title: Ultraviolet and chlorine disinfection of mycobacterium in wastewater: effect of aggregation.
abstract: Mycobacteria naturally aggregate in water, a characteristic that may serve to protect them against disinfection in wastewater. Secondary effluent was spiked with Mycobacterium terrae (M. terrae), sequentially filtered through 100-, 41-, and 20-microm nylon filters to partition aggregate sizes, confirmed using particle-size analysis and microscopy. Each sample was exposed to doses of UV light (10 to 60 mJ/cm2 at 254 nm) and free chlorine (27 to 150 mg-min/L at 4 degrees C). Inactivation of M. terrae in wastewater was initially rapid, with 2.5 log reduction at 14 mJ/cm2 and 56 mg-min/L for UV and free chlorine, respectively. However, in effluent and 100-microm filtered wastewater, spiked M. terrae was present to the highest doses evaluated. Interestingly, M. terrae passed through 41- and 20-microm filters were inactivated rapidly, with no survivors after moderate disinfection doses. Inactivation of Mycobacteria in wastewater may be compromised by aggregates larger than 41 microns.
authors.affiliation: Duke University, Department of Civil and Environmental Engineering, Durham, North Carolina 27708, USA.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Bohrerova
authors.forename: Karl G
authors.initials: KG
authors.lastname: Linden
mesh_terms: D002713:Chlorine / Q000737:chemistry / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D005374:Filtration; D009170:Nontuberculous Mycobacteria / Q000187:drug effects* / Q000302:isolation & purification / Q000528:radiation effects*; D010316:Particle Size; D013997:Time Factors; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology
chemical_list: D002713:Chlorine