• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 777
  • 463
  • 75
  • 56
  • 39
  • 34
  • 16
  • 12
  • 10
  • 10
  • 8
  • 8
  • 8
  • 7
  • 4
  • Tagged with
  • 1914
  • 318
  • 314
  • 301
  • 273
  • 229
  • 228
  • 195
  • 184
  • 167
  • 159
  • 121
  • 119
  • 104
  • 100
  • 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.
211

Tratamento de efluentes de curtume com consórcio de microalgas

Pena, Aline de Cássia Campos January 2017 (has links)
Os efluentes líquidos de curtumes apresentam altas cargas orgânicas e de poluentes que devem ser tratados corretamente para atingir os padrões legais para seu descarte, evitando a eutrofização de corpos hídricos e poluição das águas. O acabamento do couro é o estágio final da produção, onde o couro recebe as características desejadas de acordo com os produtos e artigos que serão produzidos. Os efluentes das etapas de processamento para acabamento do couro são responsáveis por conterem poluentes químicos devido ao uso de corantes, surfactantes, metais tóxicos, agentes emulsificantes, recurtentes, óleos, pigmentos, resinas, entre outros produtos químicos adicionados. As microalgas têm sido alvo de vários estudos no âmbito de tratamento de efluentes, devido à sua capacidade de remover diversos nutrientes, matéria orgânica do meio e por serem formas mais limpas e econômicas de tratar os poluentes. Diante disto, o objetivo deste trabalho foi avaliar o emprego de um consórcio de microalgas para tratamento de efluentes de um curtume e analisar a capacidade de remoção de poluentes que são nutrientes para estes microrganismos. Os efluentes foram caracterizados ao longo dos ensaios com o consórcio de microalgas por meio de Nitrogênio Total (NT), Amônia (NH3), Fósforo (P-PO4), Carbono total (CT), Carbono Orgânico Total (COT), Carbono inorgânico (CI), DQO e Demanda Biológica de Oxigênio (DBO) e foi acompanhado o crescimento das microalgas. Para os experimentos foram coletados efluentes em três estágios distintos em uma estação de tratamento: efluente bruto (B), efluente após tratamento primário de coagulação/floculação (P) e efluente após ao tratamento biológico secundário (S). Os resultados com concentração de efluente de 50%, diluídos em água destilada (A), após 16 dias de cultivo, mostraram que houve crescimento do consórcio nos três efluentes com um crescimento máximo de 1,77 g L-1 no efluente Bruto (50B50A). Na sequência, foi testado o cultivo em efluente bruto (100B) e em efluentes compostos nas seguintes proporções: 50% efluente bruto + 50% efluente após tratamento biológico (50B50S) e 25% efluente bruto + 75% efluente após tratamento biológico (25B75S). Foi possível cultivar o consórcio no efluente bruto sem diluição, entretanto os resultados foram ruins, pois o mesmo apresentou baixo crescimento e, consequentemente, baixos níveis de remoção de nutrientes. Com o efluente composto 25B75S percebeu-se morte rápida das microalgas, uma vez que o efluente apresentava baixas concentrações de nutrientes. Em contrapartida, no efluente 50B50S foram atingidos valores efetivos de crescimento e remoção de nutrientes. Em cultivos fotoautotrófico, mixotrófico e heterotrófico de efluente composto 50B50S e de 75% efluente bruto + 25% efluente após tratamento biológico (75B25S), os melhores resultados foram atingidos no efluente 75B25S no cultivo fotoautotrófico, crescendo até 1,42 g L-1 e atingindo valores de remoção de NNH3, Nitrogênio Total (NT), DQO, carbono orgânico total (TOC) e demanda biológica de oxigênio (DBO5), de 99,90%, 74,89%, 56,70%, 58,18% e 20,68%, respectivamente. Ao obter a microalga isolada Tetraselmis sp. predominante no consórcio foi analisado os parâmetros anteriores em cultivo fotoautotrófico, além disso foi verificada a quantidade de lipídio presente na biomassa. A microalga Tetraselmis sp. apresentou um crescimento notório no cultivo fotoautotrófico com remoções eficientes dos parâmetros e 5,0% de lipídio no peso seco. / Liquid effluents from tanneries present high organic and pollutant loads and must be treated correctly to meet the legal standards for effluent disposal and to avoid eutrophication of water bodies and water pollution. The leather finish is the final stage of production, where the leather receives the desired characteristics according to leather goods and articles. The effluents from the processing steps for leather finishing are responsible for containing chemical pollutants due to the use of dyes, surfactants, toxic metals, emulsifying agents, retanning agents, oils, pigments, resins, among other chemicals added. Microalgae have been the subject of several studies in the field of effluent treatment due to their ability to remove various nutrients, organic matter from the environment and to be cleaner and more economical ways to treat pollutants. In this work, the growth of a microalgae consortium for the treatment of effluents from a tannery was analyzed and the capacity of removal of Total Nitrogen (NT), Ammonia (NH3), Phosphorus (P-PO4), Total Carbon ), Total Organic Carbon (COD), COD and Biological Oxygen Demand (DBO), as well as the growth of microalgae biomass in these effluents. The effluents were characterized before and after the trials with the microalgae consortium. Effluents were collected in three distinct stages at a treatment plant: crude effluent (B), effluent after primary coagulation / flocculation (P) treatment and effluent after secondary biological treatment (S). The results with 50% effluent concentration, diluted in distilled water (A) after 16 days of cultivation, showed that there was a consortium growth in the three effluents with a maximum growth of 1.77 g L-1 in the crude effluent (50P50A). (50B50S) and 25% crude effluent + 75% effluent after biological treatment (25B75S) were tested in the following proportions: 50% crude effluent + 50% effluent after biological treatment (50B50S). It was not possible to cultivate the consortium in pure crude effluent, since it presented low growth and, consequently, low levels of nutrient removal. With the compound effluent 25B75S it was observed rapid death of the microalgae, since the effluent presented low concentrations of nutrients. On the other hand, in the effluent 50B50S, effective values of growth and nutrient removal were achieved. In photoautotrophic, mixotrophic and heterotrophic cultures of 50B50S effluent and 75% crude effluent + 25% effluent after biological treatment (75B25S), the best results were reached in the effluent 75B25S in photoautotrophic cultivation, growing up to 1.42 g L-1 and reaching values of removal of N-NH3, total nitrogen (NT), (DQO), total organic carbon (COT) and biological oxygen demand (DBO), of 99.90%, 74.89%, 56.70%, 58.18% and 20.68%, respectively. By obtaining the isolated microalgae Tetraselmis sp., predominant in the consortium and analyzed and the previous parameters in photoautotrophic cultivation, in addition to being verified the amount of lipid present in the biomass. The microalgae Tetraselmis sp. showed a notable growth in photoautotrophic cultivation with efficient removal of the parameters and 5.0% of lipid in dry weight.
212

