Municipal Solid Waste Combustion Research Articles

A novel green methanol – heat cogeneration system based on municipal solid waste plasma gasification and coke oven gas: Energy, exergy, economic, and environmental assessment

Burning municipal solid waste for disposal contributes significantly to atmospheric pollution. Utilizing municipal solid waste for green methanol production can alleviate environmental burdens. This study proposes a novel approach based on municipal solid waste plasma gasification, integrating coke oven gas catalytic reforming for green methanol synthesis. A comparative analysis is conducted against a conventional scheme involving water gas shift for syngas production. Simulation models of both approaches are constructed, revealing that the newly proposed system achieves higher methanol synthesis yield and energy utilization efficiency at 90.57 % and 61.28 %, respectively, with an exergy efficiency of 63.74 %. The project incurs an investment cost of 11,448.70 k$, with a dynamic payback period of 4.18 years after a 1-year construction cycle. The net present value over a 25-year operational span is 21,899.16 k$. Additionally, the proposed system emits less than 0.06 tons of carbon dioxide per ton of green methanol, significantly lower than the 0.72 tons emitted by the water gas shift-adjusted syngas synthesis scheme. It makes the proposed approach a potential negative carbon emitter compared to municipal solid waste incineration. Therefore, the system demonstrates favorable thermodynamic performance, coupling with substantial economic and environmental benefits.

Production and emission characterization of briquette for sustainable development: MSW transformation.

Global community is increasingly alarmed by resource depletion and environmental pollution. In light of pressing environmental concerns and depletion of finite resources, the surge in fossil fuel usage has sparked twin crises: dwindling fossil fuel reserves and escalating environmental pollution. The current study introduces a novel approach to minimize waste by transforming it into briquettes suitable for large-scale production. Production of briquettes involves multiple stages, including collection, drying, crushing, screening, blending, compacting, and storage. The main objective of this research is to demonstrate and investigate the physico-mechanical and emission properties of briquettes produced with readily available organic fraction of municipal solid waste (MSW) such as food and garden waste. The physical, mechanical, and elemental characteristics such as calorific value, moisture content, ash, volatile matter, fixed carbon, density, compressive strength, and SEM-EDAX were determined. A combustibility test along with emission and water boiling test was also carried out. The MSW briquettes were prepared in a densification system at 130°C temperature and 20MPa. The study's conclusion suggests that the MSW briquette with lignin content of 25-30%, calorific value of 22.53MJ/kg, compressive strength of 14.517 N/mm2, and density of 1124.12kgm-3 could be used to retain energy and lessen the harmful effects of climate change while also enhancing sustainability. Flue gas emissions from burning MSW briquettes in a biomass stove were examined in this study using flue gas analyzer and smoke meter. Furthermore, the generated briquettes exhibit a density of 1124.12kgm-3 which is on par with coal, making them suitable for co-firing in boilers. Likewise, the determined parameters are compared with the biomass briquettes and firewood. Further investigation is required to elevate its quality and economic potential.

Bioengineering solutions for expansive soil stabilization using waste materials: An experimental evaluation

Municipal solid waste incineration ash is the outcome/product of bioengineering science. The incineration or burning of municipal solid waste (MSW) reduces the volume of this biomass by 90%, and the residual ash can be used in several applications. In this study, the potential of municipal solid waste incineration (MSWI) ash and calcium carbide residue (CCR) waste for stabilization of expansive soil has been experimentally evaluated. The abnormal shrink–swell characteristics of expansive soils pose several problems for civil engineering structures when these soils are used for construction in their original form. The study presents an experimental set-up to determine the best combination of additives to achieve the most favorable technical characteristics of expansive soil for civil engineering activities. The percentage of expansive soil has been kept fixed at 60% of the total weight of the mix for varying ratios of stabilizing agents. The optimization of the stabilizing materials is based on the highest strength parameters of the mix achieved for a particular ratio of additives and soil. The two stabilizing agents are waste materials, and their disposal through landfilling has become costly due to a scarcity of space and handling mechanisms. The values of strength parameters, unconfined compressive strength (UCS), and split tensile strength (STS) of a treated mix are found to be highest for a unique combination of 60% lime stabilized expansive soil and 20% MSWI ash and an equal quantity (20%) of CCR. The cumulative effect of adding the best mix of additives to soil and curing time depicts an improvement of 526.03% in UCS and 463.41% in STS of the mix compared to one day and 28 days of curing time. There is scope for further study, such as adding some fibers to the finalized mix to reinforce the soil mix.

