats for the production of biodiesel. Although waste oils and fats can be used as raw oils and fats for the production of biodiesel, this raw oil and fat is not only very limited in volume, but also contains impurities (such as aldehydes and ketones) that seriously affect the quality of biodiesel and cannot effectively support the industrial production of biodiesel. Therefore, vigorously developing the production technology of biodiesel raw oils and fats is the key to solving the problems of the biodiesel industry. Microbial oils, also known as single-cell oils and fats, are mainly oils and fats accumulated in the body by oil-producing microorganisms such as oil-producing yeasts, oil-producing bacteria, oil-producing microalgae, oil-producing filamentous fungi and oil-producing thrombostomycorrhizal bacteria using carbohydrates, hydrocarbons, etc. as substrates under specific conditions (such as nitrogen deficiency). Since the fatty acid composition of this microbial oil is very similar to that of vegetable oil, developing microbial oil and using it as a substitute for vegetable oil in the production of biodiesel is a promising technical path.

[0003] At the same time, urban and rural organic waste generated every year is complex and diverse, including food waste, livestock and poultry manure, agricultural straw, industrial organic wastewater, waste activated sludge, slaughterhouse waste, etc. If not properly handled, the large amount of organic components contained in these organic wastes will release a large amount of harmful substances and greenhouse gases into the air, water and soil, posing a serious threat to public health and the ecological environment.

[0004] Therefore, the problem of treating the large amount of organic waste generated every year needs to be solved urgently. How to organically combine the production of microbial oils with the treatment of organic waste is the key to solving the above two problems at the same time. Preliminary research by the research team shows that oil-producing microorganisms can use volatile organic acids produced from acidification and fermentation of organic waste to accumulate oils in microorganisms under certain conditions (such as high carbon-nitrogen ratio). In microbial oil biorefining, various organic waste raw materials are first degraded into volatile fatty acids, and volatile fatty acids are further converted into microbial oils by oil-producing microorganisms. Compared with the method of using glucose as the raw material for oil-producing microbial fermentation to produce microbial oils, the use of volatile organic acids from organic waste sources has significant advantages in reducing the production cost of microbial oils, and can also effectively realize the high-value utilization of various organic wastes. The production of biodiesel from microbial oils is a relatively new research field that has flourished in the past decade. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a fermentation system and preparation method for producing oil by acidification fermentation of organic waste, which realizes the effective conversion of multi-organic waste into microbial oil and greatly reduces the technical cost.

[0006] To achieve the above-mentioned purpose, the present invention provides a fermentation system for acidification fermentation of organic waste and preparation of oil, which comprises an acidification fermentation system, a filtration membrane device and an oil-producing microbial fermentation system connected in sequence;

[0007] The acidification fermentation system is used to place fermentation raw materials and inoculated bacterial liquid, and is provided with a solid-liquid separation screen;

[0008] The filter membrane device is used to remove impurities in the volatile organic acid mixture;

[0009] The oil-producing microbial fermentation system is used for placing the volatile organic acid mixed solution and the oil-producing microbial cells.

[0010] In the present invention, the acidification fermentation system can generally be an acidification fermentation tank.

[0011] In the present invention, the fermentation raw material refers to organic waste, such as chicken manure, kitchen waste or straw.

[0012] In the present invention, the inoculated bacterial solution may be inoculated sludge.

[0013] In the present invention, the oil-producing microbial cell may be an oil-producing yeast cell.

[0014] In the present invention, the acidification fermentation system is generally provided with a raw material feed port. A power pump is generally provided between the acidification fermentation system and the filter membrane device, and the power pump is connected to the filter membrane device through a conduit.

[0015] In the present invention, the acidification fermentation system and the oil-producing microbial fermentation system are generally provided with stirring motors respectively.

[0016] The present invention also provides an organic waste acidification fermentation and oil preparation method, which adopts the above-mentioned fermentation system, comprising: firstly mixing the pretreated fermentation raw material with the inoculated bacterial liquid for acidification to obtain a volatile organic acid mixed liquid;

[0017] The volatile organic acid mixed solution and the oil-producing microbial cells are then fermented until the carbon-nitrogen ratio is 80-100 to obtain microbial oil.

[0018] In the present invention, the pretreatment may be conventional operations such as crushing and homogenization.

[0019] In the present invention, the acidification temperature is preferably 30° C. to 60° C. In the present invention, during the acidification, the ratio of the fermentation raw material to the inoculated bacterial solution is preferably controlled so that the organic load rate of the acidification fermentation system is 20 to 30 gVS / L.