Development of a novel integrated system for bioremediating and recovering transition metals from acid mine drainage

Araujo Santos, Ana January 2018 (has links)
Mine-impacted water bodies are considered to be one of the most serious threats to the environment. These can be highly acidic and often contain elevated concentrations of sulfate and soluble metals. The microbial generation of H2S by reduction of more oxidized sulfur species, and consequent precipitation of metal sulfides, known as biosulfidogenesis, is a promising technology for remediating acid mine drainage (AMD). The objective of this work was to develop an integrated system for remediating a target AMD at an operating mine in northern Brazil using a single low pH anaerobic sulfidogenic bioreactor (aSRBR) and an aerobic manganese-oxidizing bioreactor. A synthetic version of the mine water, which contained 7.5 mM copper and lower concentrations (< 0.25 mM) of other transition metals (Zn, Ni, Co and Mn) was used in the experimental work. In the first stage, H2S generated in the aSRBR was delivered to an off-line vessel containing synthetic AMD, which removed > 99% copper (as CuS) while no co-precipitation of other metals was apparent. The partly-processed AMD was then dosed with glycerol and fed into the aSRBR where zinc, nickel and cobalt were precipitated. The effect of varying the pH and temperature of the bioreactor was examined, and > 99% of Ni, Zn and Co were precipitated in the aSRBR when it was maintained at pH 5.0 and 35ºC. The bacterial communities, which were included 4 species of acidophilic sulfate-reducing bacteria, varied in composition depending on how the bioreactor was operated, but were both robust and adaptable, and changes in temperature or pH had only short-term impact on its performance. Manganese was subsequently removed from the partly-remediated synthetic AMD using upflow bioreactors packed with Mn(IV)-coated pebbles from a freshwater stream which contained Mn(II)-oxidizers, such as the bacterium Leptothrix discosphora and a fungal isolate belonging to the order Pleosporales. This caused soluble Mn (II) to be oxidised to Mn (IV) and the precipitation of solid-phase Mn (IV) oxides. Under optimised conditions, over 99% manganese in the processed AMD was removed. Metal sulfides (ZnS, CoS and NiS) that had accumulated in the aSRBR over 2 years of operation were solubilised by oxidative (bio)leaching at low pH. With this, ~ 99% Zn, ~ 98% Ni and ~ 92% Co were re-solubilised, generating a concentrated lixiviant from which metals could be selectively recovered in further downstream processes. The use of methanol and ethanol either alone or in combination with glycerol were evaluated as alternative electron donors for biosulfidogenesis. Methanol was not consumed in the bioreactor, though sulfate reduction was not inhibited in the presence of up to 12 mM methanol. In contrast, ethanol was readily metabolised by the bacterial community and sulfate reduction rates were relatively high compared to glycerol. Two acidophilic algae were characterised and their potential to act as providers of electron donors for biosulfidogenesis was also evaluated. Although algal biomass was able to fuel sulfate reduction in pure cultures of aSRB and in the aSRBR, rates were much lower than when either glycerol or ethanol were used.
213

