Evaluating the Efficiency of Wastewater Treatment Plants in the Northern Hungarian Plains Using Physicochemical and Microbiological Parameters

The discharge of nutrients and organic pollutants is increasing at an alarming rate, driven by the rapid development of human activities. This growing pollution is contributing to significant environmental issues, including eutrophication, making the treatment of wastewater essential before its release into the environment. Prior to being released into water bodies, treated wastewater must undergo rigorous laboratory analysis. For this reason, analysis using standard methods was carried out at the Laboratory Waterworks in Debrecen on multiple samples taken from various wastewater treatment plants in Hungary. The primary objective of this research was to assess the quality of effluents from (14) wastewater treatment plants and investigate their efficiency by measuring various physicochemical and microbiological parameters as indicators. The microbiological indicator monitored was the heterotrophic count (HPC) by estimating its total number. The results revealed that substantial removal efficiencies were demonstrated by parameters including total nitrogen (TN), chemical oxygen demand (COD), and biochemical oxygen demand (BOD₅), with reductions averaging 91%, 92%, and 87%, respectively. However, the reduction in nitrogenous compounds (nitrite NO2− and nitrate NO3−) was limited, indicating areas for process improvement. Recommendations for enhancing treatment efficiency are proposed to optimize the overall performance of the wastewater treatment plants.