The Impact of Public Policy Measures during the COVID-19 Pandemic on the Characteristics of Urban Wastewater in the Republic of Serbia

The change in the way of life caused by the introduction of social restriction measures (closures, the restriction of working hours, and restriction of movement) by governments and thus, the resulting changes in people’s behavior, have affected all aspects of life, i.e., social activities, business, the environment and the performance of the infrastructure of the water supply system. Social distancing policies around the world in response to the pandemic have led to spatio-temporal variations in water consumption and therefore, to changes in the flow of wastewater, creating potential problems in the infrastructure, operation and quality of services. The goal of this work was to examine how these changes and how the pandemic itself affected the characteristics of municipal wastewater. Data on the quantity and quality of municipal wastewater in four settlements of different sizes in the Republic of Serbia in the period from 2015 to 2022 were collected. The data indicated an increase in the amount of wastewater generated in 2020, which may be a consequence of excessive water use. An increase in the mean concentrations of most parameters in 2020 compared to the previous five-year average was also observed. The most significant changes were observed concerning the concentrations of organic matter (2–124%), nitrogen (6–80%), phosphorus (14–91%), suspended matter (8–308%), fats and oils (97–218%) and surfactants (12–110%). Changes in terms of increasing concentrations were also noticed after the peak of the pandemic, i.e., in the period from 2021 to 2022. In addition, an increase in the COD/BOD ratio from around 2 to around 4 in the year 2020 was also observed (COD—Chemical Oxygen Demand; BOD—Biological Oxygen Demand). This is very important and should be taken into account in wastewater treatment procedures in order to achieve high efficiency in the operation of the plant itself.