MATHEMATICAL MODELING OF THE ESTIMATE OF METHANE GAS GENERATION, OF THE ORGANIC FRACTION OF MSW FROM THE AGRESTE ALAGOANO SANITARY LANDFILL, FROM STANDARD DATA AND EXPERIMENTAL DATA

Objective: The objective of this study is to carry out mathematical modeling in the generation of methane gas, through two mathematical models, using standard data and data obtained in the laboratory. Theoretical framework: The emission of methane gas, generated by the decomposition of solid waste in landfills, is one of the serious problems of air pollution and one way to minimize the impacts of methane on the environment is through its use to generate energy. To this end, there are ways to estimate the generation of CH4 during the useful life of the landfill. Method: For modeling, the computer programs of LandGEM and the Intergovernmental Panel on Climate Change (IPCC) were used to carry out the theoretical estimate of CH4 production during the useful life of the Agreste Alagoano landfill in two scenarios: one with standard program values for the local climate region and another with information obtained from experimental data from research by Santana (2022). Results and Discussion: When standard input data was adopted, the LandGEM model presented a 38% higher value in CH4 production compared to the IPCC model. When considering input data obtained experimentally, the IPCC showed CH4 generation 32.66% higher than the LandGEM, this was possible due to the COD value that was high as a result of the L0 of the organic fraction, exceeding the theoretical value of 0.15 to the experimental value of 0.27 in the new scenario. Implications of the research: Determining parameters for modeling methane gas generation will help in managing landfill waste and its energy recovery potential, in addition to the application of mathematical models for estimating biogas production potential as tools essential for both energy and environmental studies. Originality/value: This research presents as originality the determination of experimental parameters applied to the mathematical modeling of methane gas generation in landfills in the rural region, since studies on modeling in landfills with the climatic conditions of the rural region of Brazil are not common in the literature.


INTRODUCTION
The landfill is a form of final disposal suitable for solid urban waste (MSW), but there is a concern with the biogas generated, where methane is in greater quantity (SALOMON and LORA, 2005;ZANETTE, 2009), which is one of the most important greenhouse gases -GHG, as its global warming potential is 28 times greater than carbon dioxide (UNECE, 2019).
Methane in biogas, on the other hand, has a high energy potential and can be used as an energy source.
Therefore, proper management of municipal solid waste and the generation of energy, through methane in landfills, are environmentally sustainable solutions that can be a renewable and clean source of electricity.In addition, the study of energy generation from methane enables the reduction of greenhouse gas leakages and the maximization of the methane conversion rate, accounted for in the calculation for carbon credit emission within the clean development mechanism, besides reducing the need for fossil fuels (SANTANA, 2022).
Thus, studies on waste management and its potential for energy recovery through new technologies deserve attention, since they represent an opportunity to take advantage of these materials and reduce the pollution effects they can cause (DAMRONGSAK; CHAICHANA; WONGSAPAI, 2017;GAO et al., 2019).
According to Magalhães (2018), anaerobic processes are a promising alternative for biogas generation, due to the high conversion rates, and the application of mathematical models to estimate the potential for biogas production are essential tools, both for energy and environmental studies.
Although mathematical models offer standard input parameters, the fidelity of their application depends primarily on the reliability of this data and the degree of similarity between the reality of the site under study and other sites already modeled successfully.The input data of the mathematical models include the generation and gravimetric composition of the waste arriving at the landfill to determine its components and percentages, methane gas generation potential (L0), degradable organic carbon (COD), the kinetic constant of decay K, and other data collected from the diagnosis of the landfill.
The parameters adopted, or determined experimentally, can be used in modeling to estimate methane gas production in different scenarios and using various available models, developing a curve that predicts methane generation over time.The choice of the most appropriate model and the consideration of the different climatic and operational conditions of each landfill in the adoption of the entry parameters are of paramount importance for results closer to reality (SANTANA, 2022).
Although mathematical modeling, to estimate methane production, has been the subject of study by many authors, aiming to collaborate with the energy matrix and the reduction of the impacts brought about to the environment, the state of Alagoas or scientific literature, have studies applied to landfills in regions with the socioeconomic and environmental characteristics of the agreste region, which justifies the execution of this research.It should be noted, then, the great relevance of the theme, both for the state of the art and for the locality, due to the importance of this sanitary landfill for this region.
In view of this, the objective of this research is, through mathematical modeling, to estimate the potential of methane gas generation, during the useful life of the landfill in the agreste Alagoano, in two different scenarios, with standard data of the programs and experimental data obtained in the work of Santana (2022).Two software programs, Landgem and IPCC, will be used.

