Biofiltration and Nitrogen Contribution in N-DBP formation
Prof. Hsin-hsin Tung
Graduate Institute of Environmental Engineering National Taiwan University
Wednesday, May 29, 3-4 pm 2355 GG Brown
Abstract: Dissolved organic nitrogen (DON) has been identified as an important precursor for nitrogenous disinfection byproducts (N-DBP) formation, such as haloacetonitrile (HAN) and N-nitrosodimehtylamine (NDMA). These N-DBPs are classified as potential carcinogens. Water with frequent algae blooms may lead to ample organic nitrogen in water and increase N-DBP formation after disinfection. The objective of this study was to explore the association between DON and N-DBPs, as well as the effect of biofiltration on DBP formation. Four sources of dissolved organic matter with different DON to dissolved organic carbon (DOC) ratios were investigated in this study. The results showed that during chloramination, dihaloacetonitrile (DXAN) formation was correlated to trihalomethanes (THM) and dichloroacetic acid (DXAA) yield (in molar basis). Ozonation/biofiltration was applied to explore the relationship between DXAN, DXAA and THM formation, in which the results showed that THM, DXAA, as well as DXAN may be derived from similar precursors. NDMA formation potential was correlated with DON/DOC, especially in hydrophilic and transphilic natural organic matter (NOM) fractions. Isotope 15N-labeled monochloramine was used to explore the nitrogen source of HAN formed in chloraminated NOM fractions. The results indicated that chloramine were the major nitrogen contributor in HAN formation and the dimethylamine group of formed NDMA mainly originated from NOMs. This study could provide a better understanding of the role of organic nitrogen in N-DBP formation.