Landfill Gas Generation Research Articles

Theoretical Analysis of Landfill Gas Migration in Capillary Barrier Covers Considering Effects of Waste Temperature

The high-temperature and high-humidity conditions arising from the biochemical degradation of landfill waste result in significant temperature gradients within the landfill cover. The effects of waste temperature on landfill gas transport and microbial aerobic methane oxidation are not fully understood. In this study, a fully coupled theoretical model was developed to simulate the interactions of moisture, heat, and gas transport within a capillary barrier cover. A series of parametric studies were carried out to investigate the influence of the combined effects of temperature gradient, initial soil moisture content, and landfill gas generation rate on methane transport, oxidation, and emissions. The simulated results indicated that increasing waste temperature intensified the temperature gradient, leading to higher surface evaporation rates and variations in methane oxidation efficiencies. Additionally, variations in initial soil moisture content and landfill gas generation rates were found to significantly impact gas migration and methane oxidation in the cover. This study demonstrates the critical role of waste temperature in landfill gas migration within landfill cover systems, providing technical methodologies for the optimized design of soil cover systems.

Phytocapping for Municipal Solid Waste Landfills: A Sustainable Approach

This paper reviews the historical developments in landfill technology and its drawbacks. It introduces phytocapping, in light of previous research, as a promising, eco-friendly and sustainable technology for municipal solid waste (MSW) landfill covers in order to reduce landfill gas and leachate generation. This paper highlights the challenges to successful phytocapping, such as selection criteria for appropriate plants and growth media, and the importance of new research into overcoming these challenges. It also presents a database of plants used in landfill phytocapping studies worldwide. In addition, the performance, economics, and sustainability of phytocapping technology are evaluated in comparison to ordinary MSW landfill methods.

Evaluation of greenhouse gas emission and reduction potential of high-food-waste-content municipal solid waste landfills: A case study of a landfill in the east of China

This study proposes a comprehensive evaluation method based on a two-stage model to assess greenhouse gas (GHG) emissions and reductions in high-food-waste-content (HFWC) municipal solid waste (MSW) landfills. The proposed method considers typical processes such as fugitive landfill gas (LFG), LFG collection, flaring, power generation, and leachate treatment. A case study of an HFWC MSW landfill in eastern China is considered to illustrate the evaluation. The findings revealed that the GHG emissions equivalent of the case landfill amounted to 21.23 million tons from 2007 to 2022, averaging 1.03 tons CO2-eq per ton of MSW. There was a potential underestimation of LFG generation at the landfill site during the initial stages, which led to delayed LFG collection and substantial fugitive LFG emissions. Additionally, the time distribution of GHG emissions from HFWC MSW was significantly different from that of low-food-waste-content (LFWC) MSW landfills, with peak emissions occurring much earlier. Owing to the rapid degradation characteristics of HFWC MSW, the cumulative LFG production of the landfill by 2022 (2 years after the final cover) was projected to reach 77 % of the total LFG potential. In contrast, it would take until 2030 for LFWC MSW landfills to reach this level. Furthermore, various scenarios were analyzed, in which if the rapid LFG generation characteristics of HFWC MSW are known in advance, and relevant facilities are constructed ahead of time, the collection efficiency can be improved from 31 % to over 78 %, resulting in less GHG emissions.

The effects of municipal waste reduction and recycling policies on the economic feasibility of landfill gas generation

Landfill gas (LFG) projects for energy production have several advantages. However, to avoid the impossibility of these projects, it is crucial to assess the long-term effects of public policies that promote the diversion of waste disposed of in landfills. Therefore, the objective of the present work is to evaluate the effects of the application of public policies, which influence recycling, reduction of generation, and inadequate disposal reduction of municipal solid waste (MSW), in the potential of electricity generation in landfills, as well as to evaluate its effect on economic viability. A System Dynamics model was employed to estimate methane production while considering variations in the quantity and make-up of MSW over time. The results showed that the scenarios with the greatest potential for methane generation and electricity were those with less diversion of biodegradable waste. Furthermore, the economic performance demonstrated that none of the possibilities are viable except with carbon credits extra income. However, all scenarios could become viable by increasing the energy sale rate above 93.2 USD.MWh−1. Another option calls for lowering the discount rate through government incentives to a percentage below 10 % and an investment cost below 77 % of the original value. These elements aid in long-term planning and give decision-makers a future vision of the impact of these policies.

