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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.
81

Pós-tratamento de efluente de lagoa facultativa visando à remoção de nitrogênio amoniacal. / Post treatment of facultative pond effluent aiming removal of ammonia nitrogen.

Ruggeri Júnior, Humberto Carlos 08 April 2011 (has links)
Discute o pós-tratamento de efluente de lagoas facultativas visando à remoção de nitrogênio amoniacal. Para isso, foram utilizadas unidades terciárias em escala piloto. A escolha do tipo de unidades para o pós-tratamento do efluente levou em consideração a questão do baixo custo e simplicidade de operação. Desta forma, para o estudo, fez-se opção por lagoas rasas e filtros percoladores como unidades de pós-tratamento. O objetivo principal do trabalho foi associar as taxas de aplicação superficial e volumétricas com as remoções de nitrogênio amoniacal nessas unidades. Para lagoas em escala piloto, foram adotadas profundidades de 0,5 m e 1,0 m. As lagoas rasas foram submetidas a diferentes taxas de aplicação e TDH. Para os filtros percoladores, foram escolhidos dois materiais diferentes como meio suporte, pedra britada e anel plástico. Os filtros foram submetidos a diferentes condições operacionais. Para os dois tipos de unidades complementares de tratamento, foram verificados os efeitos das condições ambientais sobre as eficiências de remoção. Na lagoa de 0,5 m foram observadas concentrações de nitrogênio amoniacal abaixo de 20 mg-N/L para tempos de detenção de 5 dias e taxas de aplicação superficial de 50 kgDBO/ha.d. Na lagoa de 1,0 m, concentrações de nitrogênio amoniacal abaixo de 20 mg-N/L só foram possíveis com taxas de aplicação de 50 kgDBO/ha.d e TDH de 10 dias. A lagoa de 0,5 m apresentou uma eficiência maior na remoção de nitrogênio amoniacal do que a lagoa de 1,0 m. Os efluentes dos filtros apresentaram concentrações de nitrogênio amoniacal acima de 20 mg-N/L com taxas acima de 0,20 kgDBO/m³.d. Para taxas de aplicação hidráulica acima de 18 m³/m².d e 0,70 kgDBO/m².d houve o encerramento do processo de nitrificação nos filtros. Os valores de pH e as concentrações de NH3 no efluente da lagoa facultativa submeteram os filtros a operar dentro da faixa de inibição da nitratação, devido ao NH3, sendo observadas concentrações significativas de nitrito no seu efluente. Os filtros percoladores não foram adequados como unidades de pós-tratamento de efluente de lagoa. Embora as lagoas rasas não tenham atendido aos aspectos de múltiplas qualidades do efluente, elas foram mais adequadas ao pós-tratamento de efluente de lagoa facultativa do que os filtros percoladores. / This study discusses the post treatment of effluent ponds aiming at removing the ammonia nitrogen. To this end, tertiary units were used in a pilot scale. The choice of units for the post treatment of the effluent took into consideration the issue of low cost and simplicity of operation. Thus, for this study, we chose shallow ponds and trickling filters as post-treatment units. The main objective of this study was to associate the superficial and the volumetric application rates with the removal of ammonia nitrogen of these units. For the ponds on a pilot scale, two depths were adopted: a pond of 0.5 m and another one of 1.0 m depth. The shallow ponds were subjected to different loading rates and HRT. For the trickling filters, two different kinds of materials were chosen as a medium support: crushed stone and plastic ring. The filters were also subjected to different operating conditions. For both types of additional treatment units it was observed the effects of the environmental conditions on the removal efficiencies. In the pond of 0.5 m depth, it was observed concentrations of ammonia nitrogen below 20 mg-N/L for detention times of 5 days and superficial application rates of 50 kgBOD/ha.d. In the pond of 1.0 m depth, concentrations of ammonia nitrogen below 20 mg-N/L were only possible with application rates of 50 kgBOD/ha.d and HRT of 10 days. The 0.5m-depth pond showed a better efficiency in the removal of ammonia nitrogen than then1.0m-depth pond. The filters had concentrations above 20mg-N/L with rates above 0.20 kgBOD/m³.d. For hydraulic application rates above 18m³/m².d and 0.70kgBOD/m².d there was the cessation of the nitrification process in the filters. The pH values and the concentrations of NH3 in the effluent of the facultative pond made the filters operate within the range of inhibition of nitration, due to the NH3, and it was observed significant concentrations of nitrite in the effluent of the filters. The trickling filters were not suitable as units of post-treatment pond effluent. Although the shallow ponds have not met the multiple aspects of quality of the effluent, they were more adequately for facultative pond effluents post-treatment than trickling filters.
82

