AU2021106122A4 - Method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation - Google Patents
Method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 59
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- 210000003608 fece Anatomy 0.000 claims abstract description 86
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 85
- 239000010871 livestock manure Substances 0.000 claims abstract description 84
- 240000008042 Zea mays Species 0.000 claims abstract description 76
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 claims abstract description 76
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- 235000005822 corn Nutrition 0.000 claims abstract description 76
- 230000004151 fermentation Effects 0.000 claims abstract description 49
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- 238000001914 filtration Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 230000000694 effects Effects 0.000 claims description 5
- 230000000813 microbial effect Effects 0.000 claims description 5
- 239000002002 slurry Substances 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 17
- 239000002154 agricultural waste Substances 0.000 abstract description 4
- 239000007787 solid Substances 0.000 abstract description 2
- 210000002966 serum Anatomy 0.000 description 15
- 238000011049 filling Methods 0.000 description 12
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
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- 241001148471 unidentified anaerobic bacterium Species 0.000 description 2
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- XLYOFNOQVPJJNP-DYCDLGHISA-N deuterium hydrogen oxide Chemical compound [2H]O XLYOFNOQVPJJNP-DYCDLGHISA-N 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- -1 iron ions Chemical class 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
- C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
- C12P5/023—Methane
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/02—Biological treatment
- C02F11/04—Anaerobic treatment; Production of methane by such processes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/20—Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/40—Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Zoology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Wood Science & Technology (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Biochemistry (AREA)
- Biotechnology (AREA)
- General Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Genetics & Genomics (AREA)
- Microbiology (AREA)
- Molecular Biology (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
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- Fertilizers (AREA)
- Treatment Of Sludge (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The present invention belongs to the field of resource utilization of
agricultural wastes, and relates to a method for preparing biogas from pretreated
pig farm wastewater and plant straws through combined anaerobic fermentation,
comprising the following steps:
(1) filtering pig farm manure water to remove impurities;
(2) crushing corn straws to have a length of 1-3 cm, and drying the crushed
corn straws to have a constant weight;
(3) treating the pig farm manure water with biochar-supported nanoscale
zero-valent iron (BC-nZVI), and performing oscillation treatment;
(4) mixing the dried straw materials with the pig farm manure water obtained
in step (3) uniformly, and storing the obtained mixture for 2-3 days under medium
temperature conditions;
(5) adding active bacteria into the mixture obtained in step (4) based on the
total volume of fermentation liquid, adding water to adjust the content of total
solids (TS) in the corn straws to 6%-8% based on the total mass of fermentation
liquid, adjusting the pH of the fermentation liquid to 6-8, and performing
combined anaerobic fermentation at a medium temperature. The method provided
by the present invention can increase the biogas production efficiency and shorten
the fermentation period.
Description
Description
Technical Field
The present invention belongs to the field of resource utilization of agricultural wastes, and relates to a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation.
Background
Statistics show that nearly 4 billion tons of livestock and poultry manure in total is produced in China every year, has a chemical oxygen demand (COD) of up to 12.68 million tons, accounts for 96% of total emissions from agricultural sources, and is an important cause of agricultural non-point source pollution. Taking Heilongjiang Province as an example, with the implementation of a strategic layout of "South-to-North Pig Transfer", the pig breeding in Heilongjiang Province has developed rapidly. In 2020, the number of commodity pigs in Heilongjiang Province was 17.9 million; and the amount of pigs on hand at the year-end was 13.71 million. Based on a pollutant producing and emitting coefficient of pig breeding in Heilongjiang Province, it is estimated that 11.94 million tons of pig manure, 19.70 million tons of urine, 779,400 tons of BOD (Biochemical Oxygen Demand) and 798,300 tons of COD were produced in 2020, in which 40% of feces was unused effectively; the unused feces, particularly urine produced during breeding, water used to wash pigpens, are discharged arbitrarily and become sources of non-point source pollution, thereby bringing huge environmental pressure to the surrounding regions of the breeding farm. It is well-known that the technology of producing biogas by anaerobic fermentation is the most commonly used technology for treating such breeding
Description
