A composting method using a phenolic compound which is directly degradable by laccase
By adding phenolic compounds, such as chlorophenol and bisphenol A, that can be directly degraded by laccase during the composting process, the synergistic function of microorganisms is promoted, which solves the problem of lignin's difficulty in degradation in compost, improves the humic acid content and the quality of compost products, and achieves effective treatment of pollutants.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHEAST AGRICULTURAL UNIVERSITY
- Filing Date
- 2023-10-23
- Publication Date
- 2026-04-28
AI Technical Summary
Lignin is difficult to degrade effectively during composting, resulting in low humification levels, which affects the yield and quality of compost products, and also leads to poor pollutant treatment.
Adding phenolic compounds that can be directly degraded by laccase, such as chlorophenol and bisphenol A, during composting promotes synergistic microbial function, enhances laccase expression, and facilitates lignin degradation and pollutant treatment through pre-incubation and aeration and turning operations during composting.
It increases the humic acid content and humification index of compost products, improves compost yield and quality, and effectively treats pollutants, thus protecting the environment.
Smart Images
Figure CN117510245B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of bioremediation and solid organic waste treatment and resource utilization technology, specifically involving the application of phenolic compounds that can be directly degraded by laccase in composting and composting methods that promote humification. Background Technology
[0002] Composting is an economical and environmentally friendly method for treating organic solid waste, and it also has a certain pollution control capacity. A large number of microorganisms emerge in the composting environment, which can degrade organic matter and produce usable humus. Agricultural waste such as straw is rich in lignocellulose. Lignin is a natural polymer rich in phenolic structures and is the most abundant component of biomass, widely present in cell walls. However, because lignin is a multiphase polymer with a stable structure, it is generally difficult to degrade and utilize, resulting in a low degree of humification in composting. Therefore, promoting humification and increasing the content of humic acid are particularly important during the composting process. Summary of the Invention
[0003] The purpose of this invention is to increase the humic acid content and humification index in compost products, thereby improving the yield and quality of compost products, while treating pollutants, protecting the environment, and solving the problem of difficult treatment of organic solid waste.
[0004] To address the aforementioned problems, this invention provides the application of phenolic compounds that can be directly degraded by laccase in the preparation of compost products.
[0005] This invention also provides the application of phenolic compounds that can be directly degraded by laccase in promoting composting and humification.
[0006] Preferably, promoting compost humification includes increasing one or more of the following: humic acid content, humification index, and plant germination index.
[0007] Preferably, the phenolic compound that can be directly degraded by laccase is chlorophenol and / or bisphenol A.
[0008] The present invention also provides a composting method for promoting humification, comprising the following steps:
[0009] A solution of phenolic compounds that can be directly degraded by laccase is mixed with compost material for pre-incubation. The pre-incubated material is then composted to obtain compost products.
[0010] Preferably, the mass ratio of the phenolic compound that can be directly degraded by laccase to the compost material is (1.5-4):100.
[0011] Preferably, the phenolic compound that can be directly degraded by laccase is chlorophenol and / or bisphenol A.
[0012] Preferably, the solvent of the solution includes any one of ethanol, diethyl ether, alkaline solution and acetone.
[0013] Preferably, the pre-incubation time is ≥2 days; the temperature is 35~55℃;
[0014] During the pre-incubation process, the ventilation is performed 4 to 5 times a day, with each ventilation lasting 1 to 1.5 hours and then stopping for 2 to 3 hours. The ventilation rate is 0.05 to 0.15 L / min.
[0015] Preferably, the composting time is 45 to 65 days;
[0016] The composting process includes: during the first 0-2 days of composting, aeration is carried out 4-5 times a day, with each aeration lasting 1-1.5 hours followed by a 2-3 hour break, at a rate of 0.05-0.15 L / min.
[0017] During the 3rd to 18th day of composting, aeration should be carried out 1 to 2 times a day, for 1 to 2 hours each time, at a rate of 0.05 to 0.15 L / min.
[0018] Starting from day 19 of composting, aerate once a day for 1 to 2 hours each time, at a rate of 0.05 to 0.15 L / min.
