Method for increasing anaerobic digestion capacity of waste and relieving acid inhibition by adopting nano bubble water

Abstract

The invention provides a method for increasing anaerobic digestion productivity of waste and relieving acid inhibition by adopting nano bubble water. The method comprises the following steps: preparing hydrogen-nano bubble water, preparing inoculation mud, mixing the hydrogen-nano bubble water, the inoculation mud and agricultural wastes, and carrying out anaerobic digestion treatment; according to the method, in the anaerobic digestion process, the hydrolysis rate can be increased, the hysteresis period can be shortened, the methane yield can be increased, ammonia / acid inhibition can be effectively relieved, the consumption speed of volatile fatty acid is increased by 35% or above, and trans-fatty acid inhibition can be effectively relieved. And an innovative solution thought is provided for relieving the inhibition phenomenon generally occurring in the AD process.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial treatment, and specifically relates to a method for increasing the anaerobic digestion productivity of waste and alleviating acid inhibition by using nano-bubble water. Background Art

[0002] A large amount of agricultural waste such as livestock and poultry manure and crop straw is generated every year in the world. Only in China, the annual output of agricultural waste exceeds 4.3 billion tons. If these agricultural wastes are not effectively treated, they will not only cause serious pollution to the surrounding environment but also waste biomass resources. At present, among various methods for treating waste, anaerobic digestion, as a waste treatment means with a long history, has become an effective method to cope with the dual challenges of environmental pollution and resource shortage. The anaerobic digestion treatment method has many advantages, such as producing clean energy, controlling malodorous smells, inactivating harmful pathogens, etc. Therefore, using this technology to treat agricultural waste has the dual effects of environmental protection and resource recycling. However, volatile fatty acids that easily appear during the anaerobic digestion process can cause ammonia / acid inhibition. The ammonia / acid inhibition problem not only reduces the treatment efficiency of agricultural waste, is not conducive to clean energy production, but also seriously hinders its application in the field of agricultural waste resource utilization. Therefore, the ammonia / acid inhibition problem is not conducive to the efficient treatment of agricultural waste during the anaerobic digestion process, and scientific and effective methods are needed to eliminate the inhibition, enhance the buffering capacity of the anaerobic digestion system, and improve the treatment efficiency of agricultural waste.

[0003] Research shows that there are currently many methods that can be used to alleviate the ammonia / acid inhibition generated during anaerobic digestion. For example, it can be eliminated by methods such as adding alkaline agents, adding trace elements, biochar, and jointly using biological enhancers and activated carbon. These traditional methods have a certain effect on alleviating ammonia / acid inhibition, but have defects such as secondary pollution of chemical drugs, energy consumption, high costs, and complex operations. The existence of these defects limits the wide application of anaerobic digestion in agricultural waste resource utilization. Therefore, in terms of eliminating ammonia / acid inhibition during the anaerobic digestion of agricultural waste and increasing the production of clean energy, there is an urgent need to discover new methods that can effectively eliminate ammonia / acid inhibition during the anaerobic digestion process, while having no secondary pollution, being easy to operate, and having low costs. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for increasing the anaerobic digestion productivity of waste and alleviating acid inhibition by using nano-bubble water. This method can improve the hydrolysis rate, shorten the lag period, increase the methane production, and effectively alleviate ammonia / acid inhibition during the anaerobic digestion process, and provides an innovative solution idea for alleviating the "inhibition phenomenon" commonly occurring in the AD process.

[0005] The present invention is realized through the following scheme

[0006] The present invention provides a method for increasing the anaerobic digestion productivity of waste and alleviating acid inhibition by using nano-bubble water, which method comprises preparing hydrogen-nano-bubble water, preparing inoculum sludge, and mixing the hydrogen-nano-bubble water, inoculum sludge and agricultural waste for anaerobic digestion treatment;

[0007] Wherein, during the anaerobic digestion, the inoculation ratio (mass-volume ratio) of the waste, inoculum sludge and hydrogen-nano-bubble water is 0.5-1.5 g: 0.5-1.5 g: 1.5-2.5 ml.

[0008] Furthermore, the preparation of the inoculum sludge comprises the following steps:

[0009] (1) Feeding digestion sludge and pig manure into a bottle according to an inoculation ratio of 0.5-1.5: 0.5-1.5, adjusting the initial pH value thereof to 7.00±0.05, and sealing;

[0010] (2) Using nitrogen to evacuate the sealed bottle in step (1);

[0011] (3) Placing the evacuated and sealed bottle in a constant temperature incubator and culturing until no gas is produced for 6 consecutive days, then the inoculum sludge can be collected and stored for standby at 4°C.

