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  • 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.
491

Biotic Arsenic Mobilization in Natural and Anthropogenic Systems from Redox Transformations of Arsenic, Iron and Sulfur

Stuckman, Mengling Yi 02 June 2014 (has links)
No description available.
492

Effect of Hydrogen Sulfide in Landfill Gas on Anode Poisoning of Solid Oxide Fuel Cells

Khan, Feroze 06 June 2012 (has links)
No description available.
493

[pt] ESTUDO DOS IMPACTOS SOCIOECONÔMICOS E AMBIENTAIS NA VIDA DOS CATADORES DE MATERIAIS RECICLÁVEIS PÓS-ENCERRAMENTO DO LIXÃO DE GRAMACHO / [en] STUDY OF THE SOCIOECONOMIC AND ENVIRONMENTAL IMPACTS IN THE LIFE OF THE SCAVENGERS OF THE GARBAGE DUMP JARDIM GRAMACHO AFTER ITS CLOSURE

ANDREA DE OLIVEIRA MAGALHÃES 26 October 2016 (has links)
[pt] Esta dissertação busca estudar quais foram os impactos socioeconômicos e ambientais, ocorridos na vida dos catadores de materiais recicláveis que atuavam diretamente no Aterro Metropolitano de Jardim Gramacho, que, após decorridos trinta anos, teve seu funcionamento encerrado. Nossa pesquisa teve como objetivo qualificar a presença das políticas públicas como uma das vias de acesso ao processo sustentável para esses trabalhadores e avaliar se o que é projetado tem os impactos desejados e efetivos na vida desse grupo social ou se é ineficiente, já que não contariam mais com o espaço para desenvolver a atividade de catação na busca da própria subsistência, bem como de seus familiares. Para fundamentar este estudo buscamos, através de levantamento bibliográfico sobre o tema, pesquisa documental, observação participante e da fala dos sujeitos, entrevistas semiestruturadas, descrever o processo atual de trabalho, ponderando perdas e ganhos viabilizados pelo apoio governamental e, pela nova forma de tratar a separação e venda de material reciclável, prevista na Lei 12.305/2010 – Política Nacional de Resíduos Sólidos (PNRS) bem como, nos benefícios da Política de Assistência Social que, nem sempre atendem na mesma proporção a necessidade dos beneficiários, tornando-os cada vez mais excluídos dos bens e serviços e, por vezes, incluídos perversamente. O estudo proposto examinou o universo dos catadores que atualmente desenvolvem suas atividades de separação de resíduos no Polo de Reciclagem, espaço cedido pela Secretaria de Estado do Ambiente do Rio de Janeiro (SEA), no próprio sub-bairro onde funcionava o lixão, cujo objetivo é a continuação da atividade de separação de resíduos, porém de forma salubre, seletiva e ordenada na garantia da manutenção de trabalho e renda para todos. / [en] Concern for the environment and also an interest in the discovery of new actions towards sustainable development1 are extremely relevant factors for modern society. There is a need for constant consideration of this issue, as Brazilian policies are based on a model of developmentalist development, while policies for assistance are based on a similar perspective. This is what led me to embark on this study, looking at the social and environmental issue from the standpoint of interdisciplinarity, as I believe that there is an underlying social function under whatever perspective is considered. Even though the current reality of the recyclables market allows one to envisage a sustainable horizon which is economically attractive for large businesspeople in the industrial segment, in stark contradiction it denies access to essential goods and services to the very people who are part of the production chain, the waste scavengers or catadores. This is initially justified by the devaluation of the activity which is carried out, an activity which is often considered unhealthy, dangerous, arduous, and generating less value for the potential employer and less profit. This, together with the fact that most of the workers have a low level of schooling, means that this category of workers has become stigmatised as unable to manage their own business.
494

Membrane Electrochemical Treatment of Landfill Leachate: Processes, Performance and Challenges

