M.Tech. / This project aimed to develop the Potpaz ceramic water filter into an improved filter design optimally suited to South African rural conditions, to provide potable water rather than contaminated water to households. Communities that do not have access to in-house treated water often end up with a contaminated water supply, as the water to be consumed is usually sourced from communal water collection points and stored in containers. There is evidence that the water consumed at point-of-use in rural areas is not always of a potable quality due to possible contamination between collection and consumption. The existing Potpaz home water treatment device has been scientifically proven to return contaminated water to a potable state. A limited number have been imported to South Africa for use in a project that studied the effect of household point-of-use treatment on the health of the consumer. It was not at all certain whether the households would use these devices effectively because this filter was not part of their everyday water system. Part of investigating whether or not they would effectively use this filter was the inclusion of industrial design within the filter assessment section of a larger research project conducted in the Vhembe region to understand the requirements of the user. Industrial design concerns itself with the requirements of the user, as well as knowledge regarding product design, development and manufacturing. Households that took part in the point-of-use project used the Potpaz home water treatment device for more than two months and were approached to provide feedback regarding its use. From the feedback, it became evident that there were aspects of the Potpaz design that needed modification towards an improved water filter more suited for its intended use in rural households. An Action Researchinfluenced methodology and User Centred Design approach informed the collection of original data and feedback on areas of improvement. This, together with visits to local shops and community potters, provided sufficient background to understand the needs and preferences of the intended rural users regarding the use of the device. This informed the design process and increased the chances of developing a readily accepted, more suitable product to the intended users and the domestic environment in which they live. To achieve this, this project focused on the following aspects regarding Potpaz filters: placement, use and design aspects of usability and ergonomics. Development of the improved filter design culminated in rapid prototyping of a scale model and the fabrication of a full-size working model allowing for physical interface to evaluate the success of the design solution.

No description available.

Water treatment facilities commonly reduce soluble contaminants, such as soluble manganese (Mn2+), in water by oxidation and subsequent filtration. Previous studies have shown that conventional porous filter system removes Mn2+ from drinking water by developing Mn-oxides (MnOx(s)) bearing coating layers on the surface of filter media. Multiple models have been developed to explain this Mn2+ removal process and the formation mechanism of MnOx(s) coatings. Both, experimental and theoretical studies to date have been largely focused on the micrometer to millimeter scale range; whereas, coating layers are composed of nanoscale particles and films. Hence, understanding the nanoscale particle and film formation mechanisms is essential to comprehend the complexity of soluble contaminant removal processes. The primary objective of this study was to understand the initial MnOx(s) coating formation mechanisms and evaluate the influence of filter media characteristics on these processes. We pursued this objective by characterizing at the micro and nanoscale MnOx(s) coatings developed on different filter media by bench-scale column tests with simulating inorganic aqueous chemistry of a typical coagulation fresh water treatment plant, where free chlorine is present across filter bed. Analytical SEM and TEM, powder and synchrotron-based XRD, XPS, and ICPMS were used for characterization of coatings, filter media and water solution elemental chemistry. A secondary objective was to model how surface coating formation occurred and its correlation with experimentally observed physical characteristics. This modeling exercise indicates that surface roughness and morphology of filtering media are the major contributing factors in surface coating formation process. Contrary to previous models that assumed a uniform distribution and growth of surface coating, the experimental results showed that greater amounts of coating were developed in rougher areas. At the very early stage of coating formation, unevenly distributed thin films and/or particle aggregates were observed, which provided active sites for further surface coating growth. The predominant MnOx(s) phase in the surface coatings was identified to be poorly crystalline birnessite having scavenging activity by intercalation and/or sorption. This would explain the enhancement of efficiency in removing soluble manganese and other contaminants during water filtration. Moreover, the increased Mn2+ removal effect of having aluminum (Al) in pre-treated water is explained. These results indicate that the surface roughness and morphology need to be incorporated into particle capture models to more precisely describe the soluble manganese removal process. / Ph. D.

As the economy has been growing fast in China, Chinese people have more incomes and then higher standard of living. In the case of household water treatment, more and more urban residents in China use bottled water or water filtration system instead of tap water because people start to worry about polluted tap water. According to a survey from China Water Supply Services Promotion Alliance in 2014, 59% of urban residents drinking water is from tap water (after being boiled), 41% from bottled water and water filtration system. The 41% participants prefer bottled water as the first choice over a water filtration system. The comparative advantages and disadvantages of home water filtration system and bottled water are analyzed using comparative analysis. The reasons why home water filtration industry has grown slowly in urban China even though it is less expensive and has environmental benefits are analyzed using a system dynamics model. The model focuses on the physical system of home water filtration industry. The study shows that order delivery delay and service time are key factors to the adoption rate of home water filtration system. However, initial cost becomes a limiting factor to the growth of the market of home water filtration system. The study proposes the according market policy, demand policy, and supply policy to improve the current scenario.

