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ABSTRACT: The key objective of this study was to investigate the attenuation mechanisms of seven N-nitrosamine compounds at environmental concentrations and under conditions relevant to groundwater recharge operations. The study used a combination of controlled laboratory-scale soil-column experiments and groundwater monitoring at a full-scale riverbank filtration facility. Findings of the controlled column experiments suggest that N-nitrosodimethylamine and six other N-nitrosamines (N-nitrosodiethylamine, N-nitrosomethylethylamine, N-nitroso-n-propylamine, N-nitrosodi-n-butylamine, N-nitrosopiperidine, and N-nitrosopyrrolidine) are biodegradable under oxic and anoxic oxidation-reduction conditions. Half lives determined in this study for the targeted compounds varied between 1.3 and 7 days, which will ensure a removal to below detection limits (<2 ng/L) within short travel times in groundwater recharge systems. Findings of this study suggest that complete removal of N-nitrosamines requires the presence of an adapted biocommunity, which will be established over several weeks to months. Water Environ. Res., 78, 2466 (2006).
KEYWORDS: N-nitrosodimethylamine, N-nitrosamines, groundwater recharge, disinfection byproducts, water reuse,
doi: 10.2175/106143006X115408
Introduction
With increasing water demands and lack of sufficient water supplies in many arid and semiarid regions, the impetus to use impaired surface water or treated wastewater to augment potable water supplies is growing. Utilities are increasingly interested in supplementing their groundwater supplies by means of riverbank filtration, artificial groundwater recharge and recovery, or soil-aquifer treatment (Drewes and Shore, 2001). There is, however, increasing concern that impaired water sources used for artificial recharge of aquifers might contain contaminants harmful to aquatic life and human health. Contaminants of concern include endocrine-disrupting compounds, pharmaceutically active compounds, personal care products, and household chemicals (Daughton and Ternes, 1999; Drewes and Shore, 2001). While none of these compounds likely pose unacceptable risks to human health at concentrations commonly observed in impaired waters considered for groundwater recharge operations, N-nitrosamines present environmental concerns, especially in groundwater recharge systems, because of their aqueous miscibility, exceptional animal toxicity, and carcinogenicity (Integrated Risk Information System, 2006; Lee et al., 1996; Mitch et al., 2003). W-nitrosodimethylamine (NDMA), among other nitresamines, is formed in many industrial (i.e., rocket fuel, rubber manufacture, and tanneries) and natural processes (Najm and Trussell, 2001; Wilczak et al., 2003). The NDMA is also formed as a byproduct of chlorination of water and is frequently found in municipal wastewater effluents and surface waters receiving wastewater discharges at concentrations between...