Method for establishing nitrous oxide emission model, emission estimation method and system for landfill

Abstract

The present invention discloses a method for establishing a nitrous oxide emission model of a landfill, an emission estimation method and a system, wherein the emission model establishment method comprises: obtaining historical garbage-nitrous oxide emission information of a landfill; establishing a N2O emission model based on a Logistic model, wherein the model parameters are a coefficient of change of oxygen concentration over time, a rate of change of garbage N2O production potential with oxygen concentration, an intercept of change of garbage N2O production potential with oxygen concentration, a landfill N2O emission half-life, and a constant indicating the midpoint position of an S curve of N2O emission; inputting the acquired garbage-nitrous oxide emission information into the N2O emission model, fitting the model parameters, and obtaining the model parameter value ranges of different garbage types. The N2O emission model established by the method can solve the problem of low estimation accuracy of a single landfill, and can quickly estimate the total amount of N2O emissions from landfills in a large area.

Description

Technical Field

[0001] The invention relates to a method for establishing a nitrous oxide emission model for a landfill, an emission estimation method and a system, and belongs to the field of greenhouse gas monitoring. Background Art

[0002] Nitrous oxide (N2O) is a greenhouse gas that has a significant impact on the global climate. Landfills are one of the main ways to treat municipal solid waste and are also important sources of N2O and methane (CH4) emissions. N2O has a very high warming effect, with a warming potential per molecule of about 273 times that of carbon dioxide (CO2), and can exist stably in the atmosphere for a long time, which has a strong destructive effect on the ozone layer. In landfills, N2O emissions are an issue that needs to be paid attention to in environmental management.

[0003] At present, the field monitoring of N2O emission flux is mainly completed by static box and eddy covariance methods. On this basis, the average value of data from multiple measurement points is used to and landfill area ,time The N2O emission can be calculated by multiplying the product of

[0004]

[0005] On the one hand, this method has a large error. On the landfill site, N2O emissions have significant spatial differences. N2O is mainly concentrated on the landfill operation surface, and the emissions in other areas of the landfill are significantly lower. However, due to the large area of ​​the landfill, it is often difficult to arrange enough flux monitoring points in actual monitoring activities due to cost constraints. Therefore, the above formula The value of has a large error, which leads to inaccurate emission estimates. On the other hand, the on-site monitoring method is not suitable for estimating the total amount of N2O emissions from landfills in a large area (specific geographical area, specific country), and it takes a lot of manpower and material resources to conduct on-site monitoring of all landfills within the range. Summary of the invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for establishing a nitrous oxide emission model, an estimation method and a system for a landfill in view of the shortcomings of the prior art. The N2O estimation model established by this method can solve the problem of low estimation accuracy of a single landfill and can quickly estimate the total amount of N2O emissions from landfills in a large area.

[0007] In order to solve the above technical problems, the present invention discloses a method for establishing a nitrous oxide emission model for a landfill, comprising:

[0008] S11. Obtain historical garbage-nitrous oxide emission information of the landfill, wherein the garbage-nitrous oxide emission information includes:

[0009] The nitrogen content of the incoming garbage, whether the garbage has been pre-processed by mechanical crushing, and the continuous monitoring data of N2O emissions on the same working surface; the continuous monitoring data of N2O emissions on the same working surface includes the time step of two adjacent layers of landfill and the N2O emissions in the time period between two adjacent layers of landfill;

[0010] S12, inputting the obtained garbage-nitrous oxide emission information into the N2O emission model, fitting the parameters of the N2O emission model, and obtaining the value ranges of the model parameters for different garbage types;

[0011] The N2O emission model is:

[0012] ;

[0013] Where n is the landfill layer number, n>1; is the time step for filling two adjacent layers, in h; For the The time point when the landfill of the layer ends, in hours. ; for N2O emissions during the time period, in mg N·kg -1 waste; is the coefficient of change of oxygen concentration over time, in %·h -1 ; is the rate of change of the potential for N2O generation from garbage with oxygen concentration, in mg N·kg -1 waste % -1 ; is the intercept of the change of N2O generation potential of garbage with oxygen concentration, in mg N·kg -1 waste; k is the half-life of N2O emissions from landfills, in hours -1 ; is a constant indicating the midpoint of the S-curve of N2O emissions;

[0014] The parameters of the N2O emission model are: , , , k, .

