• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 72
  • 58
  • 30
  • 21
  • 15
  • 14
  • 5
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 291
  • 291
  • 127
  • 38
  • 37
  • 36
  • 33
  • 32
  • 27
  • 27
  • 26
  • 26
  • 25
  • 22
  • 21
  • 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.
191

Waste Water Treatment - A Case Study : Removal of Ni, Cu and Zn through precipitation and adsorption

Karlsson, Lovisa January 2012 (has links)
Waste water containing high concentrations of dissolved metals were delivered to the environmental company SAKAB. After standard treatment procedure, involving regulation of pH and addition of flocculation agents, the water still contained nickel concentrations of 26 mg/l. Since SAKAB’s regulatory concentration limit value for nickel in outgoing water is 0.5 mg/l, further treatment was necessary. According to the supplier of the water, a complexing agent similar to EDTA had been added to the water. The aim of this study was to decrease concentrations of nickel, zinc and copper. One part of this study was the precipitation experiments as hydroxide, sulphide and adsorption to hydrous ferric oxide. The other part was adsorption to natural, organic materials such as peat, wood chips and one commercial bark compost. Adsorption to hydrous ferric oxide was the most efficient of the precipitation experiments. When 2000 mg FeCl3 was added to 100 ml waste water and pH of the solution was adjusted to pH 8, a decrease up to 74 % of total nickel concentrations was achieved. Most efficient of the adsorption experiments were the one with commercial bark compost which decreased nickel concentrations in solution up to 94 % after 20 hours of agitation.
192

Skillnader i vatten- och avloppshantering inom EU : En jämförelse mellan Slovakien och Sverige

Öhman, Camilla January 2010 (has links)
The management of water resources and waste water varies between the countries of the EU. For many years, a large part of the water in Europe has been contaminated by, among other things, insufficiently treated waste water and emissions from agriculture. The EU Water Framework Directive 2000/60/EC and the Urban Waste Water Directive 91/271/EEC are intended to harmonize fresh-water management and waste water management within the whole EU, aiming at safeguarding drinking water of good quality and a high quality of all water within the EU today and in the future. There are however some problems concerning the waste-water directive. One problem is the huge investment needed in Slovakia to fulfil the demands of the waste-water directive for waste-water management in larger communities (with more than 2000 inhabitants). Many waste-water treatment plants need to be upgraded or built, and in addition a large part of the households in eastern Slovakia are not yet connected to a municipal water-supply and waste-water collecting system (including waste-water treatment). Subsidies from the EU’s structural funds are needed for Slovakia to fulfil the requirements of the waste-water directive. Because this directive only applies to larger communities, smaller communities and private sewage are not affected by the directive and therefore, in general, not eligible for financial funding from EU. Financial funding, however, is needed for addressing inadequate sewage in small communities with poor socioeconomic and municipal financial resources. For water protection to be effective, it is important to take also private sewage emissions into consideration, even though they might appear insignificant. Point emissions from insufficient private sewage (private sewage systems with insufficient waste-water treatment or emission of untreated waste water), primarily in small, tightly clustered communities in Slovakia or for example in Sweden in areas where weekend houses are being converted into permanent dwellings, are potential sources of pollution that can cause health or/and environmental problems. Inadequate private sewage can thus reduce the quality of both surface and ground water and have a negative impact on aquatic ecosystems, which in turn makes it more difficult to reach the quality standards of the Water Framework Directive and its daughter directives. This applies to both Slovakia and Sweden. The private sewage solutions that are recommended today are often satisfactory but not without problems. To give an example, miniature waste water treatment plants are expensive to put in place, require technological knowledge on the part of the property owner and they also require a daily flow of waste water to function properly. Improper handling of the miniature water treatment plant may cause inefficient or no water treatment at all, in some cases the bacterial content of the waste water may increase instead of being reduced. To address the problem concerning private sewage it is important that (1) waste-water solutions are adapted to local circumstances and financial funding are given to economically week municipalities (2) the property owner (owner of the private sewage) regularly controls the quality of the out-going treated wastewater (if it is possible) and (3) that efficient inspections with injunctions (from authorities) are carried out to discover faulty private sewage. Unfortunately financial funding, in general, is not given to small municipalities and/or inappropriate private sewage and inspections, both in Slovakia and Sweden, are generally slow.
193

