A method for preparing and applying a slow-release oxygen agent for reducing methane emissions

Abstract

The application discloses a preparation method of a slow-release oxygen agent for reducing methane emission, and mainly comprises the following steps: preparing a PHB solution, adding CaO2, copper sulfate (CuSO4) and goethite (FeO(OH)) into the PHB solution, and drying to prepare a degradable slow-release oxygen agent with spherical embedded CaO2 / CuSO4 / FeO(OH). The degradable slow-release oxygen agent prepared by the application can inhibit methane generation and promote methane oxidation and consumption, and can break the limitation of directly adding CaO2 to only inhibit the methane generation process and lack of promotion of methane oxidation and consumption, and effectively solve the problems of short action period of the added powder CaO2, high pH and other water quality problems. The application further discloses an application method of the slow-release oxygen agent for reducing methane emission, and the slow-release oxygen agent is added into the sediment of the slow-flow water body in the form of shallow injection at a depth of 4-8 cm, so that the oxygen utilization efficiency of the CaO2 and the methane emission reduction effect on the sediment can be increased, and the action depth of the slow-release oxygen agent on the sediment of the slow-flow water body can be increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, and particularly relates to a preparation method and application method of a slow-release oxygen agent for reducing methane emission. BACKGROUND

[0002] Methane (CH4) is the second largest global greenhouse gas after carbon dioxide, and its warming effect is 28-34 times that of carbon dioxide. Although lakes and other slow-flowing water bodies account for only 0.9% of the total area of the earth, the amount of methane emission from lake ecosystems accounts for about 16%-24% of the total amount of natural ecosystem emission, which is much higher than that of the ocean with a larger area. In recent years, the eutrophication of lakes has become increasingly serious, and the excessive proliferation of algae reduces the dissolved oxygen in water through respiration. The slow-flowing water body lacks hydrodynamic disturbance, resulting in a slow negative oxygen in the atmosphere, which aggravates the degree of oxygen deficiency in the water body. Under the condition of oxygen deficiency / anaerobic condition, algae and nutrients continue to accumulate in the sediment, and a large amount of organic matter is enriched in the sediment, which produces methane through anaerobic fermentation, resulting in an increasing amount of methane emission year by year. Therefore, from the perspective of inhibiting global warming, it is of great significance to focus on and reduce the methane emission of lakes.

[0003] At present, the research focus of greenhouse gases in slow-flowing water bodies is to measure their emission values to improve the understanding of the generation mechanism of greenhouse gases, but there is little research on the control of greenhouse gases in slow-flowing water bodies. The existing methods for controlling methane emission in slow-flowing water bodies include artificial aeration, sediment dredging, and biological remediation.

[0004] In recent years, there have been increasing reports on the use of oxidizing agents (hydrogen peroxide, magnesium peroxide, calcium nitrate, sodium percarbonate, calcium peroxide (CaO2), etc.) to create oxygen and oxidation conditions at the sediment-water interface of slow-flowing water bodies. Among them, CaO2 has high stability, is a common food additive, is non-toxic and harmless, does not pollute the environment, is cheap and easy to produce, and has a purity of 60%-80%, and is a widely used excellent oxygen supplier and deodorant. When CaO2 is added to water, it releases oxygen and hydrogen peroxide, creating an aerobic and oxidative environment to destroy the survival conditions of methanogenic microorganisms, thereby controlling the release of methane from the sediment of slow-flowing water bodies, and also controlling the release of endogenous pollutants. However, the direct addition of CaO2 causes excessive oxygen release in the early stage, resulting in waste of oxygen source, and the oxygen release decreases in the later stage, with a short action period. Moreover, the direct addition of CaO2 can cause an increase in the pH of the water body, affecting the water quality. There have been some researches on the preparation method of slow-release oxygen agents at home and abroad, but the embedding materials of the prepared slow-release oxygen agents are mostly not degradable in the natural environment, which may cause secondary pollution to the environment. Moreover, the existing CaO2 slow-release oxygen agent only inhibits the methane production process, and cannot promote the oxidation and consumption process of the produced methane, so it cannot improve the methane emission reduction effect of slow-flowing water bodies. SUMMARY