High-temperature corrosion-resistant alloy for waste-to-energy plants: Alloy designing, fabrication, and possible corrosion-resistance mechanism

This study designed a novel high-temperature corrosion-resistant alloy through thermodynamic equilibrium computations. The strength was determined by the integration of precipitation-strengthening species of nickel boride and tungsten solid solution strengthening, while high-temperature corrosion-resistant property was realized through optimized compositional design. Phase stability was enabled by the presence of a face-centered cubic structure. The alloy was fabricated and its corrosion-resistance performance was experimentally compared with other commercially available nickel- and iron-based alloys under simulated municipal solid waste combustion. The designed alloy with a composition of Ni-5B-6W-28Cr-13Al showed a low corrosion rate of ∼72 % < 13CrMo4-5TS and 1.08 % > Inconel 625. Economic analysis showed that Ni-5B-6W-28Cr-13Al has a cost-effectiveness ratio of 1:1.57 with respect to Inconel 625 and 1:0.09 with respect to 13CrMo4-5TS. Corrosion-resistance mechanism was explored using scanning electron microscopy coupled with energy dispersive spectroscopy, x-ray diffractometer, and DFT computations. The corrosion resistance occurred through the formation of a uniform tungsten-chromium-oxide film which inhibits inward diffusion of corrosive chlorine species. These findings provide insights into the development of alloys for high-temperature technologies.

Towards a low-emission resource circulation of valuable metals from municipal solid waste incineration fly ash

The incineration fly ash (IFA) resulting from municipal solid waste combustion is laden with heavy metals, necessitating proper treatment not only for environmental management but also to reclaim the metal values. The surge in non-traditional metals like cobalt as emerging contaminant within IFA samples further attracts to address this issue. In response, the hydrometallurgical recycling of a cobalt-bearing IFA has been studied. Thereby, approximately 98 % zinc and 96 % cobalt were leached using a 1.0 mol/L H2SO4 solution at 90 °C and 1 h of leaching time. In-depth analysis of the leaching process unveiled metals' dissolution primarily via the ion-exclusion mechanism, as evidenced by lower diffusion coefficients (between 10−9 and 10−11 m2/s) and activation energies (9.6–14.9 kJ/mol). Above 99 % separation of zinc from the cobalt-bearing leach liquor was achieved by extraction with 1.0 mol/L D2EHPA at an equilibrium pH below 3.0, followed by stripping with a 2.0 mol/L H2SO4 solution. Cobalt, remained in the raffinate was efficiently precipitated by adding a 20 % excess dosage of oxalic acid to the stoichiometric ratio of C2O42−:Co2+, resulting in only 5 mg/L cobalt left in the solution when precipitation occurred at a pH of 2.8. Additionally, the conversion of CoC2O4 to high-purity Co3O4 was conducted through heat-treatment at 600 °C. The resulting Co3O4 was mixed with Li2CO3 at a Li/Co molar ratio of 1.1, yielding a LiCoO2 precursor that exhibited good electrochemical properties with a capacity of 128 mAh/g, thus affirming the high quality of the recycled cobalt. A comprehensive life-cycle assessment of the recycling process revealed that cobalt precipitation alone contributes approximately 50 % of the total global warming potential (GWP = 4.2624 kg CO2-eq). Notably, this value is remarkably lower than the GWP reported for primary cobalt production, highlighting the environmentally-friendly approach of this recycling endeavor.

