Polycyclic musk fragrance (PMF) removal, adsorption and biodegradation in a conventional activated sludge wastewater treatment plant in Northern Italy

The first Italian annual monitoring study was carried out in Northern Italy to analyse the fate and removal of polycyclic musk fragrances (PMFs) in a wastewater treatment plant (WWTP) with conventional activated sludge (CAS) system. Water was sampled in four different stations along wastewater treatments to better understand the behaviour of PMFs along different steps of the plant. Galaxolide (HHCB) and galaxolidone (HHCB-lactone) were found in concentrations at μg L⁻¹ level, 1 order of magnitude greater than tonalide (AHTN), whilst phantolide (AHDI) was never detected and celestolide (ADBI) was measured only at trace levels. Considering water concentrations, HHCB and AHTN evidenced a slight reduction, 20% and 50%, respectively, during wastewater treatments, thus resulting in a modest removal efficiency, mainly due to adsorption processes during the biological treatment. This was also confirmed by the high PMF concentrations measured in activated sludges which remained stable throughout the year. On the contrary, HHCB-lactone registered an increase up to 70% during wastewater treatments caused by the biotransformation of the parental compound HHCB during the biological treatment, as shown by the different HHCB-lactone/HHCB ratio measured before and after this step. No significant differences were recorded between seasons in terms of PMF input onto WWTP, in accordance with the common use of these chemicals in civil houses. Overall, this study suggests that current technologies employed in conventional WWTP are not enough efficient in removing these organic micropollutants from wastewaters and, therefore, WWTP effluents represent possible point sources of pollution for aquatic ecosystems. Additional treatments are necessary to enhance the removal of PMFs in order to increase the quality of the WWTP effluents.