Solar Disinfection Kinetic Design Parameters for Continuous Flow Reactors

Abstract

The main UV dose-related kinetic parameters influencing solar disinfection have been investigated for the design of a continuous flow reactor suitable for a village-scale water treatment system. The sensitivities of different pathogenic microorganisms under solar light in batch processes have been compared in order to define their relative disinfection kinetics with E. coli used as a baseline organism. Dose inactivation kinetics have been calculated for small scale disinfection systems operating under different conditions such as reflector type, flow rate, process type, photocatalytic enhancement, and temperature enhancement using E. coli K-12 as a model bacterium. Solar disinfection was shown to be successful in all experiments with a slight improvement in the disinfection kinetic found when a fixed TiO2 photocatalyst was placed in the reactor. There was also evidence that the photocatalytic mechanism prevented regrowth in the post-irradiation environment. A definite synergistic solar UV∕temperature effect was noticed at a temperature of 45°C. The disinfection kinetics for E. coli in continuous flow reactors have been investigated with respect to various reflector shapes and flow regimes by carrying out a series of experiments under natural sunlight. Finally, photocatalytic and temperature enhancements to the continuous flow process have been evaluated.