Seasonal occurrence and removal of polycyclic and nitro musks from wastewater treatment plants in Ontario, Canada

Polycyclic and nitro musk (PNM) fragrances in personal care products persist and bioaccumulate in the environment following wastewater discharges and land application of biosolids. Influent and effluent concentrations, seasonal variations, and process removal efficiencies of 11 PNMs were investigated at six wastewater treatment plants representing four typical Canadian treatment processes: lagoon, oxidation ditch, extended aeration, and conventional activated sludge. Influent concentrations were as high as 40 000 ng/L for polycyclic musks and 400 ng/L for nitro musks, and showed some seasonal fluctuation. Effluent concentrations were as high as 4000 ng/L and 150 ng/L for polycyclic and nitro musks, respectively. Lagoon treatment produced the highest percent removal (>95%) and the lowest effluent concentrations of PNMs, with process temperature exerting some influence on removal. Results indicate that simple hydraulic or solids retention time are not strong predictors of PNM removals from wastewater. Effluent PNM concentrations were extrapolated to all treatment plants in the watershed to estimate concentrations along the Grand River and its tributaries.