Impact of meteorological and social events on human-excreted contaminant loads in raw wastewater: From daily to weekly dynamics.

The temporal dynamics of the wastewater influent loads of 25 drug target residues (DTR, both pharmaceuticals and illicit drugs) was assessed during 84 consecutive days. This monitoring scale enables longer temporal patterns than weekday/weekend patterns to be explored. In this study, we focus on day to day variations and the potential statistical correlation of each DTR analyzed in order to better understand the potential forcings that lead to the load variation of DTRs (alone or in clusters). The weekly patterns based on the weekly loads of DTRs were also analyzed and the impact of social and meteorological events on their variations was investigated. Two cold events occurred during the monitoring period and were associated with the highest loads of analgesics and non-steroidal anti-inflammatory drugs, as well as the lowest loads of stimulants. During the Easter holidays, a significant decrease in some year-long medication as well as analgesics was found, consistent with the demographic decrease within the catchment during this period. Lastly, a good correlation between the academic calendar and the loads of stimulants was found, emphasizing the overrepresentation of students in the consumption of recreational drugs. This study furnishes new insights in order to better understand the variations in DTR loads in wastewater influents, beyond the weekday/weekend pattern and the seasonal effect. Further investigations remain necessary, especially a real-time monitoring of the population figures within the catchment in order to improve our understanding of these results.