Tap water collected according to standard methods was examined for microbial presence. Epifluorescent diagnoses using redox probe 5-cyano-2,3ditolyl tetrazolium chloride (CTC), 4',6-diamidino-2-phenylindole (DAPI), and acridine orange (AO) were employed for direct evidence of microorganisms. Evidence of total (DAPI or AO), respiring (CTC) bacteria, and heterotrophic plate count (HPC) was determined on multiple occasions during the summer, fall, and winter 1996-1997. Pseudomonas aeruginosa, Acinetobacter sp., Bacillus licheniformis, and Methylobacterium rhodinum were isolated and identified by the API and Biolog system using GN and GP procedures. On the basis of comparisons presented in this study between the CTC method and the standard HPC procedure, it appeared that the number of CTC-reducing bacteria in the tap water samples was typically higher than that determined by HPC, indicating that many respiring bacteria detected by the CTC reduction technique fail to produce visible colonieson the agar media used. In the seasonal data obtained by the CTC method, no difference was shown among respiring bacterial counts obtained from June through January. In the examination of P. aeruginosa viability in presence of chlorine, the number of CTC-positive bacteria exceeded the number of CFU by more than 2 logs after exposure to chlorine, suggesting that reliance on HPC overestimate the efficacy of disinfection treatment. In inactivation assays using the Biolog MT plate, no sensitivity to chlorine or chloramine disinfectants was noted even at high concentration levels (5 mg/liter). Following initial drop, bacterial activities increased as contact time increased. Thus, it appears that the MT microplate provides too low a cell concentration, too great a contact time, and/or too low a concentration of tetrazolium dye within the well for successful analysis of disinfectant capability to selected bacterial strains isolated from distribution water. / Department of Biology

<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>