Disinfection model based on excess inactivation sites: implications for linear disinfection curves and the Chick-Watson dilution coefficient.
Current disinfection models generally are either empirical modifications of Chick's law (linear survivor curves) or hit or site models modified from the radiation literature. In this paper, a general disinfection model is developed that assumes a large number of inactivation sites. From a probabilistic model of damaged site distribution, the normalized number of surviving organisms is described as the cumulative distribution function (cdf) of the normal distribution, with the independent variable equal to a measure of damage and the mean and variance equal and determined by dose-response submodels. Submodels were developed for chemical disinfectants without disinfectant demand, ultraviolet radiation, and chemical disinfectants with first-order disinfectant demand. This infinite site model reproduces linear, shouldering, and tailing survivor curves from literature data. In addition, it predicts Chick-Watson dilution coefficients in the range observed in the literature. The infinite site model offers the interpretation that linear, shoulder, tailing, and biphasic survivor curves and the apparent Chick-Watson dilution coefficient are ramifications of the normal cdf, rather than mechanistic laws.
Jensen
James N
JN
Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, New York 14260, USA. jjensen@buffalo.edu
D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000706:statistics & numerical data*; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D016014:Linear Models; D008954:Models, Biological; D008956:Models, Chemical; D014466:Ultraviolet Rays
D004202:Disinfectants