AWWA ACE58236

Dissolved organic nitrogen (DON) concentrations in raw and finished drinking waters are the focus of this paper. The percentage of DON removal during alum coagulation in five natural waters was comparable or better than dissolved organic carbon (DOC) removal. Approximately 75 % of DON occurs in the larger than 1000 Daltons fraction. During alum coagulation the > 1000 Dalton molecular weight DON was preferentially removed. Significant amounts of DON were extracted from bacteria. However, bacterial DON removal during alum coagulation was lower than removal of surface water DON. DON of wastewater origin had higher removals by powdered activated carbon (PAC) adsorption than non-wastewater impacted drinking waters. Analytical challenges for measuring DON in natural waters where the nitrate fraction of the total dissolved nitrogen is more than 90 % must be addressed in future research. As DON affects disinfectant demand, disinfection byproduct formation and speciation, and potentially biostability of drinking water, further research on DON treatability is required. Includes 13 references, tables, figures.