CN117583365A - Method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar - Google Patents
Method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar Download PDFInfo
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- CN117583365A CN117583365A CN202311719884.1A CN202311719884A CN117583365A CN 117583365 A CN117583365 A CN 117583365A CN 202311719884 A CN202311719884 A CN 202311719884A CN 117583365 A CN117583365 A CN 117583365A
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- 125000000524 functional group Chemical group 0.000 claims description 7
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/60—Biochemical treatment, e.g. by using enzymes
- B09B3/65—Anaerobic treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B2101/00—Type of solid waste
- B09B2101/70—Kitchen refuse; Food waste
-
- 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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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar, which comprises the following steps of; carrying out iron leaching pretreatment on wood dust, and preparing the magnetic biochar after pyrolysis and carbonization; adding magnetic biochar into an anaerobic digestion system taking kitchen waste as a matrix, and monitoring the changes of methane yield, VFAs concentration and pH value in the reaction process; when the substrate is consumed, the magnet is used for adsorbing the magnetic biochar on the bottom of the serum bottle through the serum bottle, the sludge mixed liquid in the original system is discharged from the bottle mouth, and the inoculated sludge and the substrate are added into the system again for anaerobic digestion reaction, so that the effect of the magnetic biochar is continuously exerted. On one hand, the magnetic biochar can be recycled after being used, so that the loss of microorganisms is avoided, and the action of the biochar is enhanced; on the other hand, the problem that the high-load kitchen waste is difficult to treat and the anaerobic digestion system is easy to acidify can be solved.
Description
Technical Field
The invention relates to the technical field of solid waste treatment, in particular to a method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar.
Background
At present, the mode of treating kitchen waste in China comprises the technologies of aerobic composting treatment, feed conversion treatment, anaerobic digestion treatment and the like. Among the solutions, the anaerobic digestion technology not only can remove organic pollutants, but also can convert the pollutants into biogas, generate clean energy, complete the secondary utilization of the pollutants, and become one of the most promising technologies for recycling the energy of the organic household garbage.
Anaerobic digestion of kitchen waste refers to a process of converting organic matters into gases such as methane, hydrogen, carbon dioxide and the like under the action of microorganisms in an anaerobic environment. Because the kitchen waste has high content of biochemically degradable organic matters, hydrolysis acidification bacteria can be rapidly proliferated in the anaerobic digestion process, macromolecular organic matters are degraded into micromolecular Volatile Fatty Acids (VFAs), and the generation time of methanogenic bacteria is obviously longer than that of hydrolysis acidification bacteria, so that the VFAs can not be timely consumed, and excessive accumulation of the VFAs is caused. Excessive accumulation of VFAs in turn causes a drop in the pH of the system, resulting in acidification of the system, which makes it difficult to run it stably.
At present, research shows that the methanation efficiency of anaerobic digestion of kitchen waste can be promoted by adding biochar. However, the biochar is difficult to recycle after being used, and the methanation of the kitchen waste cannot be continuously promoted; on the other hand, the biochar is difficult to fix in the reactor, and has better adsorption and fixation effects on microorganisms, so that the microorganisms are easy to run off along with the biochar in vitro, the cost of the anaerobic digestion system is increased, and the action effect of the biochar is weakened.
Disclosure of Invention
In order to overcome the technical problems, the invention aims to provide a method for realizing continuous synergism of methanation of kitchen waste by adding magnetic biochar, which can be recycled after being used, avoid loss of microorganisms and strengthen the action of the biochar; on the other hand, the problem that the high-load kitchen waste is difficult to treat and the anaerobic digestion system is easy to acidify can be solved.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar comprises the following steps of;
carrying out iron leaching pretreatment on wood dust, and preparing the magnetic biochar after pyrolysis and carbonization; adding magnetic biochar into an anaerobic digestion system taking kitchen waste as a matrix, and monitoring the changes of methane yield, VFAs concentration and pH value in the reaction process;
when the substrate is consumed, the magnet is used for adsorbing the magnetic biochar at the bottom of the serum bottle through the serum bottle, the sludge mixed liquid in the original system is discharged from the bottle mouth, and inoculated sludge and the substrate are added into the system again for anaerobic digestion reaction, so that the effect of the magnetic biochar is continuously exerted, and continuous synergism is carried out.