THEORETICAL FRAME
In Brazil, solid urban waste is generally sent to landfills, where it is decomposed and produces leachate and biogas.According to Ruosso (2022), these components are highly polluting and therefore a viable solution to meet the demand for clean energy, providing the correct treatment of MSW and mitigating methane emission is the deployment of energy recovery systems.
Biogas is a gas mixture, resulting from the anaerobic digestion process of organic matter, and is considered a renewable resource because it is part of the carbon biogeochemical cycle.It consists primarily of methane and carbon dioxide, with smaller amounts of hydrogen sulfide, ammonia and water vapor with traces of hydrogen and ammonia (ZANETTE, 2009;DAI, LI, ZHANG et al, 2016;HARYANTO et al., 2018).
According to Technical Note No. 001/2021 of CIBIOGAS (2020), which establishes the biogas landscape in Brazil, there are a total of 675 biogas plants in Brazil, and 638 are in operation for energy purposes.Plants that process solid waste account for only 9% of the plants in operation, but they are responsible for the production of 73% of all the biogas produced in the country.
Mathematical models can be important tools in the planning and analysis of real systems and situations, consisting of the representation of a given process by means of mathematical equations, can assist in the systematization of information, identification of the phenomena that may be involved and can still alert on details not considered previously, perform cause and effect analyzes and still make predictions about the behavior of a specific real system well defined (SANTANA 2022).
Several models have been proposed for predicting methane during the lifetime of a landfill.These can be divided according to their order, the most commonly used are divided into zero-order, first-order, multiphase, and second-order models.
These mathematical models for landfills are tools used to project methane generation over time from a landfilled mass of waste.They are used to scale landfill gas collection systems (LFG), assessments and projections of LFG energy use and regulatory purposes (VOGT and AUGENSTEIN, 1997).
However, current landfill gas generation models are overly simplified, not taking into account specific landfill variations in waste composition, moisture content and ambient temperature (KARANJEKAR et al, 2015).

EPA MODEL (2005)
This model is typically presented for application in full-scale landfills, considering the amount and composition of waste and biogas annually.The EPA model (2005)  6 The mathematical model used in the landfill is based on a first-order decay equation, which can be applied using site-specific data, provided by the user, to generate the necessary parameters to estimate emissions or, if data is not available, using standard value sets included in the landfill (SANTANA, 2022) This model is simple and objective and can be used when one has at least data related to the disposal of MSW at the destination location and average annual composition of the waste arriving at the landfill.Equation 1 represents the global equation for methane generation.
The methane generation constant (k) represents the rate of methane generation as a decomposition of a waste mass at the landfill.This rate depends on the composition of the residues, particle size, humidity, temperature and pH (KARANJEKAR et al. 2015).
High k-values indicate accelerated gas production over time.In controlled systems, this constant is a function of humidity, nutrient availability for methanogenic bacteria, pH and temperature of the mass of waste.However, applied in real situations, this constant varies according to precipitation, composition of waste and operating conditions of the landfill (FIRMO, 2013).
The methane generation potential (L0) represents the total methane production (m 3 methane per ton of waste).The value of L0 is dependent on the composition of the residue and in particular on the fraction of organic matter present.The methane potential is estimated based on the carbon content of the residue, the biodegradable carbon fraction and a stoichiometric conversion factor.Typical values for this parameter range from 125 m 3 ton CH4/ton waste to 310 m34 ton CH4/ton waste.The higher compaction of the residue has no direct effect on the parameter of L0.The methane generation potential (L0) of a landfill depends on the composition of the waste and its degradable organic content (KARANJEKAR et al. 2015).