[0019] Beneficial effects:
[0020] This invention utilizes phenolic compounds that can be directly degraded by laccase in composting. Composting often fosters large microbial communities, but the function of these communities is difficult to control. Under nutrient-sufficient conditions, most microorganisms exhibit competitive responses; however, under stress, they tend to cooperate. In conventional composting, it is difficult to induce microorganisms to co-express the required functions. Therefore, in the early stages of composting, the humification process within the compost pile is often slow, and microorganisms utilize large amounts of humic acid precursors, further hindering composting. The toxicity of phenolic compounds that can be directly degraded by laccase can promote the co-function of microorganisms within the compost pile. Furthermore, because they can enhance laccase expression, they can promote the co-metabolism of pollutants and lignin by laccase, thus degrading pollutants while promoting composting and protecting the environment.
[0021] Furthermore, laccase also exhibits highly efficient degradation of chlorophenols. The oxygen ion free radicals generated during degradation act as catalysts for laccase, enhancing its effectiveness. In addition, chlorophenols, as a microbial carbon source, produce phenolic substances that are intermediate products of composting, which can be incorporated into the humification process as substrates. When chlorophenols are used in composting, they create a stress response upon contact with the microbial community, inhibiting the original microbial community and stimulating synergy among microorganisms. As the microbial community undergoes succession and begins to secrete laccase, the contaminant chlorophenols are decomposed and utilized, forming a supplementary reaction that promotes composting and humification. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.
[0023] Figure 1 This is a graph showing the relative abundance of laccase genes during composting.
[0024] Figure 2 This is a graph showing the changes in laccase activity during composting.
[0025] Figure 3 This is a graph showing the changes in the compost humification index.
[0026] Figure 4 This is a graph showing the germination index of bok choy seeds when compost products are applied. Detailed Implementation
[0027] This invention provides the application of phenolic compounds that can be directly degraded by laccase in composting.
[0028] This invention provides the application of phenolic compounds that can be directly degraded by laccase in promoting composting and humification.
[0029] In this invention, promoting composting humification preferably includes increasing the humic acid content and / or humification index of the compost, and more preferably increasing the humic acid content and humification index of the compost.
[0030] In the early stages of composting, the humification process within the compost pile is often slow, and microorganisms utilize large amounts of humic acid precursors, further hindering the composting process. The toxicity of phenolic compounds, which can be directly degraded by laccase, can promote the synergistic function of microorganisms within the compost pile. Furthermore, because they can enhance laccase expression, they can promote the co-metabolism of pollutants and lignin by laccase, thus degrading pollutants and protecting the environment while simultaneously promoting composting and humification.
[0031] In this invention, the phenolic compounds that can be directly degraded by laccase are preferably chlorophenol and / or bisphenol A, and more preferably chlorophenol. Laccase has a highly efficient degradation effect on chlorophenol, and the oxygen ion free radicals generated during degradation will, in turn, become a catalyst for laccase, enhancing its effect. Furthermore, chlorophenol, as a microbial carbon source, produces phenolic substances that are compost intermediates and can be incorporated into the humification process as substrates. When chlorophenol is used in composting, it forms a stress response upon contact with the microbial community, inhibiting the original microbial community and stimulating synergy among microorganisms, thus inducing the succession of the functional microbial community, enhancing the community's resistance to and degradation capacity against pollutants, and thereby enhancing the expression of laccase genes and laccase. When the microbial community undergoes succession and begins to secrete laccase, the pollutant chlorophenol will be decomposed and utilized, forming a supplementary reaction. Using chlorophenol as a phenolic compound that can be directly degraded by laccase in the preparation of compost products further promotes composting and humification.
[0032] The present invention also provides a composting method for promoting humification, comprising the following steps:
[0033] A solution of phenolic compounds that can be directly degraded by laccase is mixed with compost material for pre-incubation. The pre-incubated material is then composted to obtain compost products.
[0034] This invention dissolves phenolic compounds that can be directly degraded by laccase in a solvent to obtain a solution of phenolic compounds that can be directly degraded by laccase.