The magnetic biochar is synthesized by an immersion pyrolysis method, wood dust is added into ferric trichloride solution for immersion, and the mixture is filtered and then is put into an oven for drying; transferring the dried iron-impregnated wood scraps into a crucible, wrapping the iron-impregnated wood scraps with tinfoil, and putting the iron-impregnated wood scraps into a muffle furnace for pyrolysis and carbonization; and cooling to room temperature after complete carbonization, and taking out from a muffle furnace to obtain the magnetic biochar.
Further, the iron-impregnated wood chips are prepared by adding 100g of red cypress wood chips into 1L of ferric trichloride solution with the concentration of 4g/L for impregnation, filtering after one day of impregnation, and drying in an oven at 80 ℃;
the magnetic biochar is prepared by placing dried iron-impregnated wood scraps into a muffle furnace for pyrolysis and carbonization, controlling the heating rate to 15+/-1 ℃/min, and maintaining for 2 hours after the temperature reaches 500 ℃; cooling to room temperature after complete carbonization, and taking out from a muffle furnace; washing floating dust with ultrapure water, drying in an oven at 80deg.C, mixing, grinding, sieving with stainless steel screen to obtain 0.25-1mm magnetic biochar, and storing in a drying container.
The addition amount of the magnetic biochar is 5-10g/L, and the addition mode is one-time addition.
The anaerobic digestion reaction in the anaerobic digestion system is carried out in a 120mL sealed serum bottle, and the reaction temperature is controlled to be a high temperature condition of 55+/-5 ℃.
The kitchen waste is prepared manually based on the integral condition of kitchen waste components of the student canteen.
The magnetic biochar has a high specific surface area and a porous structure, and can provide an enrichment place for microorganisms; the basic functional groups on the surface can regulate the acid-base balance of the environment; in addition, the magnetic biochar has redox functional groups and conductivity, the redox functional groups can enable the magnetic biochar to serve as an electron shuttle body to accept and release electrons generated in the reaction process, and the conductivity can enable the magnetic biochar to serve as an electron conductor to promote electron transfer among microorganisms, so that methanation of kitchen waste is accelerated.
The invention has the beneficial effects that:
in the invention, the magnetic biochar is prepared by using biomass waste, and is environment-friendly and low in cost; the magnetic biochar can be magnetically recycled after anaerobic digestion is finished; the effect is obvious, and the technical cost is low; the operability is strong and the environment is friendly.
The invention utilizes self-made magnetic biochar which is added into an anaerobic digestion system, and can improve the methanation efficiency of kitchen waste by promoting the electron transfer process between microorganisms; in addition, the magnetic biochar surface is provided with an alkaline functional group, so that the recovery of the environmental pH value can be accelerated, and the environmental pH value suitable for the survival of microorganisms can be recovered more quickly; and finally, enriching microorganisms on the surface of the reacted magnetic biochar, and fixing the microorganisms in a reaction system along with magnetic recovery to act on the anaerobic digestion process of the kitchen waste in multiple periods, so that the magnetic biochar has a sustainable promotion effect on methanation efficiency of the kitchen waste.
Drawings
FIG. 1 shows the change in solution of magnetic biochar after the addition of a magnet.
FIG. 2 is a graph of cumulative methane yield during anaerobic digestion of magnetic recovery three-cycle kitchen waste.
FIG. 3 shows the maximum methanogenesis rate (R) obtained after fitting the Gompertz equation max ) Methanogenic delay (t) 0 )。
FIG. 4 is a graph showing pH change during a three-cycle reaction.