Liu, Xingjian 13 April 2020 (has links)
Landfilling is the most common approach to dispose of municipal solid wastes but inevitably leads to leachate formation. Persistent UV quenching substances (UVQS) in landfill leachate can affect the effectiveness of UV disinfection in municipal wastewater treatment systems when leachate co-treatment is applied. Membrane electrochemical reactor (MER) treatment was investigated to reduce the UV quenching capability and simultaneously recover resources in the leachate as an effective onsite pre-treatment. Ion-selective membranes were used in this MER to create two different conditions: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher removals of both dissolved organic carbon and UV254nm absorbance than membrane-less electrochemical treatment. The MER was able to remove a large percentage of total nitrogen from the leachate while recovering about half of the influent ammonia in the catholyte with less specific energy consumption. The second study coupled MER with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal. This two-stage coupled system reduced the more leachate COD than the standalone Fenton process treating raw leachate. Also, the usage of chemicals as Fenton reagents has been greatly reduced: FeSO4 and H2O2 by 39%, H2SO4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison, the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6 -55.2 kg N m-3 reactor d-1. Those results demonstrated that coupling MER with the Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. The third study investigated the formation of total halogenated organics (DBP) and the associated toxicity as the side effect of leachate treatment in the MER. Compared to the 4538±100 µg L-1 from the control membrane-less electrochemical oxidation reactor, the amount of DBP generated in the MER only accounted for 19.1±4.5 % after the same treatment period. The total toxicity value (26.6 ×10-3 ) was low for MER effluent, only 15.1% of that in the control group. Both high pH and high ammonia concentration introduced more DBP mass and toxicity production after MER treatment. DBP concentrations were shown to increase with applied current density and possible temperature raise. With 67.5% of DBP mass concentration and 74.4% of the additive toxicity removal, the granular activated carbon (GAC) electrode system was shown more effective than GAC adsorption alone in remediating DBP harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate through performance demonstration, process integration and by-product remediation. / Doctor of Philosophy / Municipal solid waste is often disposed of in landfills because of the most economics and convenience. However, one of the most challenging problems is the leachate formation and treatment. In the US, leachate is currently often diluted in domestic wastewater treatment systems; meanwhile, the persistent contaminants in landfill leachate can lower the effectiveness of UV disinfection and result in high cost and permit violation. In this study, the membrane electrochemical reactor (MER) using electricity as the driving force was applied to solve the issue and simultaneously recover valuable resources in the leachate. Membranes as a barrier for selective ions were used in this MER to create two different conditions with different purposes: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher contaminants removals than membrane-less electrochemical treatment. The second study coupled MER with one of the established advanced oxidation processes, also known as Fenton oxidation through providing mutual benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate contaminants effectively towards the direct discharge standard. In addition, the usage of chemical reagents, as well as the amount of process residual, has significantly been reduced. The third study investigated the formation of by-products as the side effect of leachate treatment in the MER. Compared to the membrane-less reactor, the undesirable by-products generated in the MER only accounted for one fifth after the same treatment period. A granular activated carbon electrode system was shown effective in remediating the harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate as one of the toughest wastewaters.
495

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.
496

Waste-to-Energy in Kutai Kartanegara, Indonesia : A Pre-feasibility study on suitable Waste-to-Energy techniques in the Kutai Kartanegara region

