Dissolved organic nitrogen (DON) in watersheds
may react with disinfectants to form carcinogenic,
nitrogenous, disinfection byproducts. However, despite
the potential significance of DON-mediated reactions, a
systematic study has not been conducted for DON
occurrence or removal during water treatment.
Two seasonal sampling campaigns of raw and
finished waters from 28 water treatment plants in the
United States were conducted to quantify the occurrence
and removal of DON. A new dialysis-based
pretreatment method that removes dissolved inorganic
nitrogen, followed by a high-temperature combustion
analytical method, was used to measure DON.
Results demonstrated that average observed DON
concentrations were 0.19 mg/L nitrogen for raw
waters and 0.15 mg/L nitrogen for finished waters,
making the high-temperature oxidation technique
described in this article suitable for widespread use in
the drinking water industry. Results also
demonstrated that water treatment plants remove
approximately 20% of DON and that adding polymer
and ozonation aid in its removal. Includes 30 references, tables, figures.