No description available.

Recent advancements in molecular biology such as next generation sequencing and more sensitive and rapid molecular detection methods like qPCR, have historically been developed for clinical applications in human genetics and for health care diagnostic purposes. The high demand for faster and more accurate molecular assays in the health care field has driven rapid development of inexpensive molecular techniques that when applied to the science of environmental microbiology, provides an unprecedented level of understanding of the microbial world around us. The goal of this dissertation is to begin to apply more advanced molecular technologies to problems in applied environmental microbiology. Appendix A is a brief literature review of next generation sequencing technologies for applications in environmental microbiology. Appendix B focuses on the development of a more robust virus nucleic extraction kit for the detection of viral genomes from environmental samples found to contain high concentrations of qPCR inhibitors, such as humic acids or heavy metals. Appendix C summarizes one of the largest virus surveys done in the US, using state of the art qPCR technologies in both wastewater influent and effluent from two wastewater treatment plants in the Southwest. Data suggests that traditional virus indicators may not be a viable tool to evaluate fecally impacted source water or virus removal during water treatment. The third study summarized in Appendix D, provides one of the first insights into the microbial ecology of biofilms utilized as biological treatment media using Roche 454 amplicon sequencing of the 16S rRNA gene.

Exposure to arsenic (As) in water, the ubiquitous toxin that poses adverse health risks to tens of millions, is the result of both anthropogenic and geochemical mobilization. Despite recent publicity and an increased public awareness, the dangers associated with arsenic exposure rank among the top priorities of public health agencies globally. Existing sequestration applications mainly include reductions and adsorption with zero-valent metals and their oxides. The performance of adsorption media is known to preferentially favor aqueous As(V) over As(III) due to the charge of the dissolved oxyanion. Magnetic nanoparticles (MNP) have been the focus of multidisciplinary research efforts for the removal of aqueous toxic metals and metalloids since they can be magnetically separated from the treated water. This improves isolation and allows for regeneration of the MNP, reducing cost and resource consumption. This research is focused on As(III & V) sequestration through the use of synthetic ligands N,N’bis(2-mercaptoethyl)isophthalamide (abbreviated BDTH2) and 2,2’- (isophthaloybis(azanaediyl))bis-3-mercaptopropanoic acid (abbreviated ABDTH2). Additionally, As(III) sequestration with ABDTH2 functionalized on silica core-shell MNP (ABDTH2 MNP), magnetite MNP (ABDTH2@MNP), and commercial silica beads (ABDTH2 Si60) is demonstrated. Both BDTH2 and ABDTH2are effective precipitation agents for the removal of As(III) through the formation of S-As covalent bonds. ABDTH2MNP reduced a 200 ppb As(III) batch solution to below 10 ppb at pH 5,7, and 9. Additionally, complete removal was achieved in the presence of anions at concentrations of 200, 500, and 1000 ppb. This system was evaluated for the removal of total arsenic from industrial solutions accumulated during the production of renewable biogas in landfills. Direct precipitation with BDTH2 and ABDTH2 was inhibited by the complex matrix. However, batch removal with ABDTH2@MNP was effective in removing 82% of the inorganic arsenic. Sequestration of arsenic and speciation from these industrial solutions remains a challenge.

Diarrhoeal diseases are a global public health burden, killing 1.8 million people annually. Diarrhoea disproportionately affects children and those in poverty. Most diarrhoeal cases can be prevented through safe drinking water and basic hygiene and sanitation measures, with drinking water interventions having the most impact on reducing diarrhoeal disease. A metaevaluation of studies assessing a specific household water treatment method, the biosand water filter, was completed. Results from the meta-evaluation illustrated that biosand water filters improve drinking water quality and reduce diarrhoeal disease. However, short follow-up times and inconsistent measures are a concern. Furthermore, there is no generally accepted field method for determining biosand water filter effectiveness that is useable in low-resource communities. This study adds to understanding of biosand water filters.