[0005] Therefore, the main purpose of the present application is to provide a preparation method and application method of a slow-release oxygen agent for reducing methane emissions, which overcomes the limitations of directly adding CaO2 to only inhibit the methane production process, lacks the promotion of the methane oxidation and consumption process, and cannot improve the methane emission reduction effect of slow-flow water bodies.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A preparation method of a slow-release oxygen agent for reducing methane emissions, comprising:

[0008] S1. Dissolving poly-beta-hydroxybutyric acid (PHB) in dichloromethane or carbon tetrachloride organic solvent, stirring to obtain a PHB solution with a concentration of 0.2 g / mL-0.6 g / mL;

[0009] S2. Under stirring conditions, adding CaO2, CuSO4 (copper sulfate) and FeO(OH) (goethite) to the PHB solution, so that the mass ratio of PHB solution, CaO2, CuSO4 and FeO(OH) is 1000-1500:1000-1500:10-50:3-10, and stirring to uniformly suspend CaO2, CuSO4 and FeO(OH) in PHB to obtain a suspension A;

[0010] S3. Stirring the suspension A until the dichloromethane or carbon tetrachloride volatilizes, and when the suspension A is a semi-solid gel, pouring it into a mold, then placing it in an oven for drying, taking it out when the set conditions are met, and cooling it to room temperature to obtain a slow-release oxygen agent embedding CaO2 / CuSO4 / FeO(OH).

[0011] Preferably, the weight average molecular weight of the poly-beta-hydroxybutyric acid is 50,000-80,000.

[0012] Preferably, the set conditions in S3 are: the drying temperature is 40-60℃, and the drying time is 5-12h.

[0013] Preferably, the set conditions in S3 are: the drying temperature is 50℃, and the drying time is 8h.

[0014] Preferably, the mold in S3 is a spherical mold, and the inner diameter of the spherical mold is 0.75-1.5cm.

[0015] Preferably, the mold in S3 is a spherical mold, and the inner diameter of the spherical mold is 1cm.

[0016] The application further discloses an application method of the slow-release oxygen agent for reducing methane emission.

[0017] Preferably, the slow-release oxygen agent is added to the sediment of the slow-flow water body in a manner of shallow injection of 6 cm under the mud.

[0018] The application further discloses a preparation method of the slow-release oxygen agent for reducing methane emission.

[0019] 1) The addition of CaO2 can create aerobic and oxidation conditions to destroy the survival conditions of methanogenic microorganisms, thereby controlling the release of methane in the sediment of the lake, and also controlling the release of endogenous pollutants. However, the direct addition of CaO2 has defects such as fast dissolution in the early stage and weakened improvement effect in the later stage. In addition, the repair effect is limited at a low dose, and the pH and NO2 ˉ -N concentration in the overlying water may be excessively high in the early stage of the test. The use of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent can slowly dissolve CaO2, prolong the action period, and also avoid the problems of excessive increase of the pH and NO2 ˉ -N concentration in the overlying water.

[0020] 2) The addition of copper sulfate supports the normal metabolic activity of the methanotrophs, promotes the degradation of the methanotrophs to methane in the cells of the methanotrophs, and the anaerobic archaea with sulfate as the electron acceptor dominates the anaerobic oxidation of methane, so the addition of the sulfate can further promote the oxidation of the methane.

[0021] 3) The addition of goethite, as a common metal oxide, has the characteristics of relative stability and non-toxicity, can provide the electron acceptor Fe 3+ needed for the oxidation of methane for the iron-dependent methanotrophs, promotes the growth and reproduction of the iron-dependent methanotrophs, and further accelerates the oxidation of the methane; and the goethite is an iron oxide with high adsorption capacity, and can simultaneously control the release of endogenous pollutants in the slow-flow water body.

[0022] 4) CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent selects PHB as embedding agent, compared with the mode of directly adding CaO2, the oxygen release rate of CaO2 can be effectively controlled, CaO2 continuously releases oxygen when meeting water, which can long-acting inhibit the methane release of lake sediment. The slow-release oxygen agent contacts with water body, the ester bond in the PHB skeleton is broken and hydrolyzed to produce water and hydrogen ion, without secondary pollution, and has biodegradability, which will not cause a large increase in organic matter concentration in a short time, and provides high-quality carbon source for denitrifying bacteria, and realizes the synchronous removal of nitrogen pollutants in water body. In addition, the PHB skeleton also provides growth and attachment space for microorganisms, and improves the abundance of microorganisms in the sediment.

