Moisture Content Of Municipal Solid Waste Research Articles

Characterization for optimizing the integrated management of solid waste for energy recovery and circular economy.

Municipal solid waste (MSW) management poses a significant environmental challenge in municipalities across developing nations worldwide. Our studies were focused on characterizing the waste and analyzing the chemical properties of mixed waste fractions to assess their potential for waste-to-energy conversion. The objective of our study was to scrutinize the existing state of the MSW management system and gauge its waste generation rates. Specific ASTM methods were employed to carry out both physical and chemical characterizations. The outcomes reveal that the city generates a daily volume of 1155 tons of domestic solid waste (DSW), translating to a generation rate of 0.51kg-1 capita-1day-1. When analyzed by source, organic matter emerged as the predominant constituent, accounting for 73.74% of the waste, followed by combustible content waste at 15.17%. The moisture content of MSW ranged between 26 and 58% throughout the seasons, while volatile solids varied from 22.35 to 99.74%. Among the components screened, carbon and oxygen stood out as the dominant elements. The calorific values encompassed a broad range, ranging from 14.87MJkg-1 for leather waste to a substantial 25,629.27MJkg-1 for organic waste. To alleviate the escalating burden of increasing solid waste generation, alternative treatment approaches were recommended. These include composting, biomethane plants, the establishment of recycling facilities, and the enhancement of existing landfill sites to scientifically designed landfills. In summary, the findings from this study provide valuable insights for regulatory bodies and municipal authorities. These insights can guide the formulation of policies concerning waste sampling, characterization, segregation, and the implementation of education and awareness campaigns.

Exploring Key Components of Municipal Solid Waste in Prediction of Moisture Content in Different Functional Areas Using Artificial Neural Network

Moisture content is a very important parameter for municipal solid waste (MSW) treatment technology selection and design. However, the moisture content of MSW collected from different urban areas is influenced by its physical composition in these areas. The aim of this study was to analyze the key components of MSW for predicting moisture content in different functional areas via the development of an artificial neural network (ANN) model. The dataset used in this study was collected in Shanghai from 2007 to 2019. Considering the influence of functional areas, the model obtained the performance with MAE of 2.67, RMSE of 3.29, and R2 of 0.83, and an eight-fold cross validation showed acceptable results. The inter-quartile range (IQR) and isolation forest were compared to detect and remove outliers. In descending order, the moisture content was ranked as commercial/residential > office > cleaning areas. Based on a parameter exclusion method, kitchen, rubber, and plastic wastes show the greatest influence on moisture content in residential and commercial areas. In cleaning and office areas, paper, wood and bamboo waste products were the most important components. The determination of key components in different functional areas is of benefit for reducing the workload of moisture content estimation.

Spatial distribution and management of the energy potential of municipal solid waste incineration: A case study of Lhasa, China

The Qinghai-Tibet Plateau is a typical ecologically fragile region. Lhasa, as the most densely populated area on the plateau, is generating a large amount of municipal solid waste (MSW) with the development and improvement of living standards. However, due to the special geographical distribution, the energy utilization of MSW is limited, which is considered to be guided by the energy distribution of the MSW. In this work, Geographic Information System (GIS) technology is proposed to map the potential energy distribution of MSW in Lhasa City, which could provide a piece of reliable information on MSW management and energy utilization in Lhasa City. The potential energy value of MSW is high in urban areas, up to 2.082 × 109 MJ in Chengguan District, and low in suburban regions, up to 6.95 × 107 MJ. The energy potential per unit area of MSW is 87.7 kJ/m2 to 3980 kJ/m2 in urban regions and 10.5 kJ/m2 to 67.1 kJ/m2 in suburban regions. Therefore, the MSW in the urban regions and the suburban regions is suitable for centralized energy utilization and decentralized processing, respectively. The potential energy per unit mass of dry-based MSW is 13100 kJ/kg to 21600 kJ/kg and per unit mass of wet-based MSW is 8110 kJ/kg to 14300 kJ/kg due to the high moisture content of food waste, which is above 70% in most regions. Therefore, the separation of food waste and the MSW can reduce the moisture content of MSW, which is beneficial to its subsequent energy recovery and utilization, not only improving the lack of data on the potential energy distribution of MSW in high altitude plateaus, but also providing sound recommendations for the management of energy utilization in MSW incineration at high altitude.

