الفهرس 
Acknowledgements
GENERALOnly 14 pages are availabe for public view
 |  | from | 151 |  |  |
| | | from | 151 | | |
Abstract
In semi-arid regions such as in Egypt and other Arab countries, the gap between fresh water supplies and demands is rapidly increasing due to limited water resources associated with population growth. Sustainability of available water to be used for drinking or irrigation requires an applicable and economical solution. Some of the grey water are the wastewater comes from the household like that from bath, shower, bathroom and kitchen sinks and from washing machines. Also, it comes from the ablution water in Mosques. Grey water contains little pathogens and less nitrogen than black water, so, it does not require same treatment process. Sewer pipes networks are used for transporting wastewater and storm one from the source to the treatment plants. When reducing the amount of flow in these pipes -due to the reuse of grey water–they may be exposed to more flow resistance or blockage due to solids deposition. So, it is very important to study the parameters affecting on the deposition. Beside, the water safe of reusing grey water, the aim of the present research is to investigate the performance of flow characteristics in sewer pipes and its relation to constructions costs of pipes network and city wastewater treatment plant. Also, the potable water supply pipes network will be affected due to the reduction in flow demand.
In the absence of field and laboratory measurements due to their difficulty, time and money consumption, theoretical models are preferred in solving many engineering problems. Hydraulic engineers use these models for various important tasks, such as the design of new sewer pipes network and the analysis of existing ones. Sewer Cad and SWMM5, which can simulate steady state conditions and extended period simulation are widely used models. SEWERCAD V8i and SWMM5 were used in extended period simulation of the flow in the suggested sewer pipes network of present study. The distribution of velocity, sediment concentration and boundary shear stress in circular sewer flowing full and partially full with and without flat-bed simulating deposited sediments are studied numerically using three dimensional numerical model. Water depth and sediment concentration have been varied to simulate a wide range of possible flow conditions that may occur in the sewer.
The findings from this research may have practical applications especially when it is required to save the available water, save pipes construction costs, and save the environment. They may be summarized as follows: 1) Reducing the flow rate till 40% in sewer pipes as a result of grey water reuse has no bad effect on the hydraulic characteristics efficiency for self-cleaning of sewers. 2) The reduction of sewer pipes diameter by one degree improves the flow behavior for preventing the deposition of sediments and improves self-cleaning characteristics. 3) Reducing pipe diameter increases the hydraulics characteristics efficiency for self-cleaning and reduces the pipes network construction costs by about 31.5%. 4) Beside water saving and the mentioned benefits, reuse of grey water reduces the construction and operation costs of city wastewater treatment plant. 5) Velocity distribution and boundary shear stress are shown to be highly dependent on suspended sediment concentration, changes in cross sectional shape and water. 6) As a results of grey water reuse, the water demand will reduce which will affect the hydraulic performance of water supply pipes network. This will cause pressure head and water age increase in the water supply pipes network and reduce the flow velocity. To increase the flow velocity and reduce water age, the pipes diameter can be decreased which will reduce the cost of water supply pipes network.