Laboratory and Field Studies Directed toward Accelerating Arsenic Remediation at a Major US Superfund Site in New Jersey

Wovkulich, Karen January 2011 (has links)
Arsenic is a prevalent contaminant at a large fraction of US Superfund sites. Therefore, establishing techniques for accelerating As remediation could benefit many contaminated sites. Remediation of As contaminated groundwater by conventional methods, i.e. pump and treat (P&T), can be impeded by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Through experimentation at different physical scales (grain, bench, and field scale), the potential for chemical additions to increase As release from sediments and possibly accelerate P&T remediation is examined. The work described here focuses on As contamination and remediation at the Vineland Chemical Co. Superfund site in southern NJ. The site is extensively contaminated with As resulting from decades of poor chemical storage and disposal practices by the Vineland Chemical Co., which manufactured As-based biocides from 1949-1994. Despite significant intervention, including groundwater remediation by P&T and treatment of solids via soil washing, sufficient site clean up could require many decades with current technologies. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and potentially improve P&T remediation efficiency. Simple extrapolations from bench scale column experiments based on pore volumes suggest that treatment with 10 mM oxalic acid could lower the time necessary for clean up at the Vineland site from 600 years (with current techniques involving just groundwater) to potentially on the order of 4 years. Small scale (<1 mm2) X-ray fluorescence maps from columns performed within the synchrotron beamline showed As release during oxalic acid treatment that was consistent with the bulk column materials and suggested that microscale processes can be predictive of the larger system. Finally, during a 3-month pilot study at the Vineland site, oxalic acid was injected into a section of the aquifer via an injection manifold system that was designed and built for the experiment. Groundwater samples indicate that introduction of oxalic acid led to increased As release at a sampling well and pump and treat recovery well in the study area. Addition of oxalic acid shows promise for accelerating treatment of a highly contaminated site.
214

Elucidating Microbial Community Structure, Function and Activity in Engineered Biological Nitrogen Removal Processes using Meta-omics Approaches

