TThe objective of the current study was to investigate the backwashing behavior of granular media filters used in water treatment under realistic conditions and to develop better models of the backwash process based on both fundamental and practical considerations. The focus of this study was on water only backwash but the applicability of the results to auxiliary backwash systems is discussed. The effects of filter backwash rate, coagulant used, degree of filter clogging and age of filter deposits on backwash behavior and efficiency were investigated in a pilot scale in-line filtration plant treating low turbidity raw water from a large dam. The results of these experiments and their implications both for modeling and managing filter backwash are discussed. The initial stages of backwashing are shown to be dominated by mixing and flow localization effects not accounted for in existing models of backwash. These effects appear to be dependent on both the equipment and the experimental conditions making the development of an accurate model of transient backwash behavior extremely difficult. However, it is shown that the overall efficiency of backwash can be predicted based on data about the filter and backwash design and operation that should be available at any treatment plant. This is an important first step in the development of modeling tool for the design and optimization of the complete filter cycle. A significant finding of this study was that the average age of filter deposits is one of the most important factors determining the ease with which they are detached during backwashing. Deposits become more difficult to remove the longer they remain in the filter. This has important implications for the robust design and operation of filters in applications where optimal backwash cannot be guaranteed. The rate of accumulation of mud in a filter over multiple filter cycles was determined experimentally for one set of backwash conditions and a procedure for estimating the useful life of a filter bed with sub-optimal backwash is proposed.

A bench-scale study was performed to optimize backwash frequency and air sparging conditions during ultrafiltration (UF) of natural surface waters in order to maximize water production and minimize irreversible fouling as well as operating and maintenance costs. Surface shear stress representing different air sparging conditions (continuous coarse bubble, discontinuous coarse bubble, and large pulse bubble sparging) was applied in combination with various backwash frequencies (0.5, 2 and 6 h) and fouling was assessed. Results indicated that air sparging with discontinuous coarse bubbles or large pulse bubbles significantly reduced the irreversible fouling rate while providing cost savings when compared to the baseline condition, which assumed a 0.5 h-backwash frequency and no air sparging during filtration. Cost savings were more pronounced at lower backwash frequencies, due to value associated with extra water produced over longer filtration times and longer membrane life resulted from fewer recovery chemical cleans because of lower irreversible fouling.

A bench-scale study was performed to optimize backwash frequency and air sparging conditions during ultrafiltration (UF) of natural surface waters in order to maximize water production and minimize irreversible fouling as well as operating and maintenance costs. Surface shear stress representing different air sparging conditions (continuous coarse bubble, discontinuous coarse bubble, and large pulse bubble sparging) was applied in combination with various backwash frequencies (0.5, 2 and 6 h) and fouling was assessed. Results indicated that air sparging with discontinuous coarse bubbles or large pulse bubbles significantly reduced the irreversible fouling rate while providing cost savings when compared to the baseline condition, which assumed a 0.5 h-backwash frequency and no air sparging during filtration. Cost savings were more pronounced at lower backwash frequencies, due to value associated with extra water produced over longer filtration times and longer membrane life resulted from fewer recovery chemical cleans because of lower irreversible fouling.

Filter-to-waste infrastructure is now commonly incorporated in recently constructed treatment plants and is required by many jurisdictions, including the Nova Scotia Standard for Surface Water Treatment. In the absence of filter-to-waste, operational backwash procedures, such as filter resting, decreased backwash duration, and extended terminal subfluidization wash (ETSW), have shown promise for decreasing ripening time and intensity. Halifax Water’s J.D. Kline Water Supply Plant (JDKWSP) is not equipped with filter-to-waste. Due to the high cost associated with implementing this infrastructure an assessment of filter ripening was performed at this facility to determine if filter-to-waste was needed. The assessment consisted of four studies, including microbial monitoring during filter ripening, testing backwash procedural concepts and backwash water chemistry concepts, and an analysis of the current full-scale procedure.