wastewater and various agricultural wastes at present. However, the efficiency of biogas production from individual fermentation of pig farm wastewater is too low to realize the economic value. If the biogas is produced by combined anaerobic fermentation of the pig farm manure water and crop straws, the biogas production efficiency can be increased greatly. Studies have shown that the technologies for combined anaerobic fermentation of two or more organic materials not only normalize different organic wastes, but also apparently improve the biogas production efficiency of a fermentation system, and have the advantages of maintaining stable operation of the system, alleviating toxic chemical substances and ensuring nutrient balance of the system; and residues obtained after fermentation can be treated conveniently and can be directly used as organic fertilizers to avoid secondary pollution. Studies by Pang Zhenpeng et al. (2019, Journal of Safety and Environment, 19(05): 1767-1775.) show that the mixed anaerobic fermentation of pig manure and corn straws has the biogas production performance significantly superior to that of individual fermentation of pig manure, an appropriate ratio of the pig manure to the corn straws of 8: 2, an average methane mass fraction of 64.54%, as well as a cumulative biogas yield and a total solid (TS) biogas yield of 9943.1 mL and 0.273 L/g, which are respectively 79.33% and 79.61% higher than those of individual fermentation of pig manure. Studies by Li Ao et al. (2019, China Biogas 37(06): 3-10) show that the cumulative methane yields of the experimental groups with the same inoculation amount and a ratio of the pig manure to the straws of 1: 1 are all greater than 2: 1; and the experimental group with the ratio of the pig manure to the straws of 1: 1 and the inoculation amount of 50% is fastest to start, is also highest in cumulative methane yield, has an optimal combination of raw material ratio and inoculation amount in the study, and has a cumulative biogas yield and a cumulative VS methane yield of 6801.67 mL and 127.07 mL-g 1 VS, respectively.
Description
In the anaerobic fermentation technology centered on microbial transformation, the technologies of combined anaerobic fermentation of two or more matrices have the advantages of increasing the biogas yield of biological matrices, maintaining the stability of the system, diluting toxic chemicals and ensuring the nutrient balance of the system; and the residues obtained after fermentation can be treated conveniently and can be directly used as organic fertilizers to avoid secondary pollution. Although many scholars have done some study work on the mixed fermentation of the pig manure and the crop straws, the prior art still has technical problems of long fermentation period and low biogas production rate. Therefore, a novel method for preparing biogas through anaerobic fermentation is needed in the art.
Summary In view of this, the purpose of the present invention is to provide a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation, to solve the technical problems of long fermentation period and low biogas production rate in the prior art. The purpose of the present invention and a solution of the technical problems can be achieved by adopting the following technical solution. The present invention provides a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation. The method comprises the following steps: (1) filtering pig farm manure water to remove impurities; (2) crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws to have a constant weight; (3) treating the pig farm manure water with biochar-supported nanoscale zero-valent iron (BC-nZVI), and performing oscillation treatment;
Description
(4) mixing the dried corn straw materials with the pig farm manure water obtained in step (3) uniformly, and storing the obtained mixture for 2-3 days under medium temperature conditions; and (5) adding active bacteria into the mixture obtained in step (4) based on the total volume of fermentation liquid, adding water to adjust the content of TS in the corn straws to 6%-8% based on the total mass of fermentation liquid, adjusting the pH of the fermentation liquid to 6-8, and performing combined anaerobic fermentation at a medium temperature. In an embodiment of the method according to the present invention, in step (3), a mass ratio of the BC-nZVI to the pig farm manure water is 1: 8 to 1: 14; the oscillation frequency is 60-100 rpm; and the oscillation time is 12 h-36 h. In the embodiment of the method according to the present invention, in step (4), a mass ratio of the pig farm manure water to the corn straws is 1: 1 to 1: 5. In the embodiment of the method according to the present invention, in step (5), the pH is adjusted to 7. In the embodiment of the method according to the present invention, in step (5), the temperature in medium temperature fermentation is 25°C-35°C. In the embodiment of the method according to the present invention, in step (5), the amount of added active bacteria is 10-20% based on the total volume of the fermentation liquid. In the embodiment of the method according to the present invention, in step (5), the active bacteria refer to biogas slurry containing rich anaerobic microbial flora with relatively high activity obtained after performing wet anaerobic fermentation on a mixture of the corn straws and the pig farm manure water (the content of TS in the corn straws in the mixture is 6-8%) at 35°C for 60 days. In the embodiment of the method according to the present invention, the pig farm manure water refers to a liquid part obtained after performing wet and dry separation on large-scale pig farm manure. In the embodiment of the method according to the present invention, the method according to the present invention can increase the biogas yield by at least