Park, Mee Rye January 2017 (has links)
Biological nitrogen removal (BNR) has been applied for more than a century in the interests of preserving and enhancing public health and the environment. But only during the last few decades has the development of molecular techniques using biomolecules such as nucleic acids (DNA and RNA) and proteins allowed the accurate description and characterization of the phylogenetic and functional diversity of microbial communities. Moreover, thanks to recent advances in genomics and next-generation sequencing technologies, microbial community analyses have initiated a new era of microbial ecology. Notwithstanding the fact that the efficiency and robustness of a wastewater treatment mainly depend on the composition and activity of BNR communities, research on the structural and functional microbial ecology of the engineered BNR process remains rare with respect to next-generation sequencing and bioinformatics. This dissertation aims to bridge high-priority knowledge gaps in determining and applying knowledge of microbial structure (who is there and how many?) and function (what are they doing? what else can they do?) to the practice of BNR processes, and to opening up the ‘black-box’ of energy and resource efficient engineered BNR processes using a systems biology approach. Specific objectives were to (1) selectively enrich Nitrospira spp. from a mixed environmental microbial consortium (such as activated sludge) in a continuously operated bioreactor and characterize the microbial ecology during the course of enrichment, determine key kinetic parameters of enriched Nitrospira spp., (2) examine the inhibitory effects of nitrogenous intermediates (such as hydroxylamine, presented herein) on the physiological and molecular responses of Nitrospira spp. in terms of both catabolism and anabolism, (3) characterize bacterial community composition and their dynamics by 16S rRNA gene amplicon sequencing under varying reactor operational conditions from full-scale WWTPs and identify process parameters that most significantly correlate with those dynamics, (4) interpret metagenomic (DNA-based) and metatranscriptomic (RNA-based) derived structure, metabolic function and activity of the full-scale BNR microbial communities, and (5) describe gene expression in the same full-scale BNR communities in response to alternating anoxic-aerobic conditions using a metatranscriptomic approach. First, planktonic Nitrospira spp. were successfully enriched from activated sludge in a sequencing batch reactor by maintaining sustained limiting extant nitrite and dissolved oxygen concentrations for a half year. The determined parameters collectively reflected not just higher affinities of this enrichment for nitrite and oxygen, respectively, but also a higher biomass yield and energy transfer efficiency relative to other NOB such as Nitrobacter spp. Used in combination, these kinetic and thermodynamic parameters can help toward the development and application of energy-efficient biological nutrient removal processes through effective Nitrospira out-selection. Second, using quantitative activity measurements (respirometrc rates) with functional gene expression profiles, this study demonstrated that N-intermediates such as hydroxylamine (NH¬2OH) can strongly inhibit the activity and expression of key anabolic (energy synthesis) and catabolic (biomass synthesis) pathways of Nitrospira spp. A strategy that relies upon the transient accumulation and consumption of such intermediates (such as transient aeration) could provide the platform for successful suppression of Nitrospira spp. in the next generation of energy efficient engineered BNR processes. Third, 16S rRNA gene amplicon sequencing revealed that microbial community structure and their dynamics significantly varied depending on seven differing wastewater treatment processes. The findings showed that five process parameters of wastewater influenced the dynamics of BNR communities; water temperature was correlated most strongly to the variance of bacterial communities, followed by effluent NH3, effluent NO3-, removed N, and effluent NO2-. The results provided insights into the underlying ecological pattern of community compositions and dynamics in full-scale WWTPs; and correlation with process parameters brought about distinct communities that enable different microbial activities. However, one of the greatest challenges was to elucidate the relationship between microbial structure and their “active” functions, which are related to reactor performance (This challenge continued into fourth study chapter summarized below). Fourth, continuing from the previous study, combined metagenomics and metatranscriptomics revealed far superior richness of information of not just microbial structure, but also potential (through metagenomics) and expressed function (through metatranscriptimics) within the complex activated sludge processes. Via independent analysis of whole-DNA and whole-RNA, the entire microbial community and its in situ active members, involved in nitrificaiton and denitrification, were compared. Active nitrifiers and denitrifiers obtained by RNA analysis exhibited relatively high abundances in DNA-derived communities. Further gene expression annotation on nitrogen removal revealed that the expressions of denitrification-related genes except nos were increased under anoxic conditions relative to aerobic conditions, while the expressions of nitrifying genes were decreased. Our findings led to an improved understanding of metabolic activities and roles of BNR microbial communities, and offer the first metatranscriptional insights on engineered nutrient removal in anoxic conditions relative to aerobic conditions in full-scale wastewater systems. In sum, next-generation sequencing as well as traditional molecular techniques shed light on microbial diversity and different functional genes in varying engineered BNR systems. Furthermore, this dissertation provides a wealth of knowledge on systematic explorations of the linkage between structure and function of BNR communities, and offers engineering applications to BNR processes including energy and resource efficient engineered systems. It is expected that the implementation and further expansion of this work will improve the design and operation of engineered BNR processes, eventually producing benefits for the global population and the environment.
215

