Impact of Particulate Matter on Distribution System Disinfection Efficacy

摘要

Microorganisms have been shown to survive drinking water disinfection and remainrnviable in disinfected waters despite the presence of disinfectant residuals. This may bernpartially due to protection by particulate matter. The aim of this study is to determine therneffects of the presence of particulate matter on disinfection kinetics in comparison tornkinetics in particle-free water. Heterotrophic plate count bacteria and Helicobacter pylorirnwere used in inactivation experiments in the presence and absence of soil, corrosion, andrnwastewater particles. Inactivation of indicator organisms, namely Bacillus subtilis sporesrnand MS2 phages, was also studied using synthetic, demand-free buffered water, in thernpresence and absence of floc particles. Floc particles were produced using kaolin clayrnand alum in an attempt to entrap the organisms. The disinfectants assessed in this studyrninclude UV, free chlorine, chlorine dioxide, and monochloramine. Results showed thatrnthe mere presence of the soil and corrosion particles in the water could affect therninactivation kinetics, decreasing the level of inactivation by up to 1 log in some cases,rncompared to particle-free water for the same CT. Wastewater particles and coagulatedrnkaolin clay had no effect on microbial inactivation with the disinfectants used in thisrnstudy.