• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 104
  • 87
  • 14
  • 9
  • 6
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 253
  • 253
  • 253
  • 92
  • 91
  • 84
  • 69
  • 38
  • 36
  • 34
  • 31
  • 29
  • 25
  • 22
  • 22
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Effects of Waste Placement Practices on the Engineering Response of Municipal Solid Waste

Cox, Jason Taylor 01 December 2013 (has links)
An extensive laboratory and field investigation was conducted at Santa Maria Regional Landfill (SMRL) in Santa Maria, CA to determine the effects of waste placement practices on the engineering response of municipal solid waste (MSW). Laboratory and field testing was used to determine the engineering properties and monitor field response of MSW. The specific gravity (Gs) of manufactured MSW (MMSW), fresh MSW (FMSW), and old MSW (OMSW) was determined experimentally using a modified version of standard soil testing procedures. Effects of particle size, compactive effort, and degradation on the specific gravity of waste were evaluated. Specific gravity of manufactured waste samples increased with decreasing particle size, with compaction, and with increased degradation. The average specific gravity of uncompacted MMSW samples was 1.333, 1.374, and 1.424 for coarse, medium, and fine particle sizes, respectively. Specific gravity of coarse, medium, and fine MMSW samples compacted at dry of optimum (= 30%) was determined to be 1.497, 1.521, and 1.552, respectively and at wet of optimum ( = 90%) to be 1.500, 1.542, and 1.570, respectively. The compacted and uncompacted specific gravity of fresh MSW was lower than manufactured and old MSW. The average Gs of uncompacted and compacted fresh MSW was 1.072 and 1.208, respectively whereas old MSW had Gs of 2.201. Additional physical and engineering properties of MSW were determined for fresh and old wastes. A total of 8 magnetic extensometer settlement arrays and 4 thermocouple arrays were installed in old wastes. The settlement and temperature data were collected for an approximate duration of 1 year. In addition, laboratory experiments were conducted to determine the particle size distribution, organic content, and moisture content of fresh waste sampled from the active face of the landfill and from old waste sampled from different depths. The particle size distribution of OMSW was comparable to a well-graded coarse-grained soil. The average baseline moisture content of incoming MSW at SMRL was 42.7% (dry-weight basis). The average moisture content of residential MSW, commercial MSW, and self-delivered MSW were determined to be 57.7, 46.3, and 12.0%, respectively. The organic content of fresh and old MSW was determined to be 77.2 and 23.5%, respectively. Temperature increased over time due to heat generation of the waste mass. The temperature increased on average 3 to 6°C between the initial and final day of measurements for wastes that were 0.3 to 9 years old. Fresh and old wastes at SMRL exhibited unique compression behavior. A majority of the waste was undergoing secondary compression characterized using a secondary compression ratio () ranging from 0.013 to 0.067 with an average of 0.030. In addition, the fresh and old wastes exhibited recompression behavior. Fresh waste lifts were determined to be slightly overconsolidated such that the self-weight of the fresh waste was less than the preconsolidation stress. The old waste exhibited recompression behavior during loading and unloading of an earthen embankment. The modified recompression indices () for fresh and old wastes were determined to be 0.076 and 0.012, respectively. The initial compression ratio for old wastes () was quantified for the old waste lifts to be between 0.069 and 0.332. Finally, meso- and full-scale field compaction experiments were conducted to determine the effects of systematic moisture addition prior to compaction on placement efficiency and compaction characteristics of MSW. Two 16 x 46 m test plots were constructed for the meso-scale compaction tests. Approximately 890 kN (100 tons) of residential MSW (RMSW) was placed into a test plot and compacted at target moisture contents of 55 (baseline as-received), 65, 80, 95, and 110%. Compaction curves generated for RMSW were bell shaped and similar to soil compaction curves. The maximum dry unit weight () and operational unit weight () for the meso-scale compaction study were 8.5 and 13.3 kN/m3 with corresponding optimum moisture contents of and , 78.5 and 79.5%, respectively. Moisture addition prior to compaction yielded beneficial waste placement results. An operational waste placement factor (OWPF) was defined as additional amount of waste that could be placed in one unit of volume. OWPF values were determined to be 1, 1.33, 1.66, 1.37, and 0.83 for RMSW compacted at target moisture contents of 55, 65, 85, 90, and 110%, respectively. The full scale compaction investigation was conducted in a similar manner to the meso-scale investigation. However, the compaction tests were conducted on the active face of the landfill and representative of the entire incoming daily waste stream. A daily average of 2940 kN (330 tons) of MSW was placed and compacted at target moisture contents of 45 (baseline as-received), 65, 85, and 105%. Compaction curves for the delivered MSW were bell shaped and similar to soil compaction curves. The maximum dry and operational unit weights for the full-scale test were 7.0 and 9.8 kN/m3, respectively corresponding to optimum moisture contents of and , 76 and 75.5%, respectively. OWPFs were calculated to be 1, 1.28, 1.55, and 0.80 for target moisture contents of 45, 65, 85, and 105%, respectively. The spatial variability associated with moisture addition also was determined for the meso- and full-scale compaction tests and verified using test pits and spatial sampling of the surface of the active face. Particularly, the variations in degree of saturation (S) and volumetric moisture content () due to moisture addition were estimated. For waste compacted at target moisture contents of 55, 65, 80, and 110% during the meso-scale tests, S increased by 19, 4.5, 4.4, and 4.3%, respectively while increased by 28, 7.7, 8.1, and 5.7%, respectively. For the full scale compaction tests, S increased by an average of 43% and increased by an average of 78%. The average moisture content of waste at the surface after compaction at 45% moisture content (i.e., as-received) and at 80% moisture content (i.e., near optimum) were 34 and 133%, respectively. The results of the investigation have environmental, operational, and financial implications such as extend the life of a landfill, ability to place more wastes in a unit landfill volume, and increasing to values above field capacity with moisture addition during compaction.
132