Harnessing Abuja's Municipal Solid Waste as a Renewable Energy Source: Scanning Electron Microscopy Analysis

A study of Abuja’s municipal solid waste (MSW) samples using the scanning electron microscopy analysis was undertaken in this work. In the face of the severe energy poverty being experienced in Nigeria which largely depends on diminishing fossil fuel resources coupled with the associated problem of greenhouse gas emission, the energy potential available in municipal solid wastes needs to be investigated. Using MSW as a fuel source for electric energy production will also positively impact on Abuja’s waste management. This present study requires the analysis of the MSW with aim of confirming that products of its incineration will not be hazardous to the environment. ASTM E 1508 procedures for utilizing the scanning electron microscope (SEM) were followed to identify elements that would be contained in the bottom ash of the incineration process of samples of Abuja’s municipal solid wastes obtained from selected districts of the city. Elemental composition of the bottom ash that will be formed from incineration of Abuja’s MSW was obtained by the use of energy dispersive x-ray analysis. The micrographs plotted indicate that silicon and iron are the principal elements present in the samples with values for silicon and iron being highest at 49.5 and 19.55%, respectively, for the sample from Dutse-Alhaji. The tests also show the presence of silver in the organic wastes generated in Abuja, while presence of sulphur is very minimal. The silicon levels present in Abuja’s municipal solid waste compare well with values for Nigerian coals which have percent silicon contents ranging from 39.0 – 49.4% (Enugu coal – 39.0%; Okaba – 44.8%; Maiganga – 49.4%). The test results also show that Abuja’s MSW samples had grain sizes ranging from 3.5 mm 16 mm. The results indicate Abuja’s MSW combustion rate will be lower than for pulverised coal which is known to have much lower grain size in the range of 75 μm to 106 μm and will need shredding before firing since grain size is a very critical determinant factor in solid fuel combustion rate and burn-out time. The tests conclusively show that Abuja’s MSW will be a more environmentally friendly fuel than coal because of its lower sulphur content.

Assessment of the energy potential of municipal solid waste: A case study of Mussaka dumpsite, Buea Cameroon

A country's economic growth and urbanization often lead to environmental degradation due to the amount of waste generated. Proximate analysis was done. The objective of this study is to evaluate the energy potential of the municipal solid waste (MSW) in Buea municipality through landfill gas-to-energy and incineration technology. Methane emissions from the Mussaka dumpsite for two decades using the Inter-Governmental Panel on Climate Change (IPCC) default method (DM) and Landfill Gas Emission Model (LandGEM V3.03) models were estimated. The Buea municipality's 2022 combustible MSW generated 40,593.69 tons with a low heating value of 7.37 MJ/kg, potentially producing 20.5 GWh of energy. LandGEM and IPCC DM models predicted total methane emissions during the period 2010–2030 as 21.33Gg and 54.77Gg, with annual energy potentials ranging from 0 to 5.10 GWh and 2.91 to 15.31 GWh respectively. This study provides crucial information for waste management investors and policymakers.

Mechanical strength changes of combustible municipal solid waste components during their early pyrolysis stage and mechanism analysis.

Implementation of municipal solid waste (MSW) source segregation leads to a more convenient recycle of combustible MSW components. Textiles, plastics and papers are commonly available combustible components in MSW. Their shredding is conducive to resources recovery. But these components usually have high tensile strengths and are difficult to shred. To understand their mechanical strength changes in their early pyrolysis stage will help to address this problem. In this study, a universal electronic testing machine was used to determine the breaking strengths of the materials including cotton towel, polyethylene glycol terephthalate (PET), ivory board (IB), kraft paper (KP) and wool scarf in the temperature range of 30-250°C under N2 atmosphere, and the mechanisms of their strength changes were explored. The reaction force field molecular dynamics (ReaxFF-MD) simulation was used to explain the decomposition behaviours of different sugar groups of hemicellulose in cotton and paper and the change of van der Waals energy of wool during their early pyrolysis stages. The results showed that breaking strengths of all the combustible MSW components reduced as the temperature increased. The breaking strength of PET was found to have the highest descent rate with increasing temperature, then the descent rates of wool and cotton came as the second and third, respectively. Compared with cotton, the breaking strengths of KP and IB decreased more slowly. As the temperature increased, the breaking strength of cotton reduced mainly due to the decomposition of the glucuronic acid in hemicellulose, and the reduction was characterized by CO2 release. The breaking strength reduction of PET was caused by its molecular chain being relaxed. The breaking strength reduction of wool was firstly caused by the decrease in the van der Waals energy between its molecules, and then caused by molecular chain breaking. In addition, in order to understand the influence of material size on the breaking strength change during thermal treatment, the breaking strengths of cotton yarn bundles were correlated with their yarn number and temperature. This study lays the foundation for understanding changes in mechanical strengths of combustible MSW components during their early pyrolysis stage.