Ovidkommande dagvatten i spillvattenledningar - En fallstudie av dagvattenhantering i ett bostadsområde i Hok / Irrelevant stormwater in wastewater pipes - A case study of stormwater management in a residential area in Hok

El Masry, Josef, Alkazragi, Miher January 2015 (has links)
No description available.
194

Determination of the methanogenic potential of an apple processing wastewater treatment system

Paulsen, Cindy 12 1900 (has links)
Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2006. / The food and beverage industry generates large volumes of wastewater annually. The disposal of factory effluent from the fruit processing industry has always been a cause of concern to both the fruit processors and controlling bodies responsible for effluent management. Traditional disposal of wastewater into sewerage works has become undesirable due to its economical and environmental impacts. Therefore, on-site anaerobic treatment of wastewater has received considerable interest due to lower capital outlays and energy recovery possibilities. Thus, the aim of this study was to establish an operational treatment profile for an anaerobic pond system treating fruit-processing wastewater. The specific activity of the microbial populations was also monitored to determine the effect of the fruit processing seasons (peak and off-peak season). The biogas production potential at various temperatures was also assessed to determine the viability of methane recovery. The influence of the processing and environmental conditions on the ponds’ performance was established by monitoring various process parameters. The results showed that the chemical oxygen demand (COD) levels decreased during the off-peak season but the pond pH remained relatively stable between 6.0 and 6.4 during the entire year. Pond alkalinity was found to be dependent on the regular lime dosing to maintain the necessary alkalinity. The volatile fatty acid (VFA) concentrations indicated that the microbial populations of the pond were functioning well. However, a decrease in microbial activity and VFA concentrations were observed at the lower temperatures during the winter months. The temperature profile of the pond showed that the pond temperature was impacted by the fluctuations in the ambient air temperature. The general trend established by the operational treatment profile clearly showed the impact of the peak and off-peak season. The sludge activity of the anaerobic pond was evaluated to determine the effect of the apple-processing peak and off-peak season on the specific activity of the acidogenic and methanogenic populations within the sludge. An activity test using four different test media was used during the activity assays. Sludge samples were taken at four different sampling positions across the pond’s sludge bed. The sludge was also subjected to a biogas formation study, which was designed to simulate pond conditions on laboratory scale in order to evaluate the biogas production potential of the anaerobic pond. The cumulative biogas volume and total CH4 composition showed little or no difference between the four sludge sampling sites. A major difference was found between the activity of the microbial populations during the peak and off-peak seasons. The overall trend regarding the biogas production rate (SB) and the methane production rate (SM) values showed an increased activity during peak-season and a decreased activity during off-peak season. For the biogas formation test the highest incubation temperature (25°C) resulted in the most biogas being produced, followed by 18°C, and with 10°C resulting in the lowest biogas volume. The biogas formation tests indicated that microbial activity and therefore biogas production was dependent on especially favourable temperature conditions. The pond and activity of the microbial populations are therefore influenced by factors like environmental changes such as decreased air temperatures and substrate changes such as decreased COD concentrations during the off-peak season. This in turn influences the rate of biogas production as well as the methane production rate. The theoretical CH4 calculations and estimates based on the results obtained during the biogas formation tests indicated that CH4 recovery from the anaerobic pond would definitely be a worthwhile consideration. If it were assumed that the estimated CH4 volumes (based on only 15% of the pond volume for practical reasons) obtained could be applied as an energy source, the minimum yearly savings in coal usage would amount to about R 665 000. This study was valuable in evaluating the factors such as pond conditions, pond activity and air temperatures and the effect on the biogas production potential as well as more importantly, CH4 production for the purpose of energy recovery.
195