[0015] Specifically, in step S12, SPSS software is used to fit the parameters of the N2O emission model.

[0016] Specifically, the coefficient of change of oxygen concentration over time is The value range is 0.02~0.06%·h -1 ;

[0017] The rate of change of N2O generation potential from garbage with oxygen concentration The value range is: if the nitrogen content of the incoming garbage is less than 2%, Value range: 0~0.1 mg N·kg -1 waste % -1 If the nitrogen content of the incoming garbage is in the range [2%, 3%], The value is 0.1~0.5 mg N·kg -1 waste % -1 If the nitrogen content of the incoming garbage is greater than 3%, The value is 0.5~0.6 mgN·kg -1 waste % -1 ;

[0018] Intercept of N2O generation potential of garbage as a function of oxygen concentration The value is -0.5~0 mg N·kg -1 waste;

[0019] Half-life of N2O emissions from landfills The value of is: For garbage that has not been mechanically crushed before landfill, the value of k is 0~0.05 h -1 For garbage that has been pre-processed by mechanical crushing, k is 0.05~0.45 h -1 ;

[0020] A constant indicating the midpoint of the S-curve for N2O emissions The value range is 2~5.

[0021] Preferably, the parameter values ​​of the N2O emission model are:

[0022] = 0.04%·h -1 , = 0.3 mg N kg -1 waste % -1 , = -0.25 mg N kg -1 waste, = 3.5, = 0.025 h -1 .

[0023] On the other hand, the present invention also discloses a method for estimating nitrous oxide emissions from a landfill, comprising the steps of:

[0024] S21. Calculate the landfill N2O emission factor EF:

[0025] For the landfill nitrous oxide emission model established according to the above method, the model parameter values ​​are determined according to the garbage characteristics of the landfill to be estimated. As an independent variable, Get under conditions The garbage characteristics include the nitrogen content of the incoming garbage and whether the garbage has been pre-processed by mechanical crushing;

[0026] if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset Change rate threshold;

[0027] S22. The annual estimated value Q of nitrous oxide emissions from landfills is:

[0028]

[0029] Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

[0030] Specifically, in step S21, Matlab programming is used to draw Follow The changing curve obtains and calculate the value of The rate of change of landfill N2O emission factor EF is obtained.

[0031] Preferably, the preset Change rate threshold It is 0.1%.

[0032] On the other hand, the present invention also discloses a system for estimating nitrous oxide emissions from a landfill, comprising:

[0033] The landfill N2O emission factor EF calculation module 1 is used to calculate the landfill N2O emission factor EF. The specific steps are: for the landfill nitrous oxide emission model established according to the above method, according to the garbage characteristics of the landfill to be estimated, determine the model parameter values, and As an independent variable, Get under conditions The garbage characteristics include the nitrogen content of the incoming garbage and whether the garbage has been pre-processed by mechanical crushing;

[0034] if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset Change rate threshold;

[0035] The landfill nitrous oxide emission estimation value acquisition module 2 is used to calculate the annual estimation value Q of the landfill nitrous oxide emission:

[0036] ;

[0037] Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

[0038] Beneficial effects: Compared with the prior art, the landfill nitrous oxide emission model establishment method, emission estimation method and system disclosed in the present invention can realize the estimation of N2O emission from a single landfill and a large-scale landfill, with high estimation accuracy and low estimation cost. The method innovatively proposes a landfill N2O emission model, revealing the essential characteristics of landfill N2O emission: N2O is concentrated on the landfill working surface and the release amount reaches a stable level after a certain period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0040] Figure 1 It is a curve diagram of N2O emission flux under a single batch landfill simulation system;