Research on the Combustion Performance of Municipal Solid Waste in Different Sorting Scenarios: Thermokinetics Investigation via TG-DSC-FTIR-MS.

Waste sorting is regarded as one of the most important strategies for municipal solid waste (MSW) management. The changes in the combustion parameters after MSW sorting had a significant impact on the actual operation of the boiler. In the present study, the effects of heating rate on combustion characteristics and dynamics of MSW in different sorting scenarios were studied using the thermogravimetry (TG)-differential scanning calorimetry (DSC)-Fourier transform infrared (FTIR)-mass spectrometry (MS) technique. TG-DSC analysis showed that the heat released from MSW combustion at different heating rates ranged from 1394.1 to 4130.1 J/g. According to the TG-DTG curves, the combustibility of 30% sorted MSW was increased by 1.2 times compared to that of the unsorted scenario. In the 30% sorted scenario, the average activation energies were estimated to be 161.24 and 159.93 kJ/mol based on the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, respectively. Based on the Coats-Redfern (CR) method, the minimum activation energies for unsorted and 20% sorted scenarios were 148.74 and 135.53 kJ/mol at 523 to 606 K, respectively, while they were 29.42 and 33.22 kJ/mol at 606 to 780 K. XRF analysis showed that the alkali and alkaline earth metal oxides in the ash contributed to a high risk of slagging and scaling. This work can provide a scientific basis for the real situation of MSW incineration.

Modeling Analysis and Research on the Evaporation System of a Multisource Organic Solid Waste Incinerator

The co-incineration of multisource organic solid waste has gradually become an important method for solid waste recycling. Through a combination of computational fluid dynamics simulation and field monitoring, a distributed parameter model of the evaporative heating surface of an incinerator was developed. The distributions of heat flux, wall temperature, and steam quality in the incinerator were analyzed under four combustion conditions involving solid waste from various sources, types, and proportions. The results revealed that under the two working conditions with 20% waste cloth, as the calorific value of the mixed fuel increased, both the peak heat flux and the peak wall temperature increased, and the nonuniformity of heat transfer within the furnace intensified. Under the influence of the composition and calorific value of the mixed fuel, the steam quality of the working fluid at the outlet of the rear water wall in the cases with 20% waste cloth was significantly higher than that in the case of pure municipal solid waste combustion and the case with 20% sludge. This study offers valuable insights into the resource utilization of multisource organic solid waste in co-incinerators.

High temperature corrosion of particulate matter during MSW combustion: Effects of particle size, inorganic minerals and additives on corrosion rates and mechanisms

The high temperature corrosion behavior and corrosion mitigation of PM with different sizes generated by MSW combustion were studied. The experiment result showed that the corrosion rate of 304 stainless steel increases significantly as the PM size decreases. The corrosive ability of PM1 on 304 stainless steel was about 3–5 times higher than that of PM10+ at 600 °C. Kaolin can greatly restrain the corrosiveness of PM. After 5% of kaolin was added, the corrosion rate of the PM generated by MSW combustion on 304 stainless steel was reduced by 12%. Calculating the composition of the particles after the formation of a stable slagging layer and ash deposition layer on the heating surface, the corrosion control efficiency improved to 71%. High-temperature corrosion process of PM was dominated by NaCl, KCl, CaCl2, Na2SO4 and K2SO4, the corrosion of alkali and alkaline earth chloride was generally stronger than that of sulfate at 600 °C. This study confirms that the addition of kaolin can effectively mitigate high-temperature corrosion in the superheater tubes of waste incineration furnaces.

