American Journal of Environmental Engineering 2013, 3(5): 207-212 DOI: 10.5923/j.ajee.20130305.02 Investigation of Factors Affecting THMs Formation in Drinking Water Motasem Saidan 1,* , Khale d Rawajfe h 1 , Manar Fayyad 2 1 Chemical Engineering Department, University of Jordan, Jordan 2 Water Researches Center, University of Jordan, Jordan Abstract Total Trihalomethanes (THMs) content can vary greatly, depending both on water quality and on treatment conditions, in the same water supply system. Most municipal water treatment plants use chlorine to keep water biologically safe during the distribution process. The effect of various parameters on the formation of THMs has been studied in this investigation using water samples collected from Zai water treatment plant in Jordan. These parameters are reaction time, temperature, pH, TOC, free chlorine, and bromide ion content. An increase in the value of any of these parameters has positive effects on the formation of THMs. A general correlation for the prediction of THMs as a function of these parameters is proposed. Its predictions are in good agreement with the observed results regardless of the fact that it is restricted to this study. The kinetics of THMs formation were also investigated and found to follow first order kinetics with 0.0022 hr -1 rate constant. Keywords THMs Formation, Chlorination, Drinking Water, Water Quality Model 1. Introduction Chlorine, while an effective disinfectant, reacts with organic materials that might be present in the source drinking water to produce a group of chlorinated organic compounds known as Disinfection Byproducts (DBPs)[1, 2]. The DBPs include THMS (chloroform, bromodichloromethane, dibromochloromethane, and bromoform). The presence of THMs in drinking water has been the subject of increasing public concern since the 1970s[3]. Toxicological studies suggested that THMs have been linked to the occurrence of human cancer in many instances in 1976. This was soon followed by an act by the Environmental Protection agency (EPA) to regulate their concentrations in drinking water. In the past, various investigations had been conducted to determine factors that might influence THMs formation[4]. From the mid of 1980s, several models simulating the propagation and transformation of contaminants in a distribution system over time were developed and applied [5, 6]. In spite of water treatment, finished water may sustain substantial changes in quality while being transmitted through the distribution system before reaching the consumer’s tap. These changes may be associated with complex physical, chemical and biological processes that take place during transport. * Corresponding author: m.saidan@gmail.com (Motasem Saidan) Published online on October 26th 2013 at http://journal.sapub.org/ajee Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved Statistical correlations has been developed to predict the concentration of chloroform formation as function of pH, temperature and distance (near or far) between a reservoir and a point of interest in the distribution system. This correlation is qualitative in the sense that distance and time are not included implicitly in it[7]. Multiple regression model has been generated for predicting THMs level in the finished water leaving a treatment plant. The correlation implies that THMs formation is higher in summer through autumn and lower in winter through spring[8]. Mathematical model that applies second order kinetics has been proposed to predict the chlorine residuals and demonstrates that THMs formation can be characterized as a function of chlorine demand. The parameters of this model are correlated as a function of pH, TOC, temperature and chlorine residual[9]. The formation of THMs in drinking water has been shown to be a function of various water quality parameters and chlorination conditions. THMs formation is one of the slowest known reactions in water treatment and a number of important factors influence this reaction. These include residence time, pH, temperature, bromide ion concentration, chlorine dosage, type of organic precursor and the Total Organic Carbon (TOC). In the present paper, the overall objective is to develop an improved understanding of the effect of water parameters on THMs formation in drinking water, and also develop a mathematical model for the prediction of THMs concentrations for Zai water treatment plant.