الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
General Organization for Greater Cairo Water Supply is the largest water purveyor in Egypt, because it serves more than 10 million people living in a populated area of about 195 Km2 with a current daily output of about 3 million cubic meter drinking wq.ter. It comprises of 11 major water treatment plants for purification of Nile water, in addition to treated surface water ground water is produced from deep wells which are found inside the plant or outside it. Because of the annual increasing of population in Cairo, water treatment plants have started to be overloaded for increasing the quantity of water. This overloading resulted in the presence of algae in filtered water, so that the presence of algae in treated water becomes a normal case and familiar to all water treatment plants. This research was carried out to study the quality of tap and roof tank waters and compare the obtained characteristic analyses with the Egyptian standards for drinking water. A trial was made to determine the reasons that cause the pollution of water inside the roof tanks and remedial solutions were suggested for avoiding the investigated problems. A sanitary survey was carried out at all water treatment plants and distribution system. Accordingly, twenty locations were chosen as the best sampling locations for the following reasons: 1- The quality of tap water can be studied for more than 80of the water treatment plants and distribution system. 2- The districts which surrounding these locations are tiPe more populated areas in Cairo, with a considerable variation in social levels. 3- These locations include the expected dead ends of the distribution system. 4- Both surface and ground waters are the main sources in these locations. 5- Pilot study proved that the analyses of the samples from these locations do not vary significantly from those obtained by random sampling. from each location two samples were taken monthly, one from the direct tap water and the other from the roof tank, through a period so the which total number of samples analysed have become 480 samples. of 12 months and were taken and The resul1:s of physical, chemical and bacteriological analysis of tap showed water that tap water all at sampling locations, Khan comply with the Egyptian area, the quality of except Agha¬ standards for drinking water. Agha-Khan area is supplied with unchlori¬ nated ground from water the ground Ameria water treatment plant, and so source of EI¬ a rigid measures shoulf’ be taken to provide this area with safe drinking water. It was noticed that the tap water at all sampling locations contains algae, and the of algae reaches 27 unit/ml. about annual of residual chlorine average of about mg/L. 2.2 Modern studies annual average Moreover, the in tap water indicated that such conditions contribute to the formation of chlorinated organic which compounds are dangerous health. It found the that 20 of was a water quality agreed with the limits standards, the quality is slightly different, water on the public roof tanks having of the Egyptian with respect to manganese, from the desirable limits at 45 of the roof tanks and at 35of the roof tanks the water quality do not agree with the limits of the Egyptian criteria with respect to iron and manganese. The findings of the sanitary survey indicated that the ideal roof tank is that which constructed from concrete, its inside surface is covered with glazed tiles and the frequency of its inside washing is - carried out e.2’ery 15 days. The quality of water in - the metalic roof tanks which were painted by suitable nonharmful paint and their inside cleanliness was carried at a regular periods not more than 2 months comply with the limits of Egyptian standards, but if their inside washing was carried out every 3 months the water quality is slightly different from the desirable limits. The water quality within the roof tanks do not comply the Egyptian standards if the inside cleanliness was carried at a periof of 5 months. So according to the results of sanitary survey and water quality analysis it could be recommended that the roof tank must be throughly washed at a period not more than one month and the metalic tank must be painted with a suitable non heath hazaradous paint . to be protected againist the corrosive behaviour of water. The discussion of the statistical analysis data showed the presence of direct correlation between turbidity and each of volatile residue, algae and total bacterial count. This correlation indicated that in order to improve the water quality it is necessary to increase the effeciency ”of filtration process to produce water fre”e from turbidity. Because the removal of turbidity is accompanied with a reduction of volatile residue, aJ,age and bacteria which are masked by the turbidity particle from the bactericidal action of chlorine. The removal of turbidi ty particles, algae and adapted bacteria from the distribution system can be achieved by, flushing the distribution system once per year, and accordingly the free residual chlorine in the distribution system can be decreased . to 0.2-0.5 mg/L as it was recommended by W.H.O. (1984).