Abstract

The dissertation presents the analysis of chemical and microbial composition of wastewater and examines the impact of wastewater discharge on the environment. Various case studies were analysed: from small settlements in a pristine European Arctic, to large municipal wastewater treatment plants in areas subjected to greater anthropogenic pressure. In order to comprehensively analyse the impact of wastewater discharge on the receiving waterbody, a holistic approach, combining multiple analytical methods, was chosen. The results of the study show that despite high bacterial removal rates, wastewater treatment plants based on biological methods, still release significant amounts of microorganisms into the environment. Wastewater included bacteria typical to (1) activated sludge (associated with nitrogen cycling or activated sludge bulking) or (2) to the human digestive system (including those showing antibiotic resistance). The biochemical potential and taxonomic structure of the treated wastewater microbiome varied throughout the year, reflecting seasonal fluctuations of wastewater treatment efficiency. At the same time, higher values of prokaryotic cells number, prokaryotic biomass or average cell volume were found in environmental samples influenced by wastewater discharge, compared to reference points. Additionally, this thesis proposed and validated a method for monitoring the occurrence of beta-lactam antibiotic resistance among coliform bacteria. This method can be widely used to assess the spread of antibiotic resistance.

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