Posuzování životního cyklu komunálního odpadu / Life cycle assessment of municipal waste

Vlach, Josef January 2008 (has links)
The aim of this study is to present methodology life cycle (LCA) and Life Cycle Assessment of disposal the municipal solid waste chain. There is described the procedure of generation of the LCA studies according to the standards ČSN EN ISO 14 040 and ČSN EN ISO 14 044 in the first and second part. In the third part of this diploma there are described LCA analyses that have already been created. The software GEMIS (Global Emission Model for Integrated System) is described in the fourth part. The computer model GEMIS has been used as a calculation tool in this study. The fifth part of this study includes waste management and different kinds of disposal municipal solid waste. In this part is describe basic data about landfilling and incieration. There is shown LCA analysis of disposal municipial solid waste in the sixth part. Data processing was carried out by means of the software GEMIS 4.3. The results were interpreted for incineration and landfilling. Finally there is mentioned results for 1 TJ different elektrical energize to.
133

Technicko-ekonomická analýza dat z provozu moderní spalovny komunálních odpadů / Technical and economic analysis of operational data from up-to-date MSW incinerator

Kropáč, Jiří January 2008 (has links)
The goal of this work is compilation of computational model of thermal stage and heat recovery block of modern unit for thermal processing of municipal solid waste. The model is based on mass and enthalpy balances and it makes possible to estimate the value of energy transferred to water in secondary combustion chamber, outside the heat recovery blok. The model is verified by implementation of real operational data of an up-to-date unit with annual capacity of 100 kt for thermal processing of municipal solid waste and then it is used for analysis of changing input parameters, i. e. change in lower heating value of incinerated waste.
134

Využití metod stochastického programování pro hodnocení investic v energetických zdrojích / Application of stochastic programming methods for the purpose of energy producing system

Šomplák, Radovan January 2011 (has links)
This thesis deals with the evaluation of the strategic investment in the waste-to-energy plant development. The central supply of heat and the incineration plant connection can be provided for example by the distribution network. The objective is to find financially feasible solution regarding uncertain development of waste management and energy market. A heat supplies to district heating network significantly influences the strategic decision. A two-stage stochastic programming based on the scenarios and the GAMS software were applied to solve this task. The main contribution of this thesis is decision on crucial parameters of the waste-to-energy plant.
135

The role of law for improving municipal solid waste management: comparing Russia and Sweden (EU).