Primary Productivity and Community Metabolism in a Small North Central Texas Pond Ecosystem

Kelly, Martin H. 08 1900 (has links)
Rates of primary production and community metabolism were monitored over a one year period using the diurnal oxygen method. Certain physico-chemical parameters were also measured, and autotrophic standing crops were estimated. An in-depth study was made of the phytoplankton community and various diversity indicies were calculated. Simple correlations were run between all parameters measured (biotic and abiotic), and their inter-relationships examined. Multiple linear regression analyses were used to develop equations predictive of production and community metabolism. Bluegreen algae were the dominant phytoplankters with blooms occurring in late summer and fall. Yearly mean production was approximately 21 kcal per meter square per day with a mean photosynthetic efficiency of 1.2 per cent. Of the various parameters measured turbidity and water temperature were most important in determining rates of primary production.
83

Pós-tratamento de efluente de lagoa facultativa visando à remoção de nitrogênio amoniacal. / Post treatment of facultative pond effluent aiming removal of ammonia nitrogen.

Humberto Carlos Ruggeri Júnior 08 April 2011 (has links)
Discute o pós-tratamento de efluente de lagoas facultativas visando à remoção de nitrogênio amoniacal. Para isso, foram utilizadas unidades terciárias em escala piloto. A escolha do tipo de unidades para o pós-tratamento do efluente levou em consideração a questão do baixo custo e simplicidade de operação. Desta forma, para o estudo, fez-se opção por lagoas rasas e filtros percoladores como unidades de pós-tratamento. O objetivo principal do trabalho foi associar as taxas de aplicação superficial e volumétricas com as remoções de nitrogênio amoniacal nessas unidades. Para lagoas em escala piloto, foram adotadas profundidades de 0,5 m e 1,0 m. As lagoas rasas foram submetidas a diferentes taxas de aplicação e TDH. Para os filtros percoladores, foram escolhidos dois materiais diferentes como meio suporte, pedra britada e anel plástico. Os filtros foram submetidos a diferentes condições operacionais. Para os dois tipos de unidades complementares de tratamento, foram verificados os efeitos das condições ambientais sobre as eficiências de remoção. Na lagoa de 0,5 m foram observadas concentrações de nitrogênio amoniacal abaixo de 20 mg-N/L para tempos de detenção de 5 dias e taxas de aplicação superficial de 50 kgDBO/ha.d. Na lagoa de 1,0 m, concentrações de nitrogênio amoniacal abaixo de 20 mg-N/L só foram possíveis com taxas de aplicação de 50 kgDBO/ha.d e TDH de 10 dias. A lagoa de 0,5 m apresentou uma eficiência maior na remoção de nitrogênio amoniacal do que a lagoa de 1,0 m. Os efluentes dos filtros apresentaram concentrações de nitrogênio amoniacal acima de 20 mg-N/L com taxas acima de 0,20 kgDBO/m³.d. Para taxas de aplicação hidráulica acima de 18 m³/m².d e 0,70 kgDBO/m².d houve o encerramento do processo de nitrificação nos filtros. Os valores de pH e as concentrações de NH3 no efluente da lagoa facultativa submeteram os filtros a operar dentro da faixa de inibição da nitratação, devido ao NH3, sendo observadas concentrações significativas de nitrito no seu efluente. Os filtros percoladores não foram adequados como unidades de pós-tratamento de efluente de lagoa. Embora as lagoas rasas não tenham atendido aos aspectos de múltiplas qualidades do efluente, elas foram mais adequadas ao pós-tratamento de efluente de lagoa facultativa do que os filtros percoladores. / This study discusses the post treatment of effluent ponds aiming at removing the ammonia nitrogen. To this end, tertiary units were used in a pilot scale. The choice of units for the post treatment of the effluent took into consideration the issue of low cost and simplicity of operation. Thus, for this study, we chose shallow ponds and trickling filters as post-treatment units. The main objective of this study was to associate the superficial and the volumetric application rates with the removal of ammonia nitrogen of these units. For the ponds on a pilot scale, two depths were adopted: a pond of 0.5 m and another one of 1.0 m depth. The shallow ponds were subjected to different loading rates and HRT. For the trickling filters, two different kinds of materials were chosen as a medium support: crushed stone and plastic ring. The filters were also subjected to different operating conditions. For both types of additional treatment units it was observed the effects of the environmental conditions on the removal efficiencies. In the pond of 0.5 m depth, it was observed concentrations of ammonia nitrogen below 20 mg-N/L for detention times of 5 days and superficial application rates of 50 kgBOD/ha.d. In the pond of 1.0 m depth, concentrations of ammonia nitrogen below 20 mg-N/L were only possible with application rates of 50 kgBOD/ha.d and HRT of 10 days. The 0.5m-depth pond showed a better efficiency in the removal of ammonia nitrogen than then1.0m-depth pond. The filters had concentrations above 20mg-N/L with rates above 0.20 kgBOD/m³.d. For hydraulic application rates above 18m³/m².d and 0.70kgBOD/m².d there was the cessation of the nitrification process in the filters. The pH values and the concentrations of NH3 in the effluent of the facultative pond made the filters operate within the range of inhibition of nitration, due to the NH3, and it was observed significant concentrations of nitrite in the effluent of the filters. The trickling filters were not suitable as units of post-treatment pond effluent. Although the shallow ponds have not met the multiple aspects of quality of the effluent, they were more adequately for facultative pond effluents post-treatment than trickling filters.
84

