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An evaluation of BioSand Filters, a method of Household Water Treatment, was conducted in Posoltega, Nicaragua, with objectives of determining the long-term filtration efficiency and the rate of sustained use. Field methods included microbial and turbidity water quality testing and interviews with filter users regarding the operation, maintenance and perceptions towards the filters. Of the 234 BioSand Filters installed in 1999 and 2004, only 24 were found to still be in operation. The average filtration efficiency was found to be 98% for total coliforms, 96% for E. coli and 88% for turbidity. Statistically significant effects on filtration efficiency were detected for the source contamination, the inverse of the flow rate, and the standing depth of water over the sand. A follow-up laboratory QA/QC procedure was undertaken to validate the field methods, which consisted of membrane filtration (MF) with m coliBlue24 growth media, and SolarCult dipslides. It was found that MF with m coliBlue24 produced useful reproducible results, and is an appropriate method for conducting field water quality testing. The dipslides were found to be an appropriate tool for testing source water quality and assessing the applicability of BioSand Filters, and may be an appropriate tool for local health representatives to promote safe water practices within the community. However, the dipslides should not be used as a presence / absence test for drinking water due to the high limit of detection. The low rate of sustained use (10%) is mostly a result of the structural failure of the concrete walls of the filter, in particular for those filters from 2004. Anecdotal evidence suggests insufficient quality control during the construction. The filtered water and the stored post-filtered water did not meet the WHO guidelines for safe drinking water on account of the presence of E. coli. Also identified were improper maintenance practices and unsafe storage of post-filtered water. These problems could have been addressed through the development of a holistic water system approach, such as the World Health Organization Water Safety Plan.

An evaluation of BioSand Filters, a method of Household Water Treatment, was conducted in Posoltega, Nicaragua, with objectives of determining the long-term filtration efficiency and the rate of sustained use. Field methods included microbial and turbidity water quality testing and interviews with filter users regarding the operation, maintenance and perceptions towards the filters. Of the 234 BioSand Filters installed in 1999 and 2004, only 24 were found to still be in operation. The average filtration efficiency was found to be 98% for total coliforms, 96% for E. coli and 88% for turbidity. Statistically significant effects on filtration efficiency were detected for the source contamination, the inverse of the flow rate, and the standing depth of water over the sand. A follow-up laboratory QA/QC procedure was undertaken to validate the field methods, which consisted of membrane filtration (MF) with m coliBlue24 growth media, and SolarCult dipslides. It was found that MF with m coliBlue24 produced useful reproducible results, and is an appropriate method for conducting field water quality testing. The dipslides were found to be an appropriate tool for testing source water quality and assessing the applicability of BioSand Filters, and may be an appropriate tool for local health representatives to promote safe water practices within the community. However, the dipslides should not be used as a presence / absence test for drinking water due to the high limit of detection. The low rate of sustained use (10%) is mostly a result of the structural failure of the concrete walls of the filter, in particular for those filters from 2004. Anecdotal evidence suggests insufficient quality control during the construction. The filtered water and the stored post-filtered water did not meet the WHO guidelines for safe drinking water on account of the presence of E. coli. Also identified were improper maintenance practices and unsafe storage of post-filtered water. These problems could have been addressed through the development of a holistic water system approach, such as the World Health Organization Water Safety Plan.

