Method for promoting grease in-situ degradation and methane production in anaerobic fermentation system

Abstract

The invention discloses a method for promoting grease in-situ degradation and methane production in an anaerobic fermentation system through functional microorganism inoculation, and relates to the field of microorganism anaerobic ferment.The method comprises the steps that a biological enhancement microbial agent is prepared, and the biological enhancement microbial agent is bacterial liquid of bacillus safensis; and the methane production efficiency of anaerobic fermentation is improved when the catalyst is added into an anaerobic fermentation device. According to the method, bacillus safensis is inoculated into an anaerobic fermentation reactor, and natural grease degrading enzymes (such as lipase, phospholipase and the like) of the bacillus safensis are used for in-situ degradation of grease. According to the method, grease in the kitchen waste can be effectively degraded in an anaerobic environment, and the grease is prevented from wrapping and inhibiting microorganisms, so that the activity of the microorganisms is improved, and stable operation of an anaerobic fermentation system is guaranteed; meanwhile, the yield of methane in the anaerobic fermentation process can be increased, and energy conversion is promoted.

Description

Technical Field

[0001] The present invention relates to the field of microbial anaerobic fermentation, and particularly to a method for promoting in-situ degradation of oil and methane production in an anaerobic fermentation system by inoculating functional microorganisms. Background Art

[0002] In the technical process of anaerobic fermentation of biomass waste to produce methane, the presence of oil inhibits the anaerobic fermentation of food waste to produce methane. Food waste has a high oil content. After mechanical oil removal, a large amount of oil still enters the anaerobic fermentation system. Local oil accumulation wraps microorganisms, which easily causes the collapse of the anaerobic fermentation system. Therefore, it is very necessary to study methods for promoting the fermentation degradation of oil in the fermentation system. At present, the research on the anaerobic fermentation treatment of waste oil in food waste mainly includes the influence of waste oil concentration on anaerobic fermentation, co-fermentation, and biological and chemical pretreatment methods. Biological methods for treating oil have obvious effects, but the treatment time is long and the economic cost is high. Therefore, many researchers use methods such as ozone, hydrothermal treatment, and sodium percarbonate to degrade oil or its inhibitors. These pretreatment methods improve the methane production rate, but the input energy cost is high. Adopting the biological enhancement strategy of Bacillus safensis is expected to degrade oil in-situ, promote methane production, and improve the energy conversion efficiency of food waste, providing technical support for the industrial treatment of food waste. Industrially, the current pretreatment process for removing oil from food waste will increase costs and reduce technical economy. If functional microorganisms for oil can be used to degrade oil in-situ, it will not only be beneficial to improving technical economy, but also increase the biogas production.

[0003] Therefore, those skilled in the art are committed to developing a method for enhancing in-situ degradation of oil and methane production in an anaerobic fermentation system based on Bacillus safensis. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to develop a method for enhancing in-situ degradation of oil and methane production in an anaerobic fermentation system based on Bacillus safensis.

[0005] To achieve the above object, the present invention provides a method for promoting in-situ degradation of oil and methane production in an anaerobic fermentation system, including the following steps:

[0006] Step 1, prepare a biological enhancement agent, and the biological enhancement agent is a bacterial solution of Bacillus safensis;

[0007] Step 2, add the biological enhancement agent obtained in Step 1 to an anaerobic fermentation device to improve the methane production efficiency of anaerobic fermentation.

[0008] Furthermore, step 1 also includes preparing a bioaugmented liquid medium, with the components being 10 g / L of peptone, 2 g / L of ammonium sulfate, 1 g / L of dipotassium hydrogen phosphate, 0.5 g / L of magnesium sulfate heptahydrate, 30 g / L of sodium chloride, 20 mL / L of oil, 1000 mL of distilled water, and adjusting the pH to 7.0 - 7.5.

[0009] Furthermore, the bacterial liquid of Bacillus safensis in step 1 is the bacterial liquid cultured for 96 h, and the culture conditions are: culturing in a shaking incubator, with the culture temperature being 28 - 35 °C and the stirring speed being 200 - 280 rpm.

[0010] Furthermore, the raw materials in the anaerobic fermentation device in step 2 are high - oil - content biomass raw materials and inoculated sludge.

