Spatiotemporal domestic wastewater variability: Assessing implications of population mobility in pollutants dynamics

Abstract. Population mobility can change pollutants variability in domestic wastewater (DW). However, the implications of mobility on DW variability in small localities are rarely analyzed and visualized in space and time. Often, only limited mobility data is available for these types of areas. In this study, we investigate the implications of population mobility on DW variability using an Agent-Based model (ABM). The ABM simulates the spatiotemporal DW variability of chemical oxygen demand (COD) across the sewage network. Two scenarios are tested, one where inhabitants commute daily to school and work and the other when the population remains at home. In each scenario, the spatial variability of COD loads is mapped and analyzed at the sewage maintenance holes. Apparent changes are observed between these spatial patterns. The obtained maps show that DW loads vary across space, where substantial COD load differences exist between the two mobility scenarios. Population mobility implicates higher COD loads at some maintenance holes compared to a scenario with inhabitants remaining home. The spatial DW variability also gets higher upstream and lower downstream, implicating that mobility does not substantially generates variability at the wastewater treatment plant inflow. The preliminary results suggest that population mobility impacts the spatial DW variability across the sewage network, which requires further analysis with wider temporal coverage.