FIG. 5 is a graph showing the change in VFAs concentration during a three-cycle reaction.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
A method for realizing continuous synergy of methanation of kitchen waste by adding magnetic biochar comprises the following steps of;
carrying out iron leaching pretreatment on wood dust, and preparing the magnetic biochar after pyrolysis and carbonization; adding magnetic biochar into an anaerobic digestion system taking kitchen waste as a matrix, and monitoring the changes of methane yield, VFAs concentration and pH value in the reaction process;
when the substrate is consumed, the magnet is used for adsorbing the magnetic biochar on the bottom of the serum bottle through the serum bottle, the sludge mixed liquid in the original system is discharged from the bottle mouth, and the inoculated sludge and the substrate are added into the system again for anaerobic digestion reaction, so that the effect of the magnetic biochar is continuously exerted.
The kitchen waste is manually prepared based on the whole condition of kitchen waste components of the student canteen.
The manual kitchen waste preparation comprises the following components in percentage by weight: 15% of rice, 10% of noodles, 20% of Chinese cabbage, 20% of potato, 13.8% of carrot, 10% of egg, 5% of pork, 5% of chicken, 1% of oil and 0.2% of salt.
Examples:
the invention is applied to the kitchen waste anaerobic digestion treatment system, achieves good effect, and has the following specific embodiments: before the reaction starts, magnetic biochar is added into an anaerobic digestion system with kitchen waste as a matrix and an organic load of 2.25 (based on VS), and after the reaction starts, the gas yield, the gas components, the VFAs concentration and the pH value in the system are detected according to the reaction condition.
A magnetic biochar group (FB) and a non-carbon group (CT) are arranged, and parallel control groups are arranged in each group.
The specific operation steps are as follows:
preparing magnetic biochar: preparing 1L of ferric trichloride solution with the concentration of 4g/L in a beaker, completely immersing 100g of red cypress wood chips in the ferric trichloride solution, filtering the wood chips after soaking for one day, drying in an oven with the temperature of 80 ℃, transferring the dried iron-immersed wood chips into a crucible, packaging with tinfoil, putting into a muffle furnace for pyrolysis, controlling the heating rate to 15+/-1 ℃/min, and continuously pyrolyzing for 2 hours after reaching the peak temperature of 500 ℃. After complete carbonization, the prepared magnetic biochar is cooled to room temperature, taken out, washed with ultrapure water for several times to remove impurities, filtered and put into an oven at 80 ℃ for drying. And then uniformly mixing and grinding the dried magnetic biochar, selecting a sample with the particle size of 0.25-1mm, and storing the collected sample in a closed drying container before use.
Preparation of inoculation sludge: the inoculation sludge used for batch experiments was taken from a laboratory long-term steady-running one-stage CSTR reactor, and the physicochemical properties of the inoculation sludge are shown in Table 1.
Preparing kitchen waste: the kitchen waste is prepared manually based on the whole condition of kitchen waste components of a student canteen, the composition proportion of the main components is shown in table 2, and the physicochemical properties of the kitchen waste are shown in table 1.
Table 1 physicochemical Properties of mud and kitchen waste
Table 2 Artificial simulation of kitchen waste composition (based on wet weight)
Batch experiment: 4 clean and dried serum bottles were prepared, 10g/L of magnetic biochar was added to 2 of the serum bottles, and the other 2 were control groups without magnetic biochar. Then 30mL of seed sludge and 17.25mL of kitchen waste were added to the bottle, ensuring an organic load F/S in the bottle of 2.25 (VS based) and then the working volume of 90mL was replenished with tap water. Each group was treated with high purity nitrogen stripping for 2 minutes and finally the serum bottles were sealed with butyl rubber plugs and aluminum caps to ensure an absolute anaerobic environment. And placing the sealed serum bottle into a constant-temperature water bath shaking table at 55 ℃ for experiment, and setting the rotating speed to be 130r/min. After 10 minutes, the gas generated by thermal expansion in the bottle was discharged by a glass syringe. Each group was set up with parallel controls. The gas yield and gas composition in the system are measured periodically, the gas production result is analyzed, and samples are taken from serum bottles according to the gas production condition for measuring and analyzing the VFAs concentration and the pH value.
