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<p>The World Health Organization reports 9% of the world’s population lack access to an improved drinking water source. Safe drinking water is a major global challenge, especially in rural areas where according to UNICEF 80% of those without access to improved water systems reside. While water, sanitation, and hygiene (WASH) related diseases and deaths are common outcomes of unsafe water, there is also an economic burden associated with unsafe water. These burdens are most prominent in rural areas in less developed nations. Slow sand filters (SSFs), or biological sand filters (BSF), are ideal water treatment solutions for these low resource regions. SSFs are the oldest municipal drinking water treatment system and improve water quality by removing suspended particles, dissolved organic chemicals, and other contaminants, effectively reducing turbidity and associated taste and odor problems. Removal of turbidity from the water enables the use of low-cost disinfection methods such as chlorination. While the working principles of slow sand filtration remained the same, the design, sizes and application of slow sand filters have been customized over the years. The first chapter of thesis reviews these adaptations and their performance on contaminant removal, and specifically addresses engineering aspects of slow sand filters that are not widely understood, even by those that implement SSFs in the field.</p> <p>The second and third chapters detail an SSF-based water treatment and monitoring system that seeks to provide portable water to rural schools and communities. Piping drinking water to remote rural areas from centralized treatment facilities requires huge capital investments. On the other hand, delivering drinking water by the less expensive point‐of‐use technologies often results in improper operation, and lack of proper documentation on water quality and usage.</p> <p><br></p> <p>The strategy documented in this research for addressing this problem is to produce drinking water at the point-of-use, and then establish and document drinking water quality through cellphone-based monitoring of this water. By doing both (point-of-use treatment and cellphone-based monitoring), we are effectively using to advantage the best of both worlds. Decentralized (point-of-use) water treatment systems can be deployed in rural communities to produce potable water. Integrating a cellphone-enabled colorimeter-turbidity meter (CT meter), developed as part of this research, into the water treatment system will provides water quality data to ensure public health safety. The integrated water system included slow sand filtration, chlorination, and phone-based monitoring (i.e., the CT meter). To establish larger-scale (thousands of schools) feasibility, pilot treatment systems were established in 3 rural schools in Kenya. This pilot network was established through the collaborative efforts of: (i) The research team at Purdue, (ii) MaJi Safi International (MSI), a Purdue related startup based in Eldoret, Kenya, and (iii) several western Kenya Schools.</p> <p><br></p> <p>The second chapter of details the design and testing of the CT meter at Purdue. The third chapter evaluates, through pilot field tests in Kenyan schools, the integrated water treatment and monitoring system for economic and technical viability. The CT meter performance was successful both in the lab and in the field. The water systems that were installed, used daily, and monitored with the CT meter, consistently produced portable water that met the local regulatory drinking water standards.</p>

O presente trabalho avaliou o desempenho de filtros de areia biológicos no tratamento da água do mar a fim de controlar a formação de biofilmes microbianos em membranas de osmose reversa, utilizadas para o processo de dessalinização, e posteriormente em tanques de cultivo de peixes. Para isto, proteínas e carboidratos (principais componentes de biofilmes) foram quantificados em corpos de prova expostos à diferentes tratamentos. A água produzida pelos tratamentos também foi avaliada por meio da quantificação de microrganismos e teor de carbono orgânico assimilável (AOC), que está associado ao potencial de crescimento microbiano (PCM). A capacidade dos filtros em reduzir turbidez e SDI a partir da água captada no mar, também constituiu um parâmetro de avaliação. A partir dos dados obtidos foi possível verificar que os sistemas de tratamento da água do mar constituídos por filtros lentos de areia são capazes de reduzir a incidência de biofilmes em membranas de osmose reversa (reduzindo em até cerca de 80% a concentração de proteínas e 88% a de carboidratos). Porém, para que se tenha uma taxa significativa de remoção do AOC e redução do PCM, esses sistemas requerem um tempo de maturação entre 50 e 60 dias. Por outro lado, em termos de redução de turbidez e SDI, esses sistemas demonstram eficiência praticamente imediata, resultando em uma água com turbidez sempre menor que 0.3 UNT e SDI sempre menor que 4. Como forma de tratamento de água do mar para sistemas de aquicultura, os filtros lentos de areia demonstraram capacidade em reduzir a formação de biofilmes e a deposição de material particulado dentro dos tanques de cultivo, sendo esta redução mais evidente no fundo dos tanques e na observação realizada após 31 dias. O uso de filtros de areia para o tratamento da água utilizada no cultivo de peixes pode contribuir para redução da frequência de manejo e limpeza de tanques. / The present work has evaluated the performance of biological sand filters in seawater treatment in order to control microbial biofilms formation in reverse osmosis membranes used for the desalination process. The same filters were also evaluated as a seawater treatment system for aquaculture, and the performance in biofilms control inside the fish tanks was verified. To evaluate the performance in terms of biofilms control, proteins and carbohydrates (main components of biofilms) were quantified in specimens exposed to different treatments. The water produced by the treatments was also evaluated by microorganisms concentration and assimilable organic carbon content, which is associated with microbial growth potential. The performance of turbidity removal and SDI reduction from raw water was also an evaluation parameter. From the data obtained, it was observed that seawater treatment systems by of slow sand filters are able to reduce reverse osmosis membranes biofilms (up to 80% proteins concentration and 88% carbohydrate concentration). However, in order to have a significant rate of AOC removal and PCM reduction, these systems need a maturation time between 50 and 60 days. On the other hand, in terms of turbidity removal and SDI reduction, these systems demonstrate immediate efficiency, resulting in water turbidity always less than 0.3 NTU and SDI always less than 4. The slow sand filters showed efficience to reduce the biofilm formation and material deposition inside the fish tanks, this reduction was more evident at the bottom of the tanks and after 31 days. The use of sand filters as a water treatment for fish farming can contribute to reduce the number of procedures for handling and cleaning tanks.

