Polycyclic and Nitro Musks in Canadian Municipal Wastewater: Occurrence and Removal in Wastewater Treatment

Abstract

Abstract The removal and/or partitioning (to sludge) of six polycyclic and five nitro musks through the liquid treatment train of a conventional Canadian secondary activated sludge wastewater treatment plant is characterized. Raw influent, primary effluent, secondary effluent, primary sludge, and waste activated sludge concentrations were correlated to seasonal process temperatures (warm, 22°C; cold, 15°C). Maximum influent concentrations of polycyclic and nitro musks were 7,030 ± 2,120 ng/L for Galaxolide (HHCB) and 158 ± 89 ng/L for musk ketone respectively. Maximum secondary effluent concentrations were 2,000 ± 686 ng/L for HHCB and 51 ± 14 ng/L for musk ketone. Temperature appeared to influence the degree of removal of musks from wastewater during primary clarification (40% median removal at warm temperatures and 9% at cold temperatures) and overall treatment (82% median removal at warm temperatures and 74% at cold temperatures) but not secondary activated sludge treatment (71% median removal at warm temperatures and 70% at cold temperatures). In primary sludge, polycyclic musks were found at concentrations up to 35,000 ng/g for HHCB, and nitro musks were found at concentrations up to 490 ng/g for musk ketone. In waste activated sludge, polycyclic musks were found at concentrations up to 52,000 ng/g (HHCB), and nitro musks were found at concentrations up to 1,100 ng/g (musk ketone). The hydraulic retention time and the suspended solids of the treatment process appeared to influence the degree of partitioning of musks to sludge.