[0020] In the present invention, the acidified pH value is preferably pH=5-7.

[0021] In the present invention, the acidification time may be conventional in the art, preferably 8 to 14 days.

[0022] In the present invention, the impurities in the volatile organic acid mixture need to be removed before fermentation.

[0023] In the present invention, the fermentation time is preferably 3 to 7 days.

[0024] In the present invention, glucose is preferably added during the fermentation process to rapidly increase the carbon-nitrogen ratio.

[0025] In the present invention, preferably, after the carbon-nitrogen ratio reaches 80-100, the volatile organic acid mixed solution and the oil-producing microbial cells are cultured for 1-2 days.

[0026] In the present invention, generally, the preparation method further comprises a post-processing step of the microbial oil.

[0027] Technical Effects

[0028] The prior art often uses organic waste (such as kitchen waste) directly as the nutrients required for the fermentation of oil-producing microorganisms to provide protein or carbohydrate substances, but the effect is not ideal. The reason for this phenomenon is that the ingredients of kitchen waste from different sources are very different, and it is difficult to ensure the consistency of the nutrients, which seriously affects the cell growth and oil accumulation process of the oil-producing microorganisms. In addition, various organic wastes also contain components that have an inhibitory effect on oil-producing microorganisms, and certain pretreatments are required to be efficiently used as nutrient raw materials for oil-producing microbial fermentation. In this regard, the present invention proposes a device for preparing oils and fats by coupling acidification fermentation of organic waste with oil-producing microbial fermentation and its use. The method can first convert various organic wastes into volatile organic acids through acidification fermentation, and then extract the volatile organic acids from the acidification fermentation mixture for the fermentation growth of oil-producing microorganisms and oil accumulation.

[0029] The present invention achieves a more consistent composition of raw materials for oil-producing microbial fermentation by converting multiple organic wastes into a unified platform compound, volatile organic acid molecules, during the acidification stage, which is conducive to the precise control and standardized operation of the fermentation process. By extracting volatile organic matter after the oil-producing microbial fermentation, the interference of other impurities in the acidification fermentation mixture on the subsequent oil-producing microbial fermentation process is eliminated, and the raw material conversion rate of organic waste to oil is effectively improved. In the oil-producing microbial fermentation process, multiple oil-producing microorganisms are used to synergistically ferment and convert volatile organic acids, and the synergistic utilization of different volatile organic acid molecules is achieved, thereby improving the comprehensive utilization rate of organic waste and the total oil yield. In summary, in response to the urgent technical needs for the high-value utilization of existing multi-organic wastes and the development of microbial oils and fats, the present invention proposes a device for producing oils and fats by coupling acidification and fermentation of organic wastes with oil-producing microbial fermentation and its use, which can achieve "killing two birds with one stone" and can not only realize the effective utilization of organic components in multi-organic wastes, but also realize the effective accumulation of microbial oils and fats by coupling oil-producing microbial fermentation, thereby obtaining raw oils and fats that can be used as clean energy biodiesel. The whole process is green and environmentally friendly, easy to realize modularization and standardization, easy to realize industrial amplification and intelligent control, and has broad application prospects in the fields of organic waste treatment and biomass new energy development.

[0030] Finally, the following technical effects are achieved:

[0031] 1. The present invention uses volatile organic acids made from cheap organic waste as the carbon source for oil-producing microbial fermentation, avoiding the use of glucose as the carbon source, thereby achieving the effect of greatly reducing the cost of microbial oil technology.

[0032] 2. The present invention realizes the effective conversion of multi-organic waste into microbial oil by adopting the "acidification fermentation coupled oil-producing microbial fermentation system", thus avoiding the emission of a large amount of greenhouse gases due to natural degradation of a large amount of organic waste.

[0033] 3. The acidification fermentation coupled oil-producing microbial fermentation system proposed in the present invention opens up the full-chain technical route for converting organic waste into microbial oils and fats, and integrates a new route for microbial oil production based on the "volatile fatty acid" platform compound.

[0034] 4. The technical method of "acidification and fermentation of organic waste coupled with oil-producing microbial fermentation to produce oils and fats" proposed in the present invention expands the range of biomass raw materials that can be used for microbial oil production from single lignocellulosic biomass to all organic wastes, which will help promote the resource treatment of organic waste and the industrialization of oil-producing microbial oil technology, and has direct guiding significance for the actual development of microbial oil production technology and engineering project construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the device for producing oils and fats by coupling acidification fermentation of organic waste with fermentation of oil-producing microorganisms.

