Preparation method and application method of slow oxygen release agent for reducing methane emission

Abstract

The invention discloses a preparation method of a slow-release oxygen agent for reducing methane emission, which mainly comprises the following steps: preparing a PHB (polyhydroxybutyrate) solution, adding CaO2, copper sulfate (CuSO4) and goethite (FeO (OH)) into the PHB solution, and drying to prepare a spherical degradable slow-release oxygen agent embedded with CaO2 / CuSO4 / FeO (OH). The degradable slow-release oxygen agent prepared by the invention can inhibit methane generation and promote methane oxidation consumption, gets rid of the limitation that only the methane generation process is inhibited and the methane oxidation consumption is not promoted when CaO2 is directly added, and effectively solves the water quality problems that the action period is short, the pH is increased and the like when powder CaO2 is added. The invention further discloses an application method of the slow-release oxygen agent for reducing methane emission, the slow-release oxygen agent is added into slow-flow water body sediments in a shallow injection mode of 4-8 cm under mud, the utilization efficiency of oxygen in CaO2 and the emission reduction effect on methane in the sediments can be improved, and the action depth of the slow-release oxygen agent on the slow-flow water body sediments is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a preparation method and an application method of a slow-release oxygen agent for reducing methane emission. Background Art

[0002] Methane (CH4) is the second largest greenhouse gas in the world after carbon dioxide, and its warming effect is 28-34 times that of carbon dioxide. Although slow-flowing water bodies such as lakes only account for 0.9% of the total area of ​​the earth, among the emission sources of natural ecosystems, the methane emissions of lake ecosystems account for about 16% to 24% of the total emissions of natural ecosystems, which is much higher than the larger oceans. In recent years, the eutrophication of lakes has become increasingly serious. The excessive proliferation of algae reduces the dissolved oxygen in the water through respiration, and the lack of hydraulic disturbance in slow-flowing water bodies leads to slow negative oxygen in the atmosphere, which has aggravated the degree of hypoxia in the water body. Under anoxic / anaerobic conditions, algae and nutrients continue to accumulate in sediments, enriching the sediments with a large amount of organic matter, which produces methane through anaerobic fermentation, resulting in an increase in methane emissions year by year. Therefore, from the perspective of curbing global warming, it is of great significance to pay attention to and reduce methane emissions from lakes.

[0003] At present, the research hotspot of greenhouse gas in slow-flowing water bodies is to improve the understanding of the greenhouse gas production mechanism by measuring its emission values, but there is little research on the control of greenhouse gas in slow-flowing water bodies. The existing methods for controlling methane emissions in slow-flowing water bodies include artificial aeration, sediment dredging, bioremediation, etc.

[0004] In recent years, there have been increasing reports on the use of oxidants (hydrogen peroxide, magnesium peroxide, calcium nitrate, sodium percarbonate, calcium peroxide (CaO2), etc.) to create aerobic and oxidative conditions at the mud-water interface of slow-flowing water sediments. Among them, CaO2 has high stability. As a common food additive, it is non-toxic, harmless, does not pollute the environment, is cheap and easy to produce, and has a purity of up to 60%-80%. It is a widely used excellent oxygen supply agent and deodorant. When it is added to water, it will release oxygen and hydrogen peroxide, creating aerobic and oxidative conditions to destroy the living conditions of methanogenic microorganisms, thereby controlling the release of methane in slow-flowing water sediments, and at the same time has the effect of controlling the release of endogenous pollutants. However, the direct addition of CaO2 will cause excessive oxygen release in the early stage, resulting in a waste of oxygen source, and the oxygen release will decrease in the later stage, the action cycle is short, and direct addition will cause the pH of the water body to increase, affecting the water quality. There have been some studies on the preparation methods of slow-release oxygen agents at home and abroad, but most of the slow-release oxygen agent embedding materials prepared cannot be degraded 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 consumption process of the methane that has been produced, and cannot improve the methane emission reduction effect of slow-flowing water bodies. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a preparation method and application method of a slow-release oxygen agent for reducing methane emissions, which gets rid of the limitation that direct addition of CaO2 only inhibits the methane production process, lacks the promotion of the methane oxidation and consumption process, and cannot improve the methane emission reduction effect of slow-flowing water bodies. It also effectively solves the problem that the direct addition of CaO2 leads to a short action cycle, an increase in the pH of the water body, and affects the water quality.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

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

[0008] S1. dissolving poly-β-hydroxybutyric acid (PHB) in an organic solvent of dichloromethane or carbon tetrachloride and stirring to obtain a PHB solution having a concentration of 0.2 g / mL-0.6 g / mL;

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

[0010] S3. Stir the suspension A until the dichloromethane or carbon tetrachloride is volatilized and the suspension A is in a semisolid colloid state, pour it into a mold, put it into an oven for drying, take it out after drying to the set conditions, and cool it to room temperature to obtain a slow-release oxygen agent encapsulating CaO2 / CuSO4 / FeO(OH).