Kartläggning av metallflöden i avloppsvatten i Västerås

Renström, Terese January 2018 (has links)
Sludge, produced in the waste water treatment process, can be used as fertilizer in agriculture. It is rich in nutrients but also contains other substances, such as heavy metals. Metals may enter crops which means that it also enters the food chain. Some heavy metals have been proven to cause severe damage to living organisms in high doses. It is therefore important to regulate the amount of heavy metals in the soil and in the sludge used as fertilizer. In this thesis the sources of heavy metals in the waste water system in the town of Västerås was examined. The sources of the heavy metals cadmium, chromium, mercury, copper and zinc were mainly analyzed by using the Excel tool "Source Finder". In this tool collected data of emissions or calculated emissions by the use of model values were entered. Households proved to be the single largest source of all the metals in this study, with the exeption of chromium. For cadmium and chromium water leakage from the ground water into the pipe system was a large contributing source. Business did not prove to be a large source of any metal with the exception of dental units which emitted large amounts of mercury. To be able to predict change of quality, in regards of metals, in the sludge and puried water an existing model of the water treatment plant was supplemented with processes regarding separation of copper. This was done by studying other models regarding metal partitioning and separation. The final model proved unable to describe variances in the measured data, but could describe the median concentration of copper in cleansed water and sludge.
196

Analyse et modélisation du traitement de l'azote dans un procédé de granulation aérobie hydride / Analysis and modelling of nitrogen removal in a hybrid granular sludge reactor

Filali, Ahlem 16 December 2011 (has links)
Dans ce travail, le traitement des nutriments et plus particulièrement celui de l’azote en procédé de granulation aérobie a été étudié. L’approche expérimentale a dans un premier temps eu pour objet de comparer la stabilité des caractéristiques physiques et microbiologiques d’agrégats développés dans deux réacteurs fonctionnant en alternances de phases anaérobie / aérobie ou anoxie / aérobie. L’opération d’un procédé de granulation aérobie en alternance de phases anoxie / aérobie a favorisé la stabilisation des performances de traitement de l’azote et notamment celle de la nitrification. Le développement d’une boue hybride comprenant une fraction de flocs et de granules a été observé. Dans le but d’évaluer comment le caractère hybride de la boue obtenue en conditions anoxie/aérobie oriente les performances et vitesses de transformation de l’azote, une caractérisation ex-situ des limitations au transfert d’oxygène au sein des flocs, granules et boue hybride a été réalisée par respirométrie. En complément, la localisation des espèces nitrifiantes par la technique d’hybridation fluorescente in situ (FISH) a été réalisée. Les résultats obtenus indiquent que la présence de flocs au sein d’une boue granulaire permet d’augmenter la vitesse de la nitrification, en particulier pour de faibles concentrations en oxygène dissous. D’autre part, il est ici mis en évidence la nécessité de contrôler simultanément le ratio floc/granules et la taille des granules en vue de l’optimisation du traitement de l’azote.Enfin un outil mathématique permettant de décrire les phénomènes réactionnels ayant lieu au sein d’une biomasse hybride a été développé. Celui-ci a été employé dans le but d’optimiser le fonctionnement du procédé hybride par l’évaluation de l’effet des propriétés physiques de la biomasse, et plus particulièrement de la proportion de granules en présence, pouvant conduire à une élimination efficace de l’azote et à l’augmentation de la robustesse du procédé vis-à-vis de diminutions ponctuelles de l’oxygène dissous / In this work, the treatment of nutrients, especially that of nitrogen in aerobic granulation process was studied.The experimental approach has initially been intended to compare the stability and the physical and microbiological characteristics of aggregates developed in two reactors operating in alternating anaerobic / aerobic or anoxic / aerobic conditions. The presence of a pre-anoxic phase promoted the stabilization of nitrogen removal performances and especially those of nitrification. The development of a hybrid sludge process containing a fraction of flocs and granules was observed.In order to evaluate and quantify the influence of the simultaneous presence of flocs and granules in the nitrifying activity of the hybrid sludge developed in the alternating anoxic / aerobic conditions, the nitrification rate and oxygen limitation of flocs, granules and hybrid sludge was assessed using respirometric assays at different dissolved oxygen concentrations. The spatial distribution of nitrifying bacteria was investigated using fluorescence in situ hybridization (FISH). Results indicated that the presence of flocs with granules could increase the rate of nitrification to transitory reductions of aeration. On the other hand, the optimization of nitrogen removal requires the simultaneous control of the floc to granule ratio and granule size.Finally, a mathematical model to describe the reaction phenomena taking place in the hybrid biomass was developed. It was used in order to optimize the operation of the hybrid process through the evaluation of the effect of physical properties of biomass, specifically the ratio of granules and flocs in the reactor that can lead to efficient removal of nitrogen and increase the robustness of the process
197