Modelling of an Integrated Plasma Gasification Combined Cycle power plant using Aspen Plus

The development of a steady-state model of an Integrated Plasma Gasification Combined Cycle (IPGCC) power plant is presented here. The model includes the plasma gasifier, syngas conditioning units, and the power generation unit. Furthermore, the model of each component implemented in Aspen Plus is described in detail (thermodynamic method, chemical reactions, and operative conditions). The proposed model was validated by comparing the plasma gasification results with experimental and numerical data from the literature; the relative error was 6.23% and 5.24%, respectively. The model was then used to perform a two-part sensitivity analysis. In the first part, simulations with municipal solid waste (MSW) with a moisture content varying from 20% to 60% were performed. The moisture content increment reduced the torch specific power consumption by 53%. However, because of the increasing specific fuel consumption, the thermal efficiency of the IPGCC power plant also decreased by 28% as the MSW moisture content increased from 20% to 60%. In the second part, it was determined that the IPGCC power plant reached the best performance (32.5%) when a high plasma temperature (5000 °C) and a low gasification temperature (2000 °C) were used. At this highest efficiency conditions, the 1000 t/day IPGGC power plant’s net power generation was 62 MWe.

Hydrogen-rich syngas from wet municipal solid waste gasification using Ni/Waste marble powder catalyst promoted by transition metals.

Gasification of wet municipal solid waste (MSW) coupled with in-situ CO2 capture is an attractive option for MSW disposal, allowing chemical and energy recovery. In this study, the Ni-CaO based catalysts were prepared with waste marble powder (WMP) as an alternative to CaO and promoted by different transition metals (i.e., Fe, Cu, Co and Zn). The bimetallic catalysts were prepared by the impregnation method and characterized by different analytical techniques. The catalyst performance for wet MSW gasification was evaluated in a fixed-bed reactor at optimized conditions (850°C and 50% moisture content of MSW). The results revealed that the addition of Ni-WMP catalyst greatly enhanced the dry gas yield (DGY), H2 yield, carbon conversion efficiency (CCE) and reduced the tar content from 0.73 to 1.16N.m3/kg, 212 to 509mL/g, 61.70% to 76.40% and 9.11 to 3.9wt%, respectively, compared to without catalyst. In contrast to the Ni-WMP catalyst, the transition metal promoted catalysts showed higher catalytic activity towards H2 yield (549-629mL/g), DGY (1.19-1.30N.m3/kg), and lower tar content (3.45-2.93wt%). The results revealed that Co promoted bimetallic catalyst performed better than Fe, Cu and Zn promoted catalysts. The tar content produced was also analyzed via GC-MS (gas chromatography-mass spectrometry) to understand the effect of different catalysts on tar composition. According to experimental results, the bimetallic promoted catalysts can be ranked as Ni-Co-WMP>Ni-Cu-WMP>Ni-Fe-WMP>Ni-Zn-WMP based on H2 yield and tar removal.

Pyrolysis of Solid Waste for Bio-Oil and Char Production in Refugees’ Camp: A Case Study

The current research focuses on assessing the potential of municipal solid waste (MSW) conversion into biofuel using pyrolysis process. The MSW samples were taken from Zaatari Syrian Refugee Camp. The physical and chemical characteristics of MSW were studied using proximate and elemental analysis. The results showed that moisture content of MSW is 32.3%, volatile matter (VM) is 67.99%, fixed carbon (FC) content is 5.46%, and ash content is 24.33%. The chemical analysis was conducted using CHNS analyzer and found that the percentage of elements contents: 46% Carbon (C) content, 12% Hydrogen (H2), 2% Nitrogen (N2), 44% Oxygen (O2), and higher heat value (HHV) is 26.14 MJ/kg. The MSW pyrolysis was conducted using tubular fluidized bed reactor (FBR) under inert gas (Nitrogen) at 500 °C with 20 °C/min heating rate and using average particles size 5–10 mm. The products of MSW pyrolysis reaction were: pyrolytic liquid, solid char, and gaseous mixture. The pyrolytic oil and residual char were analyzed using Elemental Analyzer and Fourier Transform Infrared Spectroscopy (FTIR). The results of FTIR showed that oil product has considerable amounts of alkenes, alkanes, and carbonyl groups due to high organic compounds contents in MSW. The elemental analysis results showed that oil product content consists of 55% C, 37% O2, and the HHV is 20.8 MJ/kg. The elemental analysis of biochar showed that biochar content consists of 47% C, 49% O2, and HHV is 11.5 MJ/kg. Further research is recommended to study the effects of parameters as reactor types and operating conditions to assess the feasibility of MSW pyrolysis, in addition to the environmental impact study which is necessary to identify and predict the relevant environmental effects of this process.