[0036] Explanation of the reference numerals: 1-raw material feed port; 2-acidification fermentation system; 3-fermentation raw material; 4-solid-liquid separation screen; 5-volatile organic acid liquid; 6-valve one; 7-stirring motor one; 8-inoculated bacterial liquid; 9-power pump; 10-conduit; 11-filtration membrane device; 12-valve two; 13-stirring motor two; 14-oil-producing microbial fermentation system; 15-oil-producing microbial cells; 16-microbial oil. DETAILED DESCRIPTION

[0037] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0038] Now combined with the attached Figure 1 And embodiments describe the present invention in detail:

[0039] Example 1: Device and method for preparing oil by acidification and fermentation of kitchen waste coupled with oleaginous yeast Lipomyces starkeyi

[0040] (1) Figure 1As shown, a system suitable for producing oils and fats by coupling acidification fermentation of organic waste with oil-producing yeast Lipomyces tarkeyi fermentation, includes a raw material feed inlet 1, an acidification fermentation system 2 (an acidification fermentation tank in the present embodiment), a fermentation raw material (organic waste in the present embodiment) 3, a solid-liquid separation screen 4, a volatile organic acid liquid 5, a valve 1 6, a stirring motor 1 7, an inoculated bacterial liquid (inoculated sludge in the present embodiment) 8, a power pump 9, a conduit 10, a filter membrane device 11, a valve 2 12, a stirring motor 2 13, an oil-producing microbial fermentation system 14, oil-producing microbial cells (oil-producing yeast in the present embodiment) 15, and microbial oils and fats 16.

[0041] (2) Preparation of acid fermentation test raw materials: Food waste was collected from the student cafeteria of the Minhang Campus of Shanghai Jiao Tong University as the test raw materials for acid fermentation. The food waste was homogenized using a pulverizer at 9,000 rpm for 5 min to obtain uniform food waste raw materials, which were then placed in a -20°C refrigerator for later use.

[0042] (3) Conducting an acidification fermentation test to prepare volatile organic acids: The temperature of the acidification fermentation tank was set to 35°C, and the pretreated food waste and inoculated sludge were inoculated into the fermentation tank in a certain proportion so that the organic load rate of the fermentation tank reached 22 gVS / L. The initial fermentation pH value was adjusted to pH = 7 using HCl or NaOH, the stirring rate was set to 150 rpm, and the acidification fermentation time was controlled to 8 days. An acidification fermentation test was conducted to prepare volatile organic acids.

[0043] (4) Removal of impurities in volatile fatty acids: A solid-liquid separation screen is used to separate volatile organic acids from the fermentation product to obtain a fermentation liquid rich in volatile organic acids with a relatively lower solid content. The fermentation liquid rich in volatile organic acids is passed through a filter membrane device 11 through the control of a valve 6 and the action of a power pump 9 to remove impurities in the volatile organic acid mixture. Then, the volatile organic acids are added to the oil-producing microbial fermentation tank as a carbon source for oil-producing yeast fermentation through the control of a valve 12.

[0044] (5) Fermentation of oleaginous yeast Lipomyces starkeyi to produce lipids: The volatile organic acid liquid obtained in the above step is added to a fermentation tank for oleaginous yeast Lipomyces starkeyi, and the oleaginous yeast Lipomyces starkeyi strain stored in a solid plate culture medium is inoculated into a 250 mL culture bottle containing 50 mL YPD culture solution. After culturing at 30° C. and 180 rpm for 72 h, the obtained bacterial solution is used as the inoculation bacterial solution of oleaginous yeast Lipomyces starkeyi, and the inoculated bacterial solution is inoculated into an oleaginous microbial fermentation system 14 to carry out oleaginous microbial fermentation for 5 days, and then a certain amount of glucose is added to the oleaginous microbial fermentation system to rapidly increase the carbon-nitrogen ratio of the culture solution to 80-100, and then the culture is further carried out for 1 day to accumulate microbial lipids.

[0045] (6) Collection of oil-producing microbial cells and microbial oil extraction: The fermentation liquid accumulated in the oil-producing microbial fermentation system is pumped out of the fermentation tank by a power pump, and the oil-producing microbial cells 15 are collected and pumped into a cell wall breaking pretreatment unit. After the oil-producing microbial cells are broken, microbial oil extraction is performed to obtain microbial oil 16, and the oil yield is 0.433 g / (Lh);

[0046] (7) The above steps (1) to (6) are a complete operation process for preparing microbial oil based on acidification and fermentation of food waste coupled with fermentation of oil-producing yeast Lipomyces starkeyi; the entire system can maintain long-term continuous operation of the system through continuous discharging and feeding, thereby realizing the treatment of multiple organic wastes and microbial oil production based on the continuous operation of the acidification and fermentation coupled with oil-producing microbial fermentation system.