Study of Inclusion Removal in a Gas-stirred Ladle

Wenjie Liu (5930981) 16 January 2019 (has links)
<p>Steel refining via ladle treatment is critical to final product quality in the steel manufacturing process. The process of ladle refining serves to assist in the removal of non-metallic inclusions, which can impact steel product fatigue strength, impact toughness, and corrosion resistance. While the steelmaking industry has in place best practices for the process, it remains costly to performing trial and error testing on the ladle. In addition, an understanding of the flow phenomena within the ladle during operation can provide industry with key knowledge necessary to improve the efficiency and throughput of the process.</p> <p> </p> <p>The method by which this research aims to address this is through the development of a comprehensive computational fluid dynamics (CFD) model of the steelmaking ladle. Such a model, capable of predicting the inclusion removal process and flow patterns within the ladle, would serve to provide the necessary information to advance steelmaking efficiency and improve product quality. A full scale unsteady state three dimensional CFD model has been developed to predict removal of inclusion during gas-stirring in a ladle. The Eulerian-Eulerian model was used to simulate the multiphase flow, the Population Balanced Model (PBM) has been used to describe the inclusion distribution. The phenomena of bottom-blow argon bubble coalescence and breakup were considered. </p> <p> </p> <p>Additionally, a model has been developed to predict inclusion removal during operation. For the inclusion removal model, the CFD-PBM coupled method has been proposed to investigate the inclusion behavior. This includes representing phenomena such as inclusion-bubble collision, inclusion removal by attachment to the ladle refractory, and inclusion capture by slag floating on the surface of the melt. The unified computational model for simulation of fluid flow and inclusion removal was validated against industry measurements provided by Nucor Steel. </p> <p> </p> <p>Using this CFD model and a ladle geometry and set of baseline conditions provided by Nucor Steel, studies were carried out to examine flow development, gas bubble distribution, and inclusion removal. Examining the impacts of inclusion size on removal rate indicated that larger inclusions are removed faster. This agreed with both industry expectations and data found in published literature. In addition, the model predicts that bubble-inclusion collision are primarily responsible for 99% inclusion removal in a gas-stirred ladle.</p>
216

Caracterização do fruto de cambuci (Campomanesia phaea O. Berg.) e efeito da destanização sobre o potencial funcional in vitro / Characterization of the cambuci fruit (Campomanesia phaea O. Berg.) and deastringency effect on the in vitro functional potential

Sanches, Maria Cecilia Rocha 10 June 2013 (has links)
A espécie Campomanesia phaea (O. Berg.) Landrum é popularmente conhecida como \"cambuci\". É uma das diversas espécies brasileiras de Myrtaceae com fruto comestível e ocorre nos estados de Minas Gerais e São Paulo, principalmente na Serra do Mar. Os frutos possuem intenso aroma agradável e são importantes fontes de compostos fenólicos. Apesar do excelente sabor e aroma do cambuci, a alta adstringência dos frutos, devido ao elevado conteúdo de taninos, reduz a sua aceitabilidade e aplicabilidade na indústria alimentícia. Uma maneira eficaz para remoção da adstringência é submeter o fruto a um processo de destanização, tal como atualmente utilizado para o caqui. O objetivo deste trabalho foi avaliar a variabilidade dos frutos provenientes de uma mesma região e de diferentes regiões, caracterizar frutos em diferentes estádios de maturação, avaliar a eficiência de tratamentos de destanização e determinar o efeito da destanização sobre o potencial funcional, através da determinação do teor e perfil de compostos fenólicos, capacidade antioxidante in vitro e inibição das enzimas do metabolismo de carboidratos. Os tratamentos testados foram: câmaras de etileno, câmara de etanol, ambiente anóxico, etanol no cálice e imersão em etanol. Os resultados mostram que frutos de uma mesma localidade apresentam variações no tamanho e na acidez. Frutos de diferentes regiões apresentaram variação significativa nos teores de fenólicos totais, minerais e na capacidade antioxidante. Com a maturação não foi observado grande variação no teor de sólidos solúveis totais e nem na acidez, porém o conteúdo de fenólicos decresce do estádio mais jovem para o mais maduro. Os processos de destanização com vapor e imersão em etanol foram os mais eficientes na redução do conteúdo de taninos, no entanto esses processos reduziram a capacidade antioxidante e a capacidade de inibição das enzimas &#945;-amilase e &#945;-glicosidase dos frutos. / The specie Campomanesia phaea (O. Berg.) Landrum is popularly known as \"cambuci\". It is one of several Brazilian species of Myrtaceae with edible fruit and occurs in the states of Minas Gerais and São Paulo, especially in the mountains of the sea. The fruits have an intense aroma and are important sources of phenolic compounds. Despite the excellent flavor and aroma of cambuci, high astringency of the fruit, due to the high tannin content, reduces its acceptability and applicability in the food industry. An effective way to astringency removal is to submit the fruit to a deastringency process, as currently used for the persimmon. The aim of this study was to evaluate the variability of the fruits from the same region and from different regions, characterize fruits in different maturation stages, evaluate the efficiency of treatments to astringency removal, and determine the effect of astringency removal about the functional potential, by determining the content and profile of phenolic compounds, antioxidant capacity, and in vitro inhibition of enzymes of carbohydrate metabolism. Treatments tested for removing the astringency were: ethylene chamber, ethanol chamber, anoxic environment, ethanol in the cup, and immersion in ethanol. The results showed that fruit in the same locality exhibit variations in size and acidity. Fruits from different regions showed significant variation in levels of total phenolics, minerals and antioxidant capacity. During maturation it was not observed a wide variation in the content of total soluble solids and acidity, but the phenolic content decreased from the younger stage to the more mature stage. The processes of detannization with ethanol steam and dipped in ethanol were the most effective in reducing the tannin content, however these processes led to reduced antioxidant capacity and capacity of inhibition of the enzymes &#945;-amylase and &#945;-glucosidase in fruits.
217

