title: Regrowth evaluation of coliform bacteria injured by low chlorine doses using selective and nonselective media.
abstract: In this study, the repairing capacity of coliform bacteria injured by chlorine is determined. Chlorine doses from 0.014 to 0.070mg L(-1) were used in according to frequency (up to 38%) of chlorine concentrations detected in a drinking water distribution network, adopted as case study. m-Endo (selective) and m-T7 (nonselective) cultivation media are used. Bacterial regrowth was detected up to 0.035 mgL(-1) of chlorine for 4h of incubation. The coliform bacteria were not able to regrowth when the dose of chlorine increased to 0.07 mgL(-1). Bacterial regrowth increased by increasing C:N ratio from 1:40 to 11:40. m-T7 (nonselective) medium allowed to detect bacterial regrowth also for lower incubation periods. Chlorine doses higher than 0.2 mg L(-1) dose at water source with a low total organic carbon (TOC) content are recommended to control bacterial regrowth in the distribution network.
authors.affiliation: Department of Civil Engineering, Environmental Engineering Division, University of Salerno, Fisciano, Salerno, Italy. l.rizzo@unisa.it
authors.forename: Luigi
authors.initials: L
authors.lastname: Rizzo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Belgiorno
authors.forename: Rodolfo M A
authors.initials: RM
authors.lastname: Napoli
mesh_terms: D002713:Chlorine / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods; D004755:Enterobacteriaceae / Q000254:growth & development*; D004784:Environmental Monitoring; D018508:Water Purification / Q000379:methods*
chemical_list: D002713:Chlorine