Inactivation of E. coli Using Flow-Through Ultrasound and Ultraviolet Light Reactors in Series

Abstract

AbstractWater disinfection processes with sequential arrangements of ultrasound (US) and ultraviolet light (UV) reactors were investigated using Escherichia coli (E. coli) in a solution of 0.9% salinity. Experimental runs were carried out with reactor setups that provided sequential treatments of US followed by UV and UV followed by US. Using a mathematical model developed for three continuously stirred tank reactors in series (3-CSTR), a nonlinear regression analysis was conducted to determine the inactivation rate constants for E. coli and the formation rate constants for hydroxyl radicals. The additive, antagonistic, and synergistic effects of US (frequency 20 kHz, power density 275 mW/mL) and UV (irradiance 2.25 mW/cm2) were evaluated using kinetic constants and reactor efficiencies. Results showed that the sequential irradiation of US followed by UV yielded a synergistic effect on the inactivation of E. coli and that UV followed by US produced weak synergism.