Filters from Tree Branches Purify Drinking Water

摘要

The interiors of nonflowering trees, such as pine and ginkgo, contain sap-wood lined with straw-like conduits known as xylem that draw water up through a tree's trunk and branches. Xylem conduits are interconnected via thin membranes that act as natural sieves, filtering out bubbles from water and sap. Engineers have fabricated simple filters from peeled cross-sections of sapwood branches, demonstrating that the design effectively filters bacteria. New xylem filters were developed that can filter out pathogens such as E. coli and rotavirus in lab tests and can remove bacteria from contaminated spring, tap, and groundwater. The team also developed simple techniques to extend the filters' shelf-life, enabling the woody disks to purify water after being stored in a dry form for at least two years.