Assessment of landfill gas storage and application regarding energy management: A case study in the province of Quebec, Canada

Landfills are extensively applied to dispose of municipal solid wastes in developed and developing countries. Landfill gas generation from biodegradable organic wastes can be collected and converted to energy. When the gas collection system is shutdown, some of this gas can accumulate and be stored inside the landfill. Using the gas storage capacity of the landfill gets a better management of the landfill site because the collected stored gas could transform the landfill into a cheap gas storage system to provide short-term energy and use the energy when needed. This novel study analyzes the stored methane using the gas collection data of a landfill in Quebec province, Canada, for modulating energy production from landfill gas. Twenty episodes of the gas collection system’s shutdown and restart as well as different gas flow durations were studied. The results showed that the collected stored methane is accumulated in an average of 2.5 h. Additionally, the collected stored methane represents 10.5% of landfill gas flow. Although the results are site-specific, the methodology of this paper can be used on other landfill sites with similar size and collection conditions. Designing new landfills could take into consideration some elements to enhance gas storage capacity. For instance, designing landfill daily covers with more granular materials and higher porosities can be the next step to enhance the landfill as a gas storage system during shutdowns.

Isothermal Dual-Phase Flow Modeling to Assess the Impact of Gas Collection on Geotechnical and Hydraulic Performance of Landfills.

Liquid addition to landfilled municipal solid waste (MSW) is a practice employed to accelerate the biodegradation of the organic fraction of MSW and ensuing gas generation. Pore landfill gas (LFG) and leachate pressure from the added moisture and enhanced gas generation are expected to impact the geotechnical stability of landfill slopes. The impact of moisture addition and gas collection on the stability of landfills was numerically modeled using transient isothermal dual-phase flow and slope stability modeling. The temporal variation in the factor of safety (FS) for slope stability analysis was estimated for the simultaneous flow of LFG and leachate with and without gas collection and leachate recirculation for varying LFG generation rates and waste moisture contents. A significant decline in the FS for landfill slope stability was observed when recirculating leachate without active gas collection. Even without pressurized leachate recirculation, a significant decline in the FS value was observed for landfills with relatively high in situ moisture content without active gas collection. In some modeled scenarios without LFG collection, the FS value was lower than 1. The analysis suggests that the landfill side slope stability analysis should incorporate LFG generation and the resultant pressure for landfills containing high-moisture-content waste and for the landfill with pressurized leachate recirculation. The analysis suggests that an efficient gas collection system plays a critical role in the geotechnical stability of the slope of wet landfills and the performance of leachate recirculation trenches.

Improvement and optimization for the first order decay model parameters at typical municipal solid waste landfills in China

Landfill gas (LFG) generation is commonly modeled by using a first-order model. Methane generation potential (L0) and methane generation rate constant (k) are two key parameters in the first-order model. Coal-ash based default values or roughly analyzed values often used in China may not be appropriate for accurately estimating of LFG generation. In this study, seven groups of parameters were evaluated by comparing the theoretical predictions with real measurements from five Chinese landfills. The optimal approach for calculating L0 is the use of site-specific waste composition and the default values of degradable organic carbon (DOC) reported by the Chinese industry standard (CJJ133-2009), and the matching k can be adjusted by fitting and regression. The optimized average values were L0 = 67 m3 Mg−1, k = 0.06 per year for landfills in Beijing and Zhengzhou in cold–dry regions, L0 = 69 m3 Mg−1, k = 0.16 per year for landfill in Shanghai in cold–wet region, and L0 = 64 m3 Mg−1, k = 0.21 per year for landfills in Guangzhou and Shenzhen in hot–wet regions. Monte Carlo analysis showed that the uncertainty of LFG generation at closure year varied in −22.5% to 20.5%, −17.1% to 17.1% and −28.2% to 34.7% for three climatic regions, respectively. The k value is the key influencing factor, with a 95.6% contribution ratio in the hot–wet region landfill. The results provide references for future better waste management.

