Efficiency of a microplastic removal system from synthetic wastewater using a chemical process combined with simple filtration

Abstract

Abstract Microplastic contamination in freshwater ecosystems poses a critical environmental challenge, necessitating effective removal technologies in wastewater treatment. This research aims to evaluate the efficiency of a hybrid removal system for polyethylene microplastics (particle sizes 0.15–1 mm) by integrating chemical coagulation with simple sand filtration. The performance of three coagulants—alum, polyaluminium chloride (PAC), and ferric chloride—supplemented with chitosan as a coagulant aid, was optimized across various dosages and pH levels, followed by the evaluation of a sand filter column under different flow rates. The results indicated that coagulation efficacy was pH-dependent, peaking at pH 7, where PAC achieved the highest removal efficiency of 77.41 ± 4.47% for fine 0.15 mm particles, followed by alum (73.22 ± 3.54%) and ferric chloride (63.18 ± 3.63%); notably, the combined system operating at a flow rate of 15 mL/min (Experimental Set 1) attained an exceptional overall removal efficiency of 99.93%. These findings demonstrate that coupling chemical coagulation with low-cost sand filtration offers a robust and scalable solution for significantly reducing microplastic discharge in synthetic wastewater applications.