Examensarbetets målsättning var att studera de materialrörelser som uppkommer i direkt anslutning till stranden genom påverkan av fartygsvågor. Intressant var just att studera sådant material som Daleke et al (1989) finner en överensstämmelse med – mellan sina iakttagelser och en felaktig version av Hjulströmskurvan – men även annat material skulle studeras. Arbetet utfördes i Furusundsleden och i farleden vid Lidingö där trafiken av Finlandsfärjor är tät.I farleder som till vattenvolym är begränsade uppstår kraftiga vattenrörelser, sugeffekter förutom de vanliga svallvågor som bryter mot stranden. Dessa båda typer av vattenrörelser påverkar materialet längs stränderna. / The target for this master thesis was to study the movements of material that appears in direct connection to the shore as a result of ship wave influence. Of specific interest was to study the type of material that Daleke et al (1989) finds a compliance with – between their observations and an erroneous version of the Hjulström diagram – but also other material should be studied. The field work was performed in Furusundsleden fairway and in the fairway adjacent to Lidingö, where the Finland-ferry traffic is dense.In fairways such as this where the volume of water is confined there is a creation of powerful water movements, drawdowns, aside from the common ship backwash waves. Both these types of water movements affect the material along the shore.

Vi som har skrivit det här examensarbetet har gjort en intervjustudie med fyra engelsklärare på gymnasiet och fyra lärare i matematik på högstadiet. Det vi ville undersöka är vilken inverkan dessa lärare upplever att de nationella proven i engelska och matematik har på deras planering och genomförande av undervisningen under kursen respektive läsåret. Eftersom vår metod har varit kvalitativ med semistrukturerade intervjuer, valde vi att analysera våra resultat med hjälp av fenomenografisk teori. Utifrån våra intervjusvar kunde vi urskilja fem kategorier. Dessa kategorier var att de nationella proven ger extra stress för eleverna, den andra att de tar en hel del tid från lärarna både vid planering, genomförande och efterarbete, t.ex. rättning. Vidare fann vi som en tredje kategori att lärarna såg en fördel med proven i och med att de får en bekräftelse på den kunskapsnivå de redan sett hos eleven. Det framkom även som en fjärde kategori att lärarna vi intervjuade tränar och förbereder eleverna på de nationella proven, dock på olika sätt, och som den femte kategorin att efterarbetet ser olika ut, där lärarna oftast försöker hinna med någon sista komplettering. Vi reflekterade över hur likvärdiga resultaten av nationella proven egentligen blir med tanke på hur det varierar i de olika lärarnas sätt att förbereda och träna eleverna till de nationella proven.

The biomass from a pilot-scale two-stage (carbon oxidation first stage, ammonia oxidation second stage) fixed-film biological aerated filter (BAF) was divided in three fractions depending on their attachment strength to the media: detached, easily detachable and strongly attached. VSS measurement showed that the detached and easily detachable fractions accounted for 25 to 40% of the biomass in the bed and are present even after backwash. Protein was the major constituent of all fractions of the biomass. The ratio of carbohydrate to protein differed between fractions and between type of biofilms, with a larger value for detached and detachable fractions and a lower value for a largely heterotrophic biofilm, implying a difference in the composition of the biomass matrix that could be related to the attachment state of the biomass. The biomass did not appear to be substrate-limited anywhere in the system, although the specific activity of the biomass was dependent upon the position in the column. Activity of the strongly attached biomass was less than 70% of the total activity, even after backwash. A mass balance on VSS showed that the backwash flushed a mass equivalent to less than 35% to 45% of the detached and detachable fractions, which was less than 15% of the total biomass present in the system. Data also suggested that during backwash, part of the strongly attached biomass was sheared off the media and regenerated the mass of biomass in the detached phase. In conclusion, it can be stated that a non-negligible part of the biomass in a BAF is in a detached state. Actual mechanistic BAF models based solely on biofilm modeling may be overlooking the role of that biomass, especially in the performance recovery of BAF systems after backwash. / Master of Science