[0047] Example 2: Device and method for preparing fats by acidification and fermentation of chicken manure coupled with oleaginous yeast Lipomyces starkeyi fermentation

[0048] (1) Same as Example 1.

[0049] (2) Preparation of raw materials for acid fermentation test: Chicken manure was collected from a chicken farm in Jinshan District, Shanghai as the raw material for acid fermentation test. The chicken manure was homogenized using a grinder at 9,000 rpm for 5 min to obtain a uniform raw material of chicken manure, which was then placed in a -20°C refrigerator for later use.

[0050] (3) Conducting an acidification fermentation test to prepare volatile organic acids: The temperature of the acidification fermentation tank was set to 35°C, and the pretreated chicken manure and inoculated sludge were inoculated into the fermentation tank in a certain proportion so that the organic load rate of the fermentation tank reached 22 gVS / L. The initial fermentation pH value was adjusted to pH = 7 using HCl or NaOH, the stirring rate was set to 180 rpm, and the acidification fermentation time was controlled to 10 days. An acidification fermentation test was conducted to prepare volatile organic acids.

[0051] (4) Removal of impurities in volatile fatty acids: A solid-liquid separation screen is used to separate volatile organic acids from the fermentation product to obtain a fermentation liquid rich in volatile organic acids with a relatively lower solid content. The fermentation liquid rich in volatile organic acids is passed through a filter membrane device 11 through the control of a valve 6 and the action of a power pump 9 to remove impurities in the volatile organic acid mixture. Then, the volatile organic acids are added to the oil-producing microbial fermentation tank as a carbon source for oil-producing yeast fermentation through the control of a valve 12.

[0052] (5) Fermentation of oleaginous yeast Lipomyces starkeyi to produce lipids: The volatile organic acid liquid obtained in the above step is added to a fermentation tank for oleaginous yeast Lipomyces starkeyi, and the oleaginous yeast Lipomyces starkeyi strain stored in a solid plate culture medium is inoculated into a 250 mL culture bottle containing 50 mL YPD culture solution. After culturing at 30° C. and 180 rpm for 72 h, the obtained bacterial solution is used as the inoculation bacterial solution of oleaginous yeast Lipomyces starkeyi, and the inoculated bacterial solution is inoculated into an oleaginous microbial fermentation system 14 to carry out oleaginous microbial fermentation for 5 days, and then a certain amount of glucose is added to the oleaginous microbial fermentation system to rapidly increase the carbon-nitrogen ratio of the culture solution to 80-100, and then the culture is further carried out for 1 day to accumulate microbial lipids.

[0053] (6) Collection of oil-producing microbial cells and extraction of microbial oil: The fermentation liquid accumulated in the oil-producing microbial fermentation system is pumped out of the fermentation tank by a power pump, and the oil-producing microbial cells 15 are collected and pumped into a cell wall breaking pretreatment unit. After the oil-producing microbial cells are broken, microbial oil is extracted to obtain microbial oil 16, and the oil yield is 0.279 g / (Lh);

[0054] (7) The above steps (1) to (6) are a complete operation process for preparing microbial oil based on chicken manure acidification fermentation coupled with oil-producing yeast Lipomyces tarkeyi fermentation; the entire system can maintain long-term continuous operation of the system through continuous discharging and feeding, thereby realizing the continuous operation of multiple organic waste treatment and microbial oil production based on the acidification fermentation coupled with oil-producing microbial fermentation system.

[0055] Example 3: Device and method for producing fats by coupling straw acidification fermentation with oleaginous yeast Lipomyces starkeyi fermentation

[0056] (1) Same as Example 1.

[0057] (2) Preparation of acid fermentation test raw materials: Straw was collected from a farm in Qingpu District, Shanghai as the test raw material for acid fermentation. The straw was homogenized using a pulverizer at 10,000 rpm for 8 min to obtain a uniform straw raw material, which was then placed in a -20°C refrigerator for later use.

[0058] (3) Conducting acidification fermentation experiments to prepare volatile organic acids: The temperature of the acidification fermentation tank was set to 55°C, and the pretreated straw and inoculated sludge were inoculated into the fermentation tank in a certain proportion so that the organic load rate of the fermentation tank reached 22 gVS / L. The initial fermentation pH value was adjusted to pH = 7 using HCl or NaOH, the stirring rate was set to 200 rpm, and the acidification fermentation time was controlled to 14 days. An acidification fermentation experiment was conducted to prepare volatile organic acids.