Utilization of methane from municipal solid waste landfills

Here, we analyzed the utilization efficiency of methane (CH<sub>4</sub>) gas from landfill sites associated with its power generation potential in different systems; in addition, we analyzed the reduction in the amount of CH<sub>4</sub> emitted from landfills of untreated waste, proposed an effective method for site selection, and investigated the environmental issues caused by landfilling solid waste. Furthermore, we evaluated the geographical and chemical characteristics, iteration variables of landfill operations, application of CH<sub>4</sub>, efficiencies of energy-converting systems, and reduction in the CO<sub>2</sub> emissions from other energy sources, with the landfill gas (LFG) being considered as the fuel. For efficient and quality extraction of CH<sub>4</sub> from LFG, we investigated the ideal landfill conditions (e.g., construction, geometry, weather, temperature, moisture, pH, and biodegradable matter) and hydrogeological parameters that influence the generation of LFG and landfill leachate. The first order decay equation was used to predict the CH<sub>4</sub> generation from a single bulk municipal solid waste stream for various characteristic interims of geography and CH<sub>4</sub> generation capacity and potential. More CH<sub>4</sub> is generated in the conventional clean air act condition than wet and arid conditions. Based on the analysis, we suggest efficient and economical power generation systems for using the CH<sub>4</sub> emissions from landfills.

Optimization of landfill gas generation based on a modified first-order decay model: a case study in the province of Quebec, Canada

Landfills will likely remain an essential part of integrated solid waste management systems in many developed and developing countries for the foreseeable future. Further improvements are required to model the generated gas from landfills. The literature has not addressed detailed waste characterization in landfill gas (LFG) modeling by a first-order decay model such as LandGEM while using a genetic algorithm. Additionally, little has been done in the literature regarding H2S generation modeling. This paper uses a genetic algorithm to independently fit parameters to a CH4 and H2S generation model based on a modified first-order decay model. In the case of CH4 generation modeling, biodegradable organic waste (OW) was segregated into food waste, yard waste, paper, and wood. In addition to optimizing the OW fractions, key modeling parameters of OW, such as CH4 generation potential ({L}_{0}) and CH4 decay rate ({k}_{C{H}_{4}}), were determined independently for different periods in the landfill’s life. Similarly, in the case of H2S generation modeling, the construction and demolition waste (CD) was classified into fines (FCD) and bulky materials (BCD), and H2S generation potential ({S}_{0}) and H2S decay rate ({k}_{{H}_{2}S}) of FCD and BCD were determined. LFG collection data from a landfill site in the province of Quebec, Canada, was used to validate the LFG generation model. A range of scenarios was analyzed using the validated model, including fourteen scenarios (two benchmark and twelve optimizing) for CH4 and two for H2S modeling. The results showed that the differentiation of more waste types improves the modeling accuracy for CH4. Moreover, within the decade-long lifetime of a landfill, the waste management strategies change, requiring different assumptions for the modeling. Also, the work showed the importance of considering how different landfill sectors are filled over time. Finally, scenario twelve of optimizing scenarios, which assumed four waste types, constant three periodic waste fractions, and six sectors, had the lowest residual sum of squares (RSS) value. For H2S generation modeling, both scenarios, with or without separate fits of {S}_{0} and {k}_{{H}_{2}S} for FCD and BCD, predicted the generated H2S well and had a very similar RSS value. Further data could improve H2S generation modeling.

