Prototype MIT Filter Makes Purified Drinking Water Using Tree Branches

In many parts of the United States, people take clean drinking water for granted. In other parts of the world, access to clean drinking water is a significant challenge and is something that researchers from MIT have been working on. Recently, MIT engineers created a new type of water filtration system that can purify drinking water using tree branches.MIT has tested prototype filters in India and shows promise as a low-cost and natural filtration option. Non-flowering trees, such as pine and ginkgo, contain sapwood that's lined with straw-like conduits known as xylem. Xylem draws water up to the tree's trunk and branches. The conduits are interconnected with thin membranes acting as natural sieves able to filter out bubbles from water and sap.

Engineers from MIT are investigating sapwood's natural filtering capability and have fabricated simple filters from peeled cross-sections of sapwood branches. The experiments have demonstrated that the design can effectively filter bacteria from water. The team has shown that natural filters can remove pathogens from drinking water, such as E. coli and rotavirus, in the wild.

Laboratory testing has shown that the filters can remove bacteria from contaminated spring, tap, and groundwater. MIT also developed techniques to extend the shelf life of the filter to allow the woody discs to purify water after being stored in a dry form for at least two years. The water filtration techniques have been tested in India, where xylem filters were made from native trees and tested with local users.

MIT created a prototype simple filtration system based on user feedback fitted with replaceable xylem filters able to purify water at a rate of one liter per hour. Currently, researchers are investigating options for making xylem filters available at a large-scale in areas where contaminated drinking water is a major cause of disease and death.