[0023] The application method of the slow-release oxygen agent for reducing methane emission has the following beneficial effects:

[0024] The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent is added to the sediment of the slow-flow water body in the form of shallow injection at 4-8 cm below the mud, CaO2 is slowly dissolved and oxygen is continuously released. Compared with the direct adding mode under the same adding amount, the shallow injection can increase the utilization efficiency of oxygen in CaO2 and the methane emission reduction effect in the sediment, and can increase the action depth of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on the sediment of the slow-flow water body. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0026] Figure 1 SEM image of the slow-release oxygen agent prepared by the slow-release oxygen agent preparation method according to an embodiment of the present disclosure;

[0027] Figure 2 Comparison chart of dissolved oxygen change curve of the slow-release oxygen agent prepared according to an embodiment of the present disclosure and CaO2 added to the water body within 60 days;

[0028] Figure 3 Comparison chart of pH change curve of the slow-release oxygen agent prepared according to an embodiment of the present disclosure and CaO2 put into the water body within 60 days;

[0029] Figure 4 Comparison chart of single-mole mass change curve of methane produced by the water body within 60 days of the slow-release oxygen agent prepared according to an embodiment of the present disclosure and CaO2 put into the water body;

[0030] Figure 5 For the application method of the slow-release oxygen agent according to one embodiment of the present disclosure, a comparison chart of the single-mole mass change curve of the methane produced by the water body. DETAILED DESCRIPTION

[0031] The method of the present application will be described in further detail below with reference to the accompanying drawings and embodiments of the present application.

[0032] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0033] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0034] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] For purposes of the description hereinafter, spatial or directional terms, such as, for example, "above", "below", "top", "bottom", and the like, can be used with reference to the illustrated orientation of one element or feature to another element or feature, as the illustrative orientation is shown in the drawings. It is understood that the spatial and directional terms are used for purposes of the description hereof and in relation to the illustrated orientation and are not intended to limit the scope of the application. For example, if the device in the drawing is turned over, a component described as "above" or "below" another component would then be oriented "below" or "above" the other component. Therefore, the example term "above" can encompass both an "above" and "below" orientation. The components can also be oriented in other ways (rotated 90 degrees or at other orientations) and the included spatial or directional terms are interpreted accordingly.

[0036] Referring to Figures 1-5 The present application provides a technical solution: a preparation method of a slow-release oxygen agent for reducing methane emissions, comprising:

[0037] S1. Dissolve poly-β-hydroxybutyric acid (PHB) in dichloromethane or carbon tetrachloride organic solvent, stir uniformly, and prepare a PHB solution with a concentration of 0.2 g / mL-0.6 g / mL;

[0038] S2. Under stirring conditions, CaO2, CuSO4 (copper sulfate) and FeO(OH) (goethite) are added to the PHB solution, so that the mass ratio of PHB solution, CaO2, CuSO4 and FeO(OH) is 1000-1500:1000-1500:10-50:3-10, and CaO2, CuSO4 and FeO(OH) are uniformly suspended in PHB under stirring to obtain a suspension A;

[0039] CaO2 can create aerobic and oxidative conditions to destroy the survival conditions of methanogenic microorganisms, thereby controlling the release of methane from lake sediments, and also has the effect of controlling the release of endogenous pollutants. Direct addition of CaO2 has defects such as faster dissolution in the early stage and weakened improvement effect in the later stage. In addition, the repair effect is limited at low dosage, and the pH and NO2 ˉ -N concentration of overlying water may rise sharply at high dosage. The use of CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent can slowly dissolve CaO2, prolong its action period, and also avoid the problems of pH and NO2 ˉ -N concentration of overlying water may rise sharply at high dosage. The use of CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent can slowly dissolve CaO2, prolong its action period, and also avoid the problems of pH and NO2

[0040] The copper ion in CuSO4 supports the normal metabolic activity of the methanotroph, and can promote the degradation of the methanotroph to the methane. In addition, the sulfate as the electron acceptor of the anaerobic archaea dominates the anaerobic oxidation of the methane, and therefore the addition of the sulfate can further promote the oxidation of the methane.