[0011] Furthermore, the addition amount of the bioaugmented bacterial liquid additive in step 2 is maintained at 1% of the working volume.

[0012] Furthermore, the addition frequency of the bioaugmented bacterial liquid additive in step 5 is once every two days.

[0013] Furthermore, the anaerobic fermentation method in step 2 is a semi - continuous mode.

[0014] Furthermore, step 2 also includes dynamically monitoring methane concentration, biogas volume, pH, COD, and ammonia nitrogen.

[0015] Furthermore, the temperature of anaerobic fermentation in step 2 is 37 °C.

[0016] Furthermore, the volume of the anaerobic fermentation device in step 2 is 15 L.

[0017] Furthermore, chemical methods (such as ozone, hydrothermal method) can increase methane production rate, but the input energy cost is relatively high, and it is impossible to achieve the optimal balance in terms of technical economy; the existing technology mainly relies on mechanical separation. However, in various forms of oil presence, many oils are still not effectively removed, resulting in the incomplete solution of the inhibitory effect of the anaerobic fermentation system. Biodegradation is an excellent alternative technology to the existing technology. Compared with chemical degradation methods, Bacillus safensis as a biodegradant has higher selectivity and safety. Traditional chemical treatment may produce some toxic intermediate products or by - products, bringing secondary pollution problems. While Bacillus safensis degrades oil, the products generated are mainly biodegradable simple fatty acids and glycerol, and these products have no negative impact on the environment. Further, this process avoids the use of chemical reagents and reduces the potential harm to the environment.

[0018] Bacillus safensis reduces the inhibitory effect of grease on the anaerobic fermentation system by degrading grease. Grease is likely to coat microorganisms during the anaerobic fermentation process, affecting the activity of microorganisms and leading to the collapse of the reactor or low gas production efficiency. Compared with traditional degreasing methods, Bacillus safensis can directly degrade grease during the fermentation process, avoiding the problems of grease accumulation and microorganism coating, and ensuring the normal reproduction and metabolic activities of microorganisms. In this way, this method can improve the stability of the anaerobic fermentation process, reduce the risk of system collapse, and thus increase the methane production rate.

[0019] Traditional treatment methods, such as mechanical degreasing or chemical pretreatment, not only involve complex equipment and high operating costs, but also increase the total cost of waste treatment. The method of enhancing biodegradation by Bacillus safensis can degrade grease in situ in the reactor, without the need for additional equipment investment and chemical agents, thus significantly reducing the operating costs. At the same time, due to its high degradation ability, it can shorten the treatment time and improve the methane production efficiency, which all play a positive role in reducing the overall economic investment.

[0020] Furthermore, the reason why Bacillus safensis can effectively degrade grease is mainly that the grease-degrading enzymes (such as lipase, phospholipase, etc.) it carries can degrade different molecular structures of grease. The specific principle is as follows:

[0021] 1. Grease hydrolysis: The lipase contained in Bacillus safensis can hydrolyze fatty acid glycerides in food waste, decomposing them into free fatty acids and glycerol. This process can directly reduce the concentration of grease in the anaerobic environment and reduce the coating effect of grease on microorganisms.

[0022] 2. Degradation of emulsified oil: Bacillus safensis can also degrade emulsified oil through its unique emulsifying enzyme, making the emulsified oil further decomposed into small molecular substances that can be utilized by microorganisms. This process improves the biodegradability of grease and avoids the accumulation of grease in the reactor and the inhibition of microorganisms.

[0023] 3. Degradation of solid-phase grease: Bacillus safensis can also degrade solid-phase grease through its special biodegradation pathway. These greases are often embedded in other solid particles and are not easily removed by mechanical methods. Therefore, through the degradation of Bacillus safensis, this part of the difficult-to-separate grease can be further removed.

[0024] In the first preferred embodiment of the present invention, the technical method for preparing the bioaugmentation agent is described in detail;

[0025] In another preferred embodiment 2 of the present invention, the process of improving the methane production efficiency of anaerobic fermentation by adding a bioaugmentation agent additive is described in detail;

[0026] In another preferred embodiment 3 of the present invention, the process of improving the methane production efficiency of anaerobic fermentation by increasing the addition frequency of the bioaugmentation bacterial solution is described in detail;

[0027] In another preferred embodiment 4 of the present invention, the application process of improving the methane production efficiency of anaerobic fermentation by adding the bioaugmentation bacterial solution in an enlarged reactor is described in detail.