Torstensson, Johan, Gezelius, Jon January 2015 (has links)
The thesis outlined in this report is a pre-feasibility study of the potential to use waste-to-energy technology in the region Kutai Kartanegara, Borneo, Indonesia. The project is a collaboration between the Kutai Kartanegara government, Uppsala University, the Swedish University of Agricultural sciences and the technology consulttancy Sweco. The current waste management system in Kutai Kartanegara consists of landfills in the cities and open burnings and dumping in the lesser developed sub-districts. This is a growing problem both environmentally and logistically. The electrification in the sub-districts is sometimes as low as 17 % and access to electricity is often limited to a couple of hours per day. The current electricity production in the region is mainly from fossil fuels. Data was collected during a two month long field study in Tenggarong, the capital of Kutai Kartanegara. From the collected data, various waste-to-energy systems and collection areas were simulated in Matlab. Results from the simulations show that a system using both a waste incineration and biogas plant would be the best solution for the region. The chosen system is designed to handle a total of 250,000 tons of waste annually, collected from Tenggarong and neighbouring districts. The system will provide between 155 and 200 GWh electricity and between 207 and 314 GWh of excess heat energy annually. Some of this is used in a district heating system with an absorption-cooling machine. The system investment cost is around 42.5 MUSD and it is expected to generate an annual profit of 16 MUSD. The recommended solution will decrease the emissions of CO2-equivalents compared to the current waste system and fossil electricity production with 50%. The results in the study clearly show that there are both economic and environmental potential for waste-to-energy technologies in the region. But the waste management and infrastructure has to be improved to be able to utilize these technologies. By implementing waste-to-energy technologies, the supplied waste can be seen as a resource instead of a problem. This would give incentives for further actions and investments regarding waste management.
497

Optimering av den kemiska reningen vid Fläskebo deponi / Optimization of the Chemical Treatment at Fläskebo Landfill

Nilsson, Anna January 2006 (has links)
<p>Landfill leachate contains a variety of contaminants and is created when rainwater percolates the landfill. For landfill management the leachate is the main issue that can cause problems to the environment. At the landfill of Fläskebo, Renova AB treats the leachate in a local treatment plant. The treatment consists of a chemical treatment step with chemical precipitation, flocculation, sedimentation and filtration, and a final step with a carbon and peat filter. Renova has to ensure that the condition of the leachate reaches the regulation set for the landfill before it is released to the recipient. This regulation has not yet been established and a final suggestion will be given to the county administrative board in spring 2006.</p><p>In this master thesis the chemical treatment of Fläskebo is optimized. A comparison between the control program and the regulation was made to estimate the contamination of the leachate. Also the effectiveness of the two steps is evaluated. For optimization, the leachate was first tested in a laboratory with different coagulants and flocculants.</p><p>The purpose was to increase the precipitation of particles and metals; arsenic, cadmium, chromium, mercury, lead, copper, nickel and zinc through sweep floc coagulation and hydroxide precipitation. After the laboratory tests the precipitation was tested in the treatment plant with higher pH and coagulant. Also the process control for sodium hydroxide was examined.</p><p>The leachate had a small content of organic matter and nutrients, but had a large content of halogenated substances (AOX) and the heavy metals nickel and copper. High concentrations of contaminants were reduced better than low concentrations in the two treatment steps. The carbon and peat filter material also caused an increase of the arsenic content in the leachate after filtration. From the laboratory work the results showed a better reduction of metals with iron-chloride, PlusJÄRN and the anjonic polyacrylamid, Fennopol A. Because of the high content of chloride the iron- sulphate, PurFect was chosen for further tests. The optimal pH for the heavy metals arsenic, zinc, copper and nickel was between pH 9 and 9, 5. The precipitation in the treatment plant showed better results with sodium hydroxide and a higher pH, pH 9 in the flocculation basin. An increase of the coagulant PurFect from 202 mg/l to 225 mg/l meant only a higher chemical cost. The process control of sodium hydroxide showed an oscillating and unstable control performance, which may lead to a higher consumption of chemicals.</p> / <p>Lakvatten har varierande föroreningsgrad och karaktär och bildas då regnvatten perkolerar igenom en deponi. För en deponiverksamhet är lakvattnet den huvudsakliga påverkan på den omgivande miljön. Vid en av Renova ABs deponier, Fläskebo, utanför Göteborg sker reningen av vattnet i den lokala reningsanläggningen. Reningen består av kemisk fällning, flockning, sedimentering och filtrering samt ett kol- och torvfilter. För att få släppa ut lakvattnet har Renova just nu ett prövotidsvillkor på lakvattnets kvalité och till våren 2006 skall förslag på slutgiltiga utsläppsvillkor lämnas till Länsstyrelsen.</p><p>I detta examensarbete har den kemiska reningen av lakvattnet från Fläskebo optimerats utifrån lakvattnets karaktär. Lakvattnets föroreningsgrad bedömdes efter en jämförelse av analysresultatet inom kontrollprogrammet och riktvärdena i prövotidsvillkoret. Dessutom utvärderades effektiviteten i varje enskilt reningssteg, den kemiska reningen och kol- och torvfiltret. För optimering av den kemiska reningen testades lakvattnet först på lab med olika fällnings- och flockningsmedel. Uppgiften var att öka partikelfällningen och reducera metallerna arsenik, kadmium, krom, kvicksilver, bly, koppar, nickel och zink i lakvattnet genom svepkoagulering och hydroxidfällning.</p><p>Utifrån resultaten på lab testades sedan fällningen i full skala, pH höjdes i flockningsbassängen och så även dosen fällningsmedel till vattnet. En inledande undersökning av regleringen av lutdosering gjordes med några stegsvarsexperiment.</p><p>Lakvatten innehöll låga halter av organiskt material och närsalterna kväve och fosfor, medan de halogena ämnena (AOX) och tungmetallerna nickel och koppar var höga. De båda reningsstegen, kemisk rening och kol- och torvfiltret var generellt bra på att rena föroreningar i höga koncentrationer men var sämre vid låga. Kol- och torvfiltret ökade koncentrationen i vattnet av arsenik genom materialets interna läckage. I fällningsförsöken gav järnkloriden, PlusJÄRN och den anjoniska polyakrylamiden, Fennopol A bäst resultat i att avskilja metaller. Järnsulfaten PurFect gav näst bäst resultat och valdes istället för järnkloriden för vidare försök då kloridhalten i lakvattnet redan var högt. Optimalt pH för arsenik, zink, koppar och nickel var inom pHintervallet 9 och 9,5. Fällningen i full skala ute i verket visade ett bättre resultat vid tillsatt lut och ett högre pH (pH 9) i flockningsbassängen. Däremot betydde en höjning av fällningskemikalien från 202 mg/l PurFect till 225 mg/l enbart en ökad kemikaliekostnad och en överdosering. Det visade sig dessutom att lutregleringen var svängig och på gränsen till instabil. Regulatorn bör därför ses över så att risken för ökad kemikaliekonsumption och kostnader minskar.</p>
498