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

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

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

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

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

[0016] The present invention also discloses an application method of a slow-release oxygen agent for reducing methane emission, wherein the slow-release oxygen agent prepared by any one of the preparation methods of the slow-release oxygen agent is added into the sediment of a slow-flowing water body by shallow injection at 4-8 cm below the mud.

[0017] Preferably, the slow-release oxygen agent is added to the sediment of the slow-flowing water body by means of shallow injection 6 cm below the mud.

[0018] The method for preparing a slow-release oxygen agent for reducing methane emissions of the present invention has the following beneficial effects:

[0019] 1) Adding CaO2 can create aerobic and oxidative conditions to destroy the living conditions of methanogenic microorganisms, thereby controlling the release of methane from lake sediments and controlling the release of endogenous pollutants. Direct addition of CaO2 has the disadvantages of rapid dissolution in the early stage and weakened improvement effect in the later stage. In addition, the remediation effect is limited at low doses, and there may be changes in the pH and NO2 of the overlying water in the early stage of the experiment at high doses. ˉ -N concentration exceeds the standard. Use CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent to slowly dissolve CaO2, prolong its action period, and avoid the overlying water pH and NO2 ˉ -N concentration increased significantly.

[0020] 2) Add copper sulfate, in which copper ions support the normal metabolic activities of methanotrophic bacteria and promote the degradation of methane by methanotrophic bacteria in methanotrophic bacteria cells. In addition, anaerobic archaea that use sulfate as an electron acceptor dominate the anaerobic oxidation of methane, so the addition of sulfate can further promote the oxidation of methane.

[0021] 3) Add goethite. As a common metal oxide, goethite is relatively stable and non-toxic, and can provide iron-dependent methanotrophic bacteria with the electron acceptor Fe required for methane oxidation. 3+ , promoting the growth and reproduction of iron-dependent methanotrophic bacteria, thereby accelerating the oxidation of methane; and goethite is an iron oxide with high adsorption capacity, which can play a role in synchronously controlling the release of endogenous pollutants in slow-flowing water bodies.

[0022] 4) CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent uses PHB as an embedding agent. Compared with the direct addition of CaO2, it can effectively control the oxygen release rate of CaO2. CaO2 continuously releases oxygen when it comes into contact with water, which can inhibit the release of methane from lake sediments in the long term. When the slow-release oxygen agent comes into contact with water, the ester bonds in the PHB skeleton break and hydrolyze to produce water and hydrogen ions. There is no secondary pollution, it is biodegradable, and it will not cause a significant increase in the concentration of organic matter in a short period of time. It also provides a high-quality carbon source for denitrifying bacteria, achieving the simultaneous removal of nitrogen pollutants from water bodies. In addition, the PHB skeleton also provides growth and attachment space for microorganisms, increasing the abundance of microorganisms in sediments.

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

[0024] The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent is added to the sediment of slow-flowing water bodies by shallow injection at 4-8cm below the mud, slowly dissolving CaO2 and continuously releasing oxygen. Compared with direct addition at the same dosage, shallow injection can increase the utilization efficiency of oxygen in CaO2 and the effect of reducing methane emissions in sediments, and can increase the depth of action of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on the sediment of slow-flowing water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a SEM image of a slow-release oxygen agent prepared by a method for preparing a slow-release oxygen agent according to one embodiment of the present disclosure;

[0027] Figure 2 A comparison diagram of dissolved oxygen change curves after a slow-release oxygen agent and CaO2 prepared according to an embodiment of the present disclosure are added to a water body within 60 days;

[0028] Figure 3 A comparison diagram of pH change curves of a slow-release oxygen agent and CaO2 prepared according to an embodiment of the present disclosure placed in water within 60 days;

[0029] Figure 4 A comparison diagram of the change curve of the single molar mass of methane produced by a water body when a slow-release oxygen agent and CaO2 prepared according to an embodiment of the present disclosure are placed in a water body for 60 days;

[0030] Figure 5 The figure is a comparison chart of the change curves of the single molar mass of methane produced by water bodies between the slow-release oxygen agent application method according to one embodiment of the present disclosure and other application methods. DETAILED DESCRIPTION