Denna studie handlar om den vanliga sötvattensmusselarten Unio tumidus (U. tumidus), som har en viktig roll i vattenrening genom att filtrera organiskt material. Studien undersöker hur exponering för laboratorieförhållanden påverkar musslornas filtreringsförmåga genom att jämföra musslor som har anpassats till laboratorieförhållanden under olika tidsperioder. Experimentet undersökte effekterna av temperatur och laboratorieanpassningstid på U. tumidus. Fyra akvarier användes, två vid 5°C och två vid 15°C, och sex experimentkammare fanns i vardera akvarier. Musslorna som antingen hade hållits i laboratoriemiljö i ungefär ett år eller nyligen fångats vilda, anpassades till den nya temperaturen i cirka en dag innan experimentet startade och vattenprover togs vid tre olika tidpunkter för att mäta turbiditet och klorofyllkoncentration. En tvåfaktors ANOVA-analys användes för att mäta filtreringsförmågan. Resultaten visar att testtemperaturen var signifikant vid 3 och 46 timmar för turbiditet och vid 46 timmar för klorofyll, vilket tyder på att skillnaderna mellan testtemperaturen vid dessa tidpunkter troligen inte är slumpmässiga och att filtreringshastigheten var högre vid högre temperatur. Det fanns ingen signifikant skillnad mellan musselkälla (labb vs vilda) vid båda tidpunkterna för vare sig turbiditet eller klorofyll, vilket tyder på att det inte finns någon signifikant skillnad mellan laboratorieanpassade och vilda musslor. Vid 46 timmar var signifikansnivån för source*testtemperatur signifikant för klorofyll. Sammantaget tyder resultaten på att temperaturen kan påverka klorofyllnivåerna, där högre temperatur ger effektivare filtrering både för laboratorieanpassade och vilda musslor, med viss evidens för att laboratorieanpassning kan påverka klorofyllfiltrering vid låga temperaturer. Resultaten av denna studie är också relevanta för diskussionen om musslors ekosystemtjänster. Detta kan vara särskilt viktigt i ekosystem där vattnet är förorenat och där musslor kan hjälpa till att minska mängden föroreningar i vattnet. / This study is about the common freshwater mussel species Unio tumidus (U. tumidus), which plays an important role in water purification by filtering organic material. This study investigates how exposure to lab conditions affects the filtering ability of these mussels by comparing mussels acclimated to lab conditions over different time periods. The experiment examined the effects of temperature and lab acclimation time on U. tumidus. Four aquaria were used two at 5°C and two at 15°C and were performed with six experimental chambers each. The mussels which constituted a group held in the lab for approximately 1 year or recently wild caught, were acclimated to the new temperature for about 1 day before the experiment began, and water samples were taken at three different times to measure turbidity and chlorophyll concentration. A two-factor ANOVA analysis was used to measure filtration ability. The results show that the test temperature was significant at 3 and 46 hours for turbidity and at 46 hours for chlorophyll, indicating that the differences between test temperature at these times are likely not random and that filtration rates were higher at higher temperature. There was no significance between source (lab vs wild) at both times for both turbidity and chlorophyll, suggesting that there is no significant difference between laboratory-acclimated and wild mussels. At 46 hours the significance level for source*testtemperature was significant for chlorophyll. Overall, the results suggest that can affect chlorophyll levels with higher temperature providing more efficient filtration for both lab-acclimated and wild caught mussels, with some evidence that lab acclimation can affect performance of chlorophyll filtration at low temperatures. The result of this study is also relevant to the discussion of mussel ecosystem services. This may be particularly important in ecosystems where water is polluted and where mussels can help reduce the amount of pollutants in the water.

Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2016 / Access to safe drinking water is a major problem globally and it mostly affects people living in low-income countries. The lack of potable water leads to the use of raw water from surface or ground water sources for drinking and other household purposes. A water filtration unit was designed and constructed using fabric, gravel and sand, which were wet-packaged into a 20 L bucket. The efficiency of the filter unit to improve the bio-physicochemical properties of contaminated water was tested using surface waters from rivers in the Sekhukhune area. Physico-chemical parameters tested included turbidity, colour, total suspended solids (TSS), total dissolved solids (TDS), total hardness and pH. Turbidity and colour were the most improved characteristics, where turbidity improved by 69% and colour by 80%. Other parameters such as total hardness, TSS and TDS were non-significantly reduced following treatment with the filtration unit. The amount of soluble solids in raw water was well within allowable limits by WHO standards. Microbiological tests included heterotrophic bacteria, total coliform and faecal coliform counts. The bacterial load was too numerous to count for the untreated water, however, after treatment with the filtration unit, heterotrophic bacterial load decreased to 15 x 10103 CFU/ml, total coliforms to 14 x 10 2 CFU/100ml and faecal coliforms to 11 x 10 2 CFU/100ml. Further treatment with UV sterilization unit resulted in undetectable amount of bacteria. The unit designed in this study can be beneficial in those rural communities were clean water is not available, it is easy to construct and simple to operate and most importantly it reduced contaminants in surface water. The UV unit incorporated in this study is not cost effective, therefore, other household treatment options such as chlorination and boiling which are easily accessible to most communities can be used to further eliminate remaining microorganisms after filtration. The effective shortest boiling time and minimum dosage of Na(OCl2) have been previously tested in our laboratory and total elimination of bacteria was achieved within 2 minutes of rolling boil and after 30 minutes following addition of 5ml/20L of liquid chlorine.