IMPLEMENTATION OF THE IPCC MODEL (2006)
As well as for the application of the EPA (2005) model, the IPCC ( 2006) also needs to consider the particularities of the landfill, by performing the daily data entry of the waste, such as quantity, composition and kinetic parameters.
The IPCC Model ( 2006) is one of the latest global models and is based on 1st order kinetics for decomposition of degradable waste considering the different components of municipal solid waste and different degradation speeds for each component, and due to this is also called the multi-component model (FIRMO, 2013).
The basic equation for the first-order decay model is given by Equation 2.
The initial total amount of degradable organic carbon of each component i (MCODi) initially deposited (at time t=0) is calculated considering the total gross mass of the waste deposited at time t=0 (W), the manner of operation of the landfill site (MCF), the accessibility and anaerobic decomposition factor of the waste (CODf), as can be seen from Equation 3. where: 0 -amount of organic carbon initially deposited at time t=0 of material i (in kg); W -mass of waste that has been deposited over time (t=0) (in kg);   -the content of degradable organic carbon in component i; DOCf -fraction of organic carbon degradable under anaerobic conditions (equal in all elements and in general can vary from 0.5 to 0.7 according to landfill management or experiment); FCM -methane correction factor, which depends on the way the landfill operates (which can range from 0.4 to 1).
The model recommended input data for each type of material with respect to the fraction of Degradable Organic Carbon (DOCi) and degradation kinetic constant (ki) for each material 'i' are suggested by IPCC (2006).
Equation 4 is used to estimate the mass of methane obtained in the decomposition process of materials that make up municipal solid waste. . (4) Where: MCH4i -mass of organic carbon available for degradation (MCODi); 16/12 -stoichiometric relationship between methane and carbon; F -mass fraction of methane in biogas.For the application of these models, the population projection and the calculation of the quantity of MSW generated by the study area are fundamental in the analyzes of the production of biogas and methane in the sanitary landfill.The population projection was estimated, based on census data for each municipality involved in the consortium, for a horizon of 20 years.
For the annual calculation of the daily generation of household solid waste (DW) generated in the municipalities comprising the landfill over 20 years, the per capita generation rate (g) and population (P) were considered according to Equation 5. Where: Pd: average daily generation of waste (kg/day) Pop: population in the given year considered g: generation per capita of landfill waste in the given year under consideration (kg/hab.dia)A: percentage of landfilled waste (%).
For the determination of the generation per capita (g) of waste of each municipality, the calculation of the per capita value of collected waste was done, with quantitative data of the monthly receipt of MSW for the years 2020 and 2021, made available by the landfill.

IMPLEMENTATION OF THE IPCC MODEL
For "Scenario 1" the defaults provided by the model were considered.According to IPCC (2006) the standard values of the degradation constant 'k' according to the climatic conditions of the region are expressed in Table 1.

Table 1
Standard value of the degradation constant (ki) in the components of the MSW.According to IPCC (2006), one way to calculate the methane generation potential (L0), used in this research, is through Equation 6. Where: 0 : methane generation potential of the residue (Gg of  4 /Gg of MSW); : Methane correction factor for disposal site management = 1 : degradable organic carbon (Gg C/Gg MSW);   : fraction of DOC dissociated (%) F: fraction by volume of methane (%) = 0,5 The fraction of decoupled degradable organic carbon can be determined from Equation 7below.The degradable organic carbon (DOC) is estimated based on the composition of residues and can be calculated by Equation 8. Where: COD: Degradable organic carbon fraction in waste DOCi: Degradable organic carbon fraction in waste type i Wi: Fraction of waste type i per waste category.
According to the default values of the model, the DOCi value adopted for each type of residue is expressed in Table 2.

Table 2
Default values for the fraction of degradable organic carbon (CODi).Equation 9 was used to estimate the mass of methane obtained in the decomposition process of each waste material.

Types of waste
Where: MCH4i -is the mass of methane produced in an infinite time from the decomposition of the mass of organic carbon available for degradation (MCODi); 16/12 -is the stoichiometric relationship between methane and carbon; 12 Fis the mass fraction of methane in biogas.
The total volume of methane generated shall be obtained by summing the volume of methane of each component of the waste according to Equation 10.
For "Scenario 2", the values of methane (L0) and DOC gas generation potential of the organic fraction were considered as determined in the laboratory analyzes of the research of Santana's PhD thesis 2022, while the values of the other components of the residues will remain as the standard values of the tool for local climatic conditions.The values of FCM, CODf and F will remain the same as for scenario 1.

IMPLEMENTATION OF THE EPA MODEL (2005)
The program starts from a first order equation to make the estimates of the emissions of gases for the desired year (Equation 11). Where:

𝑄 𝐶𝐻 4
: annual methane production for a given year (m³/t); i: 1 -increase per year; n: year of calculation (initial year of opening of the landfill); j:0,1 -increase per year; k: methane generation rate (year -1 ) 0: methane generation potential (m³/Mg);   : mass of waste received each year in each section (Mg);   : year, in each section, of receipt of the mass of waste (time, to decimal precision).
For the configuration of "Scenario 1" the variables k and L0 adopted were the program standard values, which for humid climates, with precipitation of at least 635 mm annually, recommends a k of 0.05 year -1 and L0 of 170 m 3 .Mg-1 (USEPA, 2005).
A new L0 value was used in the 'Scenario 2' configuration from data from the gravimetric composition of residues and laboratory organic matter assays determined by the IPCC model equations ( 2006

13
(FMC) was considered equal to 1; decoupled carbon correction factor (  ) equal to 0.798; degradable organic carbon (COD) was obtained with gravimetric data of the residues and laboratory.