An evaluation of BioSand Filters, a method of Household Water Treatment, was conducted in Posoltega, Nicaragua, with objectives of determining the long-term filtration efficiency and the rate of sustained use. Field methods included microbial and turbidity water quality testing and interviews with filter users regarding the operation, maintenance and perceptions towards the filters. Of the 234 BioSand Filters installed in 1999 and 2004, only 24 were found to still be in operation. The average filtration efficiency was found to be 98% for total coliforms, 96% for E. coli and 88% for turbidity. Statistically significant effects on filtration efficiency were detected for the source contamination, the inverse of the flow rate, and the standing depth of water over the sand. A follow-up laboratory QA/QC procedure was undertaken to validate the field methods, which consisted of membrane filtration (MF) with m coliBlue24 growth media, and SolarCult dipslides. It was found that MF with m coliBlue24 produced useful reproducible results, and is an appropriate method for conducting field water quality testing. The dipslides were found to be an appropriate tool for testing source water quality and assessing the applicability of BioSand Filters, and may be an appropriate tool for local health representatives to promote safe water practices within the community. However, the dipslides should not be used as a presence / absence test for drinking water due to the high limit of detection. The low rate of sustained use (10%) is mostly a result of the structural failure of the concrete walls of the filter, in particular for those filters from 2004. Anecdotal evidence suggests insufficient quality control during the construction. The filtered water and the stored post-filtered water did not meet the WHO guidelines for safe drinking water on account of the presence of E. coli. Also identified were improper maintenance practices and unsafe storage of post-filtered water. These problems could have been addressed through the development of a holistic water system approach, such as the World Health Organization Water Safety Plan. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

<p>Water and sanitation are two of the world's most urgent current challenges (Elimelech, 2006). With a population racing towards seven billion people, over one sixth of the human population does not have access to adequate water and sanitation. Drinking water is inaccessible for approximately 783 million people living in the developing world (WHO, 2014). This is especially critical for people at risk of exposure to deadly pathogens such as <italic>Vibrio cholerae</italic>, <italic>Shigella</italic>, and <italic>Salmonella</italic>, such as those living in Haiti as <italic>Vibrio cholerae</italic> is now ubiquitous (Enserink, 2010). On the sanitation side, more than 2.5 billion people in the world still lack access to adequate resources (WHO, 2014). Almost half of these people have access to no sanitation facilities at all and practice open defecation (WHO, 2014). Thousands of small children still die every day from preventable diseases caused by inadequate sanitation (WHO, 2014). As global climate change is expected to exacerbate these issues, there is an urgent need for the development of sustainable treatment technologies to ensure a better tomorrow for our world (Ford, 1999). Safe water and sanitation technologies, while often disjointed, should be considered together as pathogens transmitted via drinking water are predominantly of fecal origin (Ashbolt, 2004; Montgomery, 2007). </p><p>In this dissertation project, I explore the use of both drinking water and wastewater treatment technologies which are cost effective and rely on locally available materials in low-income countries. For the drinking water treatment side, I focus on the use of biosand filters in Haiti with a specific interest in understanding their ability to remove the pathogen <italic>Vibrio cholerae</italic>, the causative agent for cholera. The wastewater treatment technology consists of biofilters packed with cocopeat, a waste product generated during coconut husk processing, and I investigate their use for the treatment of septic tank effluent in Vietnam. Both of these projects combine lab and field work. The specific objectives of this dissertation project are to 1) compare the removal efficiency of <italic>V. cholerae</italic> to indicator bacteria in field biosand filters and determine the parameters controlling removal; 2) investigate the correlation between removal efficiency of pathogens in field biosand filters having operated for varying lengths of time to schmutzdecke bacterial composition and influent water characteristics; 3) determine the effect of number of charges, total organic carbon loading, and schmutzdecke composition on <italic>V. cholerae</italic> removal efficacy; 4) isolate the effect of biological removal mechanisms and physical/chemical removal mechanisms on <italic>V. cholerae</italic> removal efficiency and determine the correlation to TOC concentration in water; 5) evaluate cocopeat as a packing medium for biofilters in terms of nitrogen, phosphorus and biological oxygen demand removal from simulated wastewater as compared to other traditional packing media; and 6) conduct an assessment of cocopeat-packed, vertical flow constructed wetlands treating septic tank effluent in the Mekong Delta of Vietnam. </p><p>In the first part of this dissertation, biosand filters in the Artibonite Valley of Haiti, the epicenter of the cholera epidemic, were tested for total coliform and <italic>V. cholerae</italic> removal efficiencies. In addition, schmutzdecke samples were collected in order to measure the amount of EPS in the biofilm, as well as characterize the microbial community. Total coliform and <italic>V. cholerae</italic> concentration were measured using novel membrane filtration technique methods. It was found that total coliform concentration does not indicate <italic>V. cholerae</italic> concentration in water, and total coliform removal efficiency does not indicate <italic>V. cholerae</italic> removal efficiency within biosand filters. Additionally, parameters controlling biosand filter performance include: schmutzdecke composition, time in operation, and idle time.