Analysis for certain selected trace inorganic ions in York-Prairie Creek Pond

Mapetla, Shadrack K. January 1980 (has links)
As a result of rapid growth in technology, efforts to remove pollutants from the natural environment have not been able to keep pace with the increasing amount of waste materials and a growing population that further aggravates the situation. This has resulted in the transformation of lakes and ponds into pollution depots. A pilot study for monitoring certain selected trace elements entering and leaving YorkPrairie Creek Pond, situated inside the campus of Ball State University, was undertaken with the view to establishing whether or not this pond has been polluted, like many lakes and ponds, by metal corrosion, engine exhaust gases, and runoff from fertilizers and streets.This investigation involved sampling pond waters at two sites, viz., Influx surface and Effluent surface. Samples were collected once daily at the same time over a total time period of 23 days. Each sample was analyzed, in duplicate, for the heavy metal cations iron, lead, and cadmium, and for the inorganic anions nitrate, orthophosphate, and chloride. Metals were analyzed by atomic absorption spectrophotometry (A. A. S.), while titrimetric and cotorimetric procedures were utilized for the anion analyses.Results have indicated that iron and chloride are the most abundant of all analytes. Precipitation tends to Increase concentrations of analytes in general, possibly due to increased runoff and the lowering of the pH of these waters; leading to increased elemental release into solution. The relative responses of the analyzed ion levels in pond influx and effluent waters have been shown to be similar although their levels were significantly different.Analyte levels were found to be generally higher in effluent than in Influx waters; only chloride was found to depart from this general behavior. This finding led to the conclusion that the selected Ions, with the exception of chloride, tend not to accumulate in the waters of the pond but rather to escape with its effluent. This conclusion is subject to modification by future researchers, to whom the author has recommended a more expanded sampling program that would include the surface and sediment of the pond's interior since the nature of the results (especially for Pb and Cd) would seem to indicate not only that the pond does not exhibit thorough mixing of its constituents (homogeneity) but also the presence of an active remobilization process within its interior.
85

荷塘月色餐廳商業計畫書 / Lotus Pond vegetarian restaurant business plan

吳晨瑜, Wu, Chen Yu Unknown Date (has links)
荷塘月色餐廳商業計畫書 / Lotus Pond Vegetarian Restaurant Business Plan
86

Membrane Stratified Solar Ponds

Schober, Benjamin January 2010 (has links)
<p>This project deals with the potential of membrane stratified solar ponds which consist of two water layers, where one is a salt solution here, and a separating translucent membrane. An experimental pond was set up to study the thermal behaviour of such collector systems. The input is mainly solar radiation, sometimes when the ambient temperatures are higher than the pond temperatures also heat from the environment is transferred into the pond.</p><p>The measured temperatures of the pond, the ambient temperature, the global radiation and wind speed were the basis data for thermal calculations which showed that the pond was working well as a solar collector and thermal storage system all in one. Heat was not extracted from the pond however, only the losses to the environment were studied.</p><p>It was found out that the pond temperatures were higher than the ambient temperature over the whole measurement period of 12 days, and insulation and pollution problems as well as future prospects and suggestions for further studies are discussed at the end of this paper.</p>
87