Description
%, compared with the combined anaerobic fermentation of pig farm manure water untreated with the BC-nZVI and corn straws. In the embodiment of the method according to the present invention, the method according to the present invention can shorten the fermentation period by at least 42 days, compared with the combined anaerobic fermentation of pig farm manure water untreated with the BC-nZVI and corn straws. Compared with the prior art, the method according to the present invention has the advantages as follows: the above embodiment shows that the method provided by the present invention produces biogas by combining the pig farm manure water treated with the BC-nZVI with the corn straws, and can normalize multiple materials, greatly increase the biogas production efficiency, increase the content of biochar and iron ions in the biogas slurry and improve the fertilizer efficiency; and compared with the method for producing biogas by combined anaerobic fermentation of untreated pig farm manure water and corn straws, the method provided by the present invention can significantly shorten the fermentation period of anaerobic fermentation, apparently improve the biogas production efficiency and significantly increase the content of methane, and is an economic, efficient and environment-friendly clean energy production technology in the field of treatment of agricultural wastes.
Description of Drawings
Fig. 1 shows a device for producing biogas by combined anaerobic fermentation of pig farm manure water treated with BC-nZVI and corn straws according to the present invention; and Fig. 2 shows a comparison chart of efficiencies of producing biogas from pig farm manure water treated with the BC-nZVI and corn straws through combined anaerobic fermentation.
Detailed Description
Description
The present invention is further described below in combination with specific embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments. It should be noted that, for those ordinary skilled in the art, several deformations and improvements can also be made without departing from the concept of the present invention, and belong to the protection scope of the present invention. Surprisingly, the inventors of the present invention have found that the production of biogas by combining pig farm manure water treated with BC-nZVI with corn straws can significantly shorten the fermentation period, increase the biogas yield and increase the content of methane. Therefore, the present invention provides a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation. The method comprises the following steps: (1) filtering pig farm manure water to remove impurities; (2) crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws to have a constant weight; (3) treating the pig farm manure water with BC-nZVI, and performing oscillation treatment; (4) mixing the dried corn straw materials with the pig farm manure water obtained in step (3) uniformly, and storing the obtained mixture for 2-3 days under medium temperature conditions; (5) adding active bacteria into the mixture obtained in step (4) based on the total volume of fermentation liquid, adding water to adjust the content of TS in the corn straws to 6%-8% based on the total mass of fermentation liquid, adjusting the pH of the fermentation liquid to 6-8, and performing combined anaerobic fermentation at a medium temperature. In an embodiment of the method according to the present invention, the corn straws are obtained after corns are harvested in autumn.
Description
The pig farm manure water refers to a liquid part obtained after dry and wet separation of large-scale pig farm manure, and has a content of TS of less than 1. The pig farm manure water often contains impurities such as sand, stones and plastics. Therefore, in the embodiment of the method according to the present invention, the above impurities in the pig farm can be filtered by a sieve. In one embodiment of the present invention, in order to improve the water absorption of the mixed corn straws and pig farm manure water, the straws can be crushed to have a length of 1-3 cm. For example, the straws can be crushed to be 1 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3 cm or any value between any two values, such as 1.2 cm and 1.3 cm. The straws are crushed and dried first, and then are uniformly mixed with the pig farm manure water, thereby fully absorbing the pig farm manure water. In one embodiment of the present invention, the BC-nZVI is well known in the art and can be prepared by a liquid-phase reduction method. In one embodiment of the present invention, in step (3), a mass ratio of the BC-nZVI to the pig farm manure water is 1: 8 to 1: 14; the oscillation frequency is -100 rpm; and the oscillation time is 12 h-36 h. In a specific embodiment of the present invention, in step (3), the oscillation frequency may be 60, 70, 75, 80, 85, 90, 95 or 100 rpm; and the oscillation time may be 12 h, 12.5 h, 13 h, 13.5 h, 14 h, 14.5 h, 15 h, 15.5 h, 16 h, 16.5 h, 17 h, 17.5 h, 18 h, 18.5 h, 19 h, 19.5 h, 20 h, 20.5 h, 21 h, 21.5 h, 22 h, 22.5 h, 23 h, 23.5 h, 24 h, 24.5 h, 25 h, 25.5 h, 26 h, 26.5 h, 27 h, 27.5 h, 28 h, 28.5 h, 29 h, 29.5 h, h, 30.5 h, 31 h, 31.5 h, 32 h, 32.5 h, 33 h, 33.5 h, 34 h, 34.5 h, 35 h, 35.5 h or 36 h. In a specific embodiment of the present invention, in step (3), a mass ratio of the BC-nZVI to the pig farm manure water may be, for example, 1: 8, 1: 9, 1: 10, 1: 11, 1: 12, 1: 13, 1: 14 or any ratio between two ratios, such as 1: 8.2, 1: 9.3, 1: 10.4, 1: 11.2, 1: 12.3, 1: 13.5 and 1: 14.5.