Amelkina, Olga January 2020 (has links)
Waste generation increases, and its management is one of the global challenges. Improper waste management creates many problems, but on the other hand, effective waste management can save natural resources, minimize GHG emissions, and provide additional workplaces. Sweden has already achieved some successful results in managing household waste, while modern Russia only began to reform the municipal solid waste management system in December 2014. This study makes a legal comparison of the Russian and the Swedish (EU) framework waste legislations, using the functional method of comparative law. The results show that Russia has already introduced many institutions, which are similar to those in the Swedish (EU) waste legislation. Nevertheless, there is still a huge potential to make the municipal solid waste management system in Russia more effective by improving framework waste legislation. Based on the findings from the comparison, there are following recommendations to Russia: to establish a separate waste collection system on the Federal level; make producers responsible for the whole life cycle of waste, including its waste management (from collection till disposal); correct the waste hierarchy; introduce the concepts of “preparing for re-use”, “re-use”, and a waste prevention program; change the norm of waste recovery to the recycling target.
136

The Effect of Product Characteristics on Recycling

Campbell, Audrey M. 01 January 2016 (has links)
The United States generated 251 million tons of municipal solid waste in 2012, half of which ended up in landfills; paper and paperboard make up the largest portion. Although the effects of antecedent and consequent manipulations on recycling are fairly well understood, with few exceptions (e.g., Trudel & Argo, 2013), the effect of stimulus characteristics on recycling has not been evaluated. Using a between subjects experimental group design, Trudel and Argo (2013) found size, and for cans, condition, affected recycling, such that more participants recycled large pieces of paper and large undented aluminum cans and fewer participants recycled small pieces of paper and small dented and undented aluminum cans. However, Trudel and Argo’s (2013) data provide little information regarding how context or group sessions affect recycling or whether the condition of paper might differentially affect recycling, as it did with cans. The present study used individual sessions, controlled for contextual variables (i.e., participant viewed all sizes of paper), and examined the effect of both size and condition of paper (i.e., crumpled or smooth) on recycling. Participants ( N = 60) were told this was a study about memory. They were instructed to complete a set of sorting tasks twice (for a total of two trials) with four different pieces of paper (standard-size smooth, standard-size crumpled, half-size, eighth-size), and, after each sorting task, to dispose of a piece until all four pieces were disposed. Results indicated neither size nor condition affected recycling; nearly all participants (90%) recycled all the paper. Factors other than paper size or condition (e.g., participant reactivity, geographic differences, exposure to all types of paper) may explain why results of the current study differed from previous research.
137

Life-cycle Greenhouse Gas Emissions and Water Footprint of Residential Waste Collection and Management Systems