[0028] The beneficial technical effects of the present invention are as follows:

[0029] By inoculating Bacillus safensis into the anaerobic fermentation reactor, the in-situ degradation of oil and fat is carried out with its natural oil-degrading enzymes (such as lipase, phospholipase, etc.). This method can not only effectively degrade the oil and fat in food waste in an anaerobic environment, prevent the encapsulation and inhibition of microorganisms by oil and fat, thereby improving the activity of microorganisms and ensuring the stable operation of the anaerobic fermentation system; at the same time, it can also increase the methane production during anaerobic fermentation and promote energy conversion.

[0030] The bioaugmentation application technology of Bacillus safensis proposed by the present invention can solve the problems of low efficiency, high cost, environmental pollution, etc. existing in traditional oil and fat degradation methods (such as mechanical oil removal and chemical pretreatment). Bacillus safensis can process various forms of oil and fat in food waste (including emulsified oil, dissolved oil, solid-phase oil, etc.) through its efficient biodegradation function, and has obvious advantages compared with traditional technologies. This method not only does not require additional high-energy input, nor does it rely on chemical agents, reducing the operation complexity and environmental protection burden of the system, and can achieve efficient oil and fat degradation in a short time. In addition, the present invention can also effectively increase the methane production during anaerobic fermentation. The degradation of oil and fat provides more available substrates for methanogens, further promoting methane production and improving energy recovery efficiency. Compared with existing technologies (such as simple oil and fat removal or traditional chemical degradation), this method not only has significant advantages such as simple operation, low raw material cost, and no secondary pollution, but also can significantly increase methane production and optimize the energy conversion efficiency of food waste, and has good industrial application prospects. Specifically:

[0031] Improve the oil and fat degradation efficiency: The introduction of Bacillus safensis significantly improves the degradation speed and efficiency of oil and fat. Compared with traditional mechanical separation or chemical pretreatment methods, biodegradation can not only process various forms of oil and fat, but also complete the degradation process in a shorter time, reducing the processing time.

[0032] Improve the methane production rate: The degradation of oil and fat helps to improve the substrate availability during methane fermentation, thereby increasing the methane production rate. After the oil and fat are degraded, the remaining organic substances can better provide carbon sources for methanogens, further promoting methane production.

[0033] Reduce economic costs: By degrading oil and fat in-situ, not only the cost of external pretreatment is reduced, but also the use of chemical methods and high-energy-consuming treatment methods is avoided, thereby reducing the overall treatment cost and enhancing the technical economy.

[0034] Therefore, the method for promoting anaerobic fermentation of high-oil-content food waste by Bacillus safensis proposed by the present invention can not only improve the treatment effect, reduce costs, and reduce environmental impacts, but also provide an eco-friendly and efficient solution for industrial applications, with high technical advantages and economic value. Specifically:

[0035] 1. Technical advantages

[0036] The present invention utilizes the natural oil-degrading enzymes (such as lipase, phospholipase, etc.) of Bacillus safensis to achieve in-situ degradation of oil and fat in the anaerobic fermentation reactor, with the following advantages:

[0037] ① Efficiently degrade oil and fat: Utilizing the enzymatic action of the strain itself, it can effectively break the chemical bonds of oil and fat molecules in the anaerobic environment, thereby preventing the local accumulation of oil and fat in the reactor, eliminating the encapsulation effect on microorganisms, and enhancing the overall activity of the reaction system.

[0038] ② Reduce the energy consumption and cost of pretreatment: Compared with the traditional high-energy-consuming chemical methods such as ozone, hydrothermal, or sodium percarbonate for pretreatment, this solution adopts a bioaugmentation strategy, which not only reduces energy consumption but also decreases the process complexity and economic cost.

[0039] ③ Improve system stability: By degrading oil and fat in-situ, the oil and fat inhibition effect is avoided, ensuring the continuous and stable operation of the anaerobic fermentation system and effectively preventing the risk of system collapse caused by the accumulation of oil and fat.