Description
In a specific embodiment of the present invention, in step (4), a mass ratio of the pig farm manure water to the dried straws may be, for example, 1: 1, 1: 1.5, 1: 2, 1: 2.5, 1: 3 , 1: 3.5, 1: 4, 1: 4.5, 1: 5 or any ratio between two ratios, such as 1: 1.1, 1: 1.2, 1: 2.3, 1: 2.4, 1: 4.2 and 1: 4.3. In a preferred embodiment of the present invention, after the dried corn straw materials and the pig farm manure water obtained in step (3) are uniformly mixed according to a mass ratio of 1: 1-5, the mixture of the two can be oscillated at frequency of 60-100 rpm and 35.0±0.5°C for 12-36 h to ensure that the corn straws fully absorb the pig farm manure water obtained in step (3). In a specific embodiment of the present invention, the oscillation frequency may be 60, 70, 75, , 85, 90, 95 or 100 rpm; and the oscillation time may be 12 h, 12.5 h, 13 h, 13.5 h, , 14 h, 14.5 h, 15 h, 15.5 h, 16 h, 16.5 h, 17 h, 17.5 h, 18 h, 18.5 h, 19 h, 19.5 h, h, 20.5 h, 21 h, 21.5 h, 22h, 22.5 h, 23 h, 23.5 h, 24 h, 24.5 h, 25 h, 25.5 h, 26 h, 26.5 h, 27 h, 27.5 h, 28 h, 28.5 h, 29 h, 29.5 h, 30 h, 30.5 h, 31 h, 31.5 h, 32 h, 32.5 h, 33 h, 33.5 h, 34 h, 34.5 h, 35 h, 35.5 h or 36 h. In the embodiment of the present invention, the active bacteria refer to biogas slurry containing rich anaerobic microbial flora with relatively high activity obtained after performing wet anaerobic fermentation on a mixture of the corn straws and the pig farm manure water (the content of TS in the corn straws in the mixture is 6-8%) at 35°C for 60 days. The active bacteria contain a large number of active methanogens, which can be added into the fermentation system to rapidly increase the quantity and activity of effective methanogens, greatly shorten the startup time and greatly increase the biogas production efficiency. In the embodiment of the present invention, in order to remove the hardly degradable large particulate matters such as stones, sand and lignin, the active bacteria can be filtered with a 40-mesh sieve. In the embodiment of the present invention, the fermentation liquid is the mixture when the anaerobic fermentation is started, and comprises the corn straws,
Description
the pig farm manure water, the active bacteria and water. In step (5), 1 0 - 2 0 % of active anaerobic bacteria are added based on the total volume of the fermentation liquid. In a specific embodiment of the present invention, the quantity of the added active bacteria may be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or % of the total volume of the fermentation liquid. In the embodiment of the present invention, in order to fully perform anaerobic fermentation and increase the biogas yield, the fermentation liquid should be mixed uniformly during anaerobic fermentation, and the pH should be adjusted to 6-8. In a specific embodiment of the present invention, in step (5), the pH of the fermentation liquid is adjusted to 6, 6.5, 7, 7.5, 8 or a value between any two values, such as 6.2, 6.4, 7.4 , 7.6, 7.7, 7.8 and 7.9, and is preferably adjusted to neutral, i.e., pH 7. In the embodiment of the present invention, in step (5), after the active anaerobic bacteria are added, the content of TS in the corn straws is adjusted to 6%-8% by adding water based on the total mass of the fermentation liquid. In the specific embodiment of the present invention, the content of TS in the corn straws may be adjusted to 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7 .0%, 7 .1%, 7.2%, 7.3%, 7.4%, 7 .5 % or 8%, and preferably adjusted to 8%. Those skilled in the art know that the medium temperature fermentation refers to fermentation performed at 35°C or below. For example, the fermentation temperature is 25°C-35°C. In a specific embodiment, the fermentation temperature maybe 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C. In the embodiment of the present invention, compared with the combined anaerobic fermentation of the pig farm manure water untreated with the BC-nZVI and the corn straws, the method according to the present invention can increase the biogas yield by at least 70%, such as 71%, 72%, 72.5%, 73%, 74%, 74.5% and %, under the same conditions.