Development of a Common Waste Combustion System for Generating Electricity at Remote Area

Malaysia’s daily amount of municipal solid waste (MSW) has rapidly increased. This causes the landfills number to increase due to inadequate waste management systems. Apart from that, Malaysia depends on non-renewable resources for electricity generation which could have a significant effect on the environment. Therefore, this study proposed to reduce landfills in Malaysia in a proper way and supply electricity using municipal solid waste as a renewable resource. In this study, the combustion of municipal solid waste (MSW) produces steam, which will rotate a turbine that is connected to a dynamo. Then, the energized dynamo will supply electricity to appliances including a direct current motor. The motor shaft then rotates the dynamo shaft in the pulley system which causes the electricity to flow in a closed loop. In this system, a pressurized container is crucial to produce sufficient steam. Based on the experimental setup, it was observed that continuous electricity was successfully achieved by looping the system using a pulley on the dynamo and motor.

Concentrations of PAHs from urban and rural areas in southern nigeria using polyurethane foams (PUF) passive samplers: Health impact and cancer risk assessment

Nigeria loses thousands of its populace annually to cancer. Probable upsurge in the atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) has been suggested as a contributor to this menace. This baseline study has evaluated the concentrations of the 16 priority PAHs in urban and rural communities, Southern Nigeria to establish a nexus. Air samples were collected monthly for a period of 12 months from 10 sampling locations using passive samplers (polyurethane foams (PUF) disk). Results obtained revealed an average ambient air concentrations (∑16PAH) of 0.817 ± 0.33 µg/m3for the urban, 0.087 ± 0.05 µg/m3 for the rural and 0.011 ± 0.01 µg/m3 for the control site. Remarkably, the obtained urban and rural benzo(a)pyrene (BaP) mean concentrations, mainly from incessant combustion of unsorted municipal solid wastes and bush burning were outrageous (63 ng/m3 and 9 ng/m3 respectively), indicative of a significant cancer health hazard and a possible overlooked source of the global BaP burden. The Total Toxicity Equivalent Concentration (TTEC) were found to vary from 0.000063 – 0.417 µg/m3 with BaP once more reporting the highest toxicity value of 0.314 µg/m3. However, the Incremental Lifetime Cancer Risk (ILCR) values obtained, ranged from 7.8 × 10−8 to 5 × 10−5 which were within the acceptable limits. The Health Impact Assessment (HIA) reported symptoms suggestive of exposure to PAHs, with neurological and respiratory symptoms being the most prevalent by 31.4 - 61.4 % of the respondents. Spatial and temporal variations in the obtained PAH data were found to be significant (p<0.05) with higher values reported in the densely populated urban locations and during the dry season months.. Source identication studies by principal component analysis (PCA) revealed petrol, diesel and solid wastes combustion as the dominant anthropogenic source of the recorded PAHs, while the diagnostic ratio analysis revealed pyrogenic sources as the predominant PAHs emission source.

Evaluation of Multi-Utility Models with Municipal Solid Waste Combustion as the Primary Source under Specific Geographical and Operating Conditions

Developments in waste incineration technology in terms of efficient fuel preparation, combustion, and emissions reduction, as well as the growing needs of the community in terms of electricity, water, and air conditioning loads, are the prime motive for this study. This study presents a novel approach, in which three models of the fluidized bed combustion of municipal waste for simultaneous power generation, freshwater production, and district cooling are analyzed for their energy and exergy performance. The three simultaneously evaluated utility models are different configurations of a fluidized bed combustion system with Rankine cycle power generation, cooling with a vapor absorption refrigeration system, and fresh water production using multiple effect desalination. The output from the turbine, cooling system, and desalination system is determined using the Engineering Equations Solver for different boiler operating pressures. Energy and exergy analysis data for different pressures are used to identify the best configuration. Two variants of the absorption cooling system, namely, single effect and double effect, are considered. The variants of the multiple-effect desalination are the three-stage and five-stage methods. Input parameters used in this study are municipal solid waste generation and composition data collected for an urban community in an arid climate zone with high demand for electric power, cooling, and fresh water. Model 2, which contains two turbines with the reheating and cooling systems connected to a high-pressure turbine and water desalination connected to a low-pressure turbine, gave the best overall performance. Significant savings in terms of the replacement of conventional energy were observed from these waste conversion plants with greater benefits in arid weather conditions. The results obtained by different models under different operating criteria constitute a guideline for municipal planners for the selection of appropriate waste utilization technology, as well as the appropriate operations.