[0031] The method of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the 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, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

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

[0035] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0036] See also Figure 1-Figure 5 The present invention provides a technical solution: a method for preparing a slow-release oxygen agent for reducing methane emissions, comprising:

[0037] S1. dissolving poly-β-hydroxybutyric acid (PHB) in an organic solvent of dichloromethane or carbon tetrachloride, stirring evenly, and preparing 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 to make the mass ratio of PHB solution, CaO2, CuSO4 and FeO (OH) be 1000-1500: 1000-1500: 10-50: 3-10, and stirring is performed so that CaO2, CuSO4 and FeO (OH) are uniformly suspended in PHB to obtain a suspension A;

[0039] CaO2 can create aerobic and oxidative conditions to destroy the living conditions of methanogenic microorganisms, thereby controlling the release of methane from lake sediments and controlling the release of endogenous pollutants. Direct addition of CaO2 has the disadvantages of rapid dissolution in the early stage and weakened improvement effect in the later stage. In addition, the remediation effect is limited at low doses, and at high doses, there may be changes in the pH and NO2 of the overlying water in the early stage of the experiment. ˉ -N concentration exceeds the standard. Use CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent to slowly dissolve CaO2, prolong its action period, and avoid the overlying water pH and NO2 ˉ -N concentration increased significantly.

[0040] The copper ions in CuSO4 support the normal metabolic activities of methanotrophic bacteria and can promote the degradation of methane by methanotrophic bacteria in methanotrophic bacteria cells. In addition, anaerobic archaea that use sulfate as an electron acceptor dominate the anaerobic oxidation of methane. Therefore, the addition of sulfate can further promote the oxidation of methane.

[0041] As a common metal oxide, FeO(OH) is relatively stable and non-toxic, and can provide the electron acceptor Fe required for methane oxidation for iron-dependent methanotrophic bacteria. 3+ , promoting the growth and reproduction of iron-dependent methanotrophic bacteria and promoting the oxidation of methane; and FeO(OH) is an iron oxide with high adsorption capacity, which can play a role in synchronously controlling endogenous pollutants in slow-flowing water.

[0042] S3. Stir the suspension A until the dichloromethane or carbon tetrachloride is volatilized and the suspension A is in a semisolid colloid state, pour it into a mold, put it into an oven for drying, take it out after drying to the set conditions, and cool it to room temperature to obtain a slow-release oxygen agent encapsulating CaO2 / CuSO4 / FeO(OH).

[0043] Taking advantage of the fact that PHB contains a large number of ester bonds and has poor hydrophilicity, PHB is uniformly dissolved in an organic solvent of dichloromethane or carbon tetrachloride, and the PHB solution is uniformly mixed with CaO2 / CuSO4 / FeO(OH). The dichloromethane or carbon tetrachloride is removed by a solvent volatilization method, and as the dichloromethane or carbon tetrachloride volatilizes, PHB forms spherical particles, and CaO2 / CuSO4 / FeO(OH) is uniformly dispersed in the PHB spherical particles to form a slow-release oxygen agent. The skeleton of the slow-release oxygen agent prepared by the present invention is PHB, and the PHB skeleton completely encapsulates the mixed CaO2 / CuSO4 / FeO(OH), and CaO2 / CuSO4 / FeO(OH) is uniformly dispersed in the PHB spherical particles.

[0044] When the slow-release oxygen agent comes into contact with the water body, the ester bond in the PHB skeleton breaks and hydrolyzes, producing water and hydrogen ions, without secondary pollution, with small fluctuations in the pH of the water body, and slowly releasing CaO2. Compared with direct addition at the same dosage, shallow injection can increase the utilization efficiency of oxygen in CaO2 and the effect of reducing methane emissions in sediments, and can increase the depth of action of CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on sediments in slow-flowing water bodies.

[0045] The viscosity-average molecular weight of poly-β-hydroxybutyric acid is 50,000-80,000. The larger the molecular weight of poly-β-hydroxybutyric acid, the denser the skeleton structure of the slow-release oxygen agent, the less likely the ester bond of poly-β-hydroxybutyric acid will break, and the slow-release oxygen agent will not easily degrade when put into water, which will lead to too low dissolution rate of CaO2 / CuSO4 / FeO(OH), too small molecular weight of the polymer, too low viscosity of poly-β-hydroxybutyric acid, and it will not be 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] Taking into account the characteristics of dichloromethane or carbon tetrachloride, the conditions set in S3 are: drying temperature of 40-60° C., drying time of 5-12 h, preferably drying temperature of 50° C., drying time of 8 h.

