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Abstract
Water quality is distribution systems has become a prominent issue in the study of water networks. This thesis concentrates on chlorine disinfection as an indicator of water quality. The model discussed in this work is based on laboratory and field collected data. The model is applied on a real network which exists in Alm,onsha city in Upper Egypt. The concerned network services Almonsha city and 14 villages. The experimental set-up and procedure of measuring bulk chlorine decay coefficient (Kb) and wall chlorine decay coefficient (Kw) are described and observations for chlorine as disinfectant are reported. The collected field data together with experimental results are used for calibrating the model with bulk and wall decay coefficients by using extended period simulation. The aim pf this study is to find a solution for the absent of the free residual chlorine in several sections of Almonsha water distribution network.
The results of the field and experimental works have shown that, the inital chlorine concentration (C0) has an effect on bulk chlorine decay coefficient, an equation is derived to express the relation between them. Also, another equation is derived for the relation between C0 and Kw. The free residual chlorine concentrations (FRCC) have been studied in different locations of the network at several times using extended period simulation. The diurnal variations of domestic water consumption are taken into consideration. also, different values have been assigned for the daily water consumption for both rural and urban zones of the network. Different water resources (surface and underground water) have been involved in the model. Underground water reservoirs and high elevated tanks are included in the simulation. The water level in the high elevated tanks and water table in the feeding walls are studied. FRCCs were measured at different sections of the network and used for the model calibration.
With the existing system of chlorine injection, some parts of the network keep nil values of FRCC even with an injected free residual chlorine does reaching to 5 mg/L at the feeding point. A new technique is proposed. This technique is based on superposition method for chlorine disinfection. The superposition method is applied by estimating the required injected chlorine does at each water resource individually with its relying traced parts of the network which safety satisfies the minimum FRCC. Finally, the injected FRCC on the whole network is simulated for a period of 480 days to dispose the effect of the initial and boundary conditions. It is found that, the minimum injected chlorine does which should be injected at the feeding points ranges between 0.83 mg/L to 2 mg/L. This does is found to be sufficient to keep the minimum FRCC with values not less than 0.3 mg/L for the whole parts of the concerned network at all day hours.