Coagulation−flocculation for removal of microplastics: Dosage reduction while efficiency improvement with a water-borne bio-flocculant

This study developed a sustainable ternary coagulation−flocculation system incorporating a novel jute powder-derived water-borne bio-flocculant (WBBF) for efficient microplastics (MPs) remediation. Under baseline conditions using simulated water containing 100 mg/L MPs (size: 50 −100 μm), the exact optimized dosage thresholds were determined as 50 mg/L PAC, 3 mg/L PAM, and 1.2 mL/L WBBF. This ternary system achieved exceptional removal efficiencies of 98.36% for PET, 94.02% for PS, and 92.88% for PE. Crucially, the integration of WBBF yielded profound chemical-saving performance, slashing the required dosages of inorganic PAC by 50% and synthetic PAM by over 90% compared to traditional binary regimes. Coexisting anions (CO32 −, SO42−) and humic acid (HA) inhibited removal by altering Zeta potentials and inducing steric hindrance, whereas cations (Mg2+, Ca2+) exhibited concentration-dependent effects. To validate practical scalability, real-water testing in lake water demonstrated that the system maintains highly efficient and robust MP containment performance. Mechanistic analyses confirmed that WBBF operates via charge neutralization, adsorption bridging, and sweep flocculation, resulting in an effective reduction in sludge production by 12.15% and residual aluminum by 11.54%. These findings demonstrate that the WBBF-based ternary system provides a highly efficient, economically viable, and eco-friendly strategy for upgrading conventional water treatment facilities.