Research Article| May 01 2008 The effect of chlorine demand on estimation of the inactivation rate constant M. Sivaganesan; M. Sivaganesan 1US Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA Phone: (513)569-7118 Fax: (513)569-7658; E-mail: sivaganesan.mano@epa.gov Search for other works by this author on: This Site PubMed Google Scholar E. W. Rice; E. W. Rice 1US Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA Search for other works by this author on: This Site PubMed Google Scholar N. J. Adcock N. J. Adcock 1US Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2008) 57 (3): 165–170. https://doi.org/10.2166/aqua.2008.037 Article history Received: June 28 2007 Accepted: September 19 2007 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation M. Sivaganesan, E. W. Rice, N. J. Adcock; The effect of chlorine demand on estimation of the inactivation rate constant. Journal of Water Supply: Research and Technology-Aqua 1 May 2008; 57 (3): 165–170. doi: https://doi.org/10.2166/aqua.2008.037 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Ct (disinfectant concentration multiplied by exposure time) values for chlorine are used by the US EPA to evaluate the efficacy of disinfection of microorganisms under various drinking water treatment conditions. These Ct values are generally derived from laboratory studies in which chlorine decay is characterized by a first order decay model. The concentration of chlorine is often only measured at the initial and final exposure times. In this study, using bacterial spore inactivation data where residual chlorine was measured at least twice in between initial and final exposure times, chlorine decay models were evaluated to determine the effect on Ct calculations. Traditionally Ct is treated as a constant in estimating the rate constant of the simple Chick-Watson inactivation kinetics model. As Ct is estimated it is subject to estimation error. To account for this error, the parameters of the chlorine decay and the inactivation models were estimated simultaneously. chlorine, first-order decay, rate constant, second-order decay, simultaneous modelling This content is only available as a PDF. © US EPA 2008 You do not currently have access to this content.