Prediction of greenhouse gas emissions from Ontario's solid waste landfills using fuzzy logic based model

Industrial garbage-derived biocompost enhances soil organic carbon fractions, CO2 biosequestration, potential carbon credits and sustainability index in a rice-wheat ecosystem

The objectives of this experiment were i) to study on the garbage composting to improve the soil organic carbon (SOC) pools (active and passive), ii) work out the carbon (C) budgeting, and iii) cut off C footprints (CFs) in the rice (Oryza sativa L.)-wheat (Triticum aestivum L.) farming to achieve the long-term sustainability. The main plots show four fertilizer levels (F0 = control, F1 = 112.5:45:45 kg nitrogen; phosphorus; potassium (NPK) ha-1, F2 = 150:60:60 kg NPK ha-1 and F3 = 150:60:60 kg NPK ha-1+ 5 kg iron (Fe) + 5 kg zinc (Zn) were applied, while in sub plots with the combination of three industrial garbage (I1 = carpet garbage; I2 = pressmud; I3 = bagasse) and three microbial culture (M1 = Pleurotus sajor-caju, M2 = Azotobacter chroococcum; M3 = Trichoderma viride) made into nine treatment combinations were applied. Based on the interaction, treatment F3 × I1+M3 resulted in a maximum of 25.1 and 22.4 Mg ha-1 total CO2 biosequestration by rice and wheat, respectively. However, it was cut off CFs by 29.9 and 22.2% more than F1 × I3+M1. Based on the soil C fractionation study, in the main plot treatment, F3 was active very labile C (VLC) and moderately labile C (MLC) and passive less labile C (LLC) and recalcitrant C (RC) SOC fractions contributed by 68.3 and 30.0%, respectively, of total SOC. However, in the sub plot, treatment I1+M3 found 68.2% and 29.8% active and passive SOC fractions, respectively, of total SOC. Regarding the soil microbial biomass C (SMBC) study, F3 had 37.7% higher than F0. However, in the sub plot, I1+M3 was seen to be 21.5% greater than I2+M1. Furthermore, wheat and rice had higher 1002 and 897 US$ ha-1 potential C credit in F3 × I1+M3, respectively. SOC fractions were perfectly positively correlated with SMBC. A positive (+) correlation was observed among grain yield (wheat and rice) and SOC pools in soil. However, a negative correlation was found between the C sustainability index (CSI) and greenhouse gas intensity (GHGI). The variability in wheat and rice grain yield was 46 and 74%, respectively, contributed by the SOC pools. Therefore, this study hypothesised that applying inorganic nutrients and industrial garbage converted into biocompost cut off C emissions and reduced the demand for chemical fertilizers, opening garbage disposal, and simultaneously enhancing the SOC pools.

Utilizing waste compost to improve the atmospheric CO2 capturing in the rice-wheat cropping system and energy-cum‑carbon credit auditing for a circular economy

The study aimed to manage industrial wastes and create a module for using compost from waste for crops cultivation to conserve energy, reduce fertilizer use and Greenhouse gas (GHG) emissions, and improve the atmospheric CO2 capturing in agriculture for a green economy. In the main-plot, the experiment's results using NS3 found 50.1 and 41.8 % more grain yield and total carbon dioxide (CO2) sequestration in the wheat-rice cropping sequence, respectively, compared to the NS0. Moreover, the treatment CW + TV in the sub-plot observed 24.0 and 20.3 % higher grain yield and total CO2 sequestration than B + PS. Based on interaction, the NS3× CW + TV resulted in a maximum total CO2 sequestration and C credit of 47.5 Mg ha-1 and US$ 1899 ha-1, respectively. Further, it was 27.9 % lower in carbon footprints (CFs) than NS1 × B + PS. Regarding another parameter, the treatment NS3 observed a 42.4 % more total energy output in the main-plot than that of NS0. Further, in the sub-plot, the treatment CW + TV produced 21.3 % more total energy output than B + PS. Energy use efficiency (EUE) and net energy return in the interaction of NS3× CW + TV were 20.5 and 138.8 % greater than the NS0 × B + PS, respectively. In the main-plot, the treatment NS3 obtained a maximum of 585.0 MJ US$-1 and US$ 0.24 MJ-1 for energy intensity in economic terms (EIET) and eco-efficiency index in terms of energy (EEIe), respectively. While in the sub-plot, the CW + TV was observed at a maximum of 571.52 MJ US$-1 and US$ 0.23 MJ-1 EIET and EEIe, respectively. The correlation and regression study showed a perfect positive correlation between grain yield and total C output. Moreover, a high positive correlation (0.75 to 1) was found with all other energy parameters for grain energy use efficiency (GEUE). The variability in the wheat-rice cropping sequence's energy profitability (EPr) was 53.7 % for human energy profitability (HEP). Based on principal component analysis (PCA), the eigenvalues of the first two principal components (PCs) had been greater than two, explaining 78.4 and 13.7 % of the variability. The experiment hypothesis was to develop a reliable technology for safely using industrial waste compost, minimizing energy consumption and CO2 emissions by reducing chemical fertilizer input in agriculture soils.

