parameter or alternatively in an approach
that considers health risks or risk tradeoffs
(nitrosamines versus halogenated DBPs).
Complicating the regulation of NDMA is
the fact that the oral intake of NDMA from
drinking water has been estimated to be
only 0.02 percent of the total intake from all
sources. (Fristachi and Rice, 2007)
Numerous control strategies have been
identified that minimize the formation
of nitrosamines. These include removal
of nitrosamine precursors by activated
carbon; optimization of the application of
amine-based polymers; optimization of
the chloramination protocol to minimize
the formation of dichloramine, which is the
chloramine species responsible for promoting
nitrosamine formation (i.e., optimizing
monochloramine formation by increasing pH
and using proper chlorine to ammonia ratio,
ensuring optimal mixing of free chlorine and
ammonia); eliminating the use of primary
and residual chloramine; application of a
strong oxidant such as chlorine or ozone to
deactivate precursors. (Krasner et al., 2013)
Utilities have spent decades modifying
and optimizing disinfection processes to
comply with existing regulations. However,
potential nitrosamine regulations at the
low ng/L (nanograms per liter) levels may
require treatment changes that could result
in conflicts with other regulations and
other unintended consequences such as
formation of other DBPs or compromised
Changing oxidation schemes (e.g., preoxidation
with ozone or chlorine prior to
chloramine addition) may result in the
formation of regulated (e.g., bromate for
ozonation, THMs/HAAs from chlorination,
chlorite form chlorine dioxide) and
other emerging DBPs of health concern.
Alternatively, removal of nitrosamine
precursors by activated carbon will result
in increased costs for water treatment. It is
certain that as new DBPs are discovered and
more stringent regulations are established,
utilities will face continually increasing
challenges in delivering safe water. S
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