54 COMPARATIVE EVALUATION OF ALTERNATIVE
HALOGEN-BASED DISINFECTION STRATEGIES
J. E. Alleman, Associate Professor
J. E. Etzel, Professor
D. Gendron, Graduate Research Assistant
E. J. Kirsch, Professor
School of Civil Engineering
Purdue University
West Lafayette, Indiana 47907
J. Conley, Market Manager, Water Treatment
T. Fidelle, Manager of Application Research
F. Handy, Director, Disinfectants-Government Affairs
M. Hildebrandt, Product Manager, Water Treatment
Great Lakes Chemical Company
West Lafayette, Indiana 47906
INTRODUCTION
Although chlorine is widely employed for disinfection of industrial (i.e. cooling towers, condensers,
etc.) and municipal (i.e. POTWs, package plants, etc.) systems, this disinfectant species has three
readily apparent disadvantages, as follows: 1) That the disinfection effectiveness of Cl2 is significantly diminished due to complexation with ammonium-nitrogen; 2) That the chloramine species thus
formed by complexation of chlorine and ammonium-nitrogen have unattractively long half-lives (i.e.
typically measured in hours); and 3) That the effectiveness of chlorine drops substantially beyond a
pH of 7.2 to 7.5.
In contrast, bromine-based disinfection has been recognized as having a number of corresponding
advantages1-23, including: 1) Bromamines provide bacteriocidal effects comparable to free hypobro-
mous acid;  2) Bromamine species are short-lived  (i.e.  with  half-lives measured  in minutes);
3) Bromine-based disinfection remains effective more than one pH unit higher than Cl2; and
4) Bromine-based disinfection has been shown to provide improved disinfection of viruses, cysts, and
certain bacteria, as compared to equivalent chlorine doses.
This paper examines the disinfection results obtained during a controlled laboratory evaluation of
two alternative bromine-based disinfection procedures in comparison with chlorine-only treatment.
The two bromine-based strategies were as follows: 1) Sodium bromide supplementation during chlorine disinfection; and 2) The use of bromochlorodimethylhydantoin (BCDMH), an organic compound carrying both of the oxidizing halogen species.
Each of these three disinfection strategies were studied under laboratory conditions using a range of
environmental conditions and bacterial forms (as are detailed in the Methods and Materials section).
Overall, these tests demonstrated that either of the tested bromine-based disinfection strategies (i.e.
sodium bromide supplementation of chlorine, and BCDMH treatment) offered a considerable
improvement in bacteriocidal effectiveness as compared to chlorine-only treatment.
This improvement appeared to be most significant under elevated pH conditions (i.e. at pH = 8.2
versus pH = 7.0) and in conjunction with Pseudomonas and Streptococcus disinfection.
BACKGROUND
Bromine disinfection was first implemented on an extensive basis during World War II, primarily
due to the reduced availability of chlorine. Subsequent industrial use of bromine-based disinfection
has basically involved bromine chloride.
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