Development of fuzzy leachate pollution index for treatability-based classification of solid waste landfills

The fuzzy leachate pollution index (FLPI) was established to classify the landfill sites on the basis of their leachate pollution potential by considering the limitations of traditional methods. The FLPI was developed adopting 9 critical input parameters, i.e., TDS, pH, Cl, Cu, Pb, Cr, Zn, BOD, and COD, from 22 major landfill sites across India. Using these critical parameters, 3 groups, i.e., inorganic leachate strength (INLS), organic leachate strength (ORLS), and heavy metal leachate strength (HMLS), were generated to estimate the FLPI. The regression analysis, ANOVA, and sensitivity analysis were also performed to determine the significance and uncertainty of the index. The results showed that among all MFs, the triangular with overlapping open ends (TOO) MF was best fitted (R = 0.90) for FLPI estimation. Accordingly, 41% of the landfill sites showed less treatment while the others (59%) required moderate degree of treatment. The regression (R² = 0.92) and ANOVA (F value = 15.003, p = 0.000031) analyses described that the developed tool was significant (p < 0.05). The sensitivity analysis showed that Zn (R = 0.99) was the most influencing factor followed by BOD > COD > pH > Cr > Cu > Cl > Pb > TDS. The study provides an important tool that can also be used by researchers and scientists for investigating and evaluating various environmental problems.

Life cycle GHG emissions of MSW landfilling versus Incineration: Expected outcomes based on US landfill gas collection regulations

From a GHG perspective, most LCA studies find incineration (MSWI) to be preferred over landfilling because of high energy recovery offsets. In some studies, however, landfilling results in less greenhouse gases (GHG) emissions than MSWI. We investigated using LCA, the landfill gas (LFG) collection efficiencies and waste composition that led to landfills resulting in less GHG emissions. Then, we explored what theoretical minimum lifetime gas collection efficiencies can be expected when following US LFG regulations. Only landfills with high LFG collection efficiencies (at least 81%) and recovery of methane for energy resulted in less GHG emissions compared to the management of the same waste stream in MSWI; required efficiency increased to 93% without LFG energy recovery. Expected theoretical lifetime LFG collection efficiencies were modeled in the range of 30-80%, with the lower rates associated with landfills having smaller input masses, high decay rates, and low concentrations of nonmethane organic compounds (C_NMOC). Our modeling found that only under a limited combination of conditions (e.g., high C_NMOC, high waste input rate, low decay rate) could a landfill expect to achieve a LFG collection efficiency as high as 80%, and that this value falls just under the 81-93% collection efficiency threshold needed for a landfill to result in less GHG emissions than MSWI. When exploring the influence of higher oxidation rates, changing decay rates, varying electricity grids, and inclusion of nonferrous metals recovery offsets the collection effciency range needed increased in nearly all cases; the electricity grid and nonferrous metals offsets had the greatest influence.