[0035] In this invention, the solvent preferably includes ethanol, diethyl ether, alkaline solution, or acetone, and more preferably acetone. The volume ratio of the phenolic compound that can be directly degraded by laccase to the solvent is preferably 1:(4-9), more preferably 1:(5-8), and even more preferably 1:6. This invention dissolves the phenolic compound that can be directly degraded by laccase in the solvent, facilitating its volatilization within a short time during turning and aeration, and uniformly distributing the solute to every corner of the compost.
[0036] After obtaining a solution of phenolic compounds that can be directly degraded by laccase, the present invention mixes the solution of phenolic compounds that can be directly degraded by laccase with compost material to obtain a premixed material.
[0037] In this invention, the mass ratio of the phenolic compounds that can be directly degraded by laccase to the compost material is (1.5–4):100, more preferably (2–3.5):100, more preferably (2.5–3):100, and most preferably 2.8:100. The phenolic compounds that can be directly degraded by laccase in this invention are preferably chlorophenols and / or bisphenol A, more preferably chlorophenols. This invention limits the mass ratio of compost material to phenolic compounds that can be directly degraded by laccase to further exert a certain stress effect on the microorganisms within the compost pile, causing a pressure response, and ensuring that the pollutants degraded by laccase are fully degraded and utilized by the laccase produced by the microorganisms, thereby inducing a supplementary response after the pressure response.
[0038] In this invention, the raw materials for the compost preferably include organic solid waste, more preferably crop straw, and even more preferably rice straw. This invention preferably involves drying and chopping the raw materials; the length of the chopped raw materials is preferably 2-4 cm, more preferably 3 cm; the degree of drying is preferably such that the moisture content of the raw materials is ≤15%. This invention does not have strict requirements for the drying and chopping methods; conventional operations are sufficient.
[0039] This invention uses straw as a raw material, which not only further solves the problem of straw burning but also achieves the effect of bioremediation of emerging pollutants. This invention can protect the environment and solve the problem of difficult treatment of organic solid waste.
[0040] This invention preferably adjusts the moisture content and C / N ratio of the raw materials to obtain the compost material. Preferably, the moisture content of the raw materials is adjusted to 60%–70%, more preferably 65%; the C / N ratio is adjusted to 25–30, more preferably 26–28. This invention preferably uses urea or glucose to adjust the C / N ratio. Adjusting the moisture content and C / N ratio of the raw materials can further promote the efficient metabolism of organic matter by microorganisms during composting, effectively reduce odor problems, and improve compost quality.
[0041] After obtaining the premixed material, the present invention pre-incubates the premixed material to obtain pre-incubated material.
[0042] In this invention, the pre-incubation time is preferably ≥2 days, more preferably 2 days; the pre-incubation temperature is preferably 35–55°C, more preferably 40–50°C, and even more preferably 45°C. The limited incubation time in this invention further facilitates the continuation of the pressure response and promotes the succession of the microbial community. Furthermore, pre-incubation at this temperature further promotes the accumulation of laccase-producing microorganisms. This invention preferably involves inoculating the microbial agent during the pre-incubation stage; the microbial agent is preferably a laccase-producing agent, more preferably an agent that degrades added contaminants and produces high levels of laccase, thereby improving the effectiveness of the pre-incubation stage.
[0043] In this invention, during the pre-incubation process, aeration is preferably performed 4-5 times per day. Preferably, each aeration session lasts 1-1.5 hours, more preferably 1.25 hours, followed by a 2-3 hour aeration stop, more preferably 2.5 hours. The aeration rate is preferably 0.05-0.15 L / min, more preferably 0.1 L / min. This invention preferably involves turning the pile during the pre-incubation process; the turning frequency is preferably 2 times / day, with an interval of ≥12 hours between adjacent turning sessions, and each turning session lasting ≥30 minutes. Aeration and turning in this invention promote the volatilization of organic solvents. Air is preferably introduced during aeration. Aeration during the pre-incubation stage provides the necessary oxygen for microbial growth, ensuring the microorganisms can cope with the large amount of oxygen required by pollutant stress during this period, and simultaneously guaranteeing the growth and evolution of the microbial community within the pile.