Durability of HDPE Geomembranes for Municipal Solid Waste Landfill Applications

AbdelAal, Fady 27 November 2013 (has links)
A series of laboratory accelerated immersion tests are used to examine the effects of different chemicals found in municipal solid waste leachate, geomembrane thickness, and incubation temperatures on the degradation of different high density polyethylene geomembranes. It was found that surfactant was the key leachate constituent affecting antioxidant depletion while salts accelerated degradation of the mechanical properties, especially stress crack resistance. Immersed in synthetic leachate, the time to nominal failure at 35oC was predicted to be 62% longer for the 2.5 mm, and 12% longer for the 2.0 mm, than for the 1.5 mm geomembrane tested. The antioxidant depletion in synthetic leachate and air at temperatures > 85oC was consistent with what would be expected from Arrhenius modeling based on data from lower temperatures (≤ 85oC). However, the early depletion rates in water incubation decreased with the increase of the temperature above 100oC. It was also found that at temperatures above 100oC, there was significant change in the polymer morphology that affected the stress crack resistance at early incubation times prior to polymer degradation. Large-scale geosynthetic liner longevity simulators (GLLSs) which simulated field conditions were used to investigate the susceptibility of pre-aged high density polyethylene geomembranes to stress cracking and to evaluate the performance of geomembranes under a 150 mm sand protection layer. A pre-aged geomembrane with a 560 g/m2 geotextile protection layer experienced brittle rupture at local gravel indentations. The time to failure was correlated to the incubation temperatures. The use of a sand protection layer not only delayed antioxidant depletion compared to that with a traditional geotextile protection but also substantially reduced the long-term tensile strains in the geomembrane below the allowable strain limits. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-11-26 12:36:01.538
499