Impact of municipal solid waste landfill leachate on biogas production rate

Landfills/open dump sites are the final disposal facilities for municipal solid waste (MSW). These sites undergo continuous process of biochemical reactions and anaerobic degradation, which make them prone to generation of landfill gas (LFG) and leachate. Worldwide, the quantitative and qualitative assessment for leachate treatment and management has been a growing concern. The present study investigated the physico-chemical characteristics and heavy metal parameters for fresh, 3-month, 6-month and 3-year old landfill leachate samples. The total dissolved solids (13280 mg/l), alkalinity (13000 mg/l), chemical oxygen demand (42000 mg/l) and total organic carbon (16500 mg/l) was found to be maximum in 3-year old leachate sample. While, the 3 and 6-month old leachate samples had maximum heavy metal concentration. The attempt was also made to identify the key parameters responsible to enhance biogas production yield from different ages of MSW. The substrate combinations of MSW and 3-year old leachate samples was prepared at varying proportion. The study was performed in three cycles and the volume of leachate diffused in each cycle was kept constant. The control samples with no leachate diffusion was also prepared to compare the percentage increase in biogas production rate. It was found that the cumulative methane (CH4) production from fresh (358 ml/g) and 3-month old MSW (273 ml/g) was maximum, and the overall percentage increase was 43% and 32%. It was also conclusive that the excess leachate diffusion of >15 ml results in low calcination behaviour and CH4 production rate. The response surface methodology was used to correlate and validate independent input variables (volatile solids, C/N ratio and leachate concentration) responsible for maximum CH4 yield.

Development of Forecasting Model for Machine Learning-Based Landfill Leachate Generation Using Linear Interpolation

Objectives:The purpose of this study is to compare single models according to the missing value handling techniques for predicting leachate generation.Methods:Input factors such as landfill gas generation, and weather data (precipitation, wind speed, radiation, temperature, and relative humidity) were used from June 2002 to October 2018. Linear interpolation and mean method were used as the missing value handling technique. The experiment was conducted by dividing the data into train and test data according to the optimal ratio. Various single models were used, and the prediction performance of the model was compared and evaluated using coefficient of determination (<i>R</i><sup>2</sup>).Results and Discussion:The gated recurrent unit (GRU) model was the best among the single models. In the GRU model, <i>R</i><sup>2</sup> was 0.867 for linear interpolation and <i>R</i><sup>2</sup> was 0.839 for the mean method, so that the GRU model using linear interpolation was most suitable for predicting leachate generation. In the ANN model, <i>R</i><sup>2</sup> of linear interpolation (0.862) was higher than that of mean method (0.828). In the long short-term memory (LSTM) model, <i>R</i><sup>2</sup> was 0.779 for linear interpolation and 0.762 for mean method. In the random forest (RF) model, <i>R</i><sup>2</sup> for linear interpolation (0.700) was also higher than that for the mean method (0.665). The model performance was excellent in the order GRU>ANN>LSTM>RF. The linear interpolation for the missing value handling technique was superior to the mean method in all models used in this experiment.Conclusion:The GRU using linear interpolation was the most suitable model for predicting landfill leachate generation.

The effect of climate change on the potential for landfill gas generation at the Vinča landfill site

Climate change projections indicate that Republic of Serbia and the Western Balkans will face a high probability of continuing temperature increases, climatic extremes are projected to become more common, including a significant increase in the number of extreme heat events. Heavier precipitation events are expected in the winter months, whilst summers are projected to become even drier. This paper aims to analyse effect of precipitation changes on landfill gas generation on the Vinča landfill, the biggest landfill in Serbia. Quantities of generated landfill gas and methane have been estimated by using LandGem model. Site specific methane generation rate has been calculated according to GMI methodology for Central Eastern Europe. Sensitivity analyses is performed to determine influence of a precipitation regimes on the methane generation rate on the site. Any increase in precipitation (in range 10-30%) may increase landfill gas production for 4.3%. The paper shows the difference in gas emissions, with the same composition of waste, and different precipitation regimes. Changes in precipitation regimes due to climate change can affect the dynamics of landfill gas emissions. This information is significant for the possible re-circulation of leachate from the landfill which could result in an increased production of landfill gas.