[0041] Figure 2 It is the N2O cumulative emission curve under the single batch landfill simulation system;

[0042] Figure 3 A flow chart of a method for establishing a nitrous oxide emission model for a landfill disclosed in the present invention;

[0043] Figure 4 It is a schematic diagram of the curve of N2O emissions under a multi-batch landfill simulation system;

[0044] Figure 5 It is a flow chart of the method for estimating nitrous oxide emissions from landfills disclosed in the present invention;

[0045] Figure 6 The present invention is a schematic diagram of the composition of the landfill nitrous oxide emission estimation system disclosed in the present invention. DETAILED DESCRIPTION

[0046] Landfills usually use batch landfilling, with each batch filling one layer. The N2O emission flux in a single batch landfill simulation system follows the characteristics of first increasing and then decreasing. Taking two typical experiments as examples, the curve of the N2O emission flux in a single batch landfill simulation system is as follows: Figure 1 As shown; the N2O cumulative emission under the single batch landfill simulation system presents an S-shaped curve. Taking two typical experiments as examples, the N2O cumulative emission curve under the single batch landfill simulation system is shown in Figure 2 As shown, this process can be expressed by the Logistic model:

[0047] ;

[0048] Where, t is the landfill time, h; for Cumulative N2O emissions from landfill systems at time points, mg N·kg -1 waste; M is the N2O emission potential of the system waste, that is, the maximum amount of waste that can be emitted in the system, mg N·kg -1 waste; k is the half-life of N2O emission from landfill, h -1 ; is a constant indicating the midpoint of the S-curve of N2O emissions;

[0049] Many papers have shown that the N2O emission potential M of system garbage and oxygen concentration show a significant positive correlation; M and oxygen concentration The relationship can be expressed as:

[0050] ;

[0051] in, is the oxygen concentration, %; is the oxygen concentration N2O emission potential of garbage, mg N·kg -1 waste; is the rate of change of N2O generation potential of garbage with oxygen concentration, mg N·kg -1 waste % -1 ; is the intercept of the variation of N2O generation potential of garbage with oxygen concentration, mg N·kg -1 The following references 1-3 provide examples of studies on M and oxygen concentration.

[0052] Document 1: Feng, H.; Wang,

[0053] Document 2:Wang,

[0054] Literature 3: Zhang, C.; Wang,

[0055] N2O emissions from landfills are mainly concentrated on the landfill working surface. The first layer of landfill waste is exposed to an oxygen concentration of 21%. The period before the second layer of waste is landfilled (0-100%) is 100%. ) where N2O emissions are:

[0056] ;

[0057] in, The time point when the first layer of garbage landfill ends, that is, the time point when the second layer of garbage landfill begins, which is equal to the time step ; is the oxygen concentration to which the first layer of landfill waste is exposed, i.e. 21%; is the N2O emission potential of garbage at 21% oxygen concentration, mg N·kg -1 waste;

[0058] When the second layer of landfill waste covers the first layer of waste, the former is placed under 21% oxygen concentration, while the latter has a lower oxygen concentration. Assuming that the oxygen concentration decreases linearly over time:

[0059] ;

[0060] in, is the rate of change of oxygen concentration over time, %·h -1 ;

[0061] Therefore, in During this period, the N2O emissions from the two layers of landfilled garbage were:

[0062] ;

[0063] In this kind of pile, During this period, n>1, the N2O emission of the n-layer garbage is:

[0064] ;

[0065] Based on the above derivation, the present invention discloses a method for establishing a nitrous oxide emission model for a landfill, such as Figure 3 As shown, including:

[0066] S11. Obtain historical garbage-nitrous oxide emission information of the landfill, wherein the garbage-nitrous oxide emission information includes:

[0067] The nitrogen content of the incoming garbage, whether the garbage has been pre-processed by mechanical crushing, and the continuous monitoring data of N2O emissions on the same working surface; the continuous monitoring data of N2O emissions on the same working surface includes the time step of two adjacent layers of landfill and the N2O emissions in the time period between two adjacent layers of landfill;