[0048] The present invention also discloses an application method of a slow-release oxygen agent for reducing methane emissions, wherein the degradable slow-release oxygen agent prepared by the preparation method of the slow-release oxygen agent disclosed in the present invention is added to the sediment of a slow-flowing water body by shallow injection at 4-8 cm below the mud, preferably by shallow injection at 6 cm below the mud. The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent is added to the sediment of a slow-flowing water body by shallow injection at 4-8 cm below the mud, and CaO2 is slowly dissolved and oxygen is continuously released. Compared with the direct addition method at the same dosage, shallow injection can increase the utilization efficiency of oxygen in CaO2 and the methane emission reduction effect in the sediment, and can increase the depth of action of the CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on the sediment of a slow-flowing water body.

[0049] Example

[0050] At room temperature, weigh 10g of poly-β-hydroxybutyric acid (PHB) with a molecular weight of 60,000 and add it to a beaker filled with 20mL of dichloromethane, stir until dissolved, and prepare a PHB methane mixed solution with a mass volume ratio of 0.5g / mL. Then weigh 10g of calcium peroxide (CaO2), 0.5g of goethite (FeO(OH)) and 0.03g of copper sulfate (CuSO4), add the weighed CaO2, FeO(OH) and CuSO4 to the PHB solution, stir evenly, and make CaO2, FeO(OH) and CuSO4 in P The mixture is uniformly suspended in HB solution to obtain a uniformly mixed CaO2 / FeO(OH) / CuSO4 suspension, and the CaO2 / FeO(OH) / CuSO4 suspension is stirred until the dichloromethane is volatilized. When the CaO2 / FeO(OH) / CuSO4 suspension is in a semisolid colloid state, the CaO2 / FeO(OH) / CuSO4 suspension is poured into a spherical molding mold, and then placed in an oven at 40°C and dried for 5 hours, and then cooled to room temperature to obtain a spherical embedded CaO2 / CuSO4 / FeO(OH) biodegradable slow-release oxygen agent.

[0051] like Figure 1 The figure shows the SEM image of the CaO2 / CuSO4 / FeO(OH) embedded biodegradable slow-release oxygen agent. CaO2, FeO(OH) and CuSO4 are evenly dispersed in the PHB solution. The dichloromethane is removed by solvent evaporation. As the dichloromethane evaporates, CaO2, FeO(OH) and CuSO4 are evenly dispersed in the PHB skeleton to form a slow-release oxygen agent.

[0052] like Figure 2 The figure shows the change curve of dissolved oxygen in 60 days when powdered CaO2 and CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent were added to a sealed container (the container is a cylinder, 30 cm high and 10 cm in diameter; 8 cm of fresh sediment and 16 cm of overlying water were added to each reactor, and 6 cm of headspace was retained, the same below) with a concentration of 150 mg / L of CaO2 effective ingredient. The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent group maintained the dissolved oxygen in the water body above 2.0 mg / L throughout the process, while the dissolved oxygen in powdered calcium peroxide increased rapidly in the first 10 days, and then continued to decline, falling below 1.0 mg / L after 35 days. By comparison, it can be seen that the slow-release oxygen agent has a longer oxygen release period than powdered CaO2 and a more stable effect.

[0053] like Figure 3The figure shows the pH change curve within 60 days when the powdered CaO2 and the degradable and sustained-release oxygen agent CaO2 / CuSO4 / FeO(OH) are added to a sealed container filled with eutrophic lake water and sediment at a concentration of 150 mg / L of the active ingredient CaO2. When the sustained-release oxygen agent prepared in the implementation example is put into use, the pH of the water body is maintained between 7.5 and 8.5, while the pH of the powdered CaO2 is between 8.5 and 10.5, and the pH > 9.0 in the first 30 days, deviating from the pH range suitable for the survival of microorganisms and the limit value of the surface water environmental quality standard (6.0 < pH < 9.0, GB3838 - 2002). By comparison, it can be seen that the CaO2 / CuSO4 / FeO(OH) degradable and sustained-release oxygen agent will not cause large fluctuations in the pH of the water body and affect the water quality.