Quantification and control of gaseous emissions from solid waste landfill surfaces

Landfilling is the most common option for solid waste disposal worldwide. Landfill sites can emit significant quantities of greenhouse gases (GHGs; e.g., methane, carbon dioxide, and nitrous oxide) and release toxic and odorous compounds (e.g., sulfides). Due to the complex composition and characteristics of landfill surface gas emissions, the quantification and control of landfill emissions are challenging. This review attempts to comprehensively understand landfill emission quantification and control options by primarily focusing on GHGs and odor compounds. Landfill emission quantification was highlighted by combining different emissions monitoring approaches to improve the quality of landfill emission data. Also, landfill emission control requires a specific approach that targets emission compounds or a systematic approach that reduces overall emissions by combining different control methods since the diverse factors dominate the emissions of various compounds and their transformation. This integrated knowledge of emission quantification and control options for GHGs and odor compounds is beneficial for establishing field monitoring campaigns and incorporating mitigation strategies to quantify and control multiple landfill emissions.

Landfill site selection by integrating fuzzy logic, AHP, and WLC method based on multi-criteria decision analysis

Rapid population growth integrated with poor governance and urban planning is highly challenging resulting key for the selection of unsuitable landfill sites, particularly in developing counties. Therefore, the aim of this study is to investigate the suitable solid waste landfill sites in the capital of the country as a case study, by the integration of Geographical Information System (GIS) with fuzzy logic, analytical hierarchy process (AHP), and weighted linear combination (WLC) method based on multi-criteria decision-making (MCDM). We chose thirteen (13) criteria (9 factors and 4 constraints) and grouped them into two main categories (environmental and socioeconomic) to achieve the objectives. The AHP was employed to evaluate the relative importance of the factors followed by standardization of criteria factors based on fuzzy set theory. Subsequently, all criteria factors were combined based on AHP and fuzzy logic-WLC method in order to obtain land suitability map. Finally, the sites were identified by the intersection of two combined suitability index layers. The obtained results depicted that the integration of fuzzy logic, AHP, and WLC technique with GIS can produce satisfactory results for the suitable locations of solid waste landfill sites over complex topographic regions. Overall, the land suitability obtained based on fuzzy-WLC is more refined and smooth because of its better segregation and its potential to consider full tradeoff between factors and average risk. The AHP was identified (47 km2) as high suitable while fuzzy-WLC generated 36 km2 as suitable area. Finally, the intersection of both suitability index map shows numerous suitable landfill sites available in Islamabad city; however, the surface areas of the sites are small at individual level (less than 15 ha).

Techno-economic assessment of landfill gas (LFG) to electric energy: Selection of the optimal technology through field-study and model simulation

Landfill Gas (LFG) is a renewable energy resource. LFG quality and production rate are determined factors for the selection of the optimal technology for electric energy production. Environmental legislation, flue gas emissions, carbon footprint and maturity of technology should also be considered. The most common process for electric energy production from LFG is by Internal Combustion Engines (ICEs), which require approximately 40% minimum methane concentration. Microturbines have been also employed for electric energy production from LFG, requiring minimum methane concentration of approximately 35%. On the other hand, a relatively novel process, Gradual Oxidation (GO), can produce electric energy from LFG at methane concentrations as low as 1.5%. The present study examines the applicability of the above technologies for electric energy production from LFG, from various cells, at the landfill of Heraklion, Crete, Greece, from an economic point of view. The LandGEM (EPA) simulation model has been modified to account for the long them reduction of methane concentration in LFG, and has been adjusted, based on field measurements. The Net Present Values (NPVs) (for 15-years and 25-years from installation) for three distinct scenarios, with total electric energy production capacity of 800 kW, per scenario (using just ICEs, combination of ICE and GO or just microturbines), were calculated. The results indicated that the most profitable scenario (among the ones studied) was the one with the use of two microturbines with capacity 400 kW, each, yielding 15-years and 25-yeasr NPVs of 2.68 and 3.69 M€, respectively, for initial capital investment of 2.24 M€.

