الفهرس 
Acknowledgements
Ground WaterOnly 14 pages are availabe for public view
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Abstract
Oxidation of dissolved iron particles in water changes the iron to red brown solid particles (particulate) that settle out of the water. Iron that does not form particles large enough to settle out and that remains suspended (colloidal iron) leaves the water with red tint. These sediments or particulates pose threats to industrial and municipal water supplies due to colour, formation of scales and blockage of water pipes thus leading to economic loss. Many researches have been studied the removal of iron by using oxidation processes followed by filtration only. This study introduces a comparison of filtration of aerated raw water though a filter of sand bed with and without Alum as a coagulant prior to filter. A synthetic iron dozes are added to tap water to represent a pre-determined different concentrations of iron as 2 and 3 mg/L which result in a 14 and 32 NTU respectively after aeration of raw water. The effluent of water was taken at regular time intervals to monitor the progressive rate of removal of these elements for different values of filtration rates 120, 180 and 240 m3/m2/day. A single layer gravity rapid sand filter was used with sand bed of 70 cm thickness, effective diameter of 0.7 mm and uniformity coefficient of 1.57 The iron concentration, turbidity and head lass in the effluent were recorded at all the assumed different filtration rates.The results show that the removal efficiency of iron and turbidity (96%) was AL mostly the same with and without coagulants for filtration rates up to 180 m3/m2/day and influent iron concentration of 3mg/l. Also, the higher the concentration of iron and turbidity in the influent the higher the efficiency removal of filter for all filtration rates. The iron effluent concentrations for most filtration rates up to 240 m3 /m2 /day were below 0.3mg/L (allowable Concentration according to Egyptian specifications of drinking water) for both cases of using coagulation or not. The Egyptian code of Practice stated that for influent iron concentration > 1.5mg/l a coagulation process must proceed the filter, but in these experiments at low concentration of influent iron (2 : 3 mg/L) and filtration rates up to 180 m3/m2 /day there is no need to the coagulation process.