When the gas generation is not detected in the system, the substrate consumption is finished, the magnetic biochar is adsorbed at the bottom of the serum bottle through the serum bottle by using the magnet, the sludge mixed liquid in the original system is discharged from the bottle mouth, 30mL of seed sludge and 17.25mL of kitchen waste are added into the system again to reach the load of 2.25, the anaerobic digestion reaction of the second period is started, and the measurement index is the same as that of the first period. The same procedure was followed to magnetically recover the anaerobic digestion reaction for the third cycle.
The gas yield in the bottle was determined by using a 20mL glass syringe, the gas composition was determined by using a gas chromatograph, and the results of the determination and analysis are shown in fig. 2.
And (3) taking 0.7mL of mud sample by using a 2.5mL plastic needle tube periodically according to the gas production condition, wherein 0.5mL of mud sample is subjected to centrifugation, filtration and dilution, and the VFAs concentration of the mud sample is measured by using a gas chromatograph, and the measurement and analysis results are shown in figure 5.
The pH of the sludge mixture was measured with a portable pH meter (Horiba, japan) using 0.2mL of the sludge sample, and the measurement and analysis results are shown in FIG. 4.
Fitting using the Gompertz equation to obtain kinetic parameters is as follows: and calculating the maximum methanogenesis rate and the methanogenesis delay by fitting the kinetic parameters, wherein the fitting calculation result is shown in figure 3.
From the results of fig. 2 and 3, it can be seen that the addition of the magnetic biochar material can increase the maximum rate of methane production by anaerobic digestion of kitchen waste and shorten the methane production delay period. And along with the increase of the recycling times of the magnetic biochar, the promotion effect of the magnetic biochar is more obvious. R of FB group compared to CT group max The first cycle is increased by 23.29%, the second cycle is increased by 36.57%, and the third cycle is increased by 112.89%; t of FB group 0 The first cycle is shortened by 18.07%, the second cycle is shortened by 32.69%, and the third cycle is shortened by 46.17%.
As can be seen from the results of fig. 4, the pH recovery rate was faster for the FB group for the three periods than for the CT group. And the second period FB group had a faster pH recovery than the first period and the third period was faster than the second period.
From the results of FIG. 5, it can be seen that the addition of magnetic biochar can accelerate the degradation of VFAs during the reaction. And the degradation speed of the VFAs is also accelerated along with the increase of the recycling times of the magnetic biochar. The VFAs were substantially completely degraded during the first cycle of the FB group on day 10, the second cycle was shortened to 9 days, and the third cycle was substantially completely degraded on day 7.
The invention compares the maximum methane production rate, methane production delay time, VFAs degradation condition and pH change of the added magnetic biochar group and the non-added biochar group in the three-period reaction process, and discovers that the added magnetic biochar can effectively avoid the accumulation of the VFAs in the reaction process, improve the maximum methane production rate, shorten the methane production delay time and accelerate the recovery of the environmental pH in the reaction process. On the one hand, the magnetic biochar can be used as an enrichment place of microorganisms, so that the acting distance between the microorganisms is shortened; on the other hand, the catalyst can also be used as an electron shuttle body and an electron conductor to promote the electron transfer process between microorganisms, so that methanation of the kitchen waste is accelerated. In addition, through carrying out magnetism recycling to magnetic biochar, microorganism remains in the reaction system along with magnetic biochar, acts on the anaerobic digestion process of kitchen garbage in different periods for magnetic biochar also improves along with the replacement of cycle to the promotion effect of kitchen garbage methanation efficiency further, provides a feasible effective means for realizing the sustainable synergy of kitchen garbage methanation, has also effectively avoided the anaerobic digestion system cost that leads to because the biochar runs off to rise.
