Comparative Performance Of A Charcoal Dual Media Filter And A Conventional Rapid Sand Filter

B. O. Sanyaolu


Filtration tests were conducted to assess the performance of a dual media filter (DMF) using charcoal in comparison to a conventional rapid sand filter (RSF) for the same kaolin solution in influent water. Assessment of media characteristics was based on appearance, size, relative density, acid solubility and physical stability. The dual media filter exhibited a turbidity removal capacity of 1.4 times that of the conventional rapid sand filter. Gradients obtained from plots of headloss against time for the RSF and DMF were 0.2 and 0.5 respectively indicating a higher rate of head loss development in the RSF than the DMF. About 86% of the accumulated material in both RSF and DMF was washed away during the first four minutes of backwashing with combined air and water scour. The DMF had a higher bed expansion rate of 40% more than the RSF. This could be attributed to the lower density of charcoal compared with sand.   



Charcoal, Dual media filtration, rapid sand filtration

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APHA. 1992. Standard methods for examination of water and wastewater. American Water

Works Association and Water Pollution Control Federation. 18th Edition. McGraw Hill, New York.

Casey, M.A., Nelson, O.P., White, D. 2005. Laboratory and field studies on sand filters and their Biology. J. Water Environ. Research, 77(4):155-163.

Gabriele, T.M. 1985. An Improved Design for Rapid sand filter. Journal of American Water Works Association, 78(9): 103-108.

Lee, O.A., Lambert, D. 2007. Multi-layer filtration of some surface waters. Environ. Health Perspect., 115(3):56-64.

Morrison, S.A., Weber, G.J. 2004. Factors influencing the design and operation of dual media filters for raw water treatment. J. Am. Water Works Assoc., 97(6): 78-85.

Otis, T.R., Solomon, R.E. 2005. An evaluation of some filtration methods for small water supplies. Am. J. Public Health, 95(11):76-83.

Packham, D.C., Bauer, S., Dickson, L.G. 2008. Use of tri-media filters for municipal water supply. J. Environ. Sci. Tech,. 42(10): 63-80.

Sanyaolu, B.O., Malgwi, D.I., Mashauri, D.A. 2004. Performance enhancement in the slow sand filter through optimization of flow rates and thickness of natural fibre units. African Journal of Environmental Pollution and Health, 3(1): 33-36.

Schultz, C.R. 1990. Water filtration technologies for developing countries. Environmental Sanitation Review, 46: 37-78.

Terence, S.M. 1991. Direct filtration. McGraw Hill Publishers New York.


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