Parametric Study on Co-Feeding of Municipal Solid Waste and Coal in an IGCC Power Plant with Pre-Combustion Carbon Capture

Municipal solid waste (MSW) is one of the top contributors in greenhouse gas (i.e. methane) emissions - particularly from landfill disposals. However, it could be a remarkable source of renewable energy. In Bangladesh, generation of municipal solid waste is at least 2.7 million tonne per year in the major cities, implying a heavy environmental burden. On the other hand, there are several coal-based power plants are in the pipeline to meet the increasing energy demand in Bangladesh with the potential of significant CO2 emission. To find a remedy to the above situation, a power plant using Integrated Gasification and Combustion Cycle (IGCC) technology with pre-combustion carbon capture is considered in this study. IGCC has the advantage of producing high quality syngas from a wide variety of feed and assists in the capture of CO2 at a lower cost while providing high electric efficiency. The power plant was simulated by commercial simulation packages (Aspen PLUS™ and Aspen HYSYS™) using MSW and bituminous coal (Indonesian) as a combined feed. With a feed rate of 1800 tonne per day, Syngas produced from an entrained flow type gasifier was then treated for CO2 removal using mono-ethanol amine (MEA) solvent after necessary shift in a high temperature shift reactor. About 91% efficiency was achieved in the shift reactor while the CO2 capture efficiency was varied for this study from 30% to 85%. Further parametric variation was studied by varying the moisture content of MSW and MSW to coal feed ratio. Through combustion of the H2 rich syngas in a gas turbine and subsequent steam cycle with reheat resulted in 125 MW of electricity at an efficiency of 28.95% while capturing 50% of the CO2 generated in the process for an MSW to Coal feed ratio of 1:1. With variation in moisture content especially during monsoon season, the plant efficiency could be affected remarkably. On the other hand, it was observed that the energy requirement varied from 6 to 8 MW for every 10% increase in CO2 capture quantity. Overall, by capturing 50% of the generated CO2, it is possible to reduce the emission of a same size ultra-supercritical coal-based power plant from about 700 kg CO2/MWh to about 360 kg of net CO2/MWh incorporating co-feeding and pre-combustion capture in an IGCC power plant.
 Chemical Engineering Research Bulletin 21(2020) 37-42

Three-Dimensional Modeling of a Chinese Circulating Fluidized Bed Incinerator Firing Municipal Solid Waste

Currently waste incineration is a widely used method of waste management in China. Effective incineration requires understanding and tools to analyze the incineration process leading to good incinerator performance and efficiency as well as lower emissions. In this work, a Chinese circulating fluidized bed (CFB) incinerator firing municipal solid waste (MSW) and coal is modeled with a three-dimensional CFB furnace model to evaluate the incineration process. First, the modeling results are verified with measurement data from the incinerator. Then, the furnace model is applied in the simulation of a case with more dry MSW without coal. The objective of the research is to provide insight and increase understanding of the MSW incineration process. The simulation case of MSW with the lower moisture content highlights the possible reductions of fossil carbon emissions associated with the utilization of coal. To achieve this, a moderate reduction in the moisture content of MSW is required. A comparison between the MSW and coal versus only the MSW shows minor differences in the performance of the incinerator. Utilization of modeling in incinerator studies can aid in development of more efficient CFB incinerators, improving the waste management and reducing the utilization of fossil coal.

