الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In most water treatment plants that use rapid sand filters, a large amount of the treated water is consumed during the backwashing processes. This amount is estimated at 10%–15% of the produced filtered water of these treatment plants. The main aim of this study is to determine the most effective way to reduce the amount of treated (pure) water used for the backwashing process. The methodology of this study was to evaluate some parameters for reducing treated water consumption during the backwashing procedures. Studying the effects of changing the air and water rates in the backwashing process. The use of the treated water (Tap water) or slightly higher synthetic turbidity of 4.0 NTU was evaluated. The use of different media types (single or dual media) was also studied. The experimental set up was a bench-scale filter operated at a filtration rate of 189 m3/m2/day.The backwashing processes with the proper (best selection) water and air rates reduce water usage by 18%, enhance process performance, and reduce the ripening period. The backwashing process, which uses synthetic turbid water, recovered 100% of the treated water and improved the ripening duration without affecting the backwashing efficiency. This study concluded that backwashing the dual media filter with silica sand and activated carbon achieved the highest treated backwash water consumption reduction by approximately 60%. While the least reduction in the treated water consumption was discovered when using the anthracite coal as a dual-media filter. 8 Early backwashing process termination (@5NTU) achieved more pure water saving at the backwashing cycles that used the proper water and air rates. It achieved 5.15% (saving water percentage) in single media filter (silica sand), 7.71% in dual media filter (silica sand +activated carbon), and 4.55% in dual media filter (silica sand + anthracite coal). In single media filter (silica sand), backwashing time was saved by 60% from the total process duration (15 minutes). The saving energy was achieved by 6.75% and the cost was saved by 57.22%. In dual media filter (silica sand +activated carbon), the time was saved by 86.70%, from the total backwashing process duration (15 minutes). The energy was saved by 69.41% and the cost was saved by 85.72%. In dual media filter (silica sand + anthracite coal) ,the backwashing time was saved by 63.33% from the total process duration (15 minutes).The saving energy was 14.64% and the cost was saved by 60.73%.