[0044] After obtaining the pre-incubated material, the present invention composts the pre-incubated material to obtain compost products.
[0045] In this invention, intermittent aeration is performed simultaneously with composting. The aeration conditions are preferably determined based on the composting time: From day 0 to 2 of composting, aeration is preferably performed 4 to 5 times per day; each aeration session is preferably 1 to 1.5 hours, more preferably 1.25 hours, followed by a 2 to 3 hour aeration stop, preferably 2.5 hours; From day 3 to 18 of composting, aeration is preferably performed 1 to 2 times per day, preferably 1 to 2 hours per session, more preferably 1.5 hours, with an aeration rate of 0.05 to 0.15 L / min, more preferably 0.1 L / min; From day 19 onwards, aeration is preferably performed once per day, preferably 1 to 2 hours per session, more preferably 1.5 hours, with an aeration rate of 0.05 to 0.15 L / min, more preferably 0.1 L / min. This intermittent aeration during composting promotes efficient microbial metabolism of organic matter during the composting process, effectively reduces odor problems, and improves compost quality. The ventilation described in this invention preferably involves introducing air.
[0046] This invention preferably involves turning the compost pile during the composting process. The specific turning frequency is preferably determined based on the composting conditions: before entering the maturation stage, the pile is preferably turned once every 1-2 days, with each turning session lasting ≥30 minutes; after entering the maturation stage, the pile is preferably turned once every 2-3 days, with each turning session lasting ≥30 minutes. After pre-incubation, this invention reduces the aeration and turning frequency during composting to stabilize the microbial community generated during pre-incubation and to provide sufficient oxygen for microbial growth.
[0047] In this invention, the maximum temperature of the compost is preferably 55°C, which further promotes lignin degradation and maintains laccase activity; the duration of the maximum temperature is preferably 5-7 days, more preferably 6 days, which further promotes the degradation of macromolecules and the accumulation of humic acid precursors; the temperature of the compost maturation period is preferably 35°C, which further promotes the polymerization of humic acid.
[0048] This invention does not have strict requirements on the composting time. The composting time is defined as the time when the germination index reaches the plant toxicity standard and the compost maturity reaches the desired level. Preferably, it is 45-65 days, more preferably 60 days. This invention preferably ensures that the moisture content of the material is 60%-70% throughout the entire composting process, more preferably 65%.
[0049] The composting method provided by this invention can promote composting, increase the humic acid content, humification index, and plant germination index in compost products, improve the yield and quality of compost products, treat pollutants, protect the environment, and solve the problem of difficult organic solid waste treatment. Example results show that, compared with conventional composting methods, the humic acid yield in the compost products of this invention is increased by approximately 71%, the humification index by approximately 104%, and the plant germination index by 40%.
[0050] To further illustrate the present invention, a composting method using phenolic compounds that can be directly degraded by laccase is described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.
[0051] Example 1
[0052] The raw material for the compost was rice straw, sourced from field reserves in rural Heilongjiang, China (126°17'24.508"E, 45°25'44.716"N). The basic characteristics of the initial RS were: total carbon content 39.90±3.56%, total nitrogen content 0.81±0.02%, pH 8.34±0.05, and electrical conductivity 1.18±0.08 mS / cm.
[0053] A composting method that promotes humification consists of the following steps:
[0054] 1) Crush the rice straw to 20-40mm using a shredder, adjust the C / N ratio to 30 / 1 using urea, and adjust the moisture content to 70% to obtain compost material.
[0055] 2) Mix 18g of chlorophenol with 82ml of acetone, mix the mixture with 1200g of compost material obtained in step 1), put it into the composting reactor for pre-incubation, and after 2 days, put it into composting to obtain compost products.
[0056] During the pre-incubation composting period, frequent aeration and turning are required; aeration is carried out 4 to 5 times a day, with each aeration lasting 1.5 hours followed by a 2.5-hour break, at a rate of 0.1 L / min; and the compost is turned twice a day with a 12-hour interval between each turn.
