An estimated 790 million of the world’s population which corresponds to around 11 percent don’t have access to a clean water supply. Many organizations and companies are working on ways to minimize these numbers, and one such team is made up of MIT researchers.
The researchers have come up with a brilliantly simple and natural solution: wood. More specifically, turning nonflowering trees, such as pine, into water filters.
How wood works as a water filter
The inside of this type of wood contains sapwood covered with xylem, these straw-like conduits pull water up through the tree’s trunk and branches. Xylem conduits are interconnected by membranes that work like sieves.
This natural filtering ability is