[0068] S12, inputting the obtained garbage-nitrous oxide emission information into the N2O emission model, fitting the parameters of the N2O emission model, and obtaining the value ranges of the model parameters for different garbage types;

[0069] The N2O emission model is:

[0070] ;

[0071] Where n is the landfill layer number, n>1; is the time step for filling two adjacent layers, in h, usually 1 h; For the The time point when the landfill of the layer ends, in hours. ; for N2O emissions during the time period, in mg N·kg -1 waste; is the coefficient of change of oxygen concentration over time, in %·h -1 ; is the rate of change of the potential for N2O generation from garbage with oxygen concentration, in mg N·kg -1 waste % -1 ; is the intercept of the change of N2O generation potential of garbage with oxygen concentration, in mg N·kg -1 waste; k is the half-life of N2O emissions from landfills, in hours -1 ; is a constant indicating the midpoint of the S-curve of N2O emissions;

[0072] The parameters of the N2O emission model are: , , , , .

[0073] Literature 4: Ye, R.; Huo, W.; Shao, Y.; Wang, H.; Lu, W.; Zhang, H. Fungalcommunity diversity and their contribution to nitrogen cycling in in-situaerated landfills: Insights from field and laboratory studies. WasteManagement 2024, 179, 1-11, Article. DOI: 10.1016 / j.wasman.2024.02.048.

[0074] Document 5: Nag, M.; Shimaoka, T.; Komiya, T. Optimization of operations for nitrous oxide production and mitigation in aerobic and Aerobic-Anaerobiclandfill method on MSW degradation. Science of the Total Environment 2019,696. DOI: 10.1016 / j.scitotenv.2019.134045.

[0075] Document 6: Janne, R.; Mari, P.; Annalea, L.; Tea, T.; Mika, A.; Juha-Pekka, T.; Tuomas, L.; Timo, V. Nitrous oxide emissions from a municipallandfill. Environmental Science & Technology 2005, 39 (20), 7790.

[0076] This example obtains site data and laboratory data from the above-mentioned documents 1-3 and documents 4-6, uses SPSS software to fit the parameters of the N2O emission model, and analyzes the influence of each parameter on the model results. The results are as follows:

[0077] (1) Oxygen concentration variation coefficient over time :

[0078] In the model construction, it is assumed that the oxygen concentration decreases linearly with the landfill time. The value range is 0.02~0.06%·h -1 , The uncertainty has little impact on the model results;

[0079] (2) Rate of change of N2O production potential of garbage with oxygen concentration :

[0080] It is the most critical parameter affecting the model results. According to laboratory rules, the N2O generation potential of garbage is positively correlated with oxygen concentration. It has a positive correlation with the nitrogen content in the garbage. If the nitrogen content of the incoming garbage is less than 2%, Value range: 0~0.1 mg N·kg -1 waste % -1If the nitrogen content of the incoming garbage is in the range [2%, 3%], The value is 0.1~0.5 mgN·kg -1 waste % -1 If the nitrogen content of the incoming garbage is greater than 3%, The value is 0.5~0.6 mg N·kg -1 waste % -1 ;

[0081] (3) Intercept of the change of N2O production potential of garbage with oxygen concentration :

[0082] In the actual venue, -0.5~0 mg N·kg -1 waste, the uncertainty of this parameter has a negligible impact on the model results;

[0083] (4) Half-life k of N2O emission from landfill:

[0084] <0.05 h -1 The time has a significant impact on the model results. For garbage that has not been mechanically crushed before landfill, the value of k is 0~0.05 h -1 For garbage that has been pre-processed by mechanical crushing, k is 0.05~0.45 h -1 .

[0085] (5) Constant indicating the midpoint of the S-curve of N2O emissions :

[0086] The value is 2~5, and the uncertainty of this parameter has a negligible impact on the emission factor.