[0040] 2. Performance indicators

[0041] In experiments and engineering applications, the technical solution of the present invention shows good performance indicators:

[0042] ① Increase methane production: Since the degradation of oil and fat no longer inhibits the microbial activity, the methane production rate in the anaerobic fermentation process has a significant increase, which can be increased by 21.1% compared with the traditional process.

[0043] ② Stability of the reaction system: In long-term operation, the reaction system inoculated with Bacillus safensis shows higher stability and anti-interference ability, making the entire fermentation process more controllable and reliable.

[0044] 3. Production implementation and industrial application

[0045] From the perspective of production implementation, the present invention has high potential for industrial promotion:

[0046] ① System compatibility: This solution can be directly implemented in existing anaerobic fermentation devices without large-scale modification of reactor equipment. By inoculating Bacillus safensis in the reactor, in-situ degradation of grease can be achieved online, with simple operation and optimized process flow.

[0047] ② Obvious economic benefits: It reduces the high energy consumption and additional equipment investment brought by traditional oil removal pretreatment, reduces the treatment cost, and further improves the energy conversion efficiency by increasing the methane production rate, providing higher economic benefits for industrial production.

[0048] ③ Environmentally friendly and green development: This technical solution not only achieves efficient conversion in energy utilization, but also meets the requirements of environmental protection, helps in the resource utilization of food waste and other high-oil waste, and promotes circular economy and sustainable development.

[0049] The following will further illustrate the concept, specific structure and technical effects of the present invention with reference to the accompanying drawings to fully understand the purpose, features and effects of the present invention. Description of the Drawings

[0050] Figure 1 is the growth curve of Bacillus safensis in a preferred Embodiment 1 of the present invention;

[0051] Figure 2 is the methane production graph of per unit mass sample in a preferred Embodiment 2 of the present invention;

[0052] Figure 3 is the cumulative methane production graph in a preferred Embodiment 2 of the present invention;

[0053] Figure 4 is the pH change graph in a preferred Embodiment 2 of the present invention;

[0054] Figure 5 is the ammonia nitrogen change graph in a preferred Embodiment 2 of the present invention;

[0055] Figure 6 is the COD change graph in a preferred Embodiment 2 of the present invention;

[0056] Figure 7 is the methane production graph of per unit mass sample in a preferred Embodiment 3 of the present invention;

[0057] Figure 8 is the pH change graph in a preferred Embodiment 3 of the present invention;

[0058] Figure 9 is the methane production graph in a preferred Embodiment 3 of the present invention;

[0059] Figure 10 is the ammonia nitrogen change graph in a preferred Embodiment 3 of the present invention;

[0060] Figure 11 It is the COD change diagram of a preferred Embodiment 3 of the present invention;

[0061] Figure 12 It is the methane production diagram per unit mass of sample of a preferred Embodiment 4 of the present invention;

[0062] Figure 13 It is the cumulative methane production diagram of a preferred Embodiment 4 of the present invention;

[0063] Figure 14 It is the pH change diagram of a preferred Embodiment 4 of the present invention;

[0064] Figure 15 It is the COD change diagram of a preferred Embodiment 4 of the present invention. Detailed implementation manners

[0065] The following introduces multiple preferred embodiments of the present invention with reference to the accompanying drawings of the specification to make its technical content 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.

[0066] Embodiment 1: A technical method for preparing a bioaugmentation bacterium agent

[0067] (1) Using 10 g / L of peptone, 2 g / L of ammonium sulfate, 1 g / L of dipotassium hydrogen phosphate, 0.5 g / L of magnesium sulfate heptahydrate, 30 g / L of sodium chloride, 20 mL / L of oil, and 1000 mL of distilled water, adjusting the pH to 7.0 - 7.5, prepare a bioaugmentation liquid medium; use it after autoclaving with a high-pressure steam sterilizer;

[0068] (2) Inoculation: In a clean bench, inoculate 2 mL of bacterial liquid into every 100 mL of the liquid medium prepared in the above (1) method. To avoid contamination by miscellaneous bacteria, the operation should be carried out beside the flame of an alcohol lamp;

[0069] (3) Cultivation: Use a shaking incubator for cultivation, with the cultivation temperature being 28 - 35 °C and the stirring speed being 200 - 280 rpm;