Maimoun, Mousa 01 January 2015 (has links)
Three troublesome issues concerning residential curbside collection (RCC) and municipal solid waste (MSW) management systems in the United States motivated this research. First, reliance upon inefficient collection and scheduling procedures negatively affect RCC efficiency, greenhouse gas (GHG) emissions, and cost. Second, the neglected impact of MSW management practices on water resources. Third, the implications of alternative fuels on the environmental and financial performance of waste collection where fuel plays a significant rule. The goal of this study was to select the best RCC program, MSW management practice, and collection fuel. For this study, field data were collected for RCC programs across the State of Florida. The garbage and recyclables generation rates were compared based on garbage collection frequency and use of dual-stream (DS) or single-stream (SS) recyclables collection system. The assessment of the collection programs was evaluated based on GHG emissions, while for the first time, the water footprint (WFP) was calculated for the most commonly used MSW management practices namely landfilling, combustion, and recycling. In comparing alternative collection fuels, two multi-criteria decision analysis (MCDA) tools, TOPSIS and SAW, were used to rank fuel alternatives for the waste collection industry with respect to a multi-level environmental and financial decision matrix. The results showed that SS collection systems exhibited more than a two-fold increase in recyclables generation rates, and a ~2.2-fold greater recycling efficiency compared to DS. The GHG emissions associated with the studied collection programs were estimated to be between 36 and 51 kg CO2eq per metric ton of total household waste (garbage and recyclables), depending on the garbage collection frequency, recyclables collection system (DS or SS) and recyclables compaction. When recyclables offsets were considered, the GHG emissions associated with programs using SS were estimated between -760 and -560, compared to between -270 and -210 kg CO2eq per metric ton of total waste for DS programs. In comparing the WFP of MSW management practices, the results showed that the WFP of waste landfilling can be reduced through implementing bioreactor landfilling. The WFP of electricity generated from waste combustion was less than the electricity from landfill gas. Overall, the WFP of electricity from MSW management practices was drastically less than some renewable energy sources. In comparing the WFP offsets of recyclables, the recycling of renewable commodities, e.g. paper, contributed to the highest WFP offsets compared to other commodities, mainly due to its raw material acquisition high WFPs. This suggests that recycling of renewable goods is the best management practice to reduce the WFP of MSW management. Finally, the MCDA of alternative fuel technologies revealed that diesel is still the best option, followed by hydraulic-hybrid waste collection vehicles (WCVs), then landfill gas (LFG) sourced natural gas, fossil natural gas and biodiesel. The elimination of the fueling station criterion from the financial criteria ranked LFG-sourced natural gas as the best option; suggesting that LFG sourced natural gas is the best alternative to fuel WCV when accessible. In conclusion, field data suggest that RCC system design can significantly impact recyclables generation rate and efficiency, and consequently determine environmental and economic impact of collection systems. The WFP concept was suggested as a method to systematically assess the impact of MSW management practices on water resources. A careful consideration of the WFP of MSW management practices and energy recovered from MSW management facilities is essential for the sustainable appropriation of water resources and development.
138

Integrated municipal solid waste management approach in adaptation to climate change in Mekong Delta: Review paper

Nguyen, Xuan Hoang 15 November 2012 (has links)
A fast increase of municipal solid waste (MSW) has become the most concerning environmental problem in Vietnam, especially in the Mekong Delta region, that is considered one of the most vulnerable deltas to climate change in the world. There are 12 provinces and one central city in MD that occupy about 12% of the whole area of the nation with 5% of MSW generated. However, there is no currently effective management system in place for treatment and management of MSW in the MD. Landfill is the sole treatment option for MSW right now. With a low-level plain, MD is facing the most serious environmental problem in the near future with an effect of climate change and sea level rising. The landfill should not be considered for long-term use in this area. Suitable treatment options for MSW should be applied together with other solutions for reuse, recycling and reduction of MSW as well as pollution prevention issue. An integrated MSW management approach in adaptation to climate change is considered necessary. / Sự tăng nhanh chất thải rắn đã trở thành vấn đề vấn đề môi trường được quan tâm nhất ở Việt Nam, đặc biệt là ở khu Đồng bằng Sông Cửu Long một trong những đồng bằng dễ bị tổn thương bởi sự biến đổi khí hậu nhất trên thế giới. Đồng bằng Sông Cửu Long có 12 tỉnh và một thành phố trực thuộc trung ương, chiếm 12% diện tích của cả nước với khoảng 5% lượng chất thải rắn phát sinh. Tuy nhiên, hiện nay chưa có một hệ thống quản lý hiệu quả cho chất thải rắn ở khu vực. Bãi rác là lựa chọn xử lý duy nhất ở thời điểm này. Với cao độ thấp, Đồng bằng Sông Cửu Long đang đối mặt với ảnh hưởng nghiêm trọng của các vấn đề môi trường trong tương lai gần bởi ảnh hưởng của sự biến đổi khí hậu và nước biển dâng. Về lâu dài bãi rác không nên sử dụng ở khu vực này. Các lựa chọn xử lý thích hợp cho chất thải rắn cần được áp dụng cùng với các giải pháp khác như tái sử dụng, tái chế và giảm thiểu chất thải rắn cũng như các giải pháp ngăn ngừa ô nhiễm. Cách tiếp cận quản lý tổng hợp chất thải rắn nhằm ứng phó sự biến đổi khí hậu cần được xem xét.
139

