Regrowth evaluation of coliform bacteria injured by low chlorine doses using selective and nonselective media

J Environ Sci Health A Tox Hazard Subst Environ Eng. 2004;39(8):2081-92. doi: 10.1081/ese-120039376.

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.

MeSH terms

  • Chlorine / pharmacology*
  • Disinfection / methods
  • Enterobacteriaceae / growth & development*
  • Environmental Monitoring
  • Water Purification / methods*

Substances

  • Chlorine