North American drinking water utilities are currently re-evaluating their disinfection strategies for controlling microbiological growth in distribution systems. Most water systems in North America use free chlorine as a secondary disinfectant. Since chlorine is known to form potentially carcinogenic byproducts in drinking water, utilities are looking for an alternative to maintain a disinfectant residual in the distribution system. The objective of this study was to evaluate the response of model drinking water distribution systems to a change in disinfectant from either free chlorine or chloramines to chlorine dioxide, in terms of its impact on microbiological water quality (bulk water and biofilm). Switching from a chlorine residual of 0.5 mg/L to a chlorine dioxide residual of 0.25 mg/L did not impact (negatively or positively) microbial water quality as quantified by heterotrophic and total cell counts (sample size = 8 data points). Thus, on the basis of the mass of disinfectant applied, chlorine dioxide was more efficient than free chlorine at controlling microbiological growth in the model distribution system. Similarly, chlorine dioxide was more efficient than chloramines, as a chlorine dioxide residual of 0.25 mg/L inactivated 0.75–1 log more suspended organisms than 1.0 mg/L residual of chloramines. Therefore, under the tested conditions, chlorine showed similar or better disinfection efficiency than free chlorine and chloramines, respectively.
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Research Article|
August 01 2006
Changes in microbiological quality in model distribution systems after switching from chlorine or chloramines to chlorine dioxide
G. Gagnon
;
1
Department of Civil Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4, Canada
E-mail: ggagnon@dal.ca
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C. J. Volk
;
C. J. Volk
2
Aqua Plus Services, Muncie, IN 47304, USA
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C. Chauret
;
C. Chauret
3
Department of Biological and Physical Sciences, Indiana University-Kokomo, IN 46904-9003, USA
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H. M. Murphy
;
H. M. Murphy
1
Department of Civil Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4, Canada
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K. C. O'Leary
;
K. C. O'Leary
4
Cavanaugh Solutions, Winston-Salem, NC 27101, USA
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R. C. Andrews
R. C. Andrews
5
Department of Civil EngineeringUniversity of TorontoOntario,Canada,M4S 1A4
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Journal of Water Supply: Research and Technology-Aqua (2006) 55 (5): 301-311.
Article history
Received:
December 23 2005
Accepted:
February 28 2006
Citation
G. Gagnon, C. J. Volk, C. Chauret, H. M. Murphy, K. C. O'Leary, R. C. Andrews; Changes in microbiological quality in model distribution systems after switching from chlorine or chloramines to chlorine dioxide. Journal of Water Supply: Research and Technology-Aqua 1 August 2006; 55 (5): 301–311. doi: https://doi.org/10.2166/aqua.2006.011
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G. Gagnon, C. J. Volk, C. Chauret, H. M. Murphy, K. C. O'Leary, R. C. Andrews; Changes in microbiological quality in model distribution systems after switching from chlorine or chloramines to chlorine dioxide. Journal of Water Supply: Research and Technology-Aqua 1 August 2006; 55 (5): 301–311. doi: https://doi.org/10.2166/aqua.2006.011
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