Sustainable optimization of waste management network over extended planning time horizon

AbstractThis study proposes a multiperiod mixed integer linear programming model for the management of a single municipal solid waste (MSW) treatment plant with sustainability as the objective. Discrete and continuous variables define the capacity selections for diverse MSW technologies, and the operation of the MSW network, respectively. The economic target is considered to maximize the net present value. The environmental impact is the minimization of a normalized environmental objective function (NEOF). The social target is the maximization of jobs. An interesting feature about the research work is the requirement of biodrying technologies for MSW moisture content control. Due to the conflicted nature among the sustainability components, a multiobjective optimization (MO) is carried out to find the Pareto optimal solutions. The MO results show that the Pareto optimal solutions vary around profit range of $4.9–8.5 billion, NEOF impact range of 3.2–3.6 units, and social benefit range of 2700–4828 jobs.

Pilot-scale grinding and briquetting studies on variable moisture content municipal solid waste bales – Impact on physical properties, chemical composition, and calorific value

Low bulk density, variable moisture content, and particle size of municipal solid waste (MSW) create feeding, handling, storage, and transportation challenges. In this study, MSW bales were size-reduced in stage-1 and stage-2 hammer mill grinders fitted with 50.8-mm and 6.35-, 12.7-, and 19.05-mm screens. Ground MSW was densified further in a pilot-scale briquette press by varying moisture content in the range of 10–25% wet basis (w.b.). At 40% (w.b.) MSW moisture content, the stage-1 grinder fitted with a 50.4-mm screen took about 136kWh/ton, while the stage-2 grinder fitted with a 19.05-mm screen took about 151kWh/ton. The bulk density of MSW after stage-1 and stage-2 grinding was about 25–50 kg/m3. Unit bulk and tapped density were in the range of 680–850 kg/m3, 478–315 kg/m3, and 346–540 kg/m3 post briquetting, and 591–830 kg/m3, 295–458 kg/m3, and 319–519 kg/m3 post five days of storage at 20 °C. The durability was about 93.40–98.54% post briquetting, and after five days of storage. Increasing the moisture content and screen size decreased density and improved durability. Briquetting energy increased to 120 kWh/ton at a higher moisture content and larger grind size. MSW flow characteristics improved after briquetting. Higher lignin content (≈30%) and calorific value (19–21 MJ/kg) suggest MSW is suitable for thermochemical conversion. Ash content in the MSW was in the 11.9–14.8% range. CT-scan images of the briquettes showed a network of interconnected pores formed due to compression of various MSW fractions.

Seasonal Changes in the Composition and Thermal Properties of Municipal Solid Waste: A Case Study of the City of Perm, Russia

The paper presents experimental studies of municipal solid waste (MSW) composition and its thermal properties (moisture and ash content). Measurements were taken to track seasonal changes in the composition of MSW. For example, in spring, the content of organic waste was 17.0% and, in autumn, it reached 31.5% due to considerable consumption of seasonal vegetables and fruits. The share of paper in MSW changed from 21.4% in spring to 9.7% in autumn. More paper in spring is due to discarded student notebooks at the end of a school year, as well as spring household cleaning. These data indicate significant changes in waste composition during the year, which should be taken into account when planning technologies for waste management.
 Laboratory studies of moisture and ash content by season allowed the range of these changes to be determined. In autumn for instance, the moisture and ash content of organic waste was about 82% and 14%, respectively, while in winter, it was approximately 73% and 22%, respectively. These figures can be explained by the organic waste origin: autumn organic waste often comes from fruit pulp and, for example, watermelon peels, and winter organic waste tends to consist mostly of dry vegetable peels such as potato peelings.
 The low calorific value of certain components is based on their composition and the level of moisture and ash in different seasons. Therefore, it is important to take into account the moisture and ash content of individual components, not average values, in order to calculate the waste calorific value.
 MSW thermal characteristics change significantly over the seasons: the MSW moisture content is the highest in autumn (about 49%) and the lowest in winter (32%). The ash content in MSW ranges from 20% in spring and autumn to 27% in summer. The lowest calorific value per working mass in different seasons varies from 7 to 10 MJ/kg, which must be taken into consideration when developing waste management systems in general and when designing specific energy recovery facilities.