Avaliação do processo de remoção de fármacos e parabenos de esgoto doméstico em sistema de tratamento baseado em lagoas de lemnas / Evaluation of pharmaceutical and parabens removal process from domestic sewage in treatment system based on lemna pond

Anjos, Mariane Luz dos [UNESP] 16 February 2017 (has links)
Submitted by MARIANE LUZ DOS ANJOS null (mluzanjos@bol.com.br) on 2017-03-08T23:18:04Z No. of bitstreams: 1 Avaliação do processo de remoção de fármacos e parabenos de esgoto doméstico em sistema de tratamento baseado em lagoas de lemnas.pdf: 2472000 bytes, checksum: dda052a00851f9fefb87686b3c89414b (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-13T20:52:05Z (GMT) No. of bitstreams: 1 anjos_ml_me_ilha.pdf: 2472000 bytes, checksum: dda052a00851f9fefb87686b3c89414b (MD5) / Made available in DSpace on 2017-03-13T20:52:05Z (GMT). No. of bitstreams: 1 anjos_ml_me_ilha.pdf: 2472000 bytes, checksum: dda052a00851f9fefb87686b3c89414b (MD5) Previous issue date: 2017-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A presença de fármacos e parabenos em esgoto doméstico é uma questão de grande preocupação devido seus efeitos negativos em ecossistemas e na saúde humana. Neste sentido a fitoremediação surge como sendo uma alternativa vantajosa de remoção dos micropoluentes, o baixo custo de implantação e manutenção é um fator atrativo. O presente estudo visa avaliar a capacidade de duas macrófitas aquáticas (Landoltia punctata e Lemna minor.), para remoção de fármacos (Diclofenaco e Naproxeno) e parabenos (Metil e Propil parabeno) do esgoto doméstico. Foram utilizados dois tanques de 3000 mil litros, sendo Tanque A composto por Landoltia punctata e Tanque B , Lemna minor, foram coletadas amostras a cada três dias durante 21 dias nos períodos diurno e vespertino. Os resultados de remoção para os fármacos do Tanque B, em média 0,63 g/L( remoção de 96.70% ) para diclofenaco e 30,60g/L para naproxeno (remoção de 49,29%) respectivamente, enquanto o Tanque A atingiu 3,42g/L para diclofenaco e (remoção de 80,4%) 34,47g/L para naproxeno (remoção de 36,85%). Os resultados para remoções de metilparabeno foi para tanque A (diurno e vespertino) foram de 14,36 e 14,78g/l, (remoção de 90,87% e 90,60%), enquanto o tanque B foi de 16,86 g/L para período diurno ( eficiência de 90,61%), 17,22g/L, e a sua (eficiência de 89,05%) durante o período vespertino. Para propil parabeno houve uma maior remoção para tanque B de 16,18 g/L para (PrPP), ( eficiência de 89,35%), enquanto que para o período vespertino as concentrações foram de 13,97g/L para (PrPP), (eficiência de 90,60%), para o tanque A as concentrações foram em média de saída foi de 59,52g/L para o propilparabeno, e para o período vespertino foi observado uma eficiência média de 73,73%, com uma concentração de 55,10 g/L de (PrPP).Esses resultados destacam a importância das lagoas de polimento de lemna para remoção de fármacos e parabenos. / The presence of pharmaceuticals and parabens in domestic wastewater is a question of great concern, due the negative effects on ecosystems and human health. The phytoremediation appears to be an advantageous alternative to removing the micropollutants, the low cost of implantation and maintenance is an attractive factor. The objective of this study was evaluate the capacity of two macrophytes (Landoltia punctata and Lemna minor), to remove pharmaceuticals (diclofenac and naproxen) and parabens (methyl and propyl paraben) of domestic wastewater. It were used two tanks ( 3000 liters each), tank A was composed with Landoltia punctata and tank B, Lemna minor, samples were collected every three days for 21 days, during the morning and evening periods. The results for the removal of the pharmaceuticals were achieved by tank B were 0.63 ug / L (96.70% removal) to diclofenac and 30,60g / L of naproxen (removal 49,29 %) respectively, while the tank A reached 3,42g / L diclofenac and (80.4% removal) 34,47g / L of naproxen (36.85% removal). The results achieved for removal of parabens higher for methylparaben to the tank A (morning and evening) were 14.36 and 14,78g / L (removal of 90.87% and 90.60%), while tank B was 16.86 ug / L for morning (90.61% efficiency), 17,22g / L, and its (89.05% efficiency) during the afternoon. While for propyl paraben there was a greater removal to tank B 16.18 ug / L (PRPP) (89.35% efficiency), whereas for the evening period concentrations were 13,97g / L for (PRPP), (90,60% efficiency) to the tank A the concentrations were in average of 59,52g / L propylparaben, and the evening period had an average efficiency 73.73%, with a concentration of 55.10 ug / L (PRPP) .These results emphasize the importance of lemna polishing ponds for removal of pharmaceuticals and parabens.
218

