Inflow and outflow loads of 484 daily-use chemicals in wastewater treatment plants across Japan

Abstract

With the increasing number and volume of chemicals used in modern life, their adverse effects on human health and aquatic organisms have increased concerns as well. To formulate appropriate management plans, the amounts/ volumes used and emitted of these chemicals must be regulated. However, no data are available on the use of most chemicals, particularly daily-use chemicals such as pharmaceuticals and personal care products (PPCPs). Herein, we tested eight activated sludge wastewater treatment plants (WWTPs) across Japan, each servicing populations of over 200,000, to investigate the emissions of 484 chemicals including 162 PPCPs. Twenty-four-hour composite samples were collected before and after the activated sludge component of treatment in each season of 2017. Targeted substances were solid-phase extracted and subsequently measured by LC-QTOF-MS-Sequential Window Acquisition of All Theoretical Fragment-Ion Spectra Acquisition. The mean number of the detected substances and their mean total concentrations in inflows (n = 32) and outflows (n = 32) were 87 and 92 and 108,517 and 31,537 ng L − 1 , respectively. Pharmaceuticals comprised 50% of the screened chemicals in the inflow. The median removal efficiency was 31.3%: 29.2% for pharmaceuticals and 20.2% for pesticides, which were similar to those in the literature. Cluster analysis showed that spatial differences among the WWTPs are larger than seasonal differences in the same WWTP. Regardless, we detected seasonal differences in the amounts of substances in the inflows: the amounts of sucralose, UV-filters, and insecticides were larger in summer than in winter, whereas those of ibuprofen and chlorpheniramine were larger in winter than in summer. The total inflow and outflow population equivalent loads estimated using wastewater volume, detected concentrations, and populations were 44.7 and 13.0 g 1,000 capita − 1 d − 1 , respectively. The extrapolated total annual Japan-wide inflow and outflow loads were 2,079 and 671 tons y − 1 , respectively. Using the data obtained in this study, we identified 13 candidates of marker substances for estimating real-time population in a sewage treatment area and 22 candidates of marker substances for sewage contamination.