[0012] Furthermore, the anaerobic digestion treatment comprises the following steps:

[0013] (a) Feeding the waste and inoculum sludge into a reactor according to an inoculation ratio of 0.5-1.5: 0.5-1.5, and adjusting the initial pH value thereof to 7.00±0.05;

[0014] (b) Taking the hydrogen-nano-bubble water and adding it into the reactor in step (a), and sealing;

[0015] (c) Evacuating the sealed reactor in step (b), and after evacuation, placing it in a constant temperature incubator for constant temperature culture;

[0016] (d) Conducting anaerobic digestion under the constant temperature culture conditions in step (c). After the anaerobic digestion starts, every 24 hours, collecting the generated green energy such as methane, and detecting the changes of enzyme activity, volatile fatty acids (VFAs), methane, and organic acid content indexes every two days;

[0017] The organic acids include acetic acid, propionic acid, isobutyric acid, valeric acid, isovaleric acid, and n-butyric acid;

[0018] (e) After the anaerobic digestion stops producing gas for 6 consecutive days, it indicates that the anaerobic digestion process has stopped, and collecting the fermentation broth after anaerobic digestion.

[0019] Furthermore, the solution used for adjusting the initial pH value is a 2.0 M NaOH solution or a 2.0 M HCl solution.

[0020] Furthermore, the temperature of the constant-temperature culture is uniformly 37 ± 2°C.

[0021] Furthermore, the volume-mass ratio of the hydrogen-nanobubble water added in step (b) to the waste and inoculation mud in step (a) is 1.5 - 2.5 ml : 0.5 - 1.5 g : 0.5 - 1.5 g.

[0022] Application of the above method in treating waste.

[0023] Compared with the prior art, the present invention has the following positive and beneficial effects

[0024] During the anaerobic digestion process of the present invention, the consumption rate of volatile fatty acids is increased by more than 35%, effectively alleviating the inhibition of trans fatty acids; the final methane production is increased by more than 45%.

[0025] Under the action of hydrogen-nanobubble water in the present invention, the activities of hydrolase and coenzyme F420 are both increased by more than 25%, the speed of TA (total alkalinity) and PA (partial alkalinity) is increased by more than 25%, and the decline rates of IA / PA and VFA / TA (IA is intermediate alkalinity) exceed 30%. Description of the drawings

[0026] Figure 1 It shows the result diagram of detecting the anaerobic process under different conditions of the addition amount of nano water according to the steps of Example 1, Figure 1 (a) is the biogas production rate, Figure 1 (b) is the methane production rate;

[0027] Figure 2 It shows the concentration change diagram of volatile fatty acids (VFAs) as the digestion days increase, Figure 2 (a) is the change from 0 to 16 days, Figure 2 (b) is the change from 22 to 40 days; Detailed implementation manners

[0028] The present invention will be described in more detail below through specific implementation manners for the convenience of understanding the technical solution of the present invention, but it is not used to limit the protection scope of the present invention.

[0029] In the following examples, the reactor used is a Schott Duran serum bottle, the vacuum pumping equipment used is the commonly used vacuum pumping equipment in the prior art, and the equipment used for preparing nanobubble water is the equipment of Shandong Yuchuang Environmental Technology Co., Ltd.

[0030] The present invention provides a method for increasing the anaerobic digestion productivity of waste and alleviating acid inhibition by using nanobubble water, and the method includes:

[0031] S1. First, hydrogen nanobubble water was prepared. For the preparation of hydrogen nanobubble water, a dedicated nanobubble water preparation device in the prior art (Shandong Yuchuang Environmental Technology Co., Ltd.) was used. During the preparation process, hydrogen was used as the gas carrier.

[0032] S2. Then, inoculation sludge was prepared:

[0033] (1) Digestive sludge and waste were put into bottles at an inoculation ratio of 1:1.

[0034] (2) The initial pH value was adjusted to 7 ± 0.05 with sodium hydroxide solution or hydrochloric acid; then the bottles were sealed with rubber stoppers and bottle caps; afterwards, nitrogen was used to evacuate the air, and the evacuation time was 3 minutes.

[0035] (3) The bottles after evacuation in step (2) were placed in a constant temperature incubator at 37 ± 2 °C for constant temperature cultivation. During the cultivation process, the generated green energy methane was collected every 24 hours; when no gas was generated for 6 consecutive days, it indicated that the process had stopped, and then the domesticated inoculation sludge was collected, which was the inoculation sludge; the collected inoculation sludge was stored in a 4 °C refrigerator for later use.