[0057] During composting from day 0 to 2, aeration was carried out 4 to 5 times a day, with each aeration lasting 1.5 hours followed by a 2.5-hour aeration period, at a rate of 0.1 L / min. From day 3 to 18, aeration was carried out 1 to 2 times a day, with each aeration lasting 1 to 2 hours, at a rate of 0.1 L / min. Starting from day 19, aeration was carried out once a day, with each aeration lasting 1 to 2 hours, at a rate of 0.1 L / min. Composting was stopped once the composting maturation period was over. The total composting cycle lasted 61 days.
[0058] Example 2
[0059] Same as Example 1, except that chlorophenol is replaced with bisphenol A.
[0060] Example 3
[0061] Same as Example 1, except that in step 2), the amount of compost material used is 4500g of mixed material (i.e., the mass ratio of compost material to chlorophenol is 100g:4g).
[0062] Comparative Example 1
[0063] Similar to Example 1, the only difference is that chlorophenol and acetone are not used; the composting material is directly pre-incubated and composted.
[0064] Comparative Example 2
[0065] Same as Example 1, except that chlorophenol is replaced with triclosan, which is a more complex phenolic pollutant that cannot be directly degraded by laccase.
[0066] Comparative Example 3
[0067] Same as Example 1, except that in step 2), the amount of compost material used is 6750g of mixed material (i.e., the mass-volume ratio of compost material to chlorophenol is 100g:6mL).
[0068] Test Example 1
[0069] In Examples 1-3 and Comparative Examples 1-3, the compost products were collected at 4d, 10d, 18d, 30d, 46d and 61d after composting, and used as samples to be tested. The relative abundance of laccase gene, laccase activity, humic acid content, humification index and plant germination index of the samples to be tested were measured.
[0070] (1) The relative abundance of laccase genes was determined as follows: DNA was extracted from the samples to be tested using an Omega soil DNA kit (D5625-01); degenerate primers for bacterial and fungal laccases were designed; qPCR running conditions were set according to the primer sequences; and qPCR was performed on the laccase genes in the sample DNA. The results are shown in Table 1 and... Figure 1 As shown.
[0071] Table 1. Relative abundance of laccase genes in Examples 1-3 and Comparative Examples 1-3.
[0072] Relative abundance of laccase genes Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 4d 175.77 146.51 373.37 840.44 759.49 654.89 10d 84.85 65.73 144.36 226.31 482.63 189.19 18d 122.12 146.54 168.28 429.42 322.36 282.15 30d 108.90 115.75 215.29 338.40 235.12 306.65 46d 134.62 143.63 358.06 541.07 512.17 461.45 61d 139.71 296.94 436.99 864.31 772.98 689.08 mean 127.66 152.52 282.73 539.99 514.13 430.57
[0073] According to Table 1 and Figure 1 It can be seen that chlorophenol or bisphenol A can significantly increase the abundance of laccase genes during composting, with a slight decrease in effect when the pollutant content is 6% (Example 3). The addition of structurally complex triclosan has a poor promoting effect on laccase genes.
[0074] (2) Laccase activity assay was performed as follows: 1g of fresh sample to be tested was mixed with 10ml of physiological saline and shaken for 1h. The mixture was then centrifuged and the supernatant was extracted as the enzyme solution to be tested.