</p><p>In the second part of this dissertation, <italic>V. cholerae</italic> challenge tests were performed on laboratory-operated biosand filters receiving high, medium or low TOC influents in order to determine the effect of number of charges, total organic carbon loading, and schmutzdecke composition on <italic>V. cholerae</italic> removal efficacy, as well as to isolate the effect of biological removal mechanisms and physical/chemical removal mechanisms on <italic>V. cholerae</italic> removal efficiency and determine the correlation to TOC concentration in water. To this end, three biosand filters were operated in the lab. Each received lake water or diluted lake water with high, medium or low concentrations of TOC. After being charged once per day for 6 days, the filters were charged with four consecutive charges of pure cultures of <italic>V. cholerae</italic> suspended in PBS buffer, at concentrations of 10<super>2</super>, 10<super>3</super>, 10<super>5</super>, and 10<super>7</super> cfu/mL. This challenge was repeated each time the filters received an additional 6 charges, up to 66 total charges. This was done to determine how number of charges, TOC loading, and schmutzdecke composition affects removal efficiency. Schmutzdecke was analyzed for amount of EPS and microbial community. It was found that parameters controlling biosand filter performance include: TOC loading, schmutzdecke composition, time in operation, and physical/chemical attachment. Additionally, it was shown that physical/chemical attachment is critical during startup, especially at low TOC concentrations. At steady state, physical/chemical attachment is more important than schmutzdecke effects in filters receiving low TOC, and schmutzdecke effect is more important than physical/chemical attachment in filters receiving high TOC.</p><p>For the third section of this dissertation, columns packed with cocopeat, celite, or sphagnum peat were charged with simulated wastewater and removal efficiencies of nitrogen, phosphorus, and biological oxygen demand were measured. Additionally, different redox zones were tested to determine if cocopeat could successfully accomplish nitrification and denitrification. It was found that cocopeat is comparable to traditional packing media and can successfully accomplish nitrification and denitrification in the treatment of synthetic wastewater.</p><p>In the final section of this dissertation, constructed wetlands were built and packed with cocopeat to determine if cocopeat is a suitable packing media in constructed wetlands treating wastewater in Vietnam. Removal efficiencies of nitrogen, phosphorus, and biological demand were measured. Microbial community samples were collected periodically in order to analyze community shifts between wetlands and over time. This work concluded that cocopeat can be used successfully as a packing media in constructed wetlands treating wastewater for the removal of nitrogen, phosphorus, and total coliform.</p><p>Overall, this dissertation work contributes to the body of knowledge on point-of-use water and wastewater technologies. The biosand filter was studied in both lab and field conditions and it was found that total coliform is not a reliable indicator for <italic>V. cholerae</italic>, and that there are several factors controlling biosand filter performance, including idle time, TOC, filter time in operation, physical/chemical attachment, and schmutzdecke composition. Cocopeat was studied for its ability to promote nitrification and denitrification in lab-scale vertical flow columns treating synthetic wastewater. It was shown that cocopeat achieved similar levels of nitrification and denitrification as traditional packing media. Finally, cocopeat packed vertical flow constructed wetlands were operated in Vietnam for the treatment of septic tank effluent. This setup proved effective for the removal of nitrogen, phosphorus, and total coliform in the treatment of wastewater.</p> / Dissertation