[0070] (4) Measure the growth curve: During the cultivation process, measure the OD 600 value every 1 h at the initial stage to obtain the growth curve of this bacterium as Figure 1 shown;

[0071] (5) According to its growth curve, select the bacterial liquid cultivated for 96 h (4 days, one growth cycle) as the bioaugmentation bacterium agent;

[0072] (6) Strain preservation: Mix the cultured strain with glycerol preservation solution in a ratio of 4:1 (volume ratio). Dispense the mixed strain solution into sterile cryotubes or cryovials. The capacity of each tube or vial is generally 1 - 2 mL to facilitate easy resuscitation after freezing. Place the dispensed strain solution in a -20°C refrigerator for preliminary freezing, or directly transfer it to an ultra-low temperature refrigerator at -80°C for storage. Through this low-temperature freezing, the long-term survival of the strain can be ensured.

[0073] Example 2: Improving the methane production efficiency of anaerobic fermentation by adding a bioaugmentation bacterial liquid additive

[0074] (1) Mix the high-oil biomass raw material to be treated (such as food waste) with inoculated sludge in a 1000 mL fermentation tank. The ratio of volatile solids of inoculated sludge to biomass raw material is approximately 0.71. Conduct a mesophilic (37°C) semi-continuous fermentation experiment to produce biogas. Among them, the volume of inoculated sludge is 760 mL, and the volume of the mixture of biomass raw material and water is 40 mL;

[0075] (2) Add the cultured bioaugmentation inoculated bacterial liquid to the microbial anaerobic fermentation tank as the experimental group; at the same time, use another microbial anaerobic fermentation tank without adding bioaugmentation inoculated bacterial liquid as the control group;

[0076] (3) For the fermentation tanks of the experimental group and the control group, respectively implement 0 (A0), 8 mL (equivalent to 1% working volume of bioaugmentation bacterial liquid, A1), 24 mL (equivalent to 3% working volume of bioaugmentation bacterial liquid, A2), 40 mL (equivalent to 5% working volume of bioaugmentation bacterial liquid, A3) of fermentation broth, and add it to the fermentation tank together with food waste. Stir the reactor twice a day regularly. Keep the hydraulic retention time at 20 days, that is, all digesters discharge and feed once every two days. First, discharge 40 mL of digestate from each digester. Then, feed the same volume (40 mL) of raw materials into each digester. And keep it in a constant temperature water bath at 37°C.

[0077] (4) Then conduct dynamic monitoring of methane concentration, biogas volume, pH, COD, and ammonia nitrogen. The purpose of this step is to confirm that after bioaugmentation, the methane production efficiency in the anaerobic fermentation system of food waste has been improved; the methane production per unit mass of the sample is as Figure 2 shown, and the cumulative methane production is as Figure 3 shown. The average methane production rate of the experimental group A1 is 21.1% higher than that of the control group A0. However, in the experimental groups A2 and A3, their average methane production rate decreases instead of increasing, indicating that maintaining the addition amount of the bioaugmentation bacterial liquid additive at 1% is a reasonable level; the pH change is as Figure 4As shown, for pH, the experimental group A1 was maintained between 6.7 and 7.7, which is a pH range with a relatively high methane production level and there was no acidification compared with the control group A0. However, different degrees of acidification occurred in A2 and A3 of the experimental group starting from the 26th day of fermentation, indicating that adding too much bioaugmentation agent in bioaugmentation has the risk of causing acidification of the anaerobic fermentation system. Maintaining the addition amount of the bioaugmentation liquid additive at 1% is an optimal level; and the change of ammonia nitrogen is as Figure 5 shown. For the ammonia nitrogen level, ammonia nitrogen inhibition is likely to occur during the anaerobic digestion process, leading to process instability. The inhibition of the anaerobic digestion system by ammonia nitrogen is mainly manifested as strongly inhibiting the activity of methanogens. Since free ammonia has free permeability through the cell membrane, it can enter the cell by passive diffusion, causing cytoplasmic acidification, proton imbalance and K + loss, etc.; the ammonia nitrogen level is roughly proportional to the addition amount of the bioaugmentation agent. Therefore, to maintain a relatively low ammonia nitrogen level and a concentration that promotes anaerobic fermentation, adding 1% of the bioaugmentation liquid additive is the optimal addition amount. The change of COD is as Figure 6 shown.