Multiblock dynamic enhanced canonical correlation analysis for industrial MSW combustion state monitoring

Combustion state monitoring in industrial municipal solid waste incineration (MSWI) power generation process is very difficult. There are two main reasons for this dilemma: (1) there is a large time lag between the combustion chamber and the steam generation stage; (2) reactions continue to occur and raw waste is fed into the incinerator continuously, so there are strong correlations and remarkable dynamic characteristics among process variables. The complex correlations in time and in space cause difficulties in combustion state monitoring for incinerators. Those correlations are common in industrial processes because the large scale equipment is usually needed and a whole process is realized by equipment in sequence. To overcome those difficulties, a multi-block dynamic enhanced canonical correlation analysis (MBDCCA) method is proposed to help monitor the MSWI process. Firstly, canonical correlation analysis (CCA) is extended to MBDCCA to model the MSWI process. Secondly, a combustion state online monitoring approach is designed based on the proposed MBDCCA algorithm. Finally, the proposed method is applied in an industrial MSWI plant to demonstrate the effectiveness.

Burning of Municipal Solid Waste: An Invitation for Aerosol Black Carbon and PM2.5 Over Mid–Sized City in India

Waste management is the main concern of most cities in developing countries. The proper procedure is needed to reduce Municipal solid waste, that’s why burning is the cheaper way to decrease solid waste. The main aim of this study is to assess the concentration of Black Carbon and PM2.5 during the MSW burning sites in Jamshedpur. The continuous measurement was taken during the burning period in three phases at Industrial, Urban, and Rural waste burning sites having respective average BC concentrations observed as 145 ± 46, 101 ± 33 & 95 ± 33 μg m−3, and PM2.5 as 1391 ± 358, 998 ± 319, 957 ± 313 μg m−3. BC and PM2.5 concentrations show significant diurnal variations with maximum average concentration at the midnight phase due to large temperature fluctuation (lower mixed layer height) in the atmosphere. This evaluation during burning period exceeds regular day estimates by around 5–6 times. The rate distinction of BC by the Aethalometer model indicates that source apportionment of BC is more sensitive in assessing BCBB (biomass burning) with an average fraction of 82% at 880 nm because waste trash burning in the dump yard was mostly solid. Pearson correlation analysis shows strong correlations between BC and PM2.5 concentration that is primarily attributable to well-known nearby sources such as vehicular emissions.

Oxygen carrier derived from ferric sludge for chemical looping combustion of MSW syngas: Waste derived material performance and carbon footprint assessment

The utilization of water treatment sludge (i.e., ferric sludge) was explored as the oxygen carrier (OC) for chemical looping combustion (CLC) of municipal solid waste (MSW) syngas. The performance of ferric sludge (FS) in CLC and simultaneous HCl removal was evaluated in a bench-scale fluidized bed, and was compared with iron ore (IO) as a benchmarked OC. The results show that FS (92 %) performed better than IO (82 %) in terms of syngas combustion efficiency and FS was able to remove HCl (77 % removal efficiency) while IO was unable to remove any HCl. Comparison of reaction temperature reveals that FS performed better at lower CLC temperature between 800 °C and 850 °C. Agglomeration was observed when FS was used in extended CLC cycles. Thus, investigation of using inert α-Al2O3 support together with FS for extended CLC cycles was investigated. Agglomeration and sintering were drastically reduced and good combustion efficiency of 88 % for H2 and 74 % for CO was attained. Carbon footprint assessment illustrated that FS was superior as a greener material based on global warming potential of 20 and 100 years. Conversion of FS as an OC were characterized with 104.23 and 108.0 kgCO2/t lower than IO for GWP-20 and GWP-100, exhibiting the competitiveness in the usage of waste-derived material in CLC. Hence, FS can be considered as a novel, cost-effective, and greener OC for CLC. The co-utilization of waste-derived material and waste-derived syngas through CLC would be an integrated solution for improved circularity and sustainability.

