The Effect of Temperature on the Decay of Chlorine in Water Distribution Network Using EPANET Qualitative Model

Water which contains chlorine, can synchronously react with different substances in water and/or attached to pipe wall as it flows through distribution system and its amount decreases in network. Temperature affect this reaction. In this study qualitative model, EPANET, was used to investigate the effect of temperature on the decay of chlorine in distribution network of Baharestan city and to obtain the kinetic coefficients of chlorine decay by water volume pipe wall.The kinetic coefficients of chlorine decay were acquired by measuring the changes of water temperature in two warm and cold seasons (summer and winter) and measuring concentration of chlorine residuals in water distribution network of Baharestan during these two seasons. Reaction coefficients were –0.533d-1 and –0.207d-1 for pipe wall equall of –0.3 and –2 mg/m2.d for summer and winter respectively. Based on these results, chlorine decay in the summer is 2.5times more than of the winter caused by water volume, but because of the new distribution network and pipe materials (PE), in these two seasons were very low and close to zero. Results obtained from the model and those obtained from the field with convergence coefficient of R=0.367 and R=0.971 for summer and winter respectively and accepted based on zero assumption tests at the level of 0.01.