Municipal Solid Waste Incineration (MSWI) Ash Characterization and Physical Concentration

Escalante Pedraza, Sharon Daiana 24 May 2023 (has links)
Bottom ash (BA), generated from the incineration of municipal solid waste (MSW), contains valuable elements which present a potential economic incentive to attempt recovery. The first study of this thesis investigated the physical, chemical, and mineralogical characterization of MSWI-BA samples through a number of experiments. To develop a proper physical characterization of the BA material, the sample was ground and subjected to particle size distribution, wet magnetic separation, and a float-sink test. As for the chemical and mineralogical characterization, the sample was subjected to XRD, XRF, SEM-EDX, and elemental composition analysis. Additionally, sequential chemical extraction and acid-leaching tests were conducted. The results from this section revealed that carrying out a combination of beneficiation processes using the MSWI-BA sample previously classified into the coarse, middle, and fine-size fractions could lead to better metal concentration yield and recovery optimization. The wet magnetic separation showed outstanding metallurgy indicators towards Fe, with enrichment ratios close to 2.0 and recovery values near to 80%. Metals such as Cu and Co were also enriched by 1.51 and 1.66, respectively, suggesting that the magnetic separation performance and enrichment are a function of the bound of multi-metallic oxides fractions. The 2.95 SG density test reached enrichment ratios higher than 2.0 in Fe, Cu, Co, and Ni in the coarse fraction of the BA fraction, which decreases when reducing the size fraction. When reducing the density cutoff, the results showed that the sink fraction yield increased as the medium density decreased, and the enrichment ratios of the minor elements (Mn, Co, Ni, Sn, and V) were similar across the different size fractions. Complementary information was obtained by the mineralogical characterization of the enriched streams from the physical concentration test, which explains the results obtained. The Cu speciation and mineral phases identified were copper oxide, copper sulfate, and cupric sulfite. While the main Fe-rich constituents existed in chemical forms of iron oxides, such as magnetite, hematite with substituted varieties, spinel group, and metallic inclusions. The enrichment ratios of Mn, Cr, Cu, and Ni obtained through magnetic separation can be explained by the presence of metallic inclusions, where these elements exhibit an affinity for the iron-bearing particles. The acid leaching test revealed that metals such as Fe, Mn, Co, Cu, and Zn can be efficiently leached using 1M HCl within 30 min of the reaction. The second part of this research study constituted the evaluation of the effect of the particle size reduction, which was performed to assess the intraparticle heterogeneity of MSWI BA. The evaluation consisted of particle size reductions by crushing and grinding for different residence times and then subjecting the sample to a sequence of physical concentration tests, such as particle size distribution, froth flotation, and wet magnetic separation. Additionally, the elemental composition after each test was determined through ICP-MS analysis to compare the particle size effect in the recovery and concentration of the valuable elements. The elemental composition results revealed that the comminution process promotes the interaction of Fe, Zn, and Cu, in the fine fraction, by generating more surface area. In contrast, the minor elements were not significantly enriched by reducing the size fraction, suggesting that the comminution process does not impact the mobility and redistribution of the elements in low concentrations. The froth flotation performed in this study showed that when using 0.338 g/ton diesel as a collector, adjusting and controlling the pH between 8.8 to 9.2 throughout the test, the organic matter content can be efficiently reduced in the BA sample from 14.73% to 4.25% when the sample has been previously ground for 30 min. Slight enrichment ratios were observed in the concentrate stream of the froth flotation, suggesting that these elements are associated with the organic matter in the BA sample. In contrast, the wet magnetic separation results revealed significant enrichment ratios of Fe, Mn, Co, and Ni after 10 min of grinding. / Master of Science / The Bottom Ash (BA) generated by the incineration of household solid waste has been identified as a promising source of valuable elements. However, a comprehensive understanding of the BA sample's properties is required in order to determine the most suitable mineral processing method to enrich the elements. The first study of this research consisted of evaluating BA ash's physical, chemical, and mineralogical properties in the BA sample. Following the characterization study, the effect of particle size, as a function of the grinding time, in the valuable elements' enrichment was evaluated. The results suggest that Ti, Fe, Cu, and Zn are the major and most valuable elements, while Mn, Co, Ni, Sb, and V are valuable elements in a minor concentration in the BA samples. Some elements, such as Ti, Sc, Co, Mn, Ni, Sn, and V, have been declared by the US Department of the Interior as critical minerals due to their economic importance and vulnerability to supply chain disruption. Although Fe and Cu are not considered critical minerals, their consumption in 2022 was 40 and 1.9 million metric tons, respectively. The development of national industry and enhancing the understanding of the alternative sources for the valuable elements present an opportunity to diversify local suppliers, pursue a vertical integration of the economic model, and reduce the third-party international vendors' dependency. Likewise, this research supports the aims to reduce the demand for primary natural resources and contribute to the circular economy model, in which energy, resources, and material are kept in a lifecycle while reducing landfilling disposal.
140