A review on landfill system for municipal solid wastes: Insight into leachate, gas emissions, environmental and economic analysis

Landfill is one of the common processes for removing and disposing waste materials that comprises the final method of disposing municipal solid waste. Disposal of municipal solid waste through land filling has become an important environmental problem all over the world which results in environmental contamination and pollution. Microbes present in the land act on the dumped materials and decompose the organic content present. The leachate from landfill is rich in organic, inorganic and suspended particles which may cause threat to ecosystem. The pollutants from leachate may be heavy metals, organic and inorganic content and organic compounds. The geological properties of soil get altered when leachate migrates. The physical, chemical and biological properties of the dumped material are determined by the decomposition of substances and microbes acting onto it. Trace gas emission may occur due to volatilization of chemical substances, degradation of waste materials and conversion reactions. The concentration of gas released varies from region to region of dumping, covered and uncovered dumped materials. The current review recommends an engineered landfill design helpful for landfill gas generation which replaces the fossil fuel as a compressed natural gas or liquefied natural gas. The landfill area is separated into organic and inorganic cells to scope at the objective of energy generation and resource recovery. However, the impact of these released gaseous emissions has been analyzed completely.

Modelling and assessment of landfill gas generation at Erzurum municipal landfill site by LandGEM

Landfill areas have always been a common application for municipal solid waste management. However, land use problems, environmental pollution and increasing recycling implements have limited the amount of solid waste which is stored in the landfill areas. Despite all disadvantages, it is still considered a preferred disposal method fort he solid waste, especially when methane gas released from the areas is used to obtain electrical energy. In this context, the aim of this study is to estimate the landfill gas amounts originating from the Erzurum Solid Waste Landfill area using the LandGEM 3.02 version developed by EPA and to compare it with the methane gas concentrations measured on-site for the last three years. Total landfill gas, methane, carbon dioxide, and NMOC amounts were estimated with the model by choosing the basic parameters of the LandGEM (k and Lo values) according to the Clean Air Act and AP-42 inventory suggested by the EPA. The amount of the same gases was also predicted by manually calculated the k and Lo values (User Specified) with the specific data of the field. Finally, the amount of landfill gases obtained by using all three inventories (the Clean Air Act, AP-42 and User Specified) was compared with the methane concentrations measured in the field in order to confirm the model results. First result is that the methane gas concentrations predicted by the model were nearly close to the real methane measurements on site. Secondly, the operating period determined as 20 years for Erzurum landfill area when it was put into operation in 2008, while it was estimated as 23 years according to the LandGEM model results. Erzurum Solid Waste Landfill area has already been designed for power generation and the energy is produced at present. Therefore, the model can easily be used and verified for future improvement of the landfill area and the prediction of the amount of the energy obtained from the wastes.

Evaluation of methane generation rate and energy recovery potential of municipal solid waste using anaerobic digestion and landfilling: A case study of Dhanbad, India.

In this study, two most common biological waste to energy conversion techniques have been analysed and compared on the basis of methane generation and energy recovery potential. The biogas generation potential has been estimated using anaerobic co-digestion experiment. The main substrate used for this study was food waste, while cow dung and anaerobic digester sludge were used as co-digestion substrates. Food waste was used because of its maximum composition (36% of total wastes) in the study area (Dhanbad city, India) with high biogas generation potential. Cow dung acted as a natural buffer, while anaerobic digester sludge was a source of active inoculum. Based on the maximum biogas yield of 402 mL g-1 VS and annual food waste generation rate in the study area, the energy recovery potential using anaerobic digestion was estimated to be 6.59 × 106 kWh year-1. Presently, the wastes in the mixed form are being dumped on a large abandoned land with an approximate area of 93 ha in the outskirts of Dhanbad city in an uncontrolled manner. The annual landfill gas generation from the existing landfill has been estimated using Landfill Gas Emissions Model (LandGEM) based on the waste characteristics, anticipated landfill life and other region-specific parameters of the present study area. The maximum electrical energy recovery potential of 44.62 × 105 kWh from landfill gas has been estimated for the year 2041. Although, the results are based on the waste generation and characteristics of Dhanbad city, the comparison methodology can be applied to other cities.