[0041] FeO(OH) is a common metal oxide, has the characteristics of relative stability and non-toxicity, and can provide the electron acceptor Fe 3+ for the iron-dependent methanotroph to promote the growth and reproduction of the iron-dependent methanotroph and promote the oxidation of the methane. In addition, FeO(OH) is an iron oxide with high adsorption capacity, and can play a role in synchronously controlling the internal pollutants in the slow-flowing water body.

[0042] S3. Stir the suspension A until the dichloromethane or carbon tetrachloride volatilizes, and when the suspension A is in a semi-solid gel state, pour it into a mold, and then place it in an oven for drying. After drying to a set condition, take it out and cool it to room temperature to obtain the slow-release oxygen agent embedding CaO2 / CuSO4 / FeO(OH).

[0043] PHB has a large number of ester bonds and poor hydrophilicity, and therefore PHB is uniformly dissolved in dichloromethane or carbon tetrachloride organic solvent, and the PHB solution is uniformly mixed with CaO2 / CuSO4 / FeO(OH). Dichloromethane or carbon tetrachloride is removed by a solvent evaporation method. As the dichloromethane or carbon tetrachloride volatilizes, PHB forms spherical microparticles, and CaO2 / CuSO4 / FeO(OH) is uniformly dispersed in the PHB spherical microparticles to form the slow-release oxygen agent. The skeleton of the slow-release oxygen agent prepared by the present application is PHB, and the PHB skeleton embeds the complete mixing of CaO2 / CuSO4 / FeO(OH), and CaO2 / CuSO4 / FeO(OH) is uniformly dispersed in the PHB spherical microparticles.

[0044] When the slow-release oxygen agent contacts with the water body, the ester bonds in the PHB skeleton are broken and hydrolyzed to produce water and hydrogen ions, without secondary pollution, and the pH fluctuation of the water body is small, and CaO2 is slowly released. Compared with the direct addition method under the same dosage, the shallow injection can increase the utilization efficiency of oxygen in CaO2 and the effect of methane reduction in the sediment, and can increase the action depth of the degradable slow-release oxygen agent CaO2 / CuSO4 / FeO(OH) on the sediment of the slow-flowing water body.

[0045] The viscosity-average molecular weight of the poly-beta-hydroxybutyric acid is 50,000-80,000. The larger the molecular weight of the poly-beta-hydroxybutyric acid, the denser the slow-release oxygen agent skeleton structure, and the ester bond of the poly-beta-hydroxybutyric acid is not easy to break. The slow-release oxygen agent is not easy to degrade when put into water, which can cause the CaO2 / CuSO4 / FeO(OH) dissolution rate to be too low. If the polymer molecular weight is too small, the viscosity of the poly-beta-hydroxybutyric acid is too low, and it is not easy to form a slow-release oxygen agent skeleton that can embed CaO2 / CuSO4 / FeO(OH).

[0046] In order to facilitate production and storage, the mold is a spherical mold, and the inner diameter of the spherical mold is 0.75-1.5 cm, preferably 1 cm.

[0047] Considering the properties of dichloromethane or carbon tetrachloride, the conditions in S3 are set as follows: the drying temperature is 40-60 DEG C, and the drying time is 5-12 h, preferably the drying temperature is 50 DEG C, and the drying time is 8 h.

[0048] The application also discloses an application method of the slow-release oxygen agent for reducing methane emission. The degradable slow-release oxygen agent prepared by the preparation method of the slow-release oxygen agent is injected into the sediment of the slow-flow water body in a manner of shallow injection of 4-8 cm under the mud, and preferably in a manner of shallow injection of 6 cm under the mud. The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent is injected into the sediment of the slow-flow water body in a manner of shallow injection of 4-8 cm under the mud, slowly dissolves CaO2 and continuously releases oxygen. Compared with the direct injection method under the same injection amount, the shallow injection can increase the utilization efficiency of oxygen in CaO2 and the methane emission reduction effect on the sediment, and can increase the action depth of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on the sediment of the slow-flow water body.