[0075] Set the UV spectrophotometer to 420 nm and zero the instrument using a blank solution (2.0 mL 0.1 mol / L citrate-sodium citrate buffer (pH = 5.0), 0.5 mL 1.0 mmol / L ABTS, and 0.5 mL deionized water). Mix 2.0 mL of the 0.1 mol / L citrate-sodium citrate buffer (pH = 5.0) with 0.5 mL of the 1.0 mmol / L ABTS. Incubate at 30°C for 10 min, then mix with 0.5 mL of the enzyme solution to be tested. Immediately pour the mixture into a cuvette and place it in the UV spectrophotometer. Record the absorbance at 420 nm immediately, every 30 seconds for a total of 3 times. Take the average value and convert it to the absorbance change per minute (i.e., OD420 change, denoted as ΔA). Calculate the enzyme activity using the following formula:
[0076]
[0077] Where ΔA represents the change in absorbance at 420 nm. Va is the total volume of the reaction system (ml), Ve is the volume of the enzyme solution to be tested in the reaction system (ml), and Vs is the volume of the buffer solution used to dilute the laccase (ml). ε is the absorbance coefficient, ε420 = 36000 L / (mol-cm). Δt is the reaction time (min), and W is the sample weight (g).
[0078] The results are shown in Table 2 and Figure 2 As shown.
[0079] Table 2. Laccase activity in Examples 1-3 and Comparative Examples 1-3.
[0080] Laccase activity (U / g) Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 4d 16.45 18.5 17.05 18.29 17.84 16.75 10d 33.64 24.72 6.26 16.33 35.56 13.18 18d 35.53 41.64 37.57 92.74 55.11 74.52 30d 46.85 43.69 40.66 77.3 82.2 66.55 46d 38.62 30.32 58.35 69.36 64.06 47.78 61d 20.1 33.41 44.77 50.53 60.26 47.88 mean 32.10 33.53 34.86 54.73 52.84 45.32
[0081] According to Table 2 and Figure 2 It can be seen that adding pollutants for pre-incubation inhibits laccase activity in the initial stage, but due to the accumulation of laccase genes, laccase activity suddenly increases from 4 to 10 days and gradually increases during subsequent composting. The promoting effect of laccase activity from strong to weak is as follows: 1.5% chlorophenol (Example 1) > 1.5% bisphenol A (Example 2) > 4% chlorophenol (Example 3) > 1.5% triclosan (Comparative Example 2) > 6% chlorophenol (Comparative Example 3) > no chlorophenol added (Comparative Example 1).
[0082] (3) Determination of humic acid content and humification index
[0083] The method for extracting humic substances includes the following steps:
[0084] Mix 1 gram of dried sample with 20 mL of 0.1 M Na4P2O7-10H2O-NaOH mixture; place in a shaker at 200 rpm (27 °C) for 24 hours, then remove and centrifuge at 8000 rpm for 10 minutes, repeating twice; combine the supernatants and filter through a membrane (0.45 μm) to obtain a humic solution, which is humic acid (HS);
[0085] The humic material solution was used to separate fulvic acid (FA) and humic acid (HA): 6M hydrochloric acid solution was added to the humic material solution to adjust the pH to 1.5. The solution was incubated at 4°C for 12 hours, then centrifuged at 8000 rpm for 10 minutes. The supernatant was collected to obtain fulvic acid (FA). The precipitate was washed three times with 0.01M hydrochloric acid and deionized water. The precipitate was dissolved in Na₂CO₃ solution. Humic acid (HA) was obtained. The humification index was calculated using the following formula. The results are shown in Table 3. Figure 3 .
[0086] Humic index = Humic acid content / Fulvic acid content
[0087] Table 3 Compost humification index of Examples 1-3 and Comparative Examples 1-3
[0088] Humus index (%) Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 4d 0.51 0.51 0.63 0.43 0.50 0.47 10d 0.53 0.54 0.85 0.44 0.56 0.38 18d 0.77 0.78 0.92 0.93 1.15 0.81 30d 0.76 0.76 1.08 1.26 1.36 1.29 46d 0.78 0.78 1.36 1.62 1.60 1.36 61d 1.34 1.48 1.79 2.42 2.24 2.30 mean 1.73 1.91 2.12 3.18 2.96 2.77
[0089] According to Table 3 and Figure 3It can be seen that the final degree of compost humification, from highest to lowest, is as follows: Example 1 > Example 2 > Example 3 > Comparative Example 3 > Comparative Example 2 > Comparative Example 1. This indicates that the optimal addition amount of chlorophenol is 1.5–4%, and when the content is too high, the promoting effect on humification is greatly weakened. Furthermore, replacing the contaminant with a similarly simple bisphenol A can also be directly degraded by laccase and promote compost humification. However, replacing it with a structurally complex contaminant results in a poorer promoting effect on humification because it is difficult for microorganisms to degrade and utilize it.