SYSTEMATIC POSTSYNTHETIC MODIFICATION OF NANOPOROUS ORGANIC FRAMEWORKS AND THEIR PERFORMANCE EVALUATION FOR SELECTIVE CO2 CAPTURE

Islamoglu, Timur 01 January 2016 (has links)
Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups increases the CO/N2 and CO2/CH4 selectivity significantly due to selective polarization of CO2 molecule. In addition, controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris(4-bromophenyl)benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. Benzimidazole-linked polymers have also been shown to have promising CO2 capture properties. Here, an amine functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized via a combination of pre- and postsynthetic modification techniques in two steps. Experimental studies confirm enhanced CO2 uptake in BILP-6-NH2 compared to BILP-6, and DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2. Using BILP-6-NH2, higher CO2 uptake and CO2/CH4 selectivity was achieved compared to BILP-6 showing that this material has a very promising working capacity and sorbent selection parameter for landfill gas separation under VSA settings. Additionally, the sorbent evaluation criteria of different classes of organic polymers have been compared in order to reveal structure-property relationships in those materials as solid CO2 adsorbents.
500

Avaliação do risco à saúde da população vizinha às áreas de disposição final de resíduos sólidos urbanos: o aterro sanitário como cenário de exposição ambiental / Health risk assessment to population who lives near a municipal solid waste disposal site: the landfill as the environmental exposure scenery

Azevedo, Mônica de Abreu 16 January 2004 (has links)
O presente estudo visou ao desenvolvimento de um estudo epidemiológico do tipo transversal para a avaliação do risco para a saúde da população residente próxima a uma área de disposição final de resíduos sólidos urbanos. O levantamento dos dados foi realizado no bairro de Perus, na cidade de São Paulo, SP, vizinho ao aterro sanitário Bandeirantes. O aterro Bandeirantes recebe diariamente cerca de 6.000 toneladas de resíduos sólidos do tipo Classe II e III. O aterro ocupa uma área total de 1.400.000 m2, contendo aproximadamente 33 milhões de toneladas de resíduos dispostos. Os riscos para a saúde pública foram avaliados junto à população de estudo, 972 crianças na faixa etária de 1 a 5 anos incompletos, residente próxima ao aterro Bandeirantes. A área de estudo foi dividida em faixas distantes de 500 m do limite do aterro, para a definição das condições de exposição. Os indicadores de saúde utilizados foram: as prevalências de enfermidades diarréicas e parasitárias e os índices antropométricos. Na área de estudo, foi realizado um levantamento da qualidade ambiental, com intuito de relacionar os impactos ambientais, ocasionados pela prática de disposição final considerada, aos indicadores de saúde empregados. Os resultados obtidos, pela realização deste estudo, permitiram concluir que há relações estatisticamente significativas entre as exposições pesquisadas e os indicadores de saúde empregados. / This work had the objective to develop an epidemiological study, using a transversal design, to evaluate the health risk to people who lives near a municipal solid waste disposal site. The study was accomplished at bairro de Perus, in the city of São Paulo - SP, Brazil, near to the Bandeirantes landfill site. The Bandeirantes landfill receives daily around 6,000 tons of Class II and III solid waste types. The landfill occupies a total area of 1,400,000 m2, containing around 33 millions of tons of disposed waste. The public health risks were evaluated among 972 children, of one to five years old, who live near the Bandeirantes landfill. The studied area was divided in distant lines of 500 meter from the landfill limit to define the exposure conditions. The used health indicators were: diarrhoeal, intestinal parasite prevalence and nutritional status. In the studied area, an environmental quality survey was accomplished with the intentions of relating the environmental impacts occasioned by the solid waste disposal to the used health indicators. The obtained results made it clear to conclude that the there are statistical associations between the researches environmental exposures and the used health indicators.

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