Assessment of energy recovery potential and analysis of environmental impacts of waste to energy options using life cycle assessment

Effective waste management such as energy recovery from waste is not very successful in many cities of India. The present study is carried out in the Dhanbad city, India where all the generated wastes are managed unscientifically through open dumping. Most of the reported life cycle assessment-based studies for Indian cities have focussed on the common waste management options such as composting and recycling. This study aimed to evaluate the energy recovery potential and environmental impacts of mainly waste to energy options namely; anaerobic digestion, landfill gas to energy, mass incineration and refuse derived fuel incineration based on the characteristics and composition of wastes of the study area. The selection of waste to energy options is done based on the composition of waste suitable for the respective options, thus making it helpful in reproducing the present work in other cities as well. Anaerobic digestion technology is evaluated based on the biogas generation potential of total food waste generated in the study area using laboratory-scale batch experiments. Similarly, landfill gas to energy is evaluated based on the estimated landfill gas generation (using LandGEM model) from the existing landfill of the study area. While incineration (mass and refuse derived fuel) is evaluated based on the heating value of combustible waste fractions. For the comparison of energy recovery potential and environmental impacts, six scenarios are developed. The maximum energy recovery potential of 602 kWh/tonne of dry waste is found for the scenario mass incineration of combustible waste fractions (72%) and landfilling of remaining wastes (28%). This scenario also showed the maximum net environmental savings due to avoided electricity production. The sensitivity analysis revealed that the collection efficiency of generated landfill gas for electricity conversion significantly impacts the change in global warming and photochemical ozone creation potential. The outcomes of this study will help the concerned authorities in developing the efficient waste to energy system.

Estimation of landfill gas production and potential utilization in a South Africa landfill

ABSTRACT Landfill gas composition comprises mainly of methane and carbon dioxide emissions and other Nonmethane Organic Carbons (NMOCs). Methane gas has a global warming potential that is estimated to be 25–36 over 100 years. Interestingly, methane generated from landfills is a renewable source of energy that has been used over the years as a source of electricity generation especially in developed and in some developing countries. However, methane from landfills has been underutilized in South Africa. Due to the recent unreliable electricity disruptions (load shedding) in South Africa, which is caused by a variety of factors. Prioritizing methane produced from landfills for use as a fuel for electricity generation is critical. This will assist to minimize the over-reliance on coal and, reduce the ongoing landfill gas generation. Therefore, the purpose of this study is to estimate the amount of methane emitted from Weltervenden landfill site using the LandGEM version 3.02 and Afvalzorg models and to evaluate the potential utilization of the gases emitted. The study was also aimed at determining the cost and benefits related to the implementation of a landfill gas utilization technology. The findings of this study show that methane emissions from the landfill will peak in the year 2023 with values of 4613 Mg/year and 3128 Mg/year for LandGem and Afvalzorg models, respectively. Also, the total methane emissions from the year 1999 to 2050, are 111,799.25 Mg/year and 27,898.93 Mg/year for both LandGEM and Afvalzorg models, respectively. The LFGcost web model simulations showed that the implementation of a LFG utilization project using Microturbine and CHP microturbine engines are economically feasible. This is considering the sales of electricity to the people. However, considering the sales of electricity generated and Certified Emission Reductions (CER) (carbon credits) to the global market all engines used in this study will be economically feasible. Implications: The methane emitted from the Polokwane landfill estimated from LandGEM and Afvalzorg models will peak in year 2023 at 4613 Mg/year and 3128 Mg/year, respectively. Also, the total methane emissions from the year 1999 to 2050, are 111,799.25 Mg/year and 27,898.93 Mg/year for both LandGEM and Afvalzorg models, respectively. The LFGcost web model simulations showed that the implementation of a LFG utilization project using Microturbine and CHP microturbine engines are economically feasible. This is considering the sales of electricity to the people. Therefore, implementation of LFG utilization is economically feasible from sales of electricity generated and Certified Emission Reductions

