الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Slow sand filtration is a well proven water treatment technique in developing countries as well as in the western world. It has great advantages over other filtration techniques specifically in reliability, cost, and performance. However filters become quickly clogged as a result of high suspended solid contents of the raw water. This presents a major problem in Egypt. Often raw water requires pre-treatment before slow sand filtration. Simple treatment of raw water with up-flow roughing filter before slow sand filtration reduces the excessive of suspended material in surface water. Bacteriological, biological and chemical water quality improvement may be also achieved. Extensive treatment is required to ensure water of reasonable quality. Conventional treatment techniques require the use of chemicals and adequate operation and maintenance which often will be beyond local capacities. Slow sand filtration is thus a suitable alternative in situations where skilled staff is limited and chemicals supply is difficult.