(cest2017_01060) Study of disinfection efficiency of peracetic acid (PAA) on Escherichia coli by rapid colorimetric assay based on enzymatic substrates after eliminating hydrogen peroxide from the commercial PAA mixture

摘要

Disinfection of combined sewer overflows(CSO) is a quick approach to reduce the indicator bacteria(E. coli and Enterococcus spp) to maintain the bathingwater quality on the receiving waters when CSO aredischarged. Peracetic acid (PAA) has been used todisinfect combined sewer overflows.This study was conducted to investigate the disinfectionefficiency of PAA against E. coli when hydrogen peroxidewas removed from the commercial PAA mixture.Furthermore, disinfection efficiency of PAA, commercialPAA and hydrogen peroxide against E. coli was compared.Disinfection efficiency of PAA against E. coli was studiedby using rapid colorimetric assay using enzymaticsubstrates 6-Chloro-3-indolyl-β-D-galactopyranoside(Red-Gal) which develops dark red when it reacts to the β-galactosidase enzyme of E. coli. The resulting colorintensity from the enzymatic substrate interaction wascorrelated to the bacterial concentration by using platecount method. Median inhibition concentration (IC50) ofPAA without hydrogen peroxide, commercial PAA andhydrogen peroxide on E. coli was determined by using thearea under curve (Ct). IC50 of PAA alone on E. coli was 32mg·min/L whilst IC50 of commercial PAA was 23mg·min/L.