Theoretical analysis of ozone disinfection kinetic studies and development of non-biological surrogate indicators for assessment of ozone disinfection efficiency
Abstract
The objectives of this study were: (1) theoretical evaluation of experimental methods currently used for investigating ozone disinfection kinetics, and recommendation of optimum experimental methods; (2) statistical analysis of in vitro excystation method used for cyst viability determination; and (3) development of non-biological surrogate indicators for assessing disinfection efficiency achieved in full-scale ozone contactors. Semi-batch reactors with equilibrated ozone concentration were found to provide most reliable information on ozone disinfection kinetics. A new method using fluorescence dyed microspheres as non-biological surrogate indicators to assess ozone disinfection efficiency achieved in ozone contactor has been developed. Microspheres are added to the ozone contactor influent at a constant rate, and contactor effluent replicated samples are collected after the process has reached steady-state. Fluorescent dye decay of individual microspheres is then assessed by flow cytometry. Microsphere with fluorescence intensity above and below a pre-selected threshold are considered equivalent to viable and nonviable microorganisms, respectively, and therefore, the "survival" fraction of microspheres and corresponding microorganism inactivation is determined. This method is easier and more reliable than the current CT approach suggested by U.S. EPA.
Degree
Ph.D.
Advisors
Marinas, Purdue University.
Subject Area
Civil engineering|Sanitation
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