A CFD-based porous medium model for simulating municipal solid waste incineration grates: A sensitivity analysis

This study starts from a generalized CFD-based porous medium model developed in previous work simulating the combustion of municipal solid waste (MSW) on incineration grates. In this paper, three specific bed models are compared: a newly developed whole moving bed model, a newly developed multi-zone model, and a fixed bed model. Although the whole moving bed model covers the entire gas flow field, this advantage is offset by a high computational cost. In the multi-zone model, different zones of the waste bed are computed consecutively. This helps to reduce the computational time by about 75% but causes a loss of accuracy in predicting the gas flow field at the transition between the zones. For the fixed bed model, the walking column approach is needed. Additional accuracy loss is introduced but the computational time is significantly reduced even further compared to the multi-zone model. Because of the trade-off between computational cost and accuracy and the great uncertainty of the model parameters in industrial practice, the fixed bed model is suggested for simulating industrial grate-firing systems. In addition to these moving bed modeling strategies, this study also investigates how sensitive model results are to the assumed minimum and maximum solid fractions, which determine the evolution of porosity along the grate. The results show that the conversion rates are relatively insensitive to these criteria within the investigated range. Conversely, the effective surface area greatly influences the combustion characteristics as it affects the drying and char conversion rate and governs the temperature difference between the solid and gas phases. This finding calls for a better understanding of the evolution of the effective surface area and equivalent particle diameter during the combustion of MSW.

Development of a high-resolution emissions inventory of carbonaceous particulate matters and their growth during 2011–2018 over India

The carbonaceous fine particulate matters (BC and OC) are of significant concern for air quality and climate change. A high-resolution (10 × 10 km2) gridded SAFAR (System of Air Quality and Weather Forecasting And Research) emission inventory of BC-OC has been developed for 2011 and 2018 over India using bottom-up Geographical Information Systems (GIS) based statistical model with the latest activity data and updated emission factors. The emission inventory accounted for major sectors like transport, residential, industries, Thermal Power Plant (TPP), and rest (Mobile towers, Irrigation pumps, Municipal solid waste burning, Waste to energy plants, Construction, Crematorium, Incense stick, Brick kiln). The total national BC and OC emissions for the latest year, 2018 are estimated to be 1480 Gg yr−1 and 3116 Gg yr−1, respectively. The most dominant sector is found to be the transportation sector for BC with 46% share, whereas the residential sector for OC with 39% share. An overall growth of 32% and 36% is estimated in 2018 compared to 2011 for BC and OC, respectively. The highest growth during the past 8 years is found in the transport sector whereas the residential sector has recorded the lowest growth rate. The latter is mainly due to a decline in kerosene oil, and domestic wood after the government introduced the ambitious Ujjwala scheme to replace bio-fuel with LPG. This high-resolution inventory of BC-OC will be helpful to policymakers in identifying the hotspot regions and prioritizing mitigation options, thus benefitting Human health and climate. The current gridded emissions will provide much-needed input for the regional chemistry transport models.

Numerical simulation of municipal waste and food digestate blending combustion and NOx reduction under oxygen-enriched atmospheres

The paper aims at exploring an approach to clean combustion of municipal solid waste (MSW) with a focus on NOx emissions, in response to a global strategy for clean energy. The objective is to use an orthogonal approach to assess the NOx reduction potential of co-combustion of anaerobic food digestate (AFW) and MSW in an oxygen-enriched atmosphere. The first step is the combustion of MSW in different oxygen concentration atmospheres (21%, 26%, 31%) to find the most efficient oxygen-rich atmosphere. Three AFW blending ratios of 10%, 15% and 20% were then selected on a mass basis to investigate co-combustion with MSW. The results show that the O2/CO2 atmosphere is lower in temperature but more uniformly distributed for the same 21% oxygen concentration. Meanwhile, oxygen-enriched combustion reduces NOx emissions and decreases with increasing O2 concentration, reaching a minimum of 26.36% of NOx production under air atmosphere. As the proportion of food digestate blending increases, the gas phase conversion of N tends to decrease and then increase, reaching a minimum at 15% blending, when the temperature distribution in the furnace chamber is optimal and the outlet NOx emissions are the lowest.