JCHR (2018) 8(2), 107-115 Journal of Chemical Health Risks www.jchr.org ORIGINAL ARTICLE Modeling the Chlorine Gas Dispersion in the Water Treatment Plant Hadi Shamizadeh *1 , Ramin Alinejad Shahabi 1 , Mehdi Arjmand 2 1 Department of Chemical Engineering, Islamic Azad University Ahar Branch, Ahar, Iran 2 Department of Chemical engineering, Islamic Azad University south Tehran Branch, Tehran Iran (Received: 25 May 2016 Accepted: 25 July 2016) KEYWORDS Modeling; Accidents; Risk; Chlorine dispersion; Water Treatment Plant; PHAST software ABSTRACT: An issue rose for industrial safety and successful address of crisis involves quick and pragmatic decision that would reduce losses and accidents. This will become practical when in addition to studying of past accidents the industrial executives create the necessary readiness to face risks through precise estimation of the consequences of eventual accidents. The present research concerns modeling the consequences of chlorine gas dispersion in the wastewater installations. The transfer of knowledge and information in this study were gained from modeling the dispersion of chlorine in the water treatment plants, useful for managers and executives. Detection and specifying the risks of chlorine for the public and especially the staff and those residing near the water treatment plant, would result in the appropriate action against this lethal substance, which is the subject of this study. Identification of risks related to foreign agents and their negative impacts on water treatment plants containing chlorine tanks is among the objectives of this study. The modeling and accurate specification of the scope and level of danger created following the dispersion of chlorine was done using the PHAST software, which allowed a clear identification of danger zones created by the dispersion of Chlorine. This text reports the radius of areas affected by chlorine dispersion as well as the results of different conditions after running the model for variable physical and process conditions, and given their availability, these results can be compared with each other. INTRODUCTION Chlorine was discovered in 1744 in a Swedish Lab recognized as a new element in the year 1810. The name chlorine is taken from the Greek word of Khloros meaning, "light green"[1]. Chlorine gas is considered as a strategic chemical in the world as it has a broad application ranging from water treatment to industrial production. In addition to these benefits, chlorine is dangerous for human health so it is used in terrorist attacks. The unwanted dispersion of chlorine following an accident has resulted in fatalities [2]. Given the longstanding application of chlorine for disinfection of water and wastewater, the expressions chlorination has become synonymous with disinfection. Despite being considered as a disinfectant, chlorine still has its own specific risks, which require appropriate technical and management decisions to ensure immunity. This will * Corresponding author: h-shamizadeh@iau-ahar.ac.ir (H. Shamizadeh)