[0087] In this embodiment, the model parameter values ​​are set as: = 0.04%·h -1 , = 0.3 mg N kg -1 waste % -1 , = -0.25 mg N kg -1 waste, = 3.5, = 0.025 h -1 .

[0088] The model for estimating nitrous oxide emissions from landfills established in steps S11-S12 depicts a complex S-shaped curve, such as Figure 4 E1 is the surface garbage layer. The nitrous oxide emissions during the time period, there is only one layer of garbage during this time period, that is, E1 is The nitrous oxide emission from the garbage layer of the working face during the time period; E2 is the nitrous oxide emission from the second garbage layer from top to bottom. The nitrous oxide emissions in the time period, there are two layers of garbage in this time period, that is, E1 + E2 is The nitrous oxide emission from the garbage layer of the working face during the time period; E3 is the emission of the third garbage layer from top to bottom. The nitrous oxide emissions in the time period, there are three layers of garbage in this time period, namely E1+ E2+ E3 The nitrous oxide emissions from the garbage layer at the working face during the time period; when the initially landfilled garbage gradually stops producing N2O, the curve enters a stable stage, and the stable value A is the landfill N2O emission factor EF.

[0089] Thus, the present invention discloses a method for estimating nitrous oxide emissions from a landfill, such as Figure 5 As shown, the steps include:

[0090] S21. Calculate the landfill N2O emission factor EF:

[0091] For the model established by the above landfill nitrous oxide emission model establishment method, the model parameter values ​​are determined according to the garbage characteristics of the landfill to be estimated. As an independent variable, Get under conditions The value of

[0092] The garbage characteristics include the nitrogen content of the incoming garbage and whether the garbage has been pre-processed by mechanical crushing;

[0093] if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset The change rate threshold, in this embodiment The value is 0.1%.

[0094] condition To ensure , otherwise the model has no physical meaning.

[0095] In this embodiment, Matlab programming is used to draw Follow The changing curve obtains and calculate the value of The rate of change of landfill N2O emission factor EF is obtained.

[0096] S22. The annual estimated value Q of nitrous oxide emissions from landfills is:

[0097] ;

[0098] Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

[0099] The present invention also discloses a landfill nitrous oxide emission estimation system for realizing the above method, such as Figure 6 As shown, including:

[0100] The landfill N2O emission factor EF calculation module 1 is used to calculate the landfill N2O emission factor EF. The specific steps are: for the model established by the landfill nitrous oxide emission model establishment method, As an independent variable, Get under conditions The value of

[0101] if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset Change rate threshold;

[0102] The landfill nitrous oxide emission estimation value acquisition module 2 is used to calculate the annual estimation value Q of the landfill nitrous oxide emission:

[0103] ;

[0104] Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

[0105] The present invention provides a method and idea for estimating nitrous oxide emissions from landfills. There are many methods and approaches to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A method for establishing a nitrous oxide emission model for a landfill, characterized in that: Includes steps: S11. Obtain historical garbage-nitrous oxide emission information of the landfill, wherein the garbage-nitrous oxide emission information includes: The nitrogen content of the incoming garbage, whether the garbage has been pre-processed by mechanical crushing, and the continuous monitoring data of N2O emissions on the same working surface; the continuous monitoring data of N2O emissions on the same working surface includes the time step of two adjacent layers of landfill and the N2O emissions in the time period between two adjacent layers of landfill; S12, inputting the obtained garbage-nitrous oxide emission information into the N2O emission model, fitting the parameters of the N2O emission model, and obtaining the value ranges of the model parameters for different garbage types; The N2O emission model is: ； Where n is the landfill layer number, n>1; is the time step for filling two adjacent layers, in h; For the The time point when the landfill of the layer ends, in hours. ; for N2O emissions during the time period, in mg N·kg -1 waste; is the coefficient of change of oxygen concentration over time, in %·h -1 ; is the rate of change of N2O generation potential of garbage with oxygen concentration, in mg N·kg -1 waste % -1 ; is the intercept of the change of N2O generation potential of garbage with oxygen concentration, in mg N·kg -1 waste; k is the half-life of N2O emissions from landfills, in hours -1 ; is a constant indicating the midpoint of the S-curve of N2O emissions; The parameters of the N2O emission model are: , , , k, .

