The Influence of Rainwater and Snowmelt (Inflow and Infiltration) on the Performance of Wastewater Treatment in a Plant Using Membrane Bioreactors (MBR)

This article presents an analysis of wastewater inflow to a treatment plant and the impact of incidental (stormwater) inflow on the variability of its volume and quality. The study was conducted over a four-year period and showed that the average daily inflow of wastewater was 1133.2 m3 per day, which accounted for 56.7% of the plant’s design capacity. The variability of wastewater inflow was found to be significant, with stormwater having a considerable effect on increasing the volume of wastewater, especially during days with intense rainfall. Depending on precipitation levels, incidental water contributed between 12.2% and 46.2% of the total wastewater inflow. The analysis of the influent wastewater quality indicated a high variability in the concentrations of key pollution indicators. Despite this, the treatment processes in the membrane bioreactors (MBR) proved effective, consistently maintaining pollutant concentrations in the effluent below permissible limits. The conclusions highlight the necessity of considering stormwater in the design and operation of wastewater treatment plants to ensure their effective performance.