Evaluación de la remoción de nitratos y fosfatos a nivel laboratorio por microalgas libres e inmovilizadas para el Tratamiento Terciario de Aguas Residuales Municipales

Ávila Peltroche, José Giovanni Jesús January 2015 (has links)
El presente estudio tuvo como objetivo determinar la capacidad de remoción de nitratos (N-NO3⁻) y fosfatos (PO₄³¯) en Aguas Residuales Municipales (ARM) por microalgas libres e inmovilizadas. Se utilizaron cepas provenientes de los afluentes de la Planta de Recuperación de las Aguas del Río Surco (Lima, Perú) y se evaluó su capacidad de remoción de N-NO3⁻ y PO₄³¯ durante 10 días, a nivel laboratorio, en ARM con tratamiento primario, tanto de forma libre como inmovilizadas en discos de alginato de sodio al 4%. Los cepas obtenidas se identificaron como Chlorella sp y Chlamydomonas sp. Ambas tuvieron un buen crecimiento en ARM, especialmente Chlamydomonas sp, la cual reportó los mayores valores en los parámetros cinéticos de crecimiento. El cultivo de Chlorella sp. libre fue el que registró uno de los valores más altos de porcentaje (71.25%) y tasa de remoción (0.43 mg/l/día) de N-NO3⁻, y los máximos valores de dichos parámetros para PO43- (83.69%; 0.09 mg/l/día), así como para el índice de eficacia (EI) de ambos nutrientes, comparado con los de Chlamydomonas sp. Los cultivos inmovilizados de ambas especies reportaron valores altos de remoción, entre 56% a 67% para N-NO3⁻ y 78% a 81% para PO43-, este último fue removido en 24 horas en la mayoría de los cultivos. La inmovilización fue el principal factor que afectó la capacidad de remoción de nutrientes. Ambas cepas mostraron ser eficientes en la remoción de nutrientes en ARM, especialmente de PO43-, con valores cercanos a los máximos reportados para ambas especies en estudios previos.The aim of this investigation was to determinate the nitrate (N-NO3⁻) and phosphate (PO43-) removal capacity of free and immobilized microalgae in Municipal Wastewater (MW). Strains were isolated from Planta de Recuperación de las Aguas del Río Surco (Lima, Perú) influent. Their N-NO3⁻ and PO43- removal capacity were evaluated during 10 days in MW with primary treatment in batch cultures with free and immobilized cells in 4% sodium alginate discs. Strains were identified as Chlorella sp and Chlamydomonas sp. Both showed good growth in MW, especially Chlamydomonas sp., which reported the highest value of kinetic growth parameters. Free Chlorella sp. culture reported one of the highest values of N-NO3- removal percentage (71.25%) and rate (0.43 mg/l/día), and the maximum values of PO43- removal parameters (83.69%; 0.09 mg/l/día) and efficacy index (EI) for both nutrients compared with Chlamydomonas sp. Immobilized cultures reported high values of nutrient removal, between 56% to 67% for N-NO3⁻ and 78% to 81% for PO43-. In most microalgae cultures, high percentages of PO43- (76-80%) were removed in 24 hours. Method of culture (free or immobilized) was the main factor affecting the nutrient removal capacity. Strains were efficient in nutrient removal in MW, especially for PO43-, with values close to the maximum ones reported for both species in previous studies.
219