Challenges of Municipal Solid Waste Management in Colombo, Sri Lanka

Subasinghe, Nirmal January 2024 (has links)
Municipal Solid Waste Management (MSWM) in Colombo, Sri Lanka, presents significant challenges due to rapid urbanization, population growth, and limited infrastructural capacities. This research aims to analyze the current MSWM practices in Colombo, identify the key challenges faced, benchmark these practices against international standards, and propose sustainable solutions for improvement. A mixed-methods approach was employed, integrating quantitative data from primary sources and qualitative insights from interviews with key stakeholders, including municipal officials, waste management professionals, and residents. Quantitative data analysis revealed that Colombo generates an average of 1200 tons of waste daily, primarily from residential sources (60%). The predominant waste disposal method is landfilling, which accounts for 75% of waste disposal, with significant challenges identified in infrastructure, funding, and public compliance. Qualitative data from municipal officials highlighted the importance of policies focused on waste segregation, mandatory recycling programs, and penalties for illegal dumping. However, enforcement of these policies remains problematic due to resource limitations and public resistance. The study identified several critical challenges in MSWM, including inadequate infrastructure, insufficient funding, and public apathy. Collaborative efforts between the Colombo Municipal Council (CMC) and private sector stakeholders through initiatives like 'Zero Waste Colombo' have shown potential in addressing these challenges. Community engagement and educational programs have been implemented to promote waste reduction, recycling, and composting, but their success relies heavily on continuous support and participation from local organizations and residents. Future strategies for MSWM in Colombo include integrating advanced waste-to-energy technologies, expanding recycling facilities, and enhancing waste collection efficiency through smart technologies. Policy recommendations emphasize the need for stronger enforcement mechanisms, increased investment in waste management infrastructure, and continuous public education campaigns. This research contributes to the scholarly literature on urban sustainability and MSWM, providing actionable recommendations for policymakers, urban planners, and community stakeholders in Colombo. By addressing the identified challenges and leveraging the proposed solutions, Colombo can move towards a more sustainable and efficient waste management system.

Page generated in 0.1049 seconds