Engineering and characterisation of gymnosperm sapwood toward enabling the design of water filtration devices

Naturally-occurring membranes in the xylem tissue of gymnosperm sapwood enable its use as an abundantly-available material to construct filters, with potential to facilitate access to safe drinking water in resource-constrained settings. However, the material’s behaviour as a filter is poorly understood, and challenges such as short shelf life have not been addressed. Here, Rohit Karnik and co-authors from the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) characterise the operational attributes of xylem filters and show that the material exhibits a highly non-linear dependence of flow resistance on thickness upon drying, and a tendency for self-blocking. This research develops guidelines for the design and fabrication of xylem filters and enhances the understanding of xylem as a filtration material, opening opportunities for engineering a diverse range of low-cost, biodegradable xylem-based filtration products on a global scale.