A falta de água potável é um agravo que atinge populações em nível mundial e nacional e as pequenas comunidades isoladas são as que estão mais suscetíveis à essa vulnerabilidade. Essas localidades demandam soluções descentralizadas, como o filtro lento domiciliar (FLD). Nesse contexto, nesta tese propõe-se a construção de FLD com materiais de PVC, de fácil aquisição e montagem simples. Na Fase 1 do trabalho, compararam-se FLDs com regime de fluxo intermitente, com (FI) e sem (FIS) controle do nível da água por boia; e contínuo, com (FC) e sem (FCS) boia, tratando mistura de água subterrânea com caulinita. Analisaram-se turbidez remanescente, redução de Escherichia coli, tempo de amadurecimento e duração das carreiras de filtração para investigar o efeito da boia nos dois regimes. Na Fase 2, estudou-se a aceleração do amadurecimento nos dois regimes, usando como acelerador o pó de cacto Opuntia cochenillifera, tratando água natural. Compararam-se unidades intermitentes com (FIA) e sem (FI) acelerador, e unidades contínuas com (FCA) e sem (FC) acelerador. Nessa fase consideraram-se também a redução de coliformes totais, consumo de oxigênio dissolvido e remoção de cistos de Giardia e oocistos de Cryptosporidium além das variáveis consideradas na Fase 1. Nas duas fases estudaram-se as correlações de variáveis operacionais (taxa de filtração, perda de carga dividida por espessura de meio filtrante, tempo de operação, tempo após a manutenção) com eficiências para redução de bactérias e turbidez remanescente. O custo dos FLDs em PVC foi estimado em cerca de R$ 420,00. Os resultados indicaram que na Fase 1, FI demonstrou maiores carreiras de filtração que FIS, sem diferenças para as outras variáveis. FC apresentou turbidez remanescente média menor que FCS (1,24 ± 0,91 versus 1,90 ± 1,36 NTU). Na Fase 2, FIA apresentou melhor eficiência para redução de E. coli (2,32 ± 0,79 versus 1,936 ± 0,61 log) e menor turbidez remanescente média que FI, entre os contínuos, não houve diferença de eficiências (p.e. 2,51 ± 0,60 e 2,60 ± 0,56 log de E. coli), no entanto, FCA apresentou carreiras de filtração mais curtas que FC (33 ± 13 versus 60 ± 14 dias). A variável perda de carga nos primeiros 2 cm foi a com maior correlação com a redução de bactérias na Fase 1, enquanto que na Fase 2, a redução de bactérias se correlacionou melhor com turbidez remanescente. No estudo sobre de remoção de (oo)cistos de protozoários, 92% de 30 amostras não apresentaram os parasitos, no entanto, em duas amostras detectaram-se a presença de um oocisto de Cryptosporidium. Apesar de elevadas reduções de bactérias por FLDs, não houve amostras filtradas com ausência de coliformes, para tanto, fizeram-se testes com hipoclorito de sódio, que resultaram ausência de bactérias na água tratada. O controle por boia prolongou a carreira de filtração no regime intermitente e melhorou a turbidez filtrada no fluxo contínuo. O uso do acelerador de amadurecimento foi efetivo para eficiências dos FLDs apenas no fluxo intermitente. Dentre os modelos estudados, o FC apresentou melhores resultados em termos de eficiência e duração das carreiras de filtração. / The lack of drinking water is an aggravation affecting populations at the global and national levels and the small and isolated communities are the most susceptible to this vulnerability. These locations require decentralized solutions, such as the household slow sand filter (HSSF). In this context, in the present thesis is proposed the construction of a HSSF with PVC materials, of easy acquisition and simple assemble. In Phase 1 of the study, it was compared HSSFs with intermittent flow regime, with (FI) and without (FIS) water level control by float; and continuous, with (FC) and without (FCS) float, treating groundwater with kaolinite. Remaining turbidity, Escherichia coli reduction, ripening time and filtration run times were investigated to explore the effect of the float in the two regimes. In Phase 2 the acceleration of ripening was studied in both regimes, using as accelerator Opuntia cochenillifera cactus powder, treating natural water. Intermittent units were compared with (FIA) and without (FI) accelerator, and continuous units with (FCA) and without (FC) accelerator. In this phase, the reduction of total coliforms, dissolved oxygen consumption and removal of Giardia cysts and Cryptosporidium oocysts in addition to the variables considered in Phase 1 were also studied. In the two phases it was studied the correlation of operational variables (filtration rate, head loss divided by filter media thickness, time of operation, time after maintenance) with efficiencies for bacterial reduction and remaining turbidity. The cost of FLDs in PVC was estimated at around R$ 420.00. The results indicated that in Phase 1, FI had larger filtration runs than FIS, with no differences for the other variables. FC had turbidity remaining mean lower than FCS (1.24 ± 0.91 versus 1.90 ± 1.36 NTU). In Phase 2, FIA had a better efficiency to reduce E. coli (2.32 ± 0.79 versus 1.936 ± 0.61 log) and lower average remaining turbidity than FI, there were no differences in efficiencies (e.g. 2, 51 ± 0.60 and 2.60 ± 0.56 log of E. coli), however, FCA had shorter filtration runs than FC (33 ± 13 versus 60 ± 14 days). The variable head loss in the first 2 cm was the one with the highest correlation with E. coli reductions in Phase 1, while in Phase 2, the bacterial reduction correlated better with remaining turbidity. In the study on the removal of protozoa (oo)cysts, 92% of 30 samples did not present the parasites, however, in two samples the presence of a Cryptosporidium oocyst was detected. Despite high bacterial reductions by HSSFs, there were no filtered samples with absence of coliforms; therefore, sodium hypochlorite tests were performed, which resulted in no bacteria in the treated water. The float control extended the filtration run in the intermittent regime and improved the turbidity filtered in the continuous stream. The use of the ripening accelerator was effective for FLD efficiencies only in the intermittent flow. Between the studied models of filters, FC was the one with the better results of efficiencies and duration of filters run.