Bioleaching of heavy metals from anaerobically digested sewage sludge using isolated indigenous iron- and sulphur-oxidizing bacteria

Chan, Lau Chi 01 January 2001 (has links)
No description available.
220

Otimização de processos de precipitação química na remoção de fósforo de esgotos sanitários mediante a utilização de sais de ferro como coagulante. / Chemical precipitation optimization of phosphorus from domestic wastewater with a ferric salts as coagulant.

Fernanda Ferrari Gualberto 25 May 2009 (has links)
A presente pesquisa teve como objetivo a otimização de processos de precipitação química na remoção de fósforo de esgotos sanitários mediante a utilização de sais de ferro como coagulante. Analisou-se a remoção de matéria orgânica e produção de lodo obtidas. O trabalho foi desenvolvido com efluentes provenientes de duas estações de tratamento da SABESP, sendo elas a ETE Barueri lodos ativados convencional e ETE Ribeirão Pires tratamento anaeróbio com reatores UASB. Os ensaios de Jar-Test foram conduzidos em laboratório e o coagulante utilizado foi o cloreto férrico. Os resultados obtidos demonstram que a dosagem do coagulante, em ambos os efluentes estudados, resulta na remoção de fósforo total a valores inferiores a 1 mg/L. As dosagens de coagulante necessárias foram de 80 mg/L para a ETE Barueri e 60 mg/L para a ETE Ribeirão Pires. A remoção de carga orgânica também foi alcançada e valores de DBO5,20 inferiores a 10 mg/L são obtidos com dosagens inferiores às necessárias para a remoção de fósforo. A dosagem de coagulante necessária para a remoção de DBO5,20 a valores inferiores a 10 mg/L foi de 40 mg/L. A produção de lodo é o principal problema encontrado quando se utiliza precipitação química, a quantidade de lodo produzida é significativa e deve ser levada em consideração no dimensionamento do sistema de tratamento e disposição final. Incrementos na produção de lodo da ordem de 113% foram obtidos para a ETE Barueri e 51% para a ETE Ribeirão Pires quando foram consideradas as dosagens de coagulante necessárias a remoção de fósforo totais a valores inferiores a 1 mg/L. / The aim of the present study was the chemical precipitation optimization of phosphorus from domestic wastewater with a ferric salt as coagulant. The organic matter removal and the sludge production obtained were analyzed. The study was developed with effluents from two wastewater plants from SABESP, such as ETE Barueri conventional activated sludge and ETE Ribeirão Pires anaerobic treatment with UASB reactors. Jar-Test tests were done in laboratory and the coagulant used was the ferric chloride. The results show that the coagulant dosage, in both effluents studied, results in a total phosphorus removal to values lower than 1 mg/L. The necessary coagulant dosages were 80 mg/L to ETE Barueri and 60 mg/L to ETE Ribeirão Pires. The organic matter removal also was obtained and values of BOD lower than 10 mg/L are obtained to lower dosages than the necessary dosage to phosphorus removal. The necessary coagulant dosage to BOD removal to values lower than 10 mg/L was 40 mg/L. The sludge production is the main problem when chemical precipitation is used, the amount of sludge produced is significant and must be taken into consideration in the system project of treatment and final disposal. Increases in the sludge production were around 113% to ETE Barueri and 51% to ETE Ribeirão Pires when the necessary coagulants dosages were considered to total phosphorus removal to values lower than 1 mg/L.

Page generated in 0.0339 seconds