Made available in DSpace on 2014-07-29T15:01:50Z (GMT). No. of bitstreams: 1 Dissertacao - parte 1.pdf: 89652 bytes, checksum: 199b51d4bc46d91c1268d2961517e29e (MD5) Previous issue date: 2009-08-17 / This work presents an evaluation of the performance of a multi-stage filtration system (FiME) in pilot-plant scale to treat surface water from the Ribeirão Sozinha stream which supplies the city of Goianápolis-GO, Brazil. The arrangement of the installation used in this study consisted of a dynamic roughing filter (PFD), a up-flow roughing filter (PFA) and two slow sand filters, being one with sand (FLA) and the other with sand and granular activated carbon (FLACAG). The filtration rates varied from 24 to 48 m3/m2.d in the PFD, 12 to 18 m3/m2.d in the PFA, and 3 to 4 m3/m2.d in the FLA and FLACAG. The performance of each unit was evaluated for removal of color, turbidity, total iron, suspended solids, oxygen consumption, total coliforms and E.coli, and the development of headloss. Results showed that the PFD and PFA are important units in the preparation of affluent water to the slow sand filters, allowing relatively long filtration runs resulted from the removal of larger particles by these units, reducing significantly the turbidity of raw water. The slow sand filters presented larger than 90% of removal efficiency of color, turbidity, suspended solids and total iron, removal over 80% of consumed oxygen and above 95% for coliforms removal. Overall, the slow sand filters showed satisfactory performance in removing turbidity, iron and total coliforms. In particular, the slow sand filter with sand and granular activated carbon layers was more efficient in removing true color and consumed oxygen than the filter with single sand layer. Although peaks of color and turbidity during the fourth and last filtration runs, the FiME system proved to be efficient in removing total coliforms and E.coli in the last three weeks of operation. In the last filtration run, a comparison of the effluent water quality between the FiME system and a conventional full scale treatment plant was carried out for the removal of turbidity and color. Results showed that the FiME system produced similar water quality to the conventional treatment plant when turbidity was < 1,0. In general, results suggest that the FiME is an effective system to produce water quality from surface water with high levels of total coliforms and E.coli and peaks of color and turbidity according to the recommendations of the Portaria 518/2004 of the Ministry of Health, Brazil / Este trabalho apresenta uma avaliação do desempenho de um sistema de Filtração em Múltiplas Etapas (FiME), em escala piloto, no tratamento da água bruta retirada do manancial superficial (Ribeirão Sozinha) que abastece a cidade de Goianápolis-GO. O arranjo da instalação utilizado nessa pesquisa constituiu de 1 pré-filtro dinâmico (PFD), 1 pré-filtro ascendente (PFA) e 2 filtros lentos, sendo um com areia (FLA) e outro com areia e carvão ativado granular (FLACAG). As taxas de filtração utilizadas foram de 24, 48, 24 e 24 m3/m2.d para o PFD; 12, 18, 12 e 12 m3/m2.d para o PFA; e 3, 4, 3 e 3 m3/m2.d para o FLA e FLACAG. O desempenho de cada unidade foi avaliado quanto à remoção de cor, turbidez, ferro total, sólidos suspensos, oxigênio consumido, coliformes totais e termotolerantes, e o desenvolvimento da perda de carga. Os resultados obtidos demonstraram que o PFD e o PFA são unidades importantes na preparação da água afluente aos filtros lentos, possibilitando carreiras relativamente longas em função da retenção de partículas maiores, diminuindo consideravelmente a turbidez da água bruta. Os filtros lentos apresentaram eficiência superior a 90% na remoção de cor, turbidez, sólidos suspensos e ferro total, remoção de oxigênio consumido superior a 80% e de coliformes acima de 95%. Na última carreira de filtração foi realizada uma comparação da qualidade da água produzida pela tecnologia da FiME com a ETA de ciclo completo, na remoção de cor e turbidez, comprovando que a qualidade da água produzida na FiME é compatível com a qualidade da água produzida pela tecnologia de ciclo completo. De maneira geral, os filtros lentos apresentaram rendimento satisfatório na remoção de turbidez, ferro total e coliformes, sendo que o filtro lento com camada intermediária de carvão ativado granular foi mais eficiente na remoção de cor verdadeira e oxigênio consumido do que os filtro lento com camada simples de areia. Embora tenha ocorrido picos de cor e turbidez durante a quarta e última carreira de filtração, o sistema FiME mostrou-se eficiente na remoção de coliformes totais e termotolerantes nas três últimas semanas de operação. A verificação da existência de correlação na remoção de cor, turbidez, sólidos suspensos, oxigênio consumido, coliformes totais e termotolerantes, demonstrou a existência de uma boa correlação na remoção dos parâmetros cor e turbidez nos efluentes dos filtros lentos, apresentando um coeficiente de correlação igual a 0,92. Os resultados obtidos sugerem que o sistema FiME é eficiente no tratamento de águas superficiais com elevados teores de coliformes totais e termotolerantes e com picos de cor e turbidez, produzindo, quando operado adequadamente, água com baixos teores de cor, turbidez e bactérias do grupo coliforme, atendendo as recomendações da Portaria 518/2004 do Ministério da Saúde, evidenciando a viabilidade de aplicação dessa tecnologia na produção de água para consumo humano