title: Effects of primary sludge particulate (PSP) entrapment on ultrasonic (20 kHz) disinfection of Escherichia coli.
abstract: The role of primary sludge particulates (PSPs) in ultrasonic disinfection of Escherichia coli (E. coli) was investigated. Entrapment of E. coli by PSP was directly observed through scanning electron microscope (SEM) after E. coli and PSP were incubated together in water for 24 h at 35 °C. Entrapment coefficient was proposed for the first time to reflect the ability of PSP to entrap E. coli and was estimated as 1.4 × 10(3) CFU/mg PSP under our experimental conditions. Ultrasonication (20 kHz) of different E. coli-PSPs solutions showed that the entrapped E. coli cells were protected by PSP from ultrasonication and the unentrapped cells were not. However, the protection of entrapped E. coli cells gradually decreased as ultrasonication proceeded, suggesting the ability of power ultrasonication to deprotect the entrapped E. coli cells. SEM studies suggested a two-step mechanism for ultrasonic (20 kHz) disinfection of entrapped E. coli: breakdown of the protective PSP refugia and disinfection of the exposed E. coli cells. This research will enable more informed decisions about disinfection of aqueous samples where porous PSP are present.
authors.affiliation: Department of Civil and Environmental Engineering, Southern Methodist University, Suite 203, 3101 Dyer Street, Dallas, TX 75205, USA.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Cui
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Talley
authors.forename: Guojing
authors.initials: G
authors.lastname: Liu
authors.forename: Steve L
authors.initials: SL
authors.lastname: Larson
mesh_terms: D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods*; D004926:Escherichia coli / Q000528:radiation effects* / Q000648:ultrastructure; D019220:High-Energy Shock Waves; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D014865:Waste Disposal, Fluid; D014871:Water Microbiology
chemical_list: D012722:Sewage