Simultaneous Removal of Microplastics and Total Suspended Solids from Wastewater via a Novel Organosilane-Induced Agglomeration–Fixation Method at a Two-Stage Treatment Plant in Greece

Abstract

This study evaluated the performance of a pilot unit for the combined removal of microplastics and total suspended solids at the municipal wastewater treatment plant of Mykonos, Greece. The pilot unit was installed downstream of the two-stage conventional activated sludge line and operated in semi-continuous mode to demonstrate its function under real effluent conditions. Across five experimental loops, influent microplastics concentrations ranged from 633 to 5843 microplastics/L, while effluent values were reduced to 96–263 microplastics/L, corresponding to an average removal efficiency of 86 ± 8%. In parallel, total suspended solids decreased by 95 ± 3%, turbidity by 93 ± 7%, and chemical oxygen demand by 70 ± 20%, while pH and conductivity remained stable. Influent water showed pronounced variability in chemical oxygen demand, total suspended solids, and turbidity due to irregular wastewater deliveries, yet the pilot consistently stabilized the effluent quality. A correlation analysis revealed strong associations between turbidity, total suspended solids, and chemical oxygen demand in the influent, while effluent data indicated close links between microplastics removal and particulate reduction. These findings confirm the robustness of the organosilane-based agglomeration process and highlight its potential as an advanced treatment stage to reduce MP emissions, improve effluent stability, and mitigate environmental risks in receiving environments such as the Mediterranean Sea.