Analysis of the Effectiveness of the Energy-Efficient Gravity Filtration Process in Terms of Its Application as the Third Stage of Wastewater Treatment

The energy self-sufficiency of wastewater treatment plants has become an essential aspect of sustainable water and energy resource management. On the other hand, due to the expansion of urban conglomerations and agricultural activities, as well as more frequent and erratic meteorological phenomena (e.g., droughts), the majority of EU nations are confronted with water scarcity and the deterioration of water quality. As a consequence, EU member states pledged to implement “tertiary treatment” in all municipal wastewater treatment facilities by the end of 2040. This publication presents an analysis of the efficiency of an energy-efficient gravity cloth disk filter used for treating municipal wastewater in a treatment plant located in a tourist resort in Poland, operating under variable hydraulic loading conditions. Gravity cloth disk filters appear to be the least energy-consuming. The energy consumption of disk filters was 13 Wh/m 3 in 2024. The filter ensures the leveling of disturbances in the operation of earlier treatment stages, particularly in terms of retaining total suspended solids (TSSs). The achieved efficiency of TSS removal was 45%. The TSS value in the outflow from the filter did not exceed the limit value from the permit (35 mg/L). When operated correctly, additional filtration and disinfection may become essential components of a wastewater treatment plant, enabling the achievement of wastewater quality that supports water recovery for technological and agricultural purposes, particularly in small, non-industrial areas. They should also consume less energy than other advanced technologies used in the third and fourth stages of wastewater treatment.