[0090] (4) Determination of plant germination index
[0091] Dissolved organic matter (DOM) was extracted from 1 gram of material using 10 ml of water. Germination index was determined using cabbage seeds: sterile filter paper was laid flat in a sterile petri dish, and 15 seeds were evenly sprinkled on top; the filter paper in each dish was moistened with 5 ml of DOM; sterile water was used as a control, and the mixture was incubated in the dark for 3 days; this process was repeated 3 times; the number of germinated seeds and the root length of the germinated seeds were recorded, and the germination index was calculated. The results are shown in Table 4. Figure 4 As shown.
[0092] Table 4. Germination index of compost plants in Examples 1-3 and Comparative Examples 1-3
[0093]
[0094]
[0095] According to Table 4 and Figure 4 It can be seen that during the pre-incubation period, due to the addition of contaminants, Comparative Examples 2-3 and Examples 1-3 exhibited strong toxicity to plants and extremely low germination indices. However, due to the laccase-modifying effect of pre-incubation, the contaminants within the compost pile were rapidly degraded, and the germination indices of the treated plants gradually exceeded those of Comparative Example 1. At the end of the experiment, the germination index of the plants in Example 1 was 62.8% higher than that of the blank control, Comparative Example 1. Examples 2 and 3 showed slightly weaker effects. Comparative Examples 2 and 3 showed poorer effects, even lower than Comparative Example 1. This indicates that contaminants with complex structures or high content can have adverse effects on composting, inhibiting its detoxification ability.
[0096] Combine Tables 1-4 and Figures 1-4 It can be seen that the best overall improvement effect on composting was achieved by adding 1.5% chlorophenol (Example 1), followed by adding 1.5% bisphenol A (Example 2) or adding 4% chlorophenol (Example 3). The effects of adding 1.5% triclosan (Comparative Example 2) or adding 6% chlorophenol were poor (Comparative Example 3), only slightly better than no treatment (Comparative Example 1).
[0097] As can be seen from the above, the technical solution provided by the present invention can promote the humification of compost, increase the humic acid content and humification index in compost products, improve the yield and quality of compost products, and increase the plant germination index.
[0098] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A composting method for promoting humification, characterized in that, Includes the following steps: A solution of phenolic compounds that can be directly degraded by laccase is mixed with compost material for pre-incubation. The pre-incubated material is then composted to obtain compost products. The phenolic compounds that can be directly degraded by laccase are chlorophenols and / or bisphenol A; The raw material for the compost is rice straw; The mass ratio of the phenolic compounds that can be directly degraded by laccase to the compost material is (1.5~4):100; The pre-incubation time is ≥2 days; the temperature is 35~55℃.
2. The composting method according to claim 1, characterized in that, The solvent of the solution includes any one of ethanol, diethyl ether, alkaline solution and acetone.
3. The composting method according to claim 1, characterized in that, During the pre-incubation process, the ventilation is performed 4 to 5 times a day, with each ventilation lasting 1 to 1.5 hours and then stopping for 2 to 3 hours. The ventilation rate is 0.05 to 0.15 L / min.
4. The composting method according to claim 1, characterized in that, The composting time is 45-65 days; The composting process includes: during the first 0-2 days of composting, aeration is carried out 4-5 times a day, with each aeration lasting 1-1.5 hours followed by a 2-3 hour break, at a rate of 0.05-0.15 L / min. During the 3rd to 18th day of composting, aeration should be carried out 1 to 2 times a day, for 1 to 2 hours each time, at a rate of 0.05 to 0.15 L / min. Starting from day 19 of composting, aerate once a day for 1-2 hours each time, at a rate of 0.05-0.15 L / min.
5. The composting method according to claim 1, characterized in that, The promotion of compost humification includes increasing one or more of the following: humic acid content, humification index, and seed germination index.