Inactivation of Escherichia coli by ozone under bench-scale plug flow and full-scale hydraulic conditions

• Published in: Water research (Oxford) 2006-10, Vol.40 (17), p.3239-3248
• Main Authors: Smeets, P.W.M.H., van der Helm, A.W.C., Dullemont, Y.J., Rietveld, L.C., van Dijk, J.C., Medema, G.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; bacterial contamination; Campylobacter; continuous stirred tank reactor; CSTR; Disinfection; Dissolved; dissolved ozone plug flow reactor; drinking water; E. coli; Escherichia coli; Escherichia coli - drug effects; Exact sciences and technology; Giardia; inactivation; inactivation capacity; inactivation rates; laboratory techniques; Other industrial wastes. Sewage sludge; ozonation; Ozone; Ozone - pharmacology; ozone sensitive organisms; pathogens; Plug flow; Pollution; pollution control; Wastes; Water Microbiology; water pollution; water treatment; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2006.06.025

To determine the disinfection efficacy of ozonation, water companies can apply several disinfection calculation methods. The goal of this study was to evaluate the use of the T10 and continuous stirred tank reactor (CSTR) method to extrapolate inactivation rates of ozone sensitive microorganisms observed in laboratory tests to full-scale ozonation in drinking water treatment. The inactivation efficacy of the ozonation at the Amsterdam water treatment works was assessed by determining Escherichia coli concentrations in large volume samples before and after ozonation over a period of 1 year. The inactivation of dosed E. coli WR1 was tested in a bench-scale dissolved ozone plug flow reactor (DOPFR) on the same feed water as the full-scale ozonation in which a concentrated ozone solution in Milli-Q ® water was dosed. Applying the T10 method on the inactivation rates observed in the DOPFR strongly overestimated the inactivation capacity of the full-scale ozonation. The expected inactivation based on the CSTR method (LT2ESWTR) approached the observed inactivation at full-scale. Therefore, the CSTR method should be preferred to calculate inactivation of ozone sensitive organisms such as E. coli, viruses, Giardia and Campylobacter by full-scale ozonation.