Description
In the embodiment of the present invention, compared with the combined anaerobic fermentation of the pig farm manure water untreated with the BC-nZVI and the corn straws, the method according to the present invention can shorten the fermentation period by at least 42 days, such as 42, 43 and 44 days, under the same conditions. The preferred embodiments of the present invention will be described in detail below in combination with embodiments. It should be understood that the following embodiments are given for illustrative purposes only, rather than limitation to the protection scope of the present invention. Those skilled in the art can make various modifications and substitutions without departing from purposes and spirits of the present invention; and all these modifications and substitutions fall within the protection scope of claims of the present invention. The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials and reagents used in the following embodiments are all commercially available unless otherwise specified. In the following embodiments, the active bacteria refer to biogas slurry containing rich anaerobic microbial flora with relatively high activity obtained after performing mixed anaerobic fermentation on the corn straws and the pig farm manure water (the content of TS in the corn straws in the mixture is 6%-8%) at °C for 60 days. The pig farm manure water refers to a liquid part obtained after performing wet and dry separation on large-scale pig farm manure, and has a content of TS of less than 1%. DHG-9023A produced by Shanghai Yiheng Scientific Instrument Co., Ltd. is used as an air drying oven. CHA-S produced by Changzhou Guohua Electric Appliance Co., Ltd. is used as an air-bath thermostatic oscillator.
Description
Embodiment 1 Biochar is prepared from corn straws by an oxygen-limited pyrolysis method at 400°C (Tao Mengjia; Study on Preparationand Modification of Straw Biochar and Adsorption Efficiency to Nitrogen and Phosphorus in Water [D]; Harbin Institute of Technology, 2018; Dissertation). The BC-nZVI is prepared by a pyrolysis-liquid phase reduction method (Zhu Qingtao, Wu Xiaoyi, Guo Qihui, et al.; Preparation of Biochar-supported Nanoscale Zero-Valent Iron and Study Progressin the Removal of Water Pollutants [J]; Energy Chemical Industry, 2018, 39(04): 73-77). In the present embodiment, a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation comprises the following steps: step 1, filtering pig farm manure water to remove impurities such as sand and plastics, and filling the filtered pig farm manure water into a plastic bucket for later use; step 2, crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws with an air drying oven to have a constant weight; step 3, filling the pig farm manure water into 500 mL serum bottles, each of which is filled with 376 mL of pig farm manure water; step 4, filling 40 mg of BC-nZVI into a 500mL serum bottle, rapidly placing the serum bottle in an air-bath thermostatic oscillator at 35.0±0.5°C, and oscillating at 60 rpm for 12 h for mixing uniformly; step 5, weighing and filling 24 g of dried corn straws into the serum bottle of step 4, storing for 2 days under medium temperature conditions, then adding 40 mL (10% of the total volume of fermentation liquid) of active bacteria filtered with a 40-mesh sieve, adding water to adjust the content of TS in the corn straws to 6%, adjusting the pH to 7, and fermenting at medium temperature of 35°C.