[0049] Examples

[0050] At room temperature, 10 g of poly-β-hydroxybutyric acid (PHB) with a molecular weight of 600,000 was weighed into a beaker containing 20 mL of dichloromethane, stirred until dissolved, to prepare a PHB dichloromethane mixed solution with a mass / volume ratio of 0.5 g / mL, then 10 g of calcium peroxide (CaO2), 0.5 g of goethite (FeO(OH)) and 0.03 g of copper sulfate (CuSO4) were weighed, the weighed CaO2, FeO(OH) and CuSO4 were added to the PHB solution, stirred uniformly, so that the CaO2, FeO(OH) and CuSO4 were uniformly suspended in the PHB solution, to obtain a uniformly mixed CaO2 / FeO(OH) / CuSO4 suspension, the CaO2 / FeO(OH) / CuSO4 suspension was stirred until the dichloromethane evaporated, when the CaO2 / FeO(OH) / CuSO4 suspension was semi-solid gel, the CaO2 / FeO(OH) / CuSO4 suspension was poured into a spherical forming mold, then placed in a 40°C oven for drying for 5 h, cooled to room temperature, to prepare a spherical CaO2 / CuSO4 / FeO(OH) embeddable degradable slow-release oxygen agent.

[0051] As shown in Figure 1 The SEM image of the CaO2 / CuSO4 / FeO(OH) embeddable degradable slow-release oxygen agent is shown in

[0052] As shown in Figure 2 The change curve of dissolved oxygen in 60 days after the powder CaO2 and the CaO2 / CuSO4 / FeO(OH) embeddable degradable slow-release oxygen agent were added to a sealed container (the container is a cylinder with a height of 30 cm and a diameter of 10 cm; 8 cm of fresh sediment and 16 cm of overlying water were added to each reactor, and 6 cm of headspace was reserved, the same below) containing eutrophic lake water and sediments at a concentration of 150 mg / L of CaO2 effective component is shown. The water body dissolved oxygen of the CaO2 / CuSO4 / FeO(OH) embeddable degradable slow-release oxygen agent group was maintained at 2.0 mg / L or more throughout the process, while the dissolved oxygen of the powder calcium peroxide increased rapidly in the first 10 days, then continued to decline, and fell below 1.0 mg / L after 35 days. It can be seen that the slow-release oxygen agent has a longer oxygen release period and more stable effect than the powder CaO2.

[0053] As shown in Figure 3The figure shows the change of pH in 60 days after adding powder CaO2 and CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent with CaO2 effective component concentration of 150 mg / L into a sealed container containing eutrophication lake water and sediments. The pH of water body maintained between 7.5-8.5 by adding the slow-release oxygen agent of the example, while the pH of powder CaO2 was between 8.5-10.5, and the pH was >9.0 in the first 30 days, deviating from the pH range suitable for microbial survival and the limit value of surface water environmental quality standard (6.0

[0054] As shown in Figure 4 The figure shows the change of single-mole mass of methane in 60 days after adding no agent as a control group, and adding 150 mg / L powder and CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent with CaO2 effective component concentration of 150 mg / L as a test group. The sufficient substrate concentration and suitable environmental conditions before the test for 30 days made the anaerobic digestion of organic matter in the sediment sufficient, and the methane production was at a high level in the first 30 days. Then, the decrease of degradable organic matter content in the sediment caused the decrease of methane production potential, and then the methane production decreased. The strong oxidizing substances produced by the dissolution of powder in the early stage accelerated the degradation of macromolecular organic matter, and the methane production in the first 10 days was greater than that of the control group. Then, the increase of dissolved oxygen inhibited the methane production process, and the methane production increased in the late test. The degradable slow-release oxygen agent of CaO2 / CuSO4 / FeO(OH) had a long-term and stable inhibitory effect on the anaerobic digestion of organic matter in the sediment, and could significantly reduce methane emission by inhibiting methane generation and promoting the oxidation and consumption of generated methane.