Produção de lipases por Yarrowia lipolytica e potencial aplicação em tratamento de soro de queijo

Edson Rodrigues Vieira 27 May 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A fisiologia microbiana é uma área promissora da biotecnologia para a síntese de compostos de elevado valor agregado. Os micro-organismos apresentam vantagens devido ao menor período de geração, às facilidades de modificações fisiológicas e genéticas e à grande diversidade de processos metabólicos. O objetivo deste trabalho foi degradar óleos e gorduras de efluente lácteo por lipases produzidas por Yarrovia lipolytica. Planejamentos fatoriais foram utilizados para investigar os efeitos de variáveis em três etapas: em fermentação para produção de lipases, em formulação de bioproduto com atividade lipásica para estabilização da ação catalítica da enzima e em tratamento de soro de queijo para degradação de óleos e gorduras. Na presença de resíduo de refinaria de óleo vegetal a 3 % e cloreto de amônio a 0,2 g.L-1 com 48 h a 28 oC, lipases foram produzidas sob cultivo submerso. O líquido metabólico livre de células com atividade lipásica foi estabilizado com sorbato de sódio a 0,5 %, glicerol a 5 % e RENEX-95 a 10 %. Esse bioproduto apresentou 177 UI.mL-1 da atividade enzimática durante 30 dias sob armazenamento à temperatura ambiente (27 - 30 oC); pH ótimo 5,0 e 7,0, temperatura ótima de 50 oC e estabilidade térmica durante 120 min com retenção de 100 % da atividade enzimática a 50 oC e pH 5,0. A aplicação de 7 % do bioproduto durante 12 h de tratamento de efluente lácteo degradou 98 % dos óleos e gorduras presentes no soro de queijo. As lipases produzidas por Y. lipolytica e formuladas com substâncias estabilizadoras tem potencial para serem aplicadas na degradação de óleos e gorduras. / The microbial physiology is a promising area of biotechnology for the synthesis of compounds of high value. The micro-organisms have advantages because of their shorter generation facilities to physiological and genetic changes and the wide variety of metabolic processes. The aim of this study was to degrade oils and fats from lipases produced by Yarrovia lipolytica. Factorial designs were used to investigate the effects of variables in three stages: fermentation for lipase production, bioproduct formulation for stabilization the catalytic action of lipases and treatment of whey for degradation of fats and oils. In the presence of a vegetable oil residue at 3 % and ammonium chloride at 0,2 g.L-1, during 48 h at 28 oC, lipases were produced under submerged cultivation. The cell-free liquid metabolic was stability with sodium sorbate at 0.5 %, glycerol at 5 %, RENEX-95 at 10 %. This bioproduct presented 177 UI.mL-1 of the lipase activity during 30 days of storage at room temperature (27 - 30 C); it showed optimum pH at 5.0 and 7.0, optimum temperature of 50 oC and thermal stability for 120 min with retention of 100 % of the enzyme activity at 50 oC and pH 5,0. The application of the bioproduct at 7 % during 12 h degraded 98 % of oils and fats present in cheese whey. The lipases produced by Y. lipolytica and formulated with stability agents have potential to be applied in the degradation of oils and fats.
198

Avaliação do ciclo de vida da produção de biogás via estação de tratamento de esgoto e uso em célula a combustível de óxido sólido / Life cycle assessment of biogas produced in a wastewater treatment plant (WWTP) and its use in a solid oxide fuel cell (SOFC)

COSTA, LUZIA B.O. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:34:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:29Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
199

Tratamento de efluentes da produção de tintas industriais, automotivas e de repintura por irradiação com feixe de elétrons / Tretment of effuent from industrial automotive and refinish paints by electron beam irradiation

NASCIMENTO, FERNANDO C. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:42:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:53Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
200

Otimização e validação de metodologia analítica para determinação de metais e semimetais em efluentes líquidos por espectrometria de emissão óptica com plasma de argônio (ICP-OES) / Optimization and validation of analytical methodology for determination of metals and semimetals in wastewater by inductively coupled plasma optical emission spectrometry (ICP-OES)

MARQUES, JOYCE R. 08 April 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-04-08T12:43:32Z No. of bitstreams: 0 / Made available in DSpace on 2016-04-08T12:43:32Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Page generated in 0.0513 seconds