Description
In addition, the method also comprises the following steps: weighing 3 parts of 5 g corn straws and 5mL of pig farm manure water, and measuring the contents of TS and VS (organic dry matter) in the straws with a high-temperature drying oven and a muffle furnace; weighing 24 g (based on TS) of corn straws and 376 mL of pig farm manure treated with BC-nZVI (having a content of TS of less than 1%), adding 40 mL of active bacteria filtered with a 40-mesh sieve, and adjusting the pH to neutral; weighing 24 g (based on TS) of corn straws and untreated pig farm manure water, adding 40 mL of active bacteria filtered with the 40-mesh sieve, adding water to adjust the content of TS in the corn straws to 6%, adjusting the pH to 7, and performing anaerobic fermentation at a medium temperature (35°C) as a control (CK). An anaerobic fermentation reactor adopted in the experiment is mainly composed of 500 mL serum bottles, a 1000 mL Erlenmeyer flask and a 500 mL graduated glass tube (as shown in Fig. 1), which respectively serve as raw material digesting bottles, a biogas collecting bottle and a water collecting graduated cylinder, and are connected by a latex tube to form a set of gas communication device. The digesting bottles and the biogas collecting bottle must be strictly sealed, and are also provided with gas inlets and liquid inlets, which are sealed by glass cement and rubber plugs. The air tightness is checked at any time. By adopting the method of fermentation after pretreatment, 21,100 mL of biogas is produced within 60 days; and the amount of biogas produced without treatment is 12,400 mL. It can be seen that, compared with CK, the method for producing biogas from the pig farm manure water treated with BC-nZVI and the corn straws through combined anaerobic fermentation in the embodiment 1 increases the biogas yield by 70.16%; the method in the embodiment 1 can produce 8700 mL of biogas more than CK; and based on the average biogas yield of 206 mL/d of CK, the CK still needs the biogas yield of 42 days to reach 21,100
Description
mL, so the method in the embodiment 1 can shorten the fermentation period by 42 days. Embodiment 2 In the present embodiment, a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation comprises the following steps: step 1, filtering pig farm manure water to remove impurities such as sand and plastics, and filling the filtered pig farm manure water into a plastic bucket for later use; step 2, crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws with an air drying oven to have a constant weight; step 3, filling the pig farm manure water into 500 mL serum bottles, each of which is filled with 372 mL of pig farm manure water; step 4, filling 30 mg of BC-nZVI into a 500mL serum bottle, rapidly placing the serum bottle in an air-bath thermostatic oscillator at 35.0±0.5°C, and oscillating at frequency of 80 rpm for 24 h; step 5, weighing and filling 28 g of dried corn straws into the serum bottle of step 4, storing for 3 days under medium temperature conditions, then adding 40 mL of active bacteria filtered with a 40-mesh sieve, adding water to adjust the content of TS in the corn straws to 7%, adjusting the pH to 7, and fermenting at medium temperature of 35°C. In addition, the method also comprises the following steps: weighing 3 parts of 5 g corn straws and 5 mL of pig farm manure water, and measuring the contents of TS and VS (organic dry matter) in the corn straws with a high-temperature drying oven and a muffle furnace; weighing 28 g (based on TS) of corn straws and 372 mL of pig farm manure treated with BC-nZVI, adding 40 mL of active bacteria filtered with a 40-mesh sieve, adding water to adjust the content of TS in the corn straws to 7%, and adjusting the pH to 7; weighing 24 g (based on TS) of
Description
corn straws and untreated pig farm manure water, adding 40 mL of active bacteria filtered with the 40-mesh sieve, adjusting the pH to neutral, and performing anaerobic fermentation at a medium temperature (35°C) as a control (CK). An anaerobic fermentation reactor adopted in the experiment is mainly composed of 500 mL serum bottles, a 1000 mL Erlenmeyer flask and a 500 mL graduated glass tube (as shown in Fig. 1), which respectively serve as raw material digesting bottles, a biogas collecting bottle and a water collecting graduated cylinder, and are connected by a latex tube to form a set of gas communication device. The digesting bottles and the gas collecting bottle must be strictly sealed, and are also provided with gas inlets and liquid inlets, which are sealed by glass cement and rubber plugs. The air tightness is checked at any time. By adopting the method of fermentation after pretreatment, 22,300 mL of biogas is produced within 60 days; and the amount of biogas produced without treatment is 13,100 mL. It can be seen that, compared with CK, the