Esta tesis explica com mejorar la eficiencia del proceso de ultrafiltración en la desalinización de agua de mar. Esto se consigue optimizando diferentes procesos de limpieza como los contralavados y las limpiezas químicas mejoradas. Para conseguirlo se siguen diferentes estrategias como reducir el número de pasos de los contralavados, reducir la frecuencia de los contralavados, usar salmorra proveniente del concentrado de osmosis y reducir el consumo de químicos. Se propone una nueva metodología para analizar los ciclos de limpieza mediante la modelización del proceso. Diferentes tipos de fibra son analizados mediante su permeabilidad y tolerancia a la suciedad. Se presenta una nueva metodología para prevenir la cloración de las membranas de osmosis inversa causadas por las limpiezas químicas mejoradas que se llevan a cabo aguas arriba. Todos los descubrimientos son validados con datos obtenidos de plantas reales. Estas mejoras aumentan la eficiencia del proceso hasta al 98% y reducen el coste de operación de la ultrafiltración en un 7%. / This thesis gives an overview on how to improve efficiency of the ultrafiltration filtration process in seawater desalination. This is achieved by optimizing different cleaning processes such as the backwash and the chemical enhanced backwash. Key success factors rely on reducing the number of backwash steps, improving the backwash frequency, using reverse osmosis brine for backwashing and reducing the chemical consumption. A new methodology to analyze these cleanings cycles is proposed through modeling the process. Different fibers types are also analyzed according to its permeability and its fouling tolerance. A methodology to prevent reverse osmosis chlorination from upstream chemical enhanced backwash cleaning is presented. All the findings are validated through real plant operating data. The proposed improvements increase the process efficiency to 98% and lead to a 7% cost reduction in the ultrafiltration process.

Orientador: Matilde Virginia Ricardi Scaramucci / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-08T02:44:45Z (GMT). No. of bitstreams: 1 Retorta_MiriamSester_D.pdf: 14612163 bytes, checksum: f7fefea3ecb78986aa1456e541123b87 (MD5) Previous issue date: 2007 / Resumo: Este trabalho visa investigar se a prova de língua inglesa do vestibular da Universidade Federal do Paraná causa efeitos retroativos no ensino dessa língua, em escolas públicas e privadas de nível médio e cursos pré-vestibulares, e, em caso positivo, determinar quais são esses efeitos. Para atingir tais objetivos, foi desenvolvida uma pesquisa qualitativa interpretativista de cunho etnográfico, na qual puderam ser ouvidas diversas vozes da comunidade escolar: escolas públicas (urbanas e rurais) e particulares, bem como cursos pré-vestibulares (particulares e gratuitos). Na busca de multiperspectivas sobre o fenômeno, procurou-se escolher os cenários que levassem em conta a grande desigualdade social do país, e incluíssem, como participantes, a maioria dos stakeholders (pessoas ligadas ao fenômeno direta ou indiretamente) para, ao final, triangularem-se os dados coletados. Além de entrevistas dos participantes, aulas de professores também foram observadas. Os resultados deste estudo mostram que o efeito retroativo da prova de inglês do vestibular da UFPR não ocorre nas escolas públicas. O que direciona o ensino desses cenários são os livros didáticos que cada escola adota. No entanto, pudemos perceber a existência do efeito retroativo nos outros cenários ¿ escolas particulares e cursos pré-vestibulares ¿, ora exercendo efeitos positivos (motivação dos diretores e professores para buscar informações sobre o exame; motivação dos alunos para estudar mais a disciplina e passar no exame; direcionamento de ementas e construção de objetivos claros; incentivo ao ensino da leitura), ora negativos (estreitamento do currículo; ansiedade dos sujeitos dos cenários). Verificou-se também que o efeito retroativo ocorreu aí em intensidades diferentes, pois interferiram no fenômeno fatores como: informações que os professores tinham sobre o exame; concepções de língua, leitura e avaliação desses professores; nível de conhecimento de língua inglesa desses profissionais; cobrança dos diretores e do grupo social (os pais e alunos); chances de aprovação, dentre outros. O que direcionou o ensino desses cenários foi o programa oficial do exame de vestibular da UFPR. Este estudo oferece contribuições teóricas ao proporcionar melhor entendimento do conceito efeito retroativo; contribuições metodológicas, por seu desenho investigativo inovador e abrangente; e, finalmente, contribuições práticas, enquanto um conjunto de subsídios para o ensino e avaliação de língua inglesa no ensino médio / Abstract: The objective of this thesis is to investigate if the English test of the University Entrance Examination of UFPR sets off the washback effect in the teaching/learning of the language in public and private high schools as well as cramming courses and, if so, what effects were they. In order to meet these objectives a qualitative interpretativist investigation was conducted in which various voices of the school community were heard such as the participants of public schools (urban and rural), the private schools and the cramming courses (private and free ones). Since there was an intention of having a multiperspective of the phenomenon, the scenarios were chosen because of the great social inequalities of this country and, therefore, many stakeholders (participants who were directly or indirectly involved in the phenomenon) were selected to be interviewed. The data was triangulated, analyzed and discussed. Besides the interview, class observations were included. The results of this study show that there was no washback effect of the English test of the University Entrance Examination of UFPR in public schools. What helped set the teaching goals of the discipline were the contents suggested in the didactic books adopted in each school. In the other scenarios, the washback effect was observed. The positive effects were the motivation of the directors and teachers to search for information about the test; motivation of the students to study harder to pass the test; the test was used to set clear teaching objectives and reading began to be taught. The negative effects were: anxiety of the participants of some scenarios and curriculum narrowing. Different intensities of the washback effect were observed because there were other factors which interfered in the phenomenon such as information teachers had about the test, their concept of language, reading and evaluation, their knowledge of the English language, the directors demanding for the teachers¿ best, the social group (parents and students) demanding for the teachers¿ best and the chances the students had in being approved, among others. The official program of the test was used to guide the teaching/learning of these scenarios. This study offers a theoretical contribution when it helps us understand a bit more about the washback effect; methodological contribution due to the research design which is innovative and broad and, finally, a practical contribution because it intends to offer a set of information which can give support to the teaching and evaluation of the English discipline in high schools / Doutorado / Lingua Estrangeira / Doutor em Linguística Aplicada