A falta de água potável é um agravo que atinge populações em nível mundial e nacional e as pequenas comunidades isoladas são as que estão mais suscetíveis à essa vulnerabilidade. Essas localidades demandam soluções descentralizadas, como o filtro lento domiciliar (FLD). Nesse contexto, nesta tese propõe-se a construção de FLD com materiais de PVC, de fácil aquisição e montagem simples. Na Fase 1 do trabalho, compararam-se FLDs com regime de fluxo intermitente, com (FI) e sem (FIS) controle do nível da água por boia; e contínuo, com (FC) e sem (FCS) boia, tratando mistura de água subterrânea com caulinita. Analisaram-se turbidez remanescente, redução de Escherichia coli, tempo de amadurecimento e duração das carreiras de filtração para investigar o efeito da boia nos dois regimes. Na Fase 2, estudou-se a aceleração do amadurecimento nos dois regimes, usando como acelerador o pó de cacto Opuntia cochenillifera, tratando água natural. Compararam-se unidades intermitentes com (FIA) e sem (FI) acelerador, e unidades contínuas com (FCA) e sem (FC) acelerador. Nessa fase consideraram-se também a redução de coliformes totais, consumo de oxigênio dissolvido e remoção de cistos de Giardia e oocistos de Cryptosporidium além das variáveis consideradas na Fase 1. Nas duas fases estudaram-se as correlações de variáveis operacionais (taxa de filtração, perda de carga dividida por espessura de meio filtrante, tempo de operação, tempo após a manutenção) com eficiências para redução de bactérias e turbidez remanescente. O custo dos FLDs em PVC foi estimado em cerca de R$ 420,00. Os resultados indicaram que na Fase 1, FI demonstrou maiores carreiras de filtração que FIS, sem diferenças para as outras variáveis. FC apresentou turbidez remanescente média menor que FCS (1,24 ± 0,91 versus 1,90 ± 1,36 NTU). Na Fase 2, FIA apresentou melhor eficiência para redução de E. coli (2,32 ± 0,79 versus 1,936 ± 0,61 log) e menor turbidez remanescente média que FI, entre os contínuos, não houve diferença de eficiências (p.e. 2,51 ± 0,60 e 2,60 ± 0,56 log de E. coli), no entanto, FCA apresentou carreiras de filtração mais curtas que FC (33 ± 13 versus 60 ± 14 dias). A variável perda de carga nos primeiros 2 cm foi a com maior correlação com a redução de bactérias na Fase 1, enquanto que na Fase 2, a redução de bactérias se correlacionou melhor com turbidez remanescente. No estudo sobre de remoção de (oo)cistos de protozoários, 92% de 30 amostras não apresentaram os parasitos, no entanto, em duas amostras detectaram-se a presença de um oocisto de Cryptosporidium. Apesar de elevadas reduções de bactérias por FLDs, não houve amostras filtradas com ausência de coliformes, para tanto, fizeram-se testes com hipoclorito de sódio, que resultaram ausência de bactérias na água tratada. O controle por boia prolongou a carreira de filtração no regime intermitente e melhorou a turbidez filtrada no fluxo contínuo. O uso do acelerador de amadurecimento foi efetivo para eficiências dos FLDs apenas no fluxo intermitente. Dentre os modelos estudados, o FC apresentou melhores resultados em termos de eficiência e duração das carreiras de filtração. / The lack of drinking water is an aggravation affecting populations at the global and national levels and the small and isolated communities are the most susceptible to this vulnerability. These locations require decentralized solutions, such as the household slow sand filter (HSSF). In this context, in the present thesis is proposed the construction of a HSSF with PVC materials, of easy acquisition and simple assemble. In Phase 1 of the study, it was compared HSSFs with intermittent flow regime, with (FI) and without (FIS) water level control by float; and continuous, with (FC) and without (FCS) float, treating groundwater with kaolinite. Remaining turbidity, Escherichia coli reduction, ripening time and filtration run times were investigated to explore the effect of the float in the two regimes. In Phase 2 the acceleration of ripening was studied in both regimes, using as accelerator Opuntia cochenillifera cactus powder, treating natural water. Intermittent units were compared with (FIA) and without (FI) accelerator, and continuous units with (FCA) and without (FC) accelerator. In this phase, the reduction of total coliforms, dissolved oxygen consumption and removal of Giardia cysts and Cryptosporidium oocysts in addition to