Investigation of the Efficiency of Dilution Flow, Detention Time and Discharge of Contaminated Water on Quality Management of Water Distribution Network After Pollution Incidence (Case Study: Drinking Water Network of Zahedan)

Urban water distribution systems constitute a large part of urban infrastructure. Awareness and understanding of pollutant sources and transport of contamination process in the water network cause suitable modeling of this phenomenon in the water network as well as perform a proper crisis management when the contaminants enter the network. In order to simulate the movement of nitrate in the soil, the nitrate advection-dispersion equation was programmed in MATLAB in this research. The second water distribution network of Zahedan has been considered as the study area and potential points with high concentration of pollutants in the network have been identified. Network simulation, after two hours of contamination, was tested for water contamination by linking EPANET and MATLAB software. to manage the network pollution crisis, two tools were proposed including detention time and dilution flow and were used along with polluted water discharging. The results of discharging of the polluted water showed that by closing pipes from 1.25 to 2.4 of the pollution injection time and also discharging water at a rate of 5% of the base pipe flow can prevent the entering of the pollution to other parts of the network. To calculate detention time, the network was divided into four parts including: near, middle, far and very far. The results of the qualitative analysis of the network indicated that required detention time to treat the quality of water in the nodes of the middle, far and very far decreased 25 to 30, 50 and 67 to 75 percent compared to the near nodes, respectively. Moreover, efficiency and positive performance of dilution flow as a tool for quality management and control of water distribution network, was proved. Required dilution flow to treat the quality of water was determined to be nearly 20% of the base pipe flow.