The efficient and timely removal of organic matter and nutrients from water used in normal municipal functions is considered to be the main task of wastewater treatment plants (WWTPs). Therefore, these facilities are considered to be essential units that are required to avoid pollution of the water environment and decrease the possibility of triggering eutrophication. Even though these benefits are undeniable, they remain at odds with the high energy demand of wastewater treatment and sludge processes. As a consequence, WWTPs have various environmental impacts, which can be estimated and categorized using Life Cycle Assessment (LCA) analysis. In this study, a municipal WWTP based in Poznań, Poland, was examined using the method defined in ISO 14040. ReCiPe Endpoint and Midpoint (v1.11), in a hierarchical approach, were used to evaluate the environmental impacts regarding 18 different categories. All calculations were conducted using a detailed database from 2019, which describes each chosen facility. It was found that the energy component, related to the wastewater treatment process demand and electricity production, is the main determinant of the sum of the environmental impact indicators in light of the modelled energy mix. Therefore, it determines the entire process as an environmentally friendly activity.
The paper presents the comparison of the performance of the three-blade centrifugal pump operating in sewage water in the function of time. Two conditions of the analysed pump were investigated: a new one and one after a long period of utilization. The main objects of research were the impeller, due to its enormous wear, and the L–shape wear ring. Three dimensional optical scanning was applied to reflect the real geometrical parameters of the analysed pump. The investigations were conducted by means of numerical simulations and a real test. The achieved results indicate the impact of the wear on the performance curves of middle specific speed sewage pump.
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