Design of model reactor systems for evaluating disinfectants against biofilm bacteria

Abstract

Laboratory reactors are devices which grow biofilms under controlled and/or field relevant conditions for the purpose of developing biofilm control strategies. In disinfectant efficacy testing, as well as in research, choosing the best reactor to use is important because different laboratory reactors impart unique characteristics in the biofilm that influence everything form biofilm architecture and protein regulation to the response of biofilm bacteria to disinfection. In this dissertation, three laboratory reactors and associated standard operating protocols were developed to provide a reliable, standardized assessment of disinfectant efficacy against biofilm bacteria that grow: 1) in a moderate to high fluid shear environment, 2) in hot tubs, and 3) in swimming pools. The reactors and protocols were then evaluated for the statistical characteristics of repeatability, ruggedness, and responsiveness, required criteria for the standardization of a method. In the CDC biofilm reactor (CBR), biofilm was engineered to possess the characteristics of a field biofilm grown under moderate to high fluid shear. The laboratory hot tub and swimming pool reactors were each engineered to generate a field-relevant biofilm by modeling the physiochemical and biological characteristics present in such recreational water. Testing demonstrated that the CBR and laboratory hot tub system were repeatable and rugged. The hot tub and swimming pool systems were responsive to disinfectant type and concentration. This research demonstrated the feasibility of incorporating relevant engineering design into practical laboratory methods used to evaluate disinfectant efficacy.