Aerobic biotransformation of N-nitrosodimethylamine and N-nitrodimethylamine in methane and benzene amended soil columns

• Aerobic cometabolism of NDMA and N-nitrodimethylamine is shown.
• Methane and benzene amended groundwater stimulates nitrosamine cometabolism.
• We model kinetics of competitive aerobic cometabolism in soil column studies.

Aerobic biotransformation of N-nitrosodimethylamine (NDMA), an emerging contaminant of concern, and its structural analog N-nitrodimethylamine (DMN), was evaluated in benzene and methane amended groundwater passed through laboratory scale soil columns. Competitive inhibition models were used to model the kinetics for NDMA and DMN cometabolism accounting for the concurrent degradation of the growth and cometabolic substrates. Transformation capacities for NDMA and DMN with benzene (13 and 23 μg (mg cells)− 1) and methane (0.14 and 8.4 μg (mg cells)− 1) grown cultures, respectively are comparable to those presented in the literature, as were first order endogenous decay rates estimated to be 2.1 × 10− 2 ± 1.7 × 10− 3 d− 1 and 6.5 × 10− 1 ± 7.1 × 10− 1 d− 1 for the methane and benzene amended cultures, respectively. These studies highlight possible attenuation mechanisms and rates for NDMA and DMN biotransformation in aerobic aquifers undergoing active remediation, natural attenuation or managed aquifer recharge with treated wastewater (i.e., reclaimed water).