Prevention of contamination of the Southern Bug River with nitrogen compounds using constructed wetlands

The purpose of the study was to investigate trends in the pollution of the Southern Bug River with nitrogen compounds and to analyse the use of constructed wetlands to prevent this pollution. Statistical processing of the results of measurements of nitrogen-containing compounds was carried out according to open data of the State Agency for Water Resources of Ukraine and environmental risks were assessed. Using STATISTICA 12 and proprietary Python software, the authors created charts of the scale of ammonium ions and nitrate ions. The risks of exceeding the maximum permissible concentration for all observation posts for these indicators were estimated. Significant exceedances of maximum permissible levels of nitrogen compounds were detected, particularly downstream of Khmelnytskyi. Due to the self-cleaning processes occurring in the river, the levels of nitrogen-containing compounds decreased to acceptable values when measured at the drinking water intake in Vinnytsia, but simultaneously, the concentration of phytoplankton increased significantly. Correlations between pollution parameters were investigated and scatter plots were obtained. The results of the study are of practical value for monitoring and managing water quality in the Southern Bug River basin. Due to long-term statistical analysis, the study identified spatiotemporal trends in river pollution with nitrogen-containing compounds, which are key factors of eutrophication of water bodies. As an effective and economically feasible solution to the problem, the study proposed the introduction of constructed wetlands (CWs) and considered in detail two main types of CW – with free water surface and subsurface flow – their design features and cleaning mechanisms. CWs are a promising, decentralised technology for wastewater treatment in small communities that provides significant advantages over conventional systems due to their low cost, ease of operation, and environmental sustainability