Identifying appropriate microfilter media for surface water treatment in rural communities

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September, 2015
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Almost 60 percent of Ghanaian population is rural peoples. Commonly improved water sources found in the rural communities are boreholes, protected dug wells, protected springs, and rain harvested water. A large proportion of the rural population continues to be dependent on surface water resources such as rivers, streams and dams. Obviously the surface water sources are contaminated with pathogens and other contaminants. Even the quality of the “improved” water sources is questionable. There have been quite a number of efforts by Government (Community Water and Sanitation Agency) and non-profit organizations such as Community Water Solutions (CWS) and Pure Home Water Product (PHW) to provide safe water to rural inhabitants in the country. These organisations have used ceramic pot filters, bio-sand filters, cloth filters, chlorine tablets and alum for surface water sources purification. Clearly, economic sustainability, adaptability and flow performance for some of the filter media are always a problem. For these reasons it becomes imperative to identify appropriate filter media for Point-of-use (POU) microfilters to increase safe water supply in the rural communities. It is perceived the filter would improve flow performance as well as water quality. A different study was conducted to determine fabrics pore size distribution using LEICA DFC290 and image J. it was found that nylon (Nyl) and polyester (POL) had the finest average pore size of 1.5µm and 1.7µm respectively. Pore size for locally twill weave polyester (LTW POL) was also found to be 1.9µm, close to both nylon and polyester. Another study was conducted to construct filter media from nylon (Nyl) and polyester (POL) fabric. The media was categorized into nylon, polyester, composite (polyester and nylon) and hybrid (activated carbon from bamboo and polyester). The filter media was used to treat raw water from GWCL, Mampong dam and river Offin. The treatment cycle time or run time was 5-10 minutes. Percent TSS removal for nylon was 62.46, the highest among the four filter media category, followed by composite filter. The composite filter percent removal of turbidity was 60.28, slightly higher than hybrid and nylon filter. All filters were found to remove 100 percent fecal coliform and e.coli bacteria. However, percent total coliform bacteria removal for composite medium was 60, about 17% higher than polyester and nylon efficiency. In general, performance of hybrid medium in removals of heavy metals was better than any filter. The percent removal of Pb, Fe, Cu, Cd, Zn and Mn for hybrid medium are 61.25, 48.61, 69.64, 56.25, 61.31 and 87.5 respectively. Furthermore, aquatab chlorine was used for raw water treatment and also used to treat products of polyester, composite filter. It was again found that polyester and composite filter compete with raw water treatment with the aquatab in terms of pathogens removal. Percent removal of total coliform(TC) for polyester was 64.64 slightly higher than raw water treatment with aquatab chlorine(AQUATT). However, TDS, turbidity and conductivity for all aquatab chorine treatment surged. Interestingly, it was found that TSS in all aquatab treatment improved. The run time also improved the removal efficiency of pollutants in the raw water. In general, nylon media performance is better than polyester. However, when combined (composite) its effectiveness in removing pollutants in water is improved.
A thesis submitted to The Department of Chemical Engineering, Kwame Nkrumah University of Science and Technology, Kumasi in Partial fulfillment of the requirement for the award of The Degree of Master of Science (Chemical Engineering),