Circular Economy Approach to Wastewater Treatment: Reuse of Synthetic Wool Waste as a Filtration Material for Domestic Wastewater Treatment

The treatment of domestic wastewater remains a significant environmental challenge, particularly in rural areas where the construction of sewer systems is often not economically viable. Vertical-flow filters offer an alternative, but traditional filter media are prone to clogging, which justifies the search for new waste-based fillers. The aim of this study was to evaluate the potential of synthetic waste wool as a filter medium and biofilm carrier in vertical filters for domestic wastewater treatment, with particular emphasis on the effects of active bed height and hydraulic loading rate. Experimental models were used to assess the influence of these parameters on treatment performance. High removal efficiencies of organic pollutants and suspended solids were achieved. The filter with an active bed height of 0.9 m that operated at a hydraulic loading rate of 80 dm3·m−2·d−1 achieved removal efficiencies of 93.06–97.65% for BOD5, 86.53–94.20% for COD, 62.69–87.53% for TSS, and 65.73–94.31% for NH4+-N. The most favorable treatment results were obtained for a greater bed depth and lower hydraulic load values. An increase in hydraulic load resulted in a deterioration of the quality of the treated wastewater. The results obtained indicate that waste synthetic wool can serve as a promising filtration material in decentralized wastewater treatment systems, aligning with the principles of the circular economy and the sustainable development of environmental technologies.