RESULTS AND DISCUSSION
The landfill site under study is located in the state of Alagoas, in the agreste region, between the municipalities of Arapiraca and Craíbas, under the central coordinates of Latitude 9°38'41"S and Longitude 36°42'09"W.Figure 1 shows the location map and an aerial view of the landfill.The largest percentage, approximately 47.3% of the solid waste from the landfill, is organic matter, followed by flexible plastic (15.80%) and sanitary waste (11.06%).The components in smaller quantities are leather with 0.22%; wood with 0.2% and rubber with 0.9%.Table 3 presents the population estimate until 2041 and the amount of MSW generated per year.The per capita value of waste was taken as the average provided by the landfill of 0.82kg/hab.diain the year 2021.

Figure 3
Estimate of methane gas generation using Landgem model -Scenario 1.

Figure 4
Estimate of methane gas generation using IPCC model -Scenario 1.
The LandGEM program has enabled the volume of methane gas to be assessed by averaging, over a 20-year horizon at the landfill between 2021 and 2041, 13,930,352 Nm³/year with maximum CH4 production in 2042, one year after the stimulated waste reception horizon, of 27,015,535Nm³/year.The accumulated methane was 278,607,043Nm³/year.
The IPCC model averaged 10,085,810.65Nm³/year with peak generation of CH4 in the year 2042, one year after the end of the forecast horizon for receiving waste, with total of 18,197,305Nm³/year, and a cumulative total of methane in the 20 years of 201,716,213Nm³/year.
The IPCC program shows that the largest contribution comes from organic matter, accounting for approximately 60% of the total methane generation, followed by sanitary waste, with 18.26% and paper/cardboard with 18.24%.According to Fallahizadeh et al (2019), the production of methane from textiles and wood by this tool appears to be almost the same, indicating that its changes also do not affect significantly.
Figure 5 presents a comparison between Landgem and IPCC models for the analyzed scenario.

Figure 5
Comparison in CH4 estimation between Landgem and IPCC models -Scenario 1.
The results of both mathematical models have shown a significant amount of methane gas production, however the LandGEM model has a 38% higher average amount of CH4 production compared to the IPCC model.This difference in the results can be explained by the different variables that are considered in each model.
The models showed a progressive increase in the amount of methane emitted from year to year, showing graphs with increasing behavior during the period in which the landfill will receive the waste.The maximum peak in CH4 generation occurs one year after the 20 years studied, in 2042, which is when the maximum amount of waste will be disposed in the landfill, and then the curves are governed by the decay constant (k) referring to the degradation of the waste for both models.2017) also carried out a comparison between the models and found that the LandGEM model presents as a disadvantage the fact that it does not consider the different compositions of the waste content, but where there is not enough information to serve as input for other models its application is beneficial.
Fallahizadesh et al.Al (2019) found that according to the results, the LandGem model showed a generous high production of methane gas during the years of study at the landfill.The results also showed that the maximum methane production rate occurred during the following years, after the closure of the landfill and then reduced with a gentle slope and that the method and the results of his research can be used for the design and execution of methane gas collection systems and also, control of greenhouse gas emissions in landfills.

Scenario 2
For the scenario 2 configuration it was necessary to determine the degradable organic carbon (DOC) of the organic matter studied in the laboratory.
The methane potential of the organic matter reaching the landfill is From the degradable organic carbon of 16.778% the methane generation potential was determined, which resulted in  0 = 0,08926GgCH4/GgRSU → 0 = 131,53 Nm³CH4/GgRSU.
Based on the new methane generation potential, and considering the standard decay constant of the model for the region, it was possible to perform a new estimate with the Landgem program, as observed in Figure 6.

Figure 6
Estimate of methane gas generation using Landgem model -Scenario 2.
Figure 7 presents a comparison between the estimates in the two scenarios, where it is observed that with the value of the new methane gas generation potential obtained there was a 32% reduction in methane production during the 20-year projection at the landfill and 47.25% on average compared to the previous scenario.This difference in the generation of CH4, in the results of the two scenarios, is explained by the different values of DOC used in the organic matter component, since in scenario 1 the standard value of 0.15 was adopted and in scenario 2, with laboratory data, the value became 0.27, which represents a value of approximately 80% higher.