The invention has the advantages that: (1) the magnetic biochar prepared by the method is derived from biomass waste, is low in price and is environment-friendly; (2) the kitchen waste has the characteristics of high oil, high salt, high organic matters and the like, if the kitchen waste is directly used for anaerobic digestion, the degradation speed is high, so that the volatile fatty acid is accumulated, the system is easy to acidify, the problems of acid accumulation and acid inhibition common in the anaerobic digestion process of high organic matters such as the kitchen waste are favorably solved, and the methanation efficiency is obviously improved; (3) the magnetic biochar can be recycled by utilizing the magnetism of the magnetic biochar, so that the characteristics that the biochar is difficult to recycle and microorganisms are easy to run off are solved, and the continuous and stable long-term synergistic effect of the biochar in an anaerobic digestion system is realized.
In summary, the present invention is only the best mode, but the scope of the invention is not limited thereto, and any person skilled in the art can easily think about alternatives or variations within the scope of the present invention.
Claims (7)
1. The method for realizing continuous enhancement of methanation of the kitchen waste by adding the magnetic biochar is characterized by comprising the following steps of;
carrying out iron leaching pretreatment on wood dust, and preparing the magnetic biochar after pyrolysis and carbonization; adding magnetic biochar into an anaerobic digestion system taking kitchen waste as a matrix, and monitoring the changes of methane yield, VFAs concentration and pH value in the reaction process;
when the substrate is consumed, the magnet is used for adsorbing the magnetic biochar at the bottom of the serum bottle through the serum bottle, the sludge mixed liquid in the original system is discharged from the bottle mouth, and inoculated sludge and the substrate are added into the system again for anaerobic digestion reaction, so that the effect of the magnetic biochar is continuously exerted, and continuous synergism is carried out.
2. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 1, wherein the magnetic biochar is synthesized by a dipping pyrolysis method, wood chips are added into ferric trichloride solution for dipping, and the mixture is filtered and then put into an oven for drying; transferring the dried iron-impregnated wood scraps into a crucible, wrapping the iron-impregnated wood scraps with tinfoil, and putting the iron-impregnated wood scraps into a muffle furnace for pyrolysis and carbonization; and cooling to room temperature after complete carbonization, and taking out from a muffle furnace to obtain the magnetic biochar.
3. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 2, wherein the iron-impregnated wood chips are prepared by adding 100g of red cypress wood chips into 1L of ferric trichloride solution with the concentration of 4g/L for soaking for one day, filtering, and drying in an oven at 80 ℃;
the magnetic biochar is prepared by placing dried iron-impregnated wood scraps into a muffle furnace for pyrolysis and carbonization, controlling the heating rate to 15+/-1 ℃/min, and maintaining for 2 hours after the temperature reaches 500 ℃; cooling to room temperature after complete carbonization, and taking out from a muffle furnace; washing floating dust with ultrapure water, drying in an oven at 80deg.C, mixing, grinding, sieving with stainless steel screen to obtain 0.25-1mm magnetic biochar, and storing in a drying container.
4. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 1, wherein the adding amount of the magnetic biochar is 5-10g/L, and the adding mode is one-time adding.
5. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 1, wherein anaerobic digestion reaction in the anaerobic digestion system is carried out in a sealed serum bottle, and the reaction temperature is controlled to be in a high-temperature condition of 55+/-5 ℃.
6. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 1, wherein the kitchen waste is prepared manually based on the integral condition of kitchen waste components of a student canteen.
7. The method for realizing continuous enhancement of methanation of kitchen waste by adding magnetic biochar according to claim 1, wherein the magnetic biochar has a high specific surface area and a porous structure, and provides an enrichment place for microorganisms; the basic functional groups on the surface regulate the acid-base balance of the environment; the magnetic biochar has redox functional groups and conductivity, the redox functional groups enable the magnetic biochar to serve as an electron shuttle body to accept and release electrons generated in the reaction process, and the conductivity enables the magnetic biochar to serve as an electron conductor to promote electron transfer among microorganisms and accelerate methanation of kitchen waste.
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