2. The method for establishing a nitrous oxide emission model for a landfill according to claim 1, characterized in that: In the step S12, SPSS software is used to fit the parameters of the N2O emission model.

3. The method for establishing a nitrous oxide emission model for a landfill according to claim 1, characterized in that: Oxygen concentration variation coefficient over time The value range is 0.02~0.06%·h -1 ; The rate of change of N2O generation potential from garbage with oxygen concentration The value range is: if the nitrogen content of the incoming garbage is less than 2%, Value range: 0~0.1 mg N·kg -1 waste % -1 If the nitrogen content of the incoming garbage is in the range [2%, 3%], The value is 0.1~0.5 mg N·kg -1 waste % -1 If the nitrogen content of the incoming garbage is greater than 3%, The value is 0.5~0.6 mg N·kg -1 waste % -1 ; Intercept of N2O generation potential of garbage as a function of oxygen concentration The value is -0.5~0 mg N·kg -1 waste; The half-life k of N2O emission from landfill is: for garbage that has not been mechanically crushed before landfill, k is 0~0.05 h -1 For garbage that has been pre-processed by mechanical crushing, k is 0.05~0.45 h -1 ; A constant indicating the midpoint of the S-curve for N2O emissions The value range is 2~5.

4. The method for establishing a nitrous oxide emission model for a landfill according to claim 1, characterized in that: The parameter values ​​of the N2O emission model are: = 0.04%·h -1 , = 0.3 mg N kg -1 waste % -1 , = -0.25mg N kg -1 waste, = 3.5, = 0.025 h -1 .

5. A method for estimating nitrous oxide emissions from a landfill, characterized in that: Includes steps: S21. Calculate the landfill N2O emission factor EF: For the landfill nitrous oxide emission model established according to the method described in any one of claims 1 to 4, the model parameter values ​​are determined according to the garbage characteristics of the landfill to be estimated. As an independent variable, Get under conditions The value of The garbage characteristics include the nitrogen content of the incoming garbage and whether the garbage has been pre-processed by mechanical crushing; if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset Change rate threshold; S22. The annual estimated value Q of nitrous oxide emissions from landfills is: ； Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

6. The method for estimating nitrous oxide emissions from a landfill according to claim 5, characterized in that: In step S21, Matlab programming is used to draw Follow The changing curve obtains and calculate the value of The rate of change of landfill N2O emission factor EF is obtained.

7. The method for estimating nitrous oxide emissions from a landfill according to claim 5, characterized in that: Preset Change rate threshold It is 0.1%.

8. A landfill nitrous oxide emission estimation system, characterized in that: include: The landfill N2O emission factor EF calculation module (1) is used to calculate the landfill N2O emission factor EF, and the specific steps are: for the landfill nitrous oxide emission model established by the method as described in any one of claims 1 to 4, according to the garbage characteristics of the landfill to be estimated, determine the model parameter values, As an independent variable, Get under conditions The value of The garbage characteristics include the nitrogen content of the incoming garbage and whether the garbage has been pre-processed by mechanical crushing; if ,think Entering the stable phase, The value is the landfill N2O emission factor EF; For preset Change rate threshold; The landfill nitrous oxide emission estimation value acquisition module (2) is used to calculate the annual estimation value Q of the landfill nitrous oxide emission: ； Among them, the unit of Q is Gg N; W is the annual landfill volume of garbage, in tons.

9. The landfill nitrous oxide emission estimation system according to claim 8, characterized in that: The landfill N2O emission factor EF calculation module (1) is drawn using Matlab programming Follow The changing curve obtains and calculate the value of The rate of change of landfill N2O emission factor EF is obtained.

10. The landfill nitrous oxide emission estimation system according to claim 8, characterized in that: Preset Change rate threshold It is 0.1%.

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