Reduction potential of GHG emissions from municipal solid waste incineration for power generation in Beijing

Abstract With rapid economic growth and massive urbanization, China faces the problem of municipal solid waste (MSW) disposal and the pressing need for development of alternative energy. MSW incineration for power generation is playing an increasingly important role in MSW management in China. In order to study the reduction of GHG emissions caused by MSW incineration for power generation, the GHG emissions under the baseline level is calculated by using Clean Development Mechanism (CDM) methodology. Then, the GHG emission reduction is estimated based on the improved upstream-operation-downstream (UOD) framework. Finally, the GHG emission reduction in Beijing is studied and forecasted through grey prediction model and scenario analysis, and the main factors affecting the reduction potential are identified. The results show that the GHG emission reduction target can be achieved through MSW incineration for power generation. Direct and alternative GHG emissions from MSW incineration are the main sources of emissions, while indirect emissions account for a small proportion. The MSW disposal volume, the moisture content of MSW, the installed capacity of biomass energy, the average line loss of power generation and the quantity of fossil fuels consumed by power generation are five important factors that affecting GHG emission reduction potential. It is recommended that the dominant form of waste disposal in China should be replaced by MSW incineration for power generation, and the full classification of MSW needs to be promoted. Furthermore, the installed capacity of biomass energy should be increased and the average line loss of power generation should be reduced.

Determination of ignition temperature of municipal solid waste for understanding surface and sub-surface landfill fire

Open dumping of municipal solid waste (MSW) is a common practice in India which leads to a number of problems like non-uniform compaction, slope failure, percolation of water during rainy seasons, abrupt leachate generation and stability issues. It also leads to various other issues, such as manual scavenging and deliberate waste burning. During the waste degradation process, an enormous amount of heat and landfill gases (LFGs) like carbon dioxide (CO2) and methane (CH4) are generated. Biological and chemical reactions happening at the surface and inside the landfill contribute to the heat generation. Initiation of waste ignition is a major cause of spontaneous landfill fire. The risk posed by landfill fires is high in India as most of the landfills are non-engineered. The present study aims to determine the ignition temperature of waste dumped at Bhandewadi dumpsite located at Nagpur, India which will enable a better understanding of the initiation of fires in non-engineered landfill (surface and sub-surface fires), especially in Indian condition. The results of the present study showed that ignition temperature is directly proportional to the moisture content of MSW for its values ranging from 5 to 55% by mass. The correlation of smoldering time (Ts) and ignition time (Ti) of MSW with its age under gradual temperature rise in a muffle furnace (i.e., 3 °C/min) were also studied and it was found that Ts and Ti are directly proportional to the age of MSW and the values ranged from 23 to 34 min for Ts and 27 to 48 min for Ti.

Distribution and modeling of tar compounds produced during downdraft gasification of municipal solid waste

Tar compounds produced during gasification of municipal solid waste (MSW) hinder downstream utilization of syngas. This study investigated the effects of operating conditions (temperature, equivalence air ratio (ER) and MSW moisture content) during gasification using air on tar emissions. Tar was quantified by gravimetric and GC-MS methods, denoted as gravimetric and collected (GC-MS) tar, respectively. Additionally, styrene evolution was studied as it is one of the main tar compounds produced from MSW. By applying the response surface methodology for modeling, it was found that tar contents quantified by the two methods are influenced similarly by ER and MSW moisture content, but differently by temperature. This discrepancy was attributed to the different composition and properties of tar fractions measured by gravimetric and GC-MS methods. Since the selection of analytical method can have impact on the quantification of tar, adoption of different methods for the characterization of tar emissions from MSW gasifiers is essential in order to provide a holistic analysis of the tar evolution process. The content of styrene in collected (GC-MS) tar from MSW gasification was 13–29%. The lower contents of styrene were favored by operating temperature between 850 and 900 °C, higher ER and higher MSW moisture content.