페루 청정개발제도(CDM) 사업 분석을 통한 온실가스 감축 비용 추정

There has been a widespread awareness of the need to achieve carbon neutrality by mid-20th century, especially upon the publication of IPCC 1.5℃ Special Report in 2018. In order to cost-effectively achieve greenhouse gas reduction at a global level, the importance of cooperation between countries and the use of the international carbon market are emphasized more than ever. The Clean Development Mechanism (CDM) under the Kyoto Protocol will be reorganized into a “Sustainable Development Mechanism (SDM)” under the Paris Agreement. As the SDM is expected to inherit much of the CDM system, it is necessary to closely examine the performance and economic aspects of CDM projects in order to maximize the availability of the new international carbon market, SDM under the Paris Agreement. Despite its importance, research on the economic assessment of the emission reduction projects under the CDM has so far been scant. With an aim to establish an analytical basis to assess the economic feasibility of each type of emission reduction project and to draw implications for the national strategy for implementing the reduction projects abroad, this study estimated mitigation cost ($/tCO₂) of 27 CDM projects in Peru. The reservation price of Certified Emission Reduction (CER) unit that ensures minimum economic feasibility of the project has been estimated and analyzed by project type. A comparison of reduction potential and cost of mitigation by CDM project type in Peru shows that methane recovery, landfill gas, wind power, and solar power generation are the most cost-effective types in Peru. For many countries including South Korea, engaging in more active reduction activities through overseas reduction projects may be an important means of achieving the national reduction goal and contributing to global efforts to abate greenhouse gas emissions. Thus, it is important for South Korea to put efforts to improve its understanding of the reduction potential, investment opportunities and cost effectiveness of mitigation projects in Peru as well as Chile, Vietnam, Myanmar and Sri Lanka designated as target bilateral cooperation countries.

The influence of waste composition on biogas generation model parameters

Three landfill gas generation models following two established kinetic pathways – first-order decay (Landfill Gas Emissions Model and Intergovernmental Panel on Climate Change) and sigmoidal growth (modified Gompertz) – are considered and fitted against a range of methane generation data generated from large-scale degradation experiments of seven well-characterised municipal solid waste specimens that were operated in an identical manner. The parameter values are obtained for specimens with significantly different compositions, ranging from ‘waste-rich’ to ‘soil-rich’. Model parameters related to the methane yield potential, mass of degraded decomposable organic carbon and daily methane yield are found to be proportional to the biodegradability of the specimens. However, parameters related to the decay rate and time lag in the methane generation process are not significantly influenced by waste composition. This study contributes to guiding estimates of biogas generation model parameters based on waste composition data.

Design and Operation of Effective Landfills with Minimal Effects on the Environment and Human Health.

Totaling at 7.4 billion people, the world's population is rapidly growing, bringing along with it an increase in waste generation. The impact of this exponential increase in waste generation has resulted in the increased formation and utilization of landfills. In the present day, landfills are utilized to dispose of chemical, hazardous, municipal, and electronic wastes. However, despite their convenience, most landfills are improperly managed and face constant changes from the surrounding environment that interfere with their internal landfill processes. The objectives of this mixed review are to highlight the negative impacts landfills have on the environment and public health as well as outline the need for proper management practices to mitigate these effects. Inadequate management of landfills leads to issues concerning leachate collection and landfill gas (LFG) generation, which give rise to groundwater contamination and air pollution. This paper recognizes the disadvantages of utilizing landfills as the main disposal method by focusing on these two primary effects that improper management of landfills has on the environment and human health. Many experts have also reported that communities within close proximity to improperly managed landfills have an increased risk of health issues. Apart from implementing proper landfill management practices, it is important to develop solutions to reduce waste generation altogether. This review discusses some of the innovative methods implemented by other countries to reduce landfill waste and the production of greenhouse gases as well as possible steps individuals can take to minimize their ecological footprints.