[0078] (5) According to the methane production law of bioaugmentation inoculation obtained in step (4), it is analyzed that the optimal addition amount applicable to the bioaugmentation of Bacillus safensis is 8 mL (equivalent to 1% of the working volume of the fermentation broth), and it is applied to the anaerobic fermentation experiment in semi-continuous mode;

[0079] Example 3: Improving the methane production efficiency of anaerobic fermentation by adding the frequency of bioaugmentation liquid

[0080] (1) Mix the high-oil biomass raw material to be treated (such as kitchen waste) with the inoculated sludge in a 1000 mL fermentation tank. The ratio of the volatile solids of the inoculated sludge to the biomass raw material is about 0.71, and carry out a mesophilic (37 °C) semi-continuous fermentation experiment to produce biogas. Among them, the volume of the inoculated sludge is 760 mL, and the volume of the mixture of the biomass raw material and water is 40 mL;

[0081] (2) Add the cultured bioaugmentation inoculation liquid to the microbial anaerobic fermentation tank as the experimental group; at the same time, use another microbial anaerobic fermentation tank without adding the bioaugmentation inoculation liquid as the control group;

[0082] (3) For the fermenters of the experimental group and the control group, 8 mL (equivalent to 1% of the working volume of the bioaugmentation bacterial solution) was added to the fermenters together with food waste every two days (A1-2d), every four days (A1-4d), and every six days (A1-6d). The reactor was stirred twice a day at a fixed time. The hydraulic retention time was maintained at 20 days, that is, all digesters were drained and fed every two days. First, 40 mL of digestate was drained from each digester. Then, an equal volume (40 mL) of raw material was fed into each digester. And it was kept in a constant temperature water bath at 37 °C.

[0083] (4) Then, the methane concentration, biogas volume, pH, COD, and ammonia nitrogen were dynamically monitored. The purpose of this step was to confirm that the methane production efficiency in the anaerobic fermentation system of food waste was improved after bioaugmentation, and to obtain the optimal addition frequency of the bioaugmentation bacterial solution; the methane production per unit mass of the sample was as Figure 7 shown, and the cumulative methane production was as Figure 8 shown. The average methane production rate of the experimental group A1-2d was 9.7% higher than that of the control group A0. In the experimental groups A1-4d and A1-6d, the average methane production rates were increased by 4.0% and 2.4% respectively, indicating that maintaining the addition frequency of the bioaugmentation bacterial solution additive at once every two days was an optimal level; the pH change was as Figure 9 shown. For pH, all experimental groups and the control group were maintained between 7.0 and 7.7, which was a pH range with a relatively high methane production level, indicating that at an addition amount of 1%, whether it was once every two days or once every four days and once every six days, there was no acidification (no acid inhibition), and the addition frequency of the bioaugmentation bacterial solution additive at once every two days (A1-2d) was slightly higher than that of the control group and the experimental groups A1-4d and A1-6d; the ammonia nitrogen change was as Figure 10 shown. For the ammonia nitrogen level, ammonia nitrogen inhibition was likely to occur during the anaerobic digestion process, leading to process instability. The inhibition of ammonia nitrogen on the anaerobic digestion system was mainly manifested as a strong inhibition of the activity of methanogens. Because free ammonia has free permeability through the cell membrane, it can enter the cell by passive diffusion, causing cytoplasmic acidification, proton imbalance, and K + loss, etc.; the ammonia nitrogen level was roughly proportional to the addition amount of the bioaugmentation bacterial agent. Therefore, to maintain a relatively low ammonia nitrogen level and a concentration that promotes anaerobic fermentation, the addition amount of the bioaugmentation bacterial solution additive added once every two days was the optimal addition frequency. The COD change was as Figure 11 shown.