Transport mechanisms and emission of landfill gas through various cover soil configurations in an MSW landfill using a static flux chamber technique

This study evaluated the transport mechanisms and emission rates of landfill gas (LFG) from 200- (vegetated with short grass), 300- (vegetated with short grass), and 450-mm-thick (non-vegetated) interim cover soils within a municipal solid waste landfill. LFG emission and diffusion mechanisms were evaluated using static flux chambers and laboratory-scale diffusion columns. Overall, the greatest CH₄ and CO₂ emissions were consistently observed from the 200-mm-thick cover soil with an average flux rate of 39.2 mg m^-2 h^-1 and 3.07 × 10³ mg m^-2 h^-1, respectively. In addition to CH₄ and CO₂, H₂S migration through a 450-mm interim cover soil was also evaluated. The H₂S emission rate was relatively more uniform at an average of 2.47 × 10^-5 mg m^-2 h^-1. Long-term LFG emission was predicted using an emission model based on a first-order decomposition rate equation and compared with the static flux chamber method. The field-measured CO₂, CH₄ and H₂S emissions were less than the estimated emissions from the emission model, by 22%, 85%, and 91%, respectively. Further, the diffusion coefficients of CH₄, CO₂, and H₂S for the interim cover soils were determined using a laboratory-scale diffusion column test and compared with a three-parameter diffusion model. The measured and estimated diffusion coefficients for the three landfill gases were within the 10% variation limits. Based on these findings, the LFG emission rate varied depending on the physical-chemical properties of the cover soil (e.g., cover thickness, moisture content, compaction ratio, uneven distribution of soil), organic material content and age of buried refuse, and seasonal environmental conditions (such as temperature). Test results showed that fugitive CH₄ emissions can be reduced one fourth by utilizing an appropriate cover soil (300-mm to 450-mm, CL) compared to cases with a thinner cover soil.

Emission and Neutralization of Methane from a Municipal Landfill-Parametric Analysis

An attempt was made to estimate the annual production of CH4 at a municipal waste landfill site in Poland. As a matter of fact, the extent of the unorganized emission of CH4 from the landfill surface was approached based on the adopted mathematical model. The Ward agglomeration method for cluster analysis and the Pearson coefficient were employed to evaluate the distance-based similarity measure and to optimize methods for estimating methane emissions from a landfill as well as to verify the input parameters for the model. In order to calculate the content of biodegradable organic parts in the waste, morphological tests of the landfilled waste were performed. Physical quantities, measurements and the actual amount of the landfilled waste as well as the volume of CH4 neutralized in a collective flare were implemented in the model, respectively. The model-based findings and experimental outcome demonstrated stable gas production in the landfill with a high CH4 content. On the other hand, a rather low efficiency of the landfill passive degassing installation indicated the necessity to design and develop its active counterpart with the prospective application of the generated biogas for energy production in a cogeneration system.

Investigation of fugitive methane and gas collection efficiency in Halton landfill in Ontario, Canada

Methane gas is one of the significant contributors to global warming. A large portion of methane emissions comes from landfills. Developing reliable measurement methods for methane emissions from landfill sites has become very important. In this paper, the surface emissions of methane gas are quantified using a portable probe having a flame ionization detector (FID), a method proven to be successful in landfill gas measurement. Surface methane emissions from two closed cells in the Halton landfill in Ontario, Canada, were measured using the FID method. By analyzing the emissions within the perimeter of the landfill, hotspots of gas leakage were identified. The closed cells in the Halton landfill are equipped with gas extraction system for flaring and energy recovery and a clay topsoil cover. Emission concentrations of fugitive methane were found to range from 0.1 to 63 ppm. The largest emissions were detected in locations next to the leachate extraction manholes and malfunctioning gas extraction wells. The landfill gas balance showed that the landfill gas recovery efficiency was 44%, resulting in an average amount of fugitive methane from the landfill of 6124 m³/day. The results of the study were used to determine the methane generation potential (L_o) for municipal solid waste to further calibrate the USEPA LandGEM model for Ontario landfills. The model was calibrated by actual methane emission measurement and recovery data. The calibrated L_o was found to be 70 m³/t, which is lower than the estimated values in previous studies.