الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 182 |  |  |
| | | from | 182 | | |
Abstract
Direct filtration system has been employed as alternative to the conventional coagulation - flocculation – sedimentation - ,, filtration system for treating of surface water.
The purpose of this study is to present a simplified detailed analysis of the mechanism of removal in coarse media direct filtration filters and to produce a general mathematical model that might be used, in the future, by designers to predict the values of turbidity at different depths throughout the filter media.
To achieve the above objectives, three direct filtration plants were used at Sandala in Kafr El-Shiekh, at Basous in Cairo and at Magaga in El-Minia. The analysis of results recorded from the operation of the three plants understudy
During the operation of the plants, it was clearly noticed that the depth of the filter media was divided into two distinct parts; the upper part was from zero to about 40 cm from the surface of the media and the lower part from 40 to 123 cm from the surface of the media.
At a depth of 88 cm from the surface of the media it was found that the effluent turbidity lies below the allowable limit of Egyptian Specifications (5 N.T.U), thus the effective depth at which the allowable removal can be achieved is about 90 cm.
A mathematical model of coarse media filtration was derived in this study with the aim of using it, by designers, to predict the values of turbidity at various depths through the filter media.
A new relationship was developed in this study between the total concentration of particles remaining (C/Co) and the depth of media (h), grain size (D), particle diameter (d), grain density ( ), liquid density ( ) and, finally, initial porosity ( ).