Membrane Stratified Solar Ponds

Schober, Benjamin January 2010 (has links)
This project deals with the potential of membrane stratified solar ponds which consist of two water layers, where one is a salt solution here, and a separating translucent membrane. An experimental pond was set up to study the thermal behaviour of such collector systems. The input is mainly solar radiation, sometimes when the ambient temperatures are higher than the pond temperatures also heat from the environment is transferred into the pond. The measured temperatures of the pond, the ambient temperature, the global radiation and wind speed were the basis data for thermal calculations which showed that the pond was working well as a solar collector and thermal storage system all in one. Heat was not extracted from the pond however, only the losses to the environment were studied. It was found out that the pond temperatures were higher than the ambient temperature over the whole measurement period of 12 days, and insulation and pollution problems as well as future prospects and suggestions for further studies are discussed at the end of this paper.
88

Simulering och känslighetsanalys av ett pumpkraft-dagvattendammsystem : En utvärdering av potential för småskalig energilagring av solelsöverskott eller arbitrage / Simulation and sensitivity analysis of a PHES-stormwater pond system : An evaluation of potential as small-scale energy storage used for solar energy or arbitrage

Abrams, Philip January 2020 (has links)
The global move to more sustainable and renewable energy sources causes increased fluctuations in theelectric market. That fact combined with the Swedish regulations on micro producers make high levels ofself-use critical and have increased the interest in energy storage of energy from intermittent sources.Cooperation with Eksta AB have provided the opportunity to evaluate an innovative energy storage conceptfor a future exploitation area of around 17,2 hectares planned residential and urban area. This bachelorthesis studies the potential of using stormwater management ponds for small-scale energy storage in theform of pumped hydro energy storage (PHES). The focus is on storage of surplus energy from a solarenergy system designed for micro production and local energy supply. However, it also evaluates thepotential of using the equivalent dimensions for energy storage which storage level only change whenbuying or selling electricity at market prices for arbitrage purposes.Potential in the form of financial benefit and increased self-use of solar energy are studied through aquantitative methodology that, in the case of storing surplus energy from a solar system, use a simulationmodel developed for this thesis that takes Eksta´s contractual electric specifications into account. Toevaluate the case of energy storage for arbitrage a simulation model is used in the form of an algorithmbaseddrive strategy named “Optimal”, which has been recreated from research in the field of energy storageand drive strategies. The level of innovation is high on account of including such as energy additions to thestorage from rain water management, energy losses from dispersion of stored stormwater to surroundingground layers, it´s novel focus on a stormwater pond for energy storage, the rarely studied combination ofPHES and small scale solar systems and finally that the dimensions of the pump and turbine that is neededin PHES is based on PaT (pump as turbine) technology, allowing the reverse drive of a centrifugal pumpto operate as a turbine.Sensitivity analysis is included to increase the understanding of PHES-stormwater systems in the case of Eksta and as a concept for energy storage. The work also includes a brief examination of relevant regulationsin order to supply a wider perspective.The result shows that the implementation of a PHES-stormwater system during the years 2018 and 2019increased the self-use of generated solar energy by 28,59 % and provide the joint financial benefit of 5989SEK. The simulation model of energy storage for arbitrage during the years 2018 and 2019 resulted in thecombined financial benefit of 699 SEK when “Optimal” operation strategy is used and 678 SEK with apractically applicable operation strategy.The main conclusion is that PHES-stormwater systems as an energy storage for small-scale solar surplushas high potential to increase the self-use of solar energy but relatively low potential to increase the financialbenefits of small-scale solar systems. From the sensitivity analysis it can be concluded that the simulatedPHES-stormwater system is sensitive to small and medium ranged changes in storage capacity, efficiency,rate of dispersion, set electrical buying price and selectivity of which hours to empty the storage. This whilebeing generally insensitive to small and medium ranged variations in installed peak effect of the solar system,filling/emptying time and the relative size of the turbine compared to the pump.The conclusion from the simulation of arbitrage application is that the potential for financial benefit inthese circumstances is extremely low. The sensitivity analysis lead to the conclusion that the system issensitive to small and medium ranged variations in storage capacity, efficiency, filling/emptying time andmarginal operation costs.Besides the limited financial benefit, other potential hindrances may be the legality of connecting the systemelectrically, lack of financial benefits given to larger but still small-scale solar systems and the eventuality ofdisrupting the main function of the stormwater pond, which is purifying stormwater.
89