method for producing biogas from the pig farm manure water treated with BC-nZVI and the corn straws through combined anaerobic fermentation in the embodiment 2 increases the biogas yield by 70.23%; the method in the embodiment 2 can produce 9,200 mL of biogas more than CK; and based on the average biogas yield of 278 nL/d of CK, the CK still needs the biogas yield of 42 days to reach 22,300 mL, so the method in the embodiment 2 can shorten the fermentation period by 42 days. Embodiment 3 In the present embodiment, a method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation comprises the following steps: step 1, filtering pig farm manure water to remove impurities such as sand and plastics, and filling the filtered pig farm manure water into a plastic bucket for later use;
Description
step 2, crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws with an air drying oven to have a constant weight; step 3, filling the pig farm manure water into 500 mL serum bottles, each of which is filled with 368 mL of pig farm manure water; step 4, filling 50 mg of BC-nZVI into a 500mL serum bottle, rapidly placing the serum bottle in an air-bath thermostatic oscillator at 35.0±0.5°C, and oscillating at frequency of 100 rpm for 36 h; step 5, weighing and filling 32 g of dried corn straws into the serum bottle of step 4, storing for 3 days under medium temperature conditions, then adding 40 mL of active bacteria, adding water to adjust the content of TS in the corn straws to 8%, adjusting the pH to 7, and fermenting at medium temperature of 35°C. In addition, the method also comprises the following steps: weighing 3 parts of 5 g corn straws and 5 mL of pig farm manure water, and measuring the contents of TS and VS (organic dry matter) in the straws with a high-temperature drying oven and a muffle furnace; weighing 32 g (based on TS) of corn straws and untreated pig farm manure, adding 40 mL of active bacteria filtered with a -mesh sieve, adding water to adjust the content of TS in the corn straws to 8%, and adjusting the pH to 7, and performing anaerobic fermentation at medium temperature of 35°C as a control (CK). An anaerobic fermentation reactor adopted in the experiment is mainly composed of 500 mL serum bottles and a 100 mL graduated cylinder (as shown in Fig. 1), which respectively serve as raw material digesting bottles, a biogas collecting bottle and a water collecting graduated cylinder, and are connected by a latex tube to form a set of gas communication device. The digesting bottles and the gas collecting bottle must be strictly sealed, and are also provided with gas inlets and liquid inlets, which are sealed by glass cement and rubber plugs. The air tightness is checked at any time.
Description
By adopting the method of fermentation after pretreatment, 23,500 mL of biogas is produced within 60 days; and the amount of biogas produced without treatment is 13,600 mL. It can be seen that, compared with CK, the method for producing biogas from the pig farm manure water treated with BC-nZVI and the corn straws through combined anaerobic fermentation in the embodiment3 increases the biogas yield by 72.79%; the method in the embodiment 2 can produce 9,900 mL of biogas more than CK; and based on the average biogas yield of 227 nL/d of CK, the CK still needs the biogas yield of 44 days to reach 23,500 mL, so the method in the embodiment 3 can shorten the fermentation period by 44 days. Fig. 2 shows comparison of biogas production efficiencies between the embodiments 1-3 and the respective CKs. It can be clearly seen from Fig. 2 that the efficiency of preparing the biogas from the pig farm manure water treated with BC-nZVI and the corn straws through combined anaerobic fermentation is apparently higher than the efficiency of preparing the biogas from the pig farm manure water untreated with BC-nZVI and the corn straws through combined anaerobic fermentation.
Claims (10)
1. A method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation, comprising the following steps: (1) filtering pig farm manure water to remove impurities; (2) crushing corn straws to have a length of 1-3 cm, and drying the crushed corn straws to have a constant weight; (3) treating the pig farm manure water with biochar-supported nanoscale zero-valent iron (BC-nZVI), and performing oscillation treatment; (4) mixing the dried corn straw materials with the pig farm manure water obtained in step (3) uniformly, and storing the obtained mixture for 2-3 days under medium temperature conditions; (5) adding active bacteria into the mixture obtained in step (4) based on the total volume of fermentation liquid, adding water to adjust the content of TS in the corn straws to 6%-8% based on the total mass of fermentation liquid, adjusting the pH of the fermentation liquid to 6-8, and performing combined anaerobic fermentation at a medium temperature.
2. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (3), a mass ratio of the BC-nZVI to the pig farm manure water is 1: 8 to 1: 14; the oscillation frequency is 60-100 rpm; and the oscillation time is 12 h-36 h.
3. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (4), a mass ratio of the pig farm manure water to the corn straws is 1: 1 to 1: 5.
4. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (5), the pH is adjusted to 7.
Claims
5. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (5), the fermentation temperature is 25°C-35°C.
6. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (5), the amount of added active bacteria is 10-20% based on the total volume of the fermentation liquid.
7. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein in step (5), the active bacteria refer to biogas slurry containing rich anaerobic microbial flora with relatively high activity obtained after performing wet anaerobic fermentation on a mixture of the corn straws and the pig farm manure water (the content of TS in the corn straws in the mixture is 6-8%) at 35°C for 60 days.
8. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to any one of claims 1-7, wherein the pig farm manure water refers to a liquid part obtained after performing wet and dry separation on large-scale pig farm manure.
9. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 8, wherein the method can increase the biogas yield by at least 70%, compared with the combined anaerobic fermentation of pig farm manure water untreated with the BC-nZVI and corn straws.
10. The method for preparing biogas from pretreated pig farm wastewater and plant straws through combined anaerobic fermentation according to claim 1, wherein the method can shorten the fermentation period by at least 42 days, compared with the combined anaerobic fermentation of pig farm manure water untreated with the BC-nZVI and corn straws.
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| CN114736934B (en) * | 2022-05-24 | 2024-03-26 | 东北师范大学 | Method for preparing biogas by promoting anaerobic co-fermentation of livestock manure straw by adding biochar |
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| CN101818173B (en) * | 2010-03-23 | 2012-05-23 | 河南农业大学 | Process for producing biogas from crop straw by dry fermentation |
| CN102732566B (en) * | 2012-07-24 | 2014-06-04 | 黑龙江省农业科学院农村能源研究所 | Cold-region methane accelerator and preparation method thereof |
| CN103409469B (en) * | 2013-08-16 | 2015-05-20 | 农业部沼气科学研究所 | Method for promoting cellulose anaerobic degradation-based methane production |
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| CN107051379A (en) * | 2017-03-22 | 2017-08-18 | 黑龙江省农业科学院农村能源研究所 | A kind of preparation method of the modified straw charcoal biogas desulfurizer of loaded metal ion |
| CN109912155B (en) * | 2019-03-20 | 2021-04-06 | 中国农业大学 | Integration technology and application method for harmless treatment of livestock and poultry manure water |
| CN109988781A (en) * | 2019-03-28 | 2019-07-09 | 青岛科技大学 | A kind of high method for digesting recycling N, P and purifying marsh gas altogether containing carbon matrix and microalgae |
| CN110295200A (en) * | 2019-07-17 | 2019-10-01 | 大连理工大学 | The method of microbial method preparation vulcanization zeroth order iron material |
| CN111876444B (en) * | 2020-06-24 | 2021-10-29 | 华南农业大学 | Enhanced gas production method for co-fermentation of kitchen waste and hybrid pennisetum and application thereof |
| CN112023925B (en) * | 2020-08-31 | 2023-04-07 | 井冈山大学 | Preparation method and application of livestock and poultry manure biochar loaded nano zero-valent iron composite material |
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| CN114230117A (en) * | 2021-12-15 | 2022-03-25 | 西安建筑科技大学 | Method for efficiently relieving tetracycline inhibition of pig manure anaerobic fermentation system |
| CN114314825A (en) * | 2021-12-15 | 2022-04-12 | 西安建筑科技大学 | Pig farm waste recycling treatment method |
| CN115259336B (en) * | 2022-08-08 | 2023-06-20 | 北部湾大学 | Method for improving electronic utilization rate of nano zero-valent iron in reduction purification of selenite and selenate in water body |
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