Membrane desalination has become one of the most important desalination technologies used in the world. It provides high water quality for numerous applications and it demonstrates excellent desalination efficiency. One of the most troubling drawbacks of membrane desalination is membrane fouling. It decreases the performance of the membranes and increases the energy requirement. Two of the most important causes of fouling are microbes and organic matter. Hence, to maintain an optimized desalination performance, routine inspection of microbial and organic contents of water is crucial for desalination plants. In this study, water samples were obtained from different treatment points in an ultrafiltration (UF)/nanofiltration (NF) seawater desalination pilot plant. This was performed to better understand how the water quality changes along the desalination scheme. The effect of fouling control techniques, including Chemically Enhanced Backwash (CEB), Cleaning in Place (CIP), and the addition of a biocide (DBNPA) was studied. Different analytical tools were applied, including Bactiquant, Total Organic Carbon (TOC), Assimilable Organic Carbon (AOC), and Liquid Chromatography for Organic Carbon Detection (LC-OCD). Out results showed that UF did not decrease TOC but it was sufficient in removing up to 99.7% of bacteria. Nanofiltration, removed up to 95% of TOC. However, NF permeate had a high increase in AOC as compared to the raw seawater sample. The LC-OCD results suggested that this might be due to the increased low molecular weight neutrals which were the most common organic species in the NF permeate. The fouling control techniques showed various effects on the desalination efficiency. Daily CEB did not cause a reduction in TOC or bacteria but decreased AOC in the UF filtrate. The biocide addition resulted in an adequate membranes protection from fouling and it did not affect the investigated water parameters. When the dosing of biocide was stopped, the water quality parameters did not change, but the NF pressure drop increased rapidly, indicating fouling of this membrane. CIP did not show an impact on the organic and microbial contents of water, but it was efficient in restoring the operations back to acceptable pressure levels. These results indicated that the applied fouling protection techniques were beneficial in fouling control.