Effects of redox conditions and substrate concentration of N-nitrosodimethylamine (NDMA) biodegradation

N-Nitrosodimethylamine (NDMA) is known to be highly carcinogenic and is present in a variety of foods, drinking water and wastewater. Because of its presence in chloraminated water at nanogram/L concentrations. NDMA has become an emerging issue for reclaimed water which may be used for aquifer recharge or irrigation. The objective of this research was to understand the biodegradation potential of NDMA under conditions encountered during aquifer recharge and irrigation using reclaimed water. Three-soil column systems were used for this study, two of which simulate sub surface transport and the other irrigation.; The first set of columns was operated under aerobic condition with minimal primary substrate and NDMA removal was not observed. Increasing the primary substrate in the influent resulted in NDMA removal suggesting that biodegradation of NDMA might be a cometabolic process. To understand the effect of redox conditions on NDMA biodegradation, another set of columns was first ran under anoxic conditions and later changed to aerobic conditions. It was observed that NDMA biodegraded more efficiently under aerobic conditions as compared to anoxic conditions. Within the same set of columns, the majority of NDMA and substrate removal occurred in the first column for both aerobic and anoxic condition suggesting again that NDMA biodegradation is cometabolic. Irrigation columns ran with different irrigation efficiencies and plant type showed a NDMA removal varying from 75 to 90%. Batch tests verified the biodegradation removal potential of NDMA. It was observed that half-life of NDMA under aerobic condition was 11 days while methanol addition increased the half-life of NDMA to 23 days.; A simple and economical HPLC/fluorescence method was developed to measure nanogram level of NDMA in water and wastewater samples. This method uses the selective reaction of dansyl chloride with amines, which is denitrosated from NDMA, providing a chromatogram for NDMA analysis in the complex organic matrices with no interference.