Enhanced power generation through integrated renewable energy plants: Solar chimney and waste-to-energy

In the present paper, a novel method is proposed to enhance the power production and resolve the inconsistent electricity generation of solar chimney power plants (SCPPs) during nighttime. For this purpose, an integrated renewable cycle is proposed by incorporating two technologies: solar chimney and waste-to-energy. The combination is performed by exploiting the warm air of the condensers outlet into the SCPP. The waste-to-energy (WTE) plant in Tehran is thermodynamically analyzed and the mass flow rate of the condensers cooling air is found. Results indicate that by decreasing the humidity of the municipal solid waste (MSW) from 40% to 30% or by increasing MSW feeding rate (0.934–1.146 kg/s), the mass flow rate of the condenser cooling air increases from 190.3 kg/s to 233.7 kg/s. In addition, by increasing the feeding rate or by decreasing the humidity of MSW in the mentioned range, net power output of the WTE plant increases from 1350 kW to 1650 kW. The best injection method is proposed for the warm air of the condensers outlet into the SCPP. Subsequently, the average power increase is examined in different months and parametric study is performed to assess the influence of the effective WTE parameters and meteorological variables on the power output of the SCPP. The final power of the SCPP reaches 20–70 kW (even at the hottest night of the year with 5% relative humidity) and increases 20–1200% and 65–94% (monthly average) compared to the case of without injection. Results demonstrate that in the integrated system, by a 22% increase in the MSW feeding rate (from 0.934 kg/s to 1.146 kg/s) or by decreasing the MSW moisture content (from 40% to 30%), power output of the WTE plant and SCPP increases by 22% and 7%, respectively. Additionally, relative humidity of the surrounding air can increase the SCPP power production by 25%. In addition, the results indicate that wind speeds higher than 12.5 m/s will not affect power production of the SCPP, while relative humidity of the surrounding air, ambient temperature, the MSW feeding rate, and humidity of the MSW have considerable effects on the SCPP power production. In average, total energy and useful exergy efficiency of the proposed system is increased by 0.15% and 0.12% compared to the standalone WTE plant during nighttime. The integration of SCPP with the WTE plant is an applicable method to enhance the power generation and overcome the inconsistent power production of SCPP during nighttime.

Resource impacts of municipal solid waste treatment systems in Chinese cities based on hybrid life cycle assessment

Municipal Solid Waste (MSW) management in Chinese cities is a significant challenge. However, the comprehensive resource impacts of MSW treatment systems in Chinese cities are unclear. This study presents a mixed-unit hybrid life cycle assessment for MSW treatment systems. The comprehensive resource impacts of six MSW treatment systems in China are evaluated using this method: (1) landfilling, (2) landfilling with landfill gas utilization, (3) incineration with leachate spray, (4) composting+landfilling, (5) composting+incineration, and (6) incineration with leachate centralized treatment. The results show that composting+incineration has the lowest resource impacts except for raw coal extraction. Reusing by-products of MSW treatment systems can reduce resource extraction of the entire economy. By reusing the by-products, landfilling induces the largest extraction of fossil fuels and biomass, whereas landfilling with landfill gas utilization induces the largest extraction of mineral ores. Improving the diesel efficiency of the collection and transportation process, increasing by-product recovery efficiency, and decreasing moisture content of MSW have significant impacts on reducing resource impacts of MSW treatment systems. We also observed trade-offs in resource impacts of different MSW treatment systems. Compared to landfilling, landfilling with landfill gas utilization can reduce the induced fossil fuel extraction but increase the induced metal ore extraction. We observed similar situation when comparing incineration with leachate spray with composting+landfilling.Findings of this study provide scientific foundations to improve the resource efficiency of MSW treatment systems in Chinese cities. They also provide insights into the MSW management in other countries.

Investigation of solid organic waste processing by oxidative pyrolysis

A thermal analysis of a mixture of municipal solid waste (MSW) of the average morphological composition and its individual components was carried out in order to develop ways to improve the efficiency of its utilization for energy production in thermal reactors. Experimental studies were performed on a synchronous thermal analyzer NETZSCH STA 449 F3 Jupiter combined with a quadrupole mass spectrometer QMC 403. Based on the results of the experiments, the temperature ranges of the pyrolysis process were determined as well as the rate of decrease of the mass of the sample of solid waste during the drying and oxidative pyrolysis processes, the thermal effects accompanying these processes, as well as the composition and volumes of gases produced during oxidative pyrolysis of solid waste and its components in an atmosphere with oxygen content of 1%, 5%, and 10%. On the basis of experimental data the dependences of the yield of gas on the moisture content of MSW were obtained under different pyrolysis conditions under which a gas of various calorific values was produced.