[0054] As Figure 4 shown, without adding any agents as the control group, adding 150 mg / L of powdered < and the test group of the CaO2 / CuSO4 / FeO(OH) degradable and sustained-release oxygen agent with 150 mg / L of the active ingredient calcium peroxide, the figure shows the curve of the change in the single - molar mass of methane production within 60 days. In the first 30 days of the test, the sufficient substrate concentration and suitable environmental conditions in the control group enabled the anaerobic digestion of organic matter in the sediment to be sufficient, and the methane production was at a relatively high level in the first 30 days. Subsequently, the decrease in the content of degradable organic matter in the sediment led to a decrease in the methane production potential, and then the methane production decreased; the strong oxidizing substances generated by the dissolution of the powdered < in the early stage accelerated the degradation of macromolecular organic matter, making the methane production greater than that of the control group in the first 10 days. Subsequently, the increase in dissolved oxygen inhibited the methane production process. In the later stage of the test, the decrease in dissolved oxygen would increase the methane production again; the CaO2 / CuSO4 / FeO(OH) degradable and sustained-release oxygen agent has a long - term and stable inhibitory effect on the anaerobic digestion of organic matter in the sediment, and can significantly reduce methane emissions by inhibiting methane generation and promoting the coupling of methane oxidation consumption.

[0055] As Figure 5 shown, the figure shows the influence of different dosing methods on the effect of the sustained-release oxygen agent. The test is divided into four groups. The first group does not add any agents, the second group adds 150 mg / L of powdered CaO2, the third group covers the surface and adds the CaO2 / CuSO4 / FeO(OH) degradable and sustained-release oxygen agent with 150 mg / L of the active ingredient CaO2, and the fourth group adds the CaO2 / CuSO4 / FeO(OH) degradable and sustained-release oxygen agent with 150 mg / L of the active ingredient CaO2 by means of shallow injection 6 cm below the mud. The curves of the change in the single - molar mass of methane production in the four - group tests within 60 days are compared as Figure 5As shown. In the first 30 days of the experiment, the sufficient substrate concentration and suitable environmental conditions of the control group 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 reduction of the content of degradable organic matter in the sediment reduced the methane production potential, and then the methane production decreased. The strong oxidizing substances produced by the early dissolution of powdered CaO2 accelerated the degradation of macromolecular organic matter, making the methane production in the first 10 days greater than that of the control group. Then, the increase in dissolved oxygen inhibited the methane production process. In the later stage of the experiment, the decrease in 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 inhibitory effect on the anaerobic digestion of organic matter in the sediment. The CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent was added by injection in a shallow layer 6 cm below the mud, slowly dissolving CaO2 and continuously releasing oxygen. Compared with the covering addition method at the same dosage, shallow injection can increase the utilization efficiency of oxygen in CaO2, increase the depth of action of CaO2 / CuSO4 / FeO(OH) degradable slow-release oxygen agent on slow-flow water sediments, and thus enhance its emission reduction effect on methane fusibility in sediments. The methane production of the shallow injection group is lower than that of the covering addition group, and the methane emission reduction effect is more significant.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A method for preparing a slow-release oxygen agent for reducing methane emissions, characterized in that: include: S1. dissolving poly-β-hydroxybutyric acid (PHB) in an organic solvent of dichloromethane or carbon tetrachloride and stirring to obtain a PHB solution having a concentration of 0.2 g / mL-0.6 g / mL; S2. Under stirring conditions, CaO2, CuSO4 (copper sulfate) and FeO (OH) (goethite) are added to the PHB solution to make the mass ratio of PHB solution, CaO2, CuSO4 and FeO (OH) be 1000-1500: 1000-1500: 10-50: 3-10, and stirring is performed so that CaO2, CuSO4 and FeO (OH) are uniformly suspended in PHB to obtain a suspension A; S3. Stir the suspension A until the dichloromethane or carbon tetrachloride is volatilized and the suspension A is in a semisolid colloid state, pour it into a mold, put it into an oven for drying, take it out after drying under set conditions, and cool it to room temperature to obtain a degradable slow-release oxygen agent encapsulating 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 viscosity average molecular weight of the poly-β-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 conditions set in S3 are: drying temperature is 40-60° C., and drying time is 5-12 hours.

4. The method for preparing a slow-release oxygen agent for reducing methane emissions according to claim 3, characterized in that: The conditions set in S3 are: drying temperature is 50° C., and drying time is 8 hours.

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 for using a slow-release oxygen agent to reduce methane emissions, characterized in that: The degradable slow-release oxygen agent prepared by the method for preparing the slow-release oxygen agent according to any one of claims 1 to 6 is added into the sediment of the slow-flowing water body by shallow injection at 4-8 cm below the mud.

8. The method for using a slow-release oxygen agent for reducing methane emissions according to claim 7, characterized in that: The degradable slow-release oxygen agent is added into the sediment of the slow-flowing water body by injection in a shallow layer 6 cm below the mud.

Images