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Factors Influencing the Nitrification Efficiency of Fluidized Bed Filters With a Plastic Bead MediumSandu, Simonel Ioan 09 January 2001 (has links)
Nitrification performance of three, fluidized-bed filters was investigated. Each filter contained 10 L of plastic bead medium (near neutral specific gravity and 2-4 mm diameter and length) and was loaded under conditions of various flow rates and ammonia levels. Bead settled depth and biofilter diameter (12.7, 15.2 and 17.8 cm) were the factors differing among the filters. The experiments were conducted with three replicate recirculating systems. Each system included one of the three different biofilter types, connected in parallel to a reservoir containing 500 L of water. Systems were allowed to acclimate using a synthetic nutrient substrate, which was followed by a comparative analysis of biofilter performance. To evaluate filter performance, ammonia inflow concentration, ammonia loading rates, nitrite, nitrate, temperature, pH, dissolved oxygen levels, hardness, alkalinity and flow rates were monitored. Initially, four different flow rates, ranging from 6 Lpm–12 Lpm, were tested at constant ammonia feed level (8.4 g/day). Here, biofilter D3 (17.8 cm diameter) showed the best ammonia removal performance at a flow rate of 6 Lpm, followed by the performance of D1 (12.7 Lpm) and D2 (15.2 Lpm). The difference in ammonia and nitrite removal performance decreased among the biofilters, as flow rate increased. An increase in flow rate also lowered ammonia level in the systems at a constant ammonia loading, but did not affect the nitrite concentration. Five different ammonia feed rates, ranging from 8.4 – 16.8 g/day, were tested in the second part of the study, at a constant flow rate of 12 Lpm in each column. Different ammonia and nitrite removal performance was observed between biofilter sizes. Ammonia accumulated in the tanks as ammonia loading increased, but nitrite concentration remained relatively constant. The results indicated that nitrification performance improved by 17 % as the applied flow rate was increased. Ammonia concentration decreased slightly, from 0.6 mg/L to 0.5 mg/L. The performance appeared to be limited at higher ammonia loadings, at which time ammonia concentration increased from 0.5 to 0.99 mg/L. Data on biofilm development indicates a reduction in biofilm thickness as flow rate was increase, and significant biofilm accumulation as ammonia supply increased. The results of this work were compared to performance data generated using a steady state biofilm model, developed by Rittmann and McCarty (1980). The model predicted higher values of biofilm thickness (Lf) than those seen in this study.
Fluidized bed filters with plastic bead medium proved to be effective in removing ammonia and nitrite from a synthetic aquaculture water. / Master of Science
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Remoção de nitrogênio e fósforo de efluentes da atividade piscícola em sistema fechado utilizando reatores de leito móvel com biofilme / Removal of nitrogen and phosphorus from effluent from the closed-fishery system using moving bed biofilm reactorsEnriquez, Yemall Alexander Maigual 02 March 2018 (has links)
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Previous issue date: 2018-03-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A aquicultura é uma atividade de produção de espécies hidrobiológicas sob condições controladas. Esta atividade tem evoluído nos processos produtivos, mas estão gerando águas residuárias, quando lançadas diretamente nos corpos de água constituindo riscos potenciais à saúde. O reator de leito móvel com biofilme (MBBR) é uma variação do processo de lodos ativados. É um sistema de tratamento de efluentes que contem biofilme que cresce aderida aos suportes, que se movem livremente no volume do reator. O objetivo desta pesquisa foi determinar a eficiência na remoção de material, nitrogenado no MBBR dos efluentes gerados num sistema de recirculação para aquicultura “SRA”. O sistema MBBR com circulação (SC) - e com aeração (SA) obteve remoções medias de 38,7% para Nitrogênio Total Kjedahl (NTK), 28,9% de fósforo total, 44,5% de DBO, Nitrogênio Amoniacal Total (NAT) de 40% e 38,9% para amônia não ionizada e para nitrito foi 59,3%. Os sólidos Totais (ST), Sólidos Suspensos Totais (SST) e Sólidos Voláteis Totais (SVT) tiveram remoções de 28,0%, 45,9% e 57,4% respectivamente. Durante o período avaliado houve aumento do biofilme nos dois reatores. No MBBR-SA foi verificada a presença de protozoários, microinvertebrados e estruturas filamentosas semelhantes a estreptococos. No MBBR-SC, bactérias na forma de cocos, diplococos e estreptococos. Nas analises realizadas com MEV nos lodos dos dois sistemas foi encontrado traços de silício, alumínio, zinco, fósforo, sódio e magnésio. Também foi encontrado bactérias do tipo vibrio spp, bacilus spp, além da formação de aglomerados. As analises térmicas feitas nos lodos indicaram que houve perda de umidade até os 150°C. A maior parte da massa se perde entre 220°C e 580°C, faixa onde sofrem transformação térmica as proteínas, lipídeos, carboidratos, ácidos graxos, restos de paredes celulares bacterianas. Após os 600°C existe o restante, as cinzas são compostas por carbonatos e outros minerais transformando-se em matérias cristalinos, com baixa variação na massa. / Aquaculture is an activity of production of hydrobiological species under controlled conditions. These activities have evolved in the productive processes, but are producing wastewater, when thrown directly into bodies of water constituting potential health risks. The moving bed biofilm reactor (MBBR) is a variation of the activated sludge process. It is an effluent treatment system containing biofilm growing attached to the carriers, which move freely in the reactor volume. The aim of this research was to determine the efficiency in the removal of nitrogenous compounds in MBBR from the effluents generated in a recirculating aquaculture system "RAS". The MBBR system with circulation (CS) - and with aeration (AS) obtained mean removals of 38.7% for NTK, 28.9% of total phosphorus, 44.5% of BOD, 40% TAN and 38.9% for non-ionized ammonia and for nitrite was 59.3%. Total Solids (TS), Total Suspended Solids (TSS) and Total Volatile Solids (TSV) had removals of 28.0%, 45.9% and 57.4% respectively. During the evaluated period there was an increase of biofilm in the two reactors. In the MBBR-AS the presence of protozoa, microinvertebrates and filamentous structures similar to streptococcus was verified. Also, in MBBR-CS was verified coccus, diplococcus and streptococcus bacteria. In the analyzes performed with SEM in the sludge of the two systems, traces of silicon, aluminum, zinc, phosphorus, sodium and magnesium. Vibrio and bacillus type bacteria were present and besides granule formation. Thermal analyzes indicated that there was in the sludge moisture loss until 150°C. Most of the mass is loss between 220°C and 580°C, where they undergo thermal transformation of proteins, lipids, carbohydrates, fatty acids, remains of bacterial cell walls. After the 600°C the ashes are composed of carbonates and other minerals transforming into crystalline materials, with low mass variation. / CAPES: 12616-13-3
