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Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water
Wahman, D., J. Maestre, AND G. Speitel Jr. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water. JOURNAL OF AMERICAN WATER WORKS ASSOCIATION. American Water Resources Association, Middleburg, VA, 108(7):362-373, (2016).
Investigate whether or not nitrifying biofilm can biologically transform monochloramine under drinking water relevant conditions.
Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kinetic experiments were not representative of drinking water distribution systems where bacteria grow predominantly as biofilm attached to pipe walls or sediments and physiological differences may exist between suspension and biofilm growth. Therefore, the current research was an important next step in extending the previous results to investigate monochloramine cometabolism by biofilm grown in annular reactors under drinking water relevant conditions. Estimated monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism was a significant loss mechanism (25–40% of the observed monochloramine loss). These results demonstrated that monochloramine cometabolism occurred in drinking water relevant nitrifying biofilm; thus, cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in distribution systems.