Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
D-Lab, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nat Commun. 2021 Mar 25;12(1):1871. doi: 10.1038/s41467-021-22055-w.
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 behavior as a filter is poorly understood, and challenges such as short shelf life have not been addressed. Here, we characterize 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. We develop guidelines for the design and fabrication of xylem filters, demonstrate gravity-operated filters with shelf life >2 years, and show that the filters can provide >3 log removal of E. coli, MS-2 phage, and rotavirus from synthetic test waters and coliform bacteria from contaminated spring, tap, and ground waters. Through interviews and workshops in India, we use a user-centric approach to design a prototype filtration device with daily- to weekly-replaceable xylem filters, and uncover indicators of social acceptance of xylem as a natural water filter. Our work enhances the understanding of xylem as a filtration material, and opens opportunities for engineering a diverse range of low-cost, biodegradable xylem-based filtration products on a global scale.
在裸子植物边材组织中自然存在的细胞膜使边材可作为一种丰富的材料来构建过滤器，有可能在资源有限的环境中促进获得安全饮用水。然而，这种材料作为过滤器的性能尚不清楚，而且还存在寿命短等挑战。在这里，我们描述了木质部过滤器的工作特性，并表明该材料在干燥过程中表现出对厚度的流动阻力具有高度非线性的依赖性，并且具有自阻塞的趋势。我们为木质部过滤器的设计和制造制定了指导方针，展示了具有 >2 年货架寿命的重力操作过滤器，并表明该过滤器可以从合成测试水中去除 >3 对数的大肠杆菌、MS-2 噬菌体和轮状病毒，以及从受污染的泉水、自来水和地下水去除大肠菌群。通过在印度的访谈和研讨会，我们采用以用户为中心的方法设计了一种原型过滤设备，该设备使用可每日至每周更换的木质部过滤器，并揭示了木质部作为天然水过滤器被社会接受的指标。我们的工作提高了对木质部作为过滤材料的理解，并为在全球范围内设计各种低成本、可生物降解的木质部过滤产品开辟了机会。
