1 research outputs found
Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions
Chloramines
are the second most used secondary disinfectant by
United States water utilities. However, chloramination may promote
nitrifying bacteria. Recently, monochloramine cometabolism by the
pure culture ammonia-oxidizing bacteria, <i>Nitrosomonas europaea</i>, was shown to increase monochloramine demand. The current research
investigated monochloramine cometabolism by nitrifying mixed cultures
grown under more relevant drinking water conditions and harvested
from sand-packed reactors before conducting suspended growth batch
kinetic experiments. Four types of batch kinetic experiments were
conducted: (1) positive controls to estimate ammonia kinetic parameters,
(2) negative controls to account for biomass reactivity, (3) utilization
associated product (UAP) controls to account for UAP reactivity, and
(4) cometabolism experiments to estimate cometabolism kinetic parameters.
Kinetic parameters were estimated in AQUASIM with a simultaneous fit
to the experimental data. Cometabolism kinetics were best described
by a first-order model. Monochloramine cometabolism kinetics were
similar to those of ammonia metabolism, and monochloramine cometabolism
accounted for 30% of the observed monochloramine loss. These results
demonstrated that monochloramine cometabolism occurred in mixed cultures
similar to those found in drinking water distribution systems; therefore,
monochloramine cometabolism may be a significant contribution to monochloramine
loss during nitrification episodes in drinking water distribution
systems