Comparing industrial and domestic discharges as sources of: N -nitrosamines and their chloramine or ozone-reactive precursors

There have been few measurements of the concentrations of N-nitrosamines and their chloramine-reactive and ozone-reactive precursors in domestic and industrial sewage discharges contributing to municipal wastewater plants. This study measured the concentrations of 8 N-nitrosamines and their chloramine- and ozone-reactive precursors in 8 samples of primary municipal wastewater effluent, 6 composite samples of domestic and commercial sewage, 5 discharges from metal finishing or electronics-related facilities, 3 discharges from manufacturers of cosmetics and personal care products, 1 brewery discharge and 1 elastic waistband manufacturing discharge. NDMA and N-nitrosomorpholine (NMOR) were the most frequently detected N-nitrosamines. Domestic/commercial sewage accounted for the median NDMA concentrations measured in primary effluent after chloramination (48 ng L^-1) or ozonation (78 ng L^-1). Domestic/commercial sewage and discharges from metal finishing and electronics-related facilities (1760 ng L^-1 median NDMA concentration) each accounted for ∼25% of the 28 ng L^-1 median NDMA concentration measured in primary effluent, even though the metal finishing/electronics facilities accounted for only 0.25% of the sewage flow. Domestic/commercial and industrial discharges did not account for the 30 ng L^-1 median NMOR concentration in primary effluent, indicating the need to further characterize NMOR sources. Other N-nitrosamines and their precursors were rarely detected except in metal finishing/electronics discharges.