الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Most drinking water systems use filters to collect, catches, or gather particles from an incoming flow. Finally, after the filter pores become clogged, they need to be cleaned. One of the best ways to clean a drinking water system’s filter is to backwash it, meaning reversing the flow and increasing the velocity at which water passes back through the filter. Usually the backwash water is filtered water. So, the net water production of the plant decreases and the cost of filtering this water have not utilized. An important question may appears if there is no filtered water for backwashing. Further, what is the effect of uses other types of water? Many gaps about using raw or settled water for backwashing is needed to addressed. In this study raw and settled water was used as backwash water. The main objective of this study is to evaluate the performance of rapid sand filters after backwashing by raw or settled water. For this objective the pilot plant was installed at the laboratory of sanitary engineering in the faculty of engineering- Mansoura University. Experimental work was proposed using synthetic turbid water. The work has included a wide range of operational conditions during filtration and backwashing process. Farther, the study has been extended to include a comparison between raw and filtered water for backwashing.The experimental work showed that, the net water production can be increased if raw water is used for backwashing. Also the study showed the alternative technique for backwashing by two types of water. Further, important conclusions were discussed in this study about the performance of filter under various conditions of filtration and backwashing.