Lakvattenrening och kontroll vid deponier : granskning och sammanställning / Treatment of leachate and control at landfills : review and compilation

Eriksson, Linda January 2005 (has links)
<p>If not purified leachate from landfills would cause damages on the environment. At most landfills in Sweden local treatment of leachate is achieved, at the rest the leachate is transported to sewertreatment. While no comprehensive legal provisions for discharge exist in Sweden there is a difference in discharges between the installations for landfill. If no comprehensive legal provisions is produced guidance must improve.</p><p>Treatment of leachate and self monitoring system at fifteen installations in Sweden has been studied and compared. A study of literature about different treatment solutions has also been performed. Practical information about the landfills has been gathered through visits. Processes of treatment described in literature correspond to measures. Variations exists between the self monitoring systems at the installations both between parameters for analyses, how often controls take place and were testpoints are situated.</p><p>Knowledge of reactions and techniques for treatment of compounds common in leachate exist. Further research about compounds whose effect we do not know for certain must be achieved.</p> / <p>Lakvattenrening och egenkontrollprogram vid femton deponier i Sverige har studerats och jämförts. En litteraturstudie angående olika reningstekniker har även utförts. Information om deponierna och reningsprocesserna har inhämtats via studiebesök och miljörapporter. Vid jämförelse av rening har olika processer studerats separat. Den beskrivning av processerna som finns i litteraturen stämmer väl med uppmätta resultat. Exempel på detta är ammoniumhalter som reduceras i luftad damm, halter totalkväve som minskar genom rening i Satsvis Biologisk Reaktorteknik och reducerad halt suspenderat material som inträffar vid rening genom markfilter. Egenkontrollprogrammen vid de olika deponierna varierar dels i avseende på vilka parametrar som kontrolleras och dels hur ofta kontroller utförs och var provpunkter är belägna.</p><p>För de vanligast förekommande ämnen som existerar i lakvatten finns kunskap om reaktioner och fungerande tekniker för rening. Problem uppstår för de ämnen vilkas reaktioner och förändringar man ej känner till. Farhågor finns dessutom att det i lakvatten finns föreningar vars existens och verkan vi ej känner till. På grund av detta krävs ytterligare forskning på lakvatten.</p>
90

Community assembly and food web interactions across pond permanence gradients

Greig, Hamish Stuart January 2008 (has links)
Ecological communities along gradients of environmental stress are thought to be structured by trade-offs between resisting biotic interactions in physically benign habitats and successfully exploiting physically stressful habitats. However, these trade-offs are likely to be affected by the predictability of abiotic stressors, and variation in the strength of biotic interactions. I investigated community assembly and food web interactions in ponds across an unpredictable gradient of water inundation (pond permanence) in Canterbury, New Zealand. Pond community composition and species richness were strongly influenced by pond permanence. However, species in temporary ponds were a nested subset of generalists that were also found in permanent ponds, rather than a unique assemblage of temporary pond specialists. Subsequent experiments indicated predator impact decreased with pond permanence, partially due to the foraging suppression of predatory invertebrates in permanent ponds by fish. Weak predation in permanent ponds combined with unpredictable drying regimes likely selected for generalist traits, and resulted in community assembly being driven by a gradient of drying stress rather than trade-offs between biotic interactions and drying. Furthermore, predator impact increased over time in temporary ponds. In predictable snow-melt ponds in the Colorado Rocky Mountains, seasonal windows of weak predation were exploited by vulnerable species, leading to increased diversity within habitats. However in unpredictable systems like Canterbury, temporal increases in predation risk that depend on drying history are likely to increase variability in the spatial arrangement of suitable habitats for particular species. This should further favour the evolution of generalist traits and reduce the importance of trade-offs between predation and drying in the assembly of communities. Considering the predictability of disturbance regimes and the spatial and temporal variation in biotic interactions will greatly enhance understanding and management of communities in heterogeneous landscapes.

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