Figure 9
Comparison in estimate of CH4 generation between scenarios 1 and 2 of IPCC model  Among the most optimistic scenarios are the results obtained in scenario 2 with the IPCC model, using actual data for organic matter, and the results obtained with hypothetical data from the LandGEM model in scenario 1 (Figure 11).Among the most pessimistic scenarios are the IPCC model with standard data from scenario 1 and the LandGEM model in scenario 2 with real use (Figure 12).
In the most optimistic scenarios, it is observed that the growth in CH4 generation between the models are similar, reaching peak in the year 2042, with the Landgem model with the maximum value 2% higher than the IPCC model.When we compare the average and the cumulative 20 years, we have the IPCC tool showing 6.2% of CH4 more in relation to Landgem.22 The main difference is noted when the time horizon for receiving the residues is closed and, from that point onwards, the IPCC model shows a decay rate in the generation rate of methane that is higher, so that the Landgem model, with hypothetical data, is more optimistic in the generation of CH4.
When the worst-case scenarios are observed, the IPCC shows a maximum peak of 7% higher CH4 in relation to the Landgem and 6.6% higher methane over the 20 years of projection.
But, when considered in the long term, after the receipt of waste, the IPCC also showed a greater decay in the generation of methane, thus making the Landgem a more optimistic scenario in the total accumulated.

CONCLUSION
The estimation of methane gas generation was carried out by the LandGEM and IPCC models in two different scenarios.In scenario 1 the standard values recommended by each model for the regional conditions of the landfill were used.The LandGEM model presented an average, within the 20-year waste collection horizon, of 13,930,352 Nm³/year with a maximum peak of 27,015,535Nm³/year and a cumulative methane value of 278,607,043Nm³/year.This value was 38% higher than the quantities obtained by the IPCC multi-component model, which showed an average of 14,807,464Nm³/year, a peak of 26,471,848.79Nm³/year and an accumulated 20-year projection of 296,149,281.2Nm³/year,a value 46% higher when compared to the previous scenario.This increase was caused by the increase in the DOC of organic matter which resulted in more than 80% in the generation of methane by this material.When comparing the two models, the IPCC presented higher methane generation in this new configuration.
As a suggestion for future research, it is necessary to carry out the real quantification, of methane gas generation, in the landfill ducts in order to carry out the software adjustments and verify the errors of the use of each one in the real estimate of methane gas, and thus determine which computational tool manages to get closer to the real estimates of gases, thus being a very important tool in the management of the landfill.

Wangyao
et al. (2010) estimated methane gas using the IPCC waste model) compared to the actual field measurement in five managed landfills and four unmanaged landfills (landfills) in Thailand.The model's default values for tropical regions were used and the IPCC methane emissions produced similar results compared to field measurements, estimating an amount of 89.22 Gg of methane released from solid waste disposal sites in the atmosphere in 2006.InFirmo's work (2013), several simulations were made with standard data recommended by the LandGEM and IPCC models and with optimization data within the recommended limits for each region according to the established model.The input parameters were analyzed in laboratory experiments, such as BMP and pilot reactor, and with the experimental data determine the potential for biogas and methane generation.Bianek, et al. (2017) used the LandGEM and IPCC models for estimating gas generation at the Guarapuava municipal landfill (PR, Brazil), where the main parameters were chosen based on the data frequently applied for each model: default values suggested for specific local conditions, for the application of the LandGEM software; and calculation of methane generation potential (L0) from the gravimetric analysis of the waste, for the application of the equation suggested by the IPCC.Total biogas production was estimated at 44,466,711 Nm3.year -1 applying LandGEM and 60,080,906 Nm 3 .year-1applying IPCC.Da Silva (2020) carried out a study that had the objetive of estimating the generation of methane gas in a landfill located in the municipality of Minas do Leão, in the south of Brazil.The volume of methane gas was estimated using three first-order decomposition models: CdM Tool, LandGem and IPCC.The tool model estimate of the first model was 28x10 5 m 3 methane gas for the year of the largest generation, 2025.While for LandGem and IPCC Models, the maximum generation was observed in 2026, and methane gas estimates were 107x10 5 m 3 and 23x105m 3 .The CDM Tool and the IPCC Models presented similar results, revealing greater accuracy and therefore reliability.On the other hand, the LandGem model overestimated generation.Córdoba and Santalla (2021) proposed a unique tool to improve waste gas emission estimates in landfills based on the determination of the biochemical methane potential (BMP) test and the results were used to predict methane emissions from two models, LandGEM(2005)    and IPCC(2006).The results of long-term methane emissions (40 years) of stabilized waste discarded on land showed overestimations of up to 56.0% (IPCC model) and 259.5% (Landgem model) when standard data were used, instead of DOC realf were applied in stabilized waste; similar behavior was observed for raw waste (23.3% and 241.3% overestimations).In addition, the impact of the stabilization process revealed methane emission reductions of 5.1% and 20.9% based on the LandGEM and IPCC models respectively.3METHODOLOGYTwo mathematical models were used to study methane gas generation, the IPCC multicomponent model (2006) and the LandGEM (Landfill Gas Emissions Model) program, developed by the Control Technology Center of the Evironmental Protection Agency (EPA/2005).The study of methane gas generation was divided into two scenarios: (a) Scenario 1: Use of 'defaults' data recommended by the model; (b)Scenario 2: Use of experimentally obtained laboratory parameters for the organic fraction.