[0055] As shown in Figure 5 The figure shows the effect of different adding methods on the slow-release oxygen agent. The test is divided into four groups. The first group does not add agent, the second group adds 150 mg / L powder CaO2, the third group adds CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent with CaO2 effective component concentration of 150 mg / L on the surface, and the fourth group adds CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent with CaO2 effective component concentration of 150 mg / L by injection at a depth of 6 cm in the mud. The comparison of single-mole mass change of methane in 60 days of the four groups is shown in Figure 5The control group was given sufficient substrate concentration and suitable environmental conditions 30 days before the test, which made the anaerobic digestion of organic matter in the sediment sufficient, and the methane production was at a high level in the first 30 days. Subsequently, the decrease of degradable organic matter content in the sediment led to the decrease of methane production potential, and then the methane production. The strong oxidizing substances produced by the dissolution of CaO2 in the early stage accelerated the degradation of macromolecular organic matter, so the methane production in the first 10 days was greater than that of the control group. Subsequently, the increase of dissolved oxygen inhibited the methane production process. In the late stage of the test, the decrease of dissolved oxygen increased the methane production. The surface covered CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent test group had a relatively stable and efficient inhibition effect on the anaerobic digestion of organic matter in the sediment. The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent was added by shallow injection at a depth of 6 cm below the sediment, which slowly dissolved CaO2 and continuously released oxygen. Compared with the covering addition mode under the same addition amount, the shallow injection could increase the utilization efficiency of oxygen in CaO2, increase the action depth of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on the sediment of the slow-flowing water body, and further enhance its effect on the reduction of methane emission from the sediment. The methane production of the shallow injection group was lower than that of the covering addition group, and the effect of methane reduction was more significant.

[0056] The above merely describes preferred embodiments of the present application, but is not used to limit the protection scope of the present application.

Claims

1. A method for the preparation of a slow release oxygen agent for the abatement of methane emissions, characterized in that, The application relates to a preparation method of a degradable slow-release oxygen agent embedded with CaO2 / CuSO4 / FeO(OH). S1. dissolving poly-beta-hydroxybutyric acid (PHB) in dichloromethane or carbon tetrachloride organic solvent, stirring, and preparing a PHB solution with a concentration of 0.2 g / mL-0.6 g / mL; S2. under stirring, adding CaO2, CuSO4 and FeO(OH) into the PHB solution, so that the mass ratio of the PHB solution, CaO2, CuSO4 and FeO(OH) is 1000-1500:1000-1500:10-50:3-10, stirring to uniformly suspend the CaO2, CuSO4 and FeO(OH) in the PHB, and obtaining a suspension A; S3. stirring the suspension A, evaporating the dichloromethane or carbon tetrachloride, and when the suspension A is in a semi-solid glue state, pouring into a mold, and then placing into an oven for drying, taking out after drying under a set condition, and cooling to room temperature, so as to prepare the degradable slow-release oxygen agent embedded with CaO2 / CuSO4 / FeO(OH).

2. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 1, characterized in that, The weight average molecular weight of the poly-beta-hydroxybutyric acid is 50,000-80,000.

3. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 1, characterized in that, The set condition in S3 is that the drying temperature is 40-60 DEG C, and the drying time is 5-12 h.

4. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 3, characterized in that, The set condition in S3 is that the drying temperature is 50 DEG C, and the drying time is 8 h.

5. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 1, characterized in that, The mold in S3 is a spherical mold, and the inner diameter of the spherical mold is 0.75-1.5 cm.

6. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 5, characterized in that, The mold in S3 is a spherical mold, and the inner diameter of the spherical mold is 1 cm.

7. A method of using a slow-release oxygen agent to reduce methane emissions, characterized by, The degradable slow-release oxygen agent prepared by the preparation method of the slow-release oxygen agent in any one of claims 1-6 is injected into the sediment of the slow-flow water body in a manner of shallow injection at a depth of 4-8 cm under the mud.

8. The method of claim 7, wherein the slow-release oxygen agent is used to reduce methane emissions. The degradable slow-release oxygen agent is injected into the sediment of the slow-flow water body in a manner of shallow injection at a depth of 6 cm under the mud.

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