Bury, burn, or gasify: assessing municipal solid waste management options in Indian megacities by exergy analysis

With increasing consumption propelled by economic prosperity, waste generation per capita in developing countries is growing quickly. Traditional approaches of open dumping and landfilling are encountering physical constraints, particularly in megacities, and the need for alternate municipal solid waste (MSW) management strategies is urgent. Among alternatives that are commonly considered are waste-to-energy technologies including incineration and plasma gasification. Previous studies convey the benefits of such technologies, but most do not consider the waste and environmental conditions in tropical megacities such as Mumbai, India, making these studies of limited use to developing countries. This article evaluates the exergetic potential of converting MSW to useful work by thermal and biochemical conversion technologies in the Indian context, considering the facts that the scale of production, composition, climate, segregation practices, moisture content of MSW, etc. in a developing tropical country like India differ significantly from those in developed societies in temperate climate locations. Both, exergy and economic analysis find gasification to be attractive in terms of its monetary return and thermodynamic efficiency. However, this analysis also identifies major hurdles in adopting advanced waste-to-energy technologies including lack of waste segregation, high moisture content, and high capital cost of the most thermodynamically efficient technology.

Dynamic Experimental Investigation on the Volatilization Behavior of Lead and Cadmium in the Simulated Municipal Solid Waste (MSW) Influenced by Sulfur Compounds during Incineration

In China, coal, often with a high level of sulfur, is always mixed with municipal solid waste (MSW) in waste incineration plants due to the low heating value and high moisture content of MSW. The influence of sulfur compounds on the volatilization of heavy metals in MSW is of great concern for China’s waste incineration plants. In this study, the continuous dynamic volatilization process of Pb and Cd is investigated by adding different forms of sulfur compounds, elemental sulfur (S), and sodium sulfate (Na2SO4), to the simulated MSW in a laboratory incinerator, at both 1 and 3 wt %, respectively. The experimental results show that the added S begins to affect the volatilization of Pb and Cd at about 700 °C; adding S can lead up to 49.6% reduction in the volatilization of Pb, as the produced sulfur dioxide is promoting the formation of a condensed sulfate phase, and part of Pb is fixed in the form of PbS in the bottom ash. But for Cd, adding S causes up to 15.9% increase in its volatilization as S seizes part of O2 in the air, which is conducive to forming the reducing atmosphere. In the reducing atmosphere, CdO can be easily reduced to Cd, which volatilizes more easily than CdO at high temperatures. In fact, in the reducing atmosphere, the volatilization of Cd far outweighs the volatilization of Pb at 700–800 °C. On the other hand, adding Na2SO4 almost has no influence on the volatilization of lead and cadmium below 900 °C.

Effects of Degradation on Geotechnical Properties of Municipal Solid Waste from Orchard Hills Landfill, USA

In bioreactor landfills, geotechnical properties of municipal solid waste (MSW) are believed to be affected by increased moisture content and accelerated biodegra- dation due to leachate recirculation; however, studies to quantify the changes in the MSW properties are scarce. This study quantifies the change in geotechnical properties of field MSW as a function of level of degradation. Fresh MSW samples were collected from the working phase of Orchard Hills landfill (Davis Junction, Illinois, USA) and were subjected to leachate recirculation and enhanced anaerobic degradation in specially designed laboratory bioreactors. Samples were exhumed from the bioreactors at different stages of degradation as determined by the amount and composition of biogas generated, and subse- quently tested for moisture content, organic content, unit weight, hydraulic conductivity, compressibility, and shear strength. Moisture content of MSW increased significantly, while organic content decreased with degradation. Bulk unit weight increased with degradation which led to decrease in saturated hydraulic conductivity. Primary compression ratio showed slight increasing trend with degradation, while the secondary compression ratio was not affected significantly with the degradation. The friction angle decreased from 30� to 12� , but cohesion increased from 29 to 65 kPa with degradation based on direct shear test results. The testing of saturated MSW in triaxial con- solidated undrained conditions resulted in lower shear strength with no distinct correlation of friction angle and cohesion with degradation. Additional large-scale, long- duration testing is recommended using the field MSW samples with the consistent composition to establish the correlations between the engineering properties and degree of degradation. Overall this study showed that the engi- neering properties of field MSW are affected by degrada- tion and these changes should be properly accounted in the analysis and design of bioreactor landfills involving lea- chate recirculation.