[0084] (5) According to the methane production law of bioaugmentation inoculation obtained in step (4), it was analyzed that the optimal addition frequency applicable to the bioaugmentation of Bacillus safensis was once every two days, and it was applied to the anaerobic fermentation experiment in the semi-continuous mode;

[0085] Example 4: Application of improving methane production efficiency of anaerobic fermentation by adding bioaugmentation bacterial liquid in an enlarged reactor

[0086] (1) Mix the high-oil-content biomass raw material to be treated (such as food waste) with inoculated sludge in a 15-L fermentation tank. The ratio of volatile solids of inoculated sludge to biomass raw material is about 0.71. Conduct a mesophilic (37 °C) semi-continuous fermentation experiment to produce biogas. Among them, the volume of inoculated sludge is 760 mL, and the volume of the mixture of biomass raw material and water is 40 mL;

[0087] (2) Add the cultured bioaugmentation inoculation bacterial liquid into the microbial anaerobic fermentation tank as the experimental group; at the same time, use another microbial anaerobic fermentation tank without adding bioaugmentation inoculation bacterial liquid as the control group;

[0088] (3) For the fermentation tanks of the experimental group and the control group, add 8 mL (equivalent to 1% working volume of bioaugmentation bacterial liquid) into the fermentation tank together with food waste every 4 days (A1-4d), and keep the stirrer at 40 r / min all the time. Keep the hydraulic retention time at 20 days, that is, all digesters are discharged and fed every two days. First, discharge 200 mL of digested liquid from each digester. Then, feed the same volume (200 mL) of raw materials into each digester. And keep it in a constant temperature water bath at 37 °C.

[0089] (4) Then dynamically monitor the methane concentration, biogas volume, pH, and COD. The purpose of this step is to confirm that the methane production efficiency in the anaerobic fermentation system of food waste has been improved after bioaugmentation; at the same time, it also proves that the anaerobic fermentation system of food waste with bioaugmentation has a certain resistance stability to the acidification of the fermentation system. The methane production per unit mass of the sample is as Figure 12 shown, the cumulative methane production is as Figure 13 shown, the pH change is as Figure 14 shown, and the COD change is as Figure 15 shown.

[0090] (5) According to the methane production law of bioaugmentation inoculation obtained in step (4), analyze and obtain the applicable enlarged reactor for bioaugmentation of Bacillus safensis, and apply it to the anaerobic fermentation experiment in semi-continuous mode;

[0091] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and changes according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments should be within the protection scope determined by the claims.

Claims

1. A method for promoting in-situ degradation of oil and methane production in an anaerobic fermentation system, characterized in that: The method comprises the following steps: Step 1, preparing a bio-enhanced bacterial agent, wherein the bio-enhanced bacterial agent is a bacterial solution of Bacillus saffron; Step 2: adding the bio-enhancing agent obtained in step 1 to the anaerobic fermentation device to improve the methane production efficiency of anaerobic fermentation.

2. The method according to claim 1, characterized in that The step 1 also includes preparing a biofortified liquid culture medium, the components of which are 10 g / L peptone, 2 g / L ammonium sulfate, 1 g / L dipotassium hydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 30 g / L sodium chloride, 20 mL / L oil, and 1000 mL distilled water, and the pH is adjusted to 7.0-7.

5.

3. The method according to claim 1, characterized in that The bacterial solution of Bacillus sabdariffa in step 1 is a bacterial solution cultured for 96 hours, and the culture conditions are: culture on a shaking table, the culture temperature is 28-35° C., and the stirring speed is 200-280 rpm.

4. The method according to claim 1, characterized in that The raw materials in the anaerobic fermentation device in step 2 are high-oil biomass raw materials and inoculated sludge.

5. The method according to claim 1, characterized in that The amount of the bio-augmented bacterial liquid additive added in step 2 is maintained at 1% of the working volume.

6. The method according to claim 1, characterized in that The frequency of adding the bio-augmentation bacterial liquid additive in step 5 is once every two days.

7. The method according to claim 1, characterized in that The anaerobic fermentation method in step 2 is a semi-continuous mode.

8. The method according to claim 1, characterized in that The step 2 also includes dynamically monitoring methane concentration, biogas volume, pH, COD and ammonia nitrogen.

9. The method according to claim 1, characterized in that The temperature of the anaerobic fermentation in step 2 is 37°C.

10. The method according to claim 1, characterized in that The volume of the anaerobic fermentation device in step 2 is 15L.

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