[0036] S3. Anaerobic digestion process:

[0037] (1) Prepare bottles as the anaerobic digestion reactor.

[0038] (2) The waste and the inoculation sludge prepared in step S2 were put into the reactor at a ratio of 1:1; then its pH value was adjusted to 7 ± 0.05. After adjusting the pH value, hydrogen-nanobubble water was introduced into the reactor, and then the bottle was sealed with a rubber stopper and a bottle cap.

[0039] (3) The sealed bottle in step (2) was evacuated with nitrogen, and the evacuation time was 3 minutes. After evacuation, the reactor was placed in a constant temperature incubator at 37 ± 2 °C for cultivation.

[0040] (4) During the cultivation process, the generated green energy methane was collected every 24 hours, and the changes in the content of active enzymes, volatile fatty acids, and organic acids (including acetic acid, propionic acid, isobutyric acid, valeric acid, isovaleric acid, n-butyric acid) in the reactor were detected every 2 days; among them, when no gas was generated for 6 consecutive days, it indicated that the anaerobic digestion process had stopped, that is, the anaerobic digestion and fermentation of the waste had been completed.

[0041] The following details the anaerobic digestion process of the present invention through specific examples.

[0042] Example 1

[0043] This embodiment uses pig manure as waste and conducts anaerobic digestion treatment on the pig manure.

[0044] A method for increasing the energy production of anaerobic digestion of waste and alleviating acid inhibition by using nano-bubble water, the method is as follows:

[0045] S1. First, prepare hydrogen nano-bubble water, and the preparation of hydrogen nano-bubble water uses a dedicated nano-bubble water preparation device in the prior art;

[0046] S2. Then prepare the inoculum sludge:

[0047] (1) Put the digested sludge and pig manure into a 1-liter Schott Duran serum bottle at an inoculation mass ratio of 1:1 (400 g each);

[0048] (2) Adjust the initial pH value of the mixture in the bottle described in step (1) to 7 ± 0.05 with hydrochloric acid; then seal the Schott Duran serum bottle with a rubber stopper and a bottle cap; then use nitrogen to evacuate, and the evacuation time is 3 minutes;

[0049] (3) Put the evacuated bottle described in step (2) into a constant temperature incubator at 37 ± 2 °C for constant temperature cultivation. During the cultivation process, collect the generated green energy methane every 24 hours; when no gas is generated for 6 consecutive days, it means the process stops, and then collect the domesticated inoculum sludge, which is the inoculum sludge; store the collected inoculum sludge in a 4 °C refrigerator for standby;

[0050] S3. Anaerobic digestion process:

[0051] (1) Prepare a 250-ml Schott Duran serum bottle as the anaerobic digestion reactor;

[0052] (2) Put the pig manure and the inoculum sludge prepared in step S2 into the reactor described in step (1) at a mass ratio of 1:1 (50 g each); then adjust the pH value of the mixture to 7 ± 0.05 with hydrochloric acid. After adjusting the pH value, introduce 100 ml of hydrogen-nano-bubble water into the reactor, and then seal the bottle with a rubber stopper and a bottle cap;

[0053] (3) Evacuate the sealed bottle described in step (2) with nitrogen, and the evacuation time is 3 minutes. After evacuation, put the reactor into a constant temperature incubator at 37 ± 2 °C for cultivation.

[0054] (4) During the cultivation process, the generated green energy methane is collected every 24 hours, and the changes in the content indicators of active enzymes, volatile fatty acids, and organic acids in the reactor are detected every 2 days; among them, when no gas is generated for 6 consecutive days, it indicates that the anaerobic digestion process has stopped, that is, the anaerobic digestion fermentation of the waste has been completed.

[0055] The anaerobic process under different nano - water addition conditions was detected according to the steps of Example 1, and the biogas production rate is as Figure 1 (a) shown, and the methane production rate is as Figure 1 (b) shown;

[0056] As the digestion days increase, the concentration change of volatile fatty acids (VFAs) is as Figure 2 (a) and Figure 2 (b) shown;

[0057] Example 2

[0058] In this example, food waste was used as the waste, and the food waste was anaerobically digested.