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Avvikelser mellan projekterad och verifierad energiprestanda för nyproducerade lågenergibyggnader : En studie av AB Bostäders svårigheter att leva upp till uppsatta energikrav i deras nybyggda flerbostadshus / Deviations between projected and verified energy performance for newly constructed low-energy buildings : A study of AB Bostäder's difficulties of meeting the energy requirements set in their newly constructed multi-family residentialGustafsson, Sebastian, Jansson, Gösta January 2017 (has links)
EUs direktiv för energiprestanda innebär att alla nya byggnader från och med 2021 ska vara nära-nollenergibyggnader. De stundande kraven innebär att beställare måste skärpa sina energikrav vid upphandling av flerbostadshus. Vidare spelar lågenergibyggnader som koncept en viktig roll för att nå hållbar utveckling och det är av högsta vikt att kommande byggprojekt blir effektiva både i byggprocess och vidare i driftskedet. Nybyggnation av lågenergibyggnader har visat sig problematisk i många aspekter, där den uppmätta energianvändningen i många fall visat sig väsentligt högre än vad som projekterats. I och med den ny byggpraxis med bättre isolation, lufttäthet och ventilation med återvinning blir tappvarmvatten och hushållsel de största energiposterna i en byggnads energibalans. Syftet med arbetet är att konkretisera problemen som finns för nyproducerade flerbostadshus med energikrav för lågenergibyggnader. Utifrån det har fokus lagts på två byggnader som AB Bostäder låtit bygga – båda projekterade för att uppnå lågenergikrav. Likt befarat visar Examensarbetet att det är svårt att härleda problemet till specifika poster. Byggprocessen i sig kan vara en bidragande faktor, där tidsbrist, bristfällig kommunikation och okunskap kring ny byggpraxis är förekommande i en bransch som har svårt att hinna med den efterfrågade volymen av nybyggnation. Vad gäller specifika felkällor till försämrad energiprestanda stödjer vår rapport tidigare publicerade rapporter i ämnet där bristfällig indata vid energiberäkningar, byggprocessens inverkan, oaktsamhet av VVC-förluster och betydelsen av brukare har belysts. / The energy performance of buildings directive means that all new buildings must be nearly zero energy buildings by 31 December 2020. The current requirements mean that constructor companies must tighten their energy requirements when procuring multi-family houses. Lowenergy buildings as concepts play an important role in achieving sustainable development, and it is of the utmost importance that future construction projects become effective both in the construction process and on further operation. New construction of low-energy buildings has proved to be quite problematic in many aspects, where the measured energy performance in many cases proved to be significantly higher than projected. With the new building practice with better insulation, air tightness and ventilation with recycling – hot water supply and household appliances become the largest energy posts in a building's energy balance. The purpose of this master thesis is to concretize the problems that exist for newly produced multi-family houses with energy requirements for low-energy buildings. Based on this, focus has been on two building that AB Bostäder Borås recently has built – both built to achieve low energy requirements. As expected, this master thesis shows the difficulty to deduce the problem to specific aspects. The construction process itself may be the source of error, where time shortages, inadequate communication and lack of knowledge concerning low energy buildings are present in an industry with difficulties catching up with the demanded volume of new construction. Regarding specific sources of vulnerability to energy performance, our report supports previously published reports where the lack of input data for energy calculations, the impact of the construction process, negligence of losses due to recirculation of hot water and the importance of user behaviour have been highlighted.
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Skiljer sig energiberäkningarna i projekteringsstadiet från energiberäkningarna i relationshandlingarna?Ingarsson, Ellen, Sköld, Ellen January 2022 (has links)
To reduce the emissions from energy use, high demands are set on new buildings. Studies have shown big differences between predicted and actual energy performance. This gap makes it more difficult to reduce the energy use in buildings. The aim of this study is to discover if deviations occur before the building is put into use, and if it does, discuss the reasons for that. In this study, energy performance for 20 multi-family houses have been compared between the early design stage and the production stage. The result of this study is that there are no major differences in energy use between the different documents. On the other hand, there are big differences in some of the parameters that the energy use is dependent on. The reasons of this are discussed later in this thesis. None of the investigated buildings had the same value of energy performance in the production stage as in the early stage. The parameter that has shown the greatest difference is space heating and hot water recirculation. The biggest correlation was found between the energy required by the fans and the buildings total energy use.
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