[0059] (4) Removal of impurities in volatile fatty acids: A solid-liquid separation screen is used to separate volatile organic acids from the fermentation product to obtain a fermentation liquid rich in volatile organic acids with a relatively lower solid content. The fermentation liquid rich in volatile organic acids is passed through a filter membrane device 11 through the control of a valve 6 and the action of a power pump 9 to remove impurities in the volatile organic acid mixture. Then, the volatile organic acids are added to the oil-producing microbial fermentation tank as a carbon source for oil-producing yeast fermentation through the control of a valve 12.

[0060] (5) Fermentation of oleaginous yeast Lipomyces starkeyi to produce lipids: The volatile organic acid liquid obtained in the above step is added to a fermentation tank for oleaginous yeast Lipomyces starkeyi, and the oleaginous yeast Lipomyces starkeyi strain stored in a solid plate culture medium is inoculated into a 250 mL culture bottle containing 50 mL YPD culture solution. After culturing at 30° C. and 180 rpm for 72 h, the obtained bacterial solution is used as the inoculation bacterial solution of oleaginous yeast Lipomyces starkeyi, and the inoculated bacterial solution is inoculated into an oleaginous microbial fermentation system 14 to carry out oleaginous microbial fermentation for 5 days, and then a certain amount of glucose is added to the oleaginous microbial fermentation system to rapidly increase the carbon-nitrogen ratio of the culture solution to 80-100, and then the culture is further carried out for 1 day to accumulate microbial lipids.

[0061] (6) Collection of oil-producing microbial cells and microbial oil extraction: The fermentation liquid accumulated in the oil-producing microbial fermentation system is pumped out of the fermentation tank by a power pump, and the oil-producing microbial cells 15 are collected and pumped into a cell wall breaking pretreatment unit. After the oil-producing microbial cells are broken, microbial oil extraction is performed to obtain microbial oil 16, and the oil yield is 0.302 g / (Lh);

[0062] (7) The above steps (1) to (6) are a complete operation process for preparing microbial oil based on straw acidification fermentation coupled with oil-producing yeast Lipomyces tarkeyi fermentation; the entire system can maintain long-term continuous operation of the system through continuous discharging and feeding, thereby realizing the continuous operation of multiple organic waste treatment and microbial oil production based on the acidification fermentation coupled with oil-producing microbial fermentation system.

[0063] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0064] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A fermentation system for acidification fermentation of organic waste and preparation of oil, characterized in that: It includes an acidification fermentation system, a filtration membrane device and an oil-producing microbial fermentation system which are connected in sequence; The acidification fermentation system is used to place fermentation raw materials and inoculated bacterial liquid, and is provided with a solid-liquid separation screen; The filter membrane device is used to remove impurities in the volatile organic acid mixture; The oil-producing microbial fermentation system is used for placing the volatile organic acid mixed solution and the oil-producing microbial cells.

2. The fermentation system for acidification fermentation of organic waste and preparation of oil and fat according to claim 1, characterized in that: A power pump is provided between the acidification fermentation system and the filtering membrane device, and the power pump is connected to the filtering membrane device through a conduit.

3. A method for acidification and fermentation of organic waste and preparation of oil, characterized in that: The method is carried out using the fermentation system as claimed in claim 1 or 2, comprising: firstly mixing the pretreated fermentation raw material with the inoculated bacterial solution and acidifying the mixture to obtain a volatile organic acid mixture; The volatile organic acid mixed solution and the oil-producing microbial cells are then fermented until the carbon-nitrogen ratio is 80-100 to obtain microbial oil.

4. The preparation method according to claim 3, characterized in that: The acidification temperature is 30°C to 60°C.

5. The preparation method according to claim 3, characterized in that: During the acidification, the ratio of the fermentation raw material to the inoculated bacterial solution is controlled so that the organic load rate of the acidification fermentation system is 20-30 gVS / L.

6. The preparation method according to claim 3, characterized in that: The acidified pH value is pH=5-7.

7. The preparation method according to claim 3, characterized in that: The acidification time is 8 to 14 days.

8. The preparation method according to claim 3, characterized in that: The fermentation time is 3 to 7 days.

9. The preparation method according to claim 3, characterized in that: During the fermentation, glucose is added.

10. The preparation method according to claim 3, characterized in that: After the carbon-nitrogen ratio reaches 80-100, the volatile organic acid mixed solution and the oil-producing microbial cells are cultured for 1-2 days.

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