Date of Award

6-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Walid Elshorbagy

Second Advisor

Dr. James Uber

Third Advisor

Mohsen Sherif,

Abstract

A hydraulic and chlorine simulation is conducted for three selected areas in Al Ain region. WaterCad 7.0, a water distribution system model, was chosen to conduct the simulation of the hydraulic behavior within the water distribution system. The fate of residual chlorine flowing through these systems over time is tracked by this software. The conducted hydraulic model predicts the performance of Al Yahar, AI Dhaher and Sweihan networks. Skeletonaization approach is employed in setting up the model for each system. In this study, the customer storage tanks (CSTs) are taken into consideration in performing the extended period simulation. Each group of (CSTs) is represented by a so-called Internal Storage Tank (IST). AI Yahar and Sweihan areas were selected since they exist at first locations supplied from the main desalination plants located in Abu Dhabi costal boundary called Um AI Nar and Tawillah via AI Saad and Sweihan pumping stations. AI Dhaher area, the third simulated system, is also selected as it is located at the last eastern site of AI Ain region that is supplied from Tawillah and Fujairah desalination plants via UmGhafa reservoir. The three selected networks are located somewhat on the edges of AI Ain region. They are considered district metered areas (DMAs), where each network has an adjusted flow control valve at its feeding sources. Therefore, the flow and the pressure for each system is known. Moreover, a data logger was installed by AI Ain Distribution Company (AADC) at a specific location in each network to record the residual pressure for a duration of one year. The simulation is done utilizing the water demand provided by the company. Water demands vary and consideration of the probabilistic nature of variations leads to more instructive assessment of the performance of the three selected distribution systems. Calibration of the hydraulic model was conducted by tuning the ISTs' capacities and water levels (initial and maximum). Hazen-william coefficients were maintained constant (C=120), as all networks pipes and connections were installed five years ago only in addition to the very good quality of desalinated water passing through each system. Chlorine simulation is conducted and calibrated utilizing the residual chlorine data collected for one year from the same data logger location in each area. With regard to the Chlorination ByProducts, trihalomethanes (THMs) compounds are sampled and analyzed. All obtained results were less than the international limits of 80 ppb. Laboratory experiments were conducted to analyze the formation of TTHM species in flowing pipelines. The results show that bromoform lead the THM species in all samples and at all times. On the other hand, the bromoform was found to undergo major hydrolysis after sometime approaching zero levels. All simulated and calibrated results, i.e. pressures, velocities and residual chlorine are compared to that in the water distribution code issued by Al Ain Distribution Company and with the international standards. From economic point of view, the energy cost for Al Yahar and Sweihan networks is calculated based on 0.05 Dhs/kwh for one and 20 years. Some alternative systems are studied to enhance the performance and efficiency of each network. One of the most important issues discussed is the possibility of removing the customer storage tanks, where cost savings can be achieved by controlling the delivered quantities to each customer tank and eventually enforcing the demand management concept. Installing an elevated tank or more is also discussed and scrutinized. The energy cost is also determined for each option and compared with the original configuration for each network.

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