:
Carbon to methane conversion factor (Gg of  4 /Gg of C).

Figure 2
Figure 2 shows the average value of the gravimetric composition of solid urban waste received in the landfill of the agreste Alagoano, obtained through the work of Santana (2022).

Figure 2
Figure 2Gravimetric composition of the MSW of the landfill in the rural state of Alagoas.

Figure 3
Figure 3 shows the annual methane gas production in the landfill planned by LandGEM with the standard program entry parameters.In Figure 4 it is possible to analyze the generation of methane gas through the IPCC Model with the application of standard values for the climate region of the landfill.
Piñas et al. (2016) carried out a comparison between two mathematical models, LandGem being the one that presented a larger generation of methane gas during the lifetime of the landfill studied.Bianek et al. ( 207,80Nm³CH4/TonRSU, which results in: L0M.O = 0,148.Applying Equation 8 yielded a CODM value.O = 0.25 For scenario 2 of the LandGEM model, the mean value of the methane generation potential was determined based on the gravimetric composition of the waste and the mean DOC value of the waste.The mean DOC value of the residues was determined on the basis of Equation8, where the gravimetry of the MSW of the landfill was used and the DOC value of organic matter was replaced by the value found in laboratory data.The remaining DOC values of the other residues remained the standard values recommended byIPCC (2006).Therefore, a mean DOC value of 16,778 was reached.

Figure 7 Figure 8
Figure 7Comparison in the estimation of CH4 between scenarios 1 and 2 through the Landgem Model.

Figure 9
Figure 9 presents a comparison between the two scenarios.The IPCC model shows a significant increase in methane production, reaching a peak value in 2042 of 26,471,848.79Nm³/year, an average of 14,807,464Nm³/year and an accumulated 20-year projection of 296,149,281.2Nm³/year,representing an increase of 46% over the previous scenario.

Figure 10
Figure 10 presents a comparison between the LandGEM and IPCC models in the configuration of the new scenario.
presented average CH4 generation of 10,085,810.65Nm³/year with maximum production of18,197,305Nm³/year and accumulated 201,716,213Nm³/year of methane production during the 20 years.In the second scenario, the value of methane potential, determined by BPM test, was used to obtain organic degradable carbon from organic matter (CODM.O) and CODM.O = 0.27 was found.From the new DOC, the mean methane generation potential for application in the LandGEM model was determined, L0 = 131,53 Nm³CH4/TonRSU and replaced this parameter in the organic matter component in the IPCC model.The LandGEM tool showed a 32% reduction in CH4 production with average production value of 9,460,223 Nm³/year, with peak in 2042 at 16,339,291.29 Nm³/year and accumulated 189,204,469 Nm³/year.Modeling in the IPCC model Modeling of The Estimate of Methane Gas Generation, of The Organic Fraction Of Msw From The Agreste Alagoano Sanitary Landfill, From Standard Data And Experimental Data Mathematical ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.3 | p.1-24 | e06725 | 2024.

Table 3
Estimate of generation per capita of MSW of the municipalities that dispose of the waste for the CONAGRESTE landfill.Mathematical Modeling of The Estimate of Methane Gas Generation, of The Organic Fraction Of Msw FromThe Agreste Alagoano Sanitary Landfill, From Standard Data And Experimental Data ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.3 | p.1-24 | e06725 | 2024.