[0059] A method for increasing the anaerobic digestion energy production of waste and alleviating acid inhibition by using nano - bubble water is as follows:

[0060] S1. First, prepare hydrogen nano - bubble water. The preparation of hydrogen nano - bubble water uses a dedicated nano - bubble water preparation device in the prior art;

[0061] S2. Then prepare the inoculation sludge:

[0062] (1) The digestion sludge and food waste were put into a 1 - liter Schott Duran serum bottle at an inoculation mass ratio of 1:1 (400 g each);

[0063] (2) Use hydrochloric acid to adjust the initial pH value of the mixture in the bottle in step (1) to 7 ± 0.05; then seal the Schott Duran serum bottle with a rubber stopper and a bottle cap; then use nitrogen to evacuate, and the evacuation time is 3 minutes;

[0064] (3) The evacuated bottle in step (2) was placed in a constant - temperature incubator at 37 ± 2 °C for constant - temperature cultivation. During the cultivation process, the generated green energy methane was collected every 24 hours; when no gas was generated for 6 consecutive days, it indicated that the process had stopped, and then the domesticated inoculation sludge was collected, which was the inoculation sludge; the collected inoculation sludge was stored in a 4 °C refrigerator for standby;

[0065] S3. Anaerobic digestion process:

[0066] (1) Prepare 250 ml Schott Duran serumbottles as anaerobic digestion reactors;

[0067] (2) Put food waste and the inoculum mud prepared in step S2 into the reactor described in step (1) at a mass ratio of 1:1 (50 g each); then adjust the pH value of the mixture to 7 ± 0.05 with hydrochloric acid. After adjusting the pH value, introduce 110 ml of hydrogen-nanobubble water into the reactor, and then seal the bottle with a rubber stopper and a bottle cap;

[0068] (3) Vacuum the sealed bottle in step (2) with nitrogen for 3 minutes. After vacuuming, place the reactor in a constant temperature incubator at 37 ± 2 °C for cultivation.

[0069] (4) During the cultivation process, collect the generated green energy methane every 24 hours, and detect the changes in the content indicators of active enzymes, volatile fatty acids, and organic acids in the reactor every 2 days; among them, if no gas is produced for 6 consecutive days, it indicates that the anaerobic digestion process has stopped, that is, the anaerobic digestion fermentation of the waste has been completed.

Claims

1. A method for increasing the anaerobic digestion capacity of waste and alleviating acid inhibition by using nanobubble water, characterized in that: The method comprises preparing hydrogen-nano bubble water, preparing inoculated mud, mixing the hydrogen-nano bubble water, the inoculated mud and agricultural waste for anaerobic digestion treatment; During the anaerobic digestion, the inoculation ratio of the waste, the inoculation mud and the hydrogen-nano bubble water is 0.5-1.5g: 0.5-1.5g: 1.5-2.5ml.

2. The method according to claim 1, characterized in that The preparation of inoculation mud comprises the following steps: (1) Digested sludge and pig manure were added into a bottle at an inoculation ratio of 0.5-1.5:0.5-1.5, and the initial pH value was adjusted to 7.00±0.05, and the bottle was sealed; (2) evacuating the sealed bottle in step (1) with nitrogen; (3) Place the sealed bottle after vacuuming in step (2) in a constant temperature incubator and culture it until no gas is produced for 6 consecutive days, then collect the inoculated mud and store it at 4°C for future use.

3. The method according to claim 1, characterized in that Anaerobic digestion treatment includes the following steps: (a) adding the waste and the inoculum mud into the reactor at an inoculum ratio of 0.5-1.5:0.5-1.5, and adjusting the initial pH value to 7.00±0.05; (b) adding hydrogen-nano bubble water into the reactor described in step (a) and sealing; (c) evacuating the sealed reactor of step (b), and placing the reactor in a constant temperature incubator for constant temperature culture after evacuation; (d) performing anaerobic digestion under the constant temperature culture conditions of step (c), collecting the generated methane and other green energy every 24 hours after the start of anaerobic digestion, and detecting changes in enzyme activity, volatile fatty acids (VFAs), methane, and organic acid content every two days; (e) After anaerobic digestion for 6 consecutive days without gas production, the anaerobic digestion process stops, and the fermentation liquid after anaerobic digestion is collected.

4. The method according to claim 2 or 3, characterized in that: The solutions used to adjust the initial pH value were 2.0 M NaOH solution or 2.0 M HCl solution.

5. The method according to claim 2 or 3, characterized in that: The temperature of constant temperature culture was 37±2℃.

6. The method according to claim 3, characterized in that The volume mass ratio of the hydrogen-nano bubble water added in step (b) to the waste and inoculated mud in step (a) is 1.5-2.5 ml: 0.5-1.5 g: 0.5-1.5 g.

7. Use of the method according to any one of claims 1 to 6 in treating waste.

Images