THMs formation during chlorination of raw Nile River water

This study aimed to evaluate the role of contact time, pH, chlorine dose and temperature on the formation of THMs as result of prechlorination of raw river water. THM species and total THMs (TTHMs) concentrations progressively increased as the contact time was extended from 30 min up to 210 min. In presence of excess chlorine, THM formation proceeds as a pseudo first order reaction. Values of the rate constant (K) for CHCl3, CHCl2 Br and TTHMs approached each other whereas the CHClBr2 attained a higher value. The reaction rate of THMs formation increased as the pH value of water was increased from 6 to 9. The increase in THMs was not directly proportional to the applied chlorine dose. Increase in water temperature showed a rather limited effect compared to that reported by other investigators.