AWWA ACE69118

A systematic investigation about both the formation and control of halonitromethanes (HNMs) were conducted in this study. The disinfectants applied included ozone, chlorine, monochloramine, and ozone followed by chlorine or monochloramine. Raw (i.e., the influents to the treatment plants) and treated waters (i.e., the water after conventional treatment processes but before any addition of disinfectants) from five drinking water treatment plants in South Carolina (Charleston, Greenville, Myrtle Beach, SJWD, and Spartanburg) were collected and investigated at different times in a year. The results showed that HNMs molar concentrations (22-67 nM) and molar yields (10-40 nM/DOC) were the highest by the treatment of ozonation-chlorination, followed by chlorination, ozonation-chloramination, and chloramination treatment in both raw and treated waters. Higher HNMs yields were observed in the treated water than the raw water at each treatment plant, indicating that the conventional treatment processes did not remove major HNMs precursors. The results suggest that the most hydrophilic NOM fractions (HPI) that are not removed by conventional treatment processes contain the major HNM precursors. It was also found that HNMs yields increased with decreasing DOC/DON ratios (i.e., increasing nitrogen content per organic carbon in water), and the nitrogenous organic compounds, such as aminosugars or amino acids, are the most likely precursors of HNMs. It appears that DOC/DON ratio can be a simple method for utilities to asses the presence of HNM precursors in natural and treated waters. Includes 13 references, table, figures.