the variables considered in Phase 1 were also studied. In the two phases it was studied the correlation of operational variables (filtration rate, head loss divided by filter media thickness, time of operation, time after maintenance) with efficiencies for bacterial reduction and remaining turbidity. The cost of FLDs in PVC was estimated at around R$ 420.00. The results indicated that in Phase 1, FI had larger filtration runs than FIS, with no differences for the other variables. FC had turbidity remaining mean lower than FCS (1.24 ± 0.91 versus 1.90 ± 1.36 NTU). In Phase 2, FIA had a better efficiency to reduce E. coli (2.32 ± 0.79 versus 1.936 ± 0.61 log) and lower average remaining turbidity than FI, there were no differences in efficiencies (e.g. 2, 51 ± 0.60 and 2.60 ± 0.56 log of E. coli), however, FCA had shorter filtration runs than FC (33 ± 13 versus 60 ± 14 days). The variable head loss in the first 2 cm was the one with the highest correlation with E. coli reductions in Phase 1, while in Phase 2, the bacterial reduction correlated better with remaining turbidity. In the study on the removal of protozoa (oo)cysts, 92% of 30 samples did not present the parasites, however, in two samples the presence of a Cryptosporidium oocyst was detected. Despite high bacterial reductions by HSSFs, there were no filtered samples with absence of coliforms; therefore, sodium hypochlorite tests were performed, which resulted in no bacteria in the treated water. The float control extended the filtration run in the intermittent regime and improved the turbidity filtered in the continuous stream. The use of the ripening accelerator was effective for FLD efficiencies only in the intermittent flow. Between the studied models of filters, FC was the one with the better results of efficiencies and duration of filters run.

The availability to clean drinking water is something a lot of people take for granted today. Daily, there are about 1.8 billion people around the world that drinks water from a contaminated water source. Unfortunately, the deficiency is a fact, and about 361 000 children under the age of five die each year because of diarrheal disease (WHO, 2016a).  Earlier studies show that a biosand filter is an easy and efficient water purification method that cleans the water both physically, biologically and chemically. A biosand filter is often built using local material and is filled with sand, which makes the construction cheap and easy to repair is needed. Earlier studies have shown that this purification method can reduce waterborne disease by 99,9% with the help of a biofilm layer which develop in the top layer of the sand if the conditions are meet (CAWST, 2009). The purpose with this study was to build and evaluate a biosand filter as a water treatment method in Ghana. In total, three biosand filters was built with local material, each with different sand heights. The evaluation was done by studying the waters physical, biological and chemical properties before and after the filtration, which then was compared to the water quality standards from the World Health Organization (WHO) and Sweden. The results show that none of the three filters could produce water which met the standards for drinking water, which might be caused by the high flow of water through the filter which prevented the biofilm to grow. With the help from the results in Ghana, a new design of a water filter has been made to reduce the flow of water through the filter. Which gave a new biosand filter design with a diameter of 42 cm that, sand height of 80 cm and gravel height of 15 cm. / Tillgången till rent dricksvatten är idag något som många tar som en självklarhet. I dagsläget är det omkring 1.8 miljarder människor i världen som dagligen dricker vatten från en kontaminerad vattenkälla. Dessvärre är bristen på rent dricksvatten ett faktum, vilket gör att det årligen dör cirka 361 000 barn under fem års ålder på grund av diarrésjukdomar världen över (WHO, 2016a).  Tidigare studier har visat på att biosandfilter är en enkel och effektiv vattenreningsmetod för att rena vatten både fysiskt, biologiskt och kemiskt. Ett biosandfilter är ofta byggt med lokala material och fylld med sand, vilket gör konstruktionen billig och enkel att reparera vid behov. Tidigare studier har visat på att vattenreningsmetoden kan reducera vattenburna sjukdomar med upp till 99.9% med hjälp av ett biofilmslager som utvecklas i sandlagrets övre skikt om förhållandena är gynnsamma (CAWST, 2009).  Syftet med denna studie var att bygga och utvärdera biosandfilter som vattenreningsmetod i Ghana. Totalt byggdes tre biosandfilter av lokala material med olika sandhöjder. Utvärderingen gjordes utifrån att studera vattnets fysiska, kemiska och biologiska egenskaper före och efter filtrationen, som sedan jämfördes med vattenkvalitetsstandarder från World Health Organization (WHO) och Sverige. Resultaten visade på att ingen av de tre sandfiltret kunde producera vatten med en drickvattenstandard, detta tros bero på det höga flödet genom filtret som hindrat biofilmstillväxten. Med hjälp av resultat från Ghana har en ny design av ett biosandfilter tagits fram för att minska flödet genom filtret. Vilket gav en filterdiameter som är ungefär 42 cm som sedan är fylld med 80 cm sand och 15 cm grus.

When Biosand filters cannot be constructed with crushed quarry rock due to resource limitations, a suitable alternative filter media is needed. In this research, two crushed quarry rock alternatives were examined. Three bench-scale Biosand filters with crushed rock, beach sand, and heat-treated beach sand media were simultaneously dosed with Willamette River water seeded with K-12 E. coli for 31 days. Influent and effluent filtrate was analyzed for E. coli using 3M Petrifilm E. coli/Coliform plate counts; influent and effluent pH, conductivity, turbidity, dissolved oxygen, and temperature were monitored. All three filters achieved stable E. coli removal efficiencies of 99% or greater after filter maturation, suggesting that it is possible to effectively use beach sand and heat-treated beach sand in Biosand filters for pathogenic bacteria removal. Mean effluent E. coli concentrations for crushed rock, beach sand, and heat-treated beach sand filters were 12, 29, and 30 CFU/mL respectively. Crushed rock filter effluent was significantly lower in mean effluent E. coli concentration than beach sand (P < 0.001) and heat-treated beach sand (P < 0.001) filter effluents, suggesting that beach sand and heat-treated beach sand media should only be used as a secondary option to crushed rock media due to potentially greater exposure risk to pathogenic bacteria. / Graduation date: 2013

<p>Over 750 million people, 80% of whom live in rural communities, lack access to improved water sources. Even where an improved water source is easily accessible, recontamination and/or inadequate infrastructure may make it unsafe for human consumption. A lack of safe water leads to elevated rates of waterborne diseases and can exacerbate cycles of poverty by forcing individuals to miss school and work and to travel greater distances to secure better-quality water. Households in rural and remote communities may thus choose to use point-of-use treatment as a means of gaining greater control over their water quality and the health of their families. The BioSand Filter (BSF) is one such technology: it is an intermittently-operated household-scale slow sand filter currently used in over 70 nations around the world.</p> <p>This thesis situates point-of-use water treatment, and specifically the BSF, within the context of the relationship between water and health and the continuum of technologies used for water treatment. From this foundation, it presents the methodology and results of a study carried out to inform best-practices around BSF use by: (a) examining the effects on BSF media and filtration performance of physical disturbances that may commonly occur in the field; and (b) assessing whether the biological community within BSFs promotes nitrification that could produce elevated nitrate/nitrite levels.</p> <p>Results demonstrated that disturbing the filters through moving and side impacts caused marked sand compaction and decreased flow rates for plastic (Hydraid) BSFs. Although these decreased flow rates may contribute to user frustration and disuse, they were not associated with reduced filtration performance. Nitrate and nitrite concentrations were well below WHO guidelines for all samples, but changes in nitrogen speciation suggested that nitrification was mediated by the biological community within the filters. Recommendations for practitioners and for future research are discussed in light of these findings.</p> / Master of Applied Science (MASc)