Chitosan-based antimicrobial filter media for point-of-use water treatment: a proof-of-concept study

Point-of-use (POU) water treatment systems in decentralised settings often face challenges in achieving effective microbial removal, particularly for viruses. In this study, three chitosan-based antimicrobial filter media-chitosan beads, electrospun nanofibres and chitosan-coated sheep wool-were developed and evaluated using Escherichia coli and MS2 bacteriophages as model microorganisms. Despite the preliminary proof-of-concept nature of this study, all chitosan-based media demonstrated high microbial removal performance. Chitosan beads achieved markedly greater bacterial and viral removal than silica sand and mussel shells, indicating strong and largely irreversible microbial retention. Chitosan nanofibres outperformed unmodified sheep wool, achieving complete initial removal of E. coli and MS2, though repeated use revealed structural fragility requiring mechanical support. Chitosan-coated sheep wool markedly enhanced its antibacterial performance, maintaining E. coli removal above 90% after 95 wash cycles due to stable covalent attachment of chitosan. The enhanced performance is attributed to electrostatic interactions between the cationic chitosan and negatively charged microbial surfaces. Our findings demonstrate the versatility of chitosan across multiple material formats and highlight its potential as a sustainable, high-efficiency antimicrobial platform for controlling microbial contamination in POU water treatment systems. Further development and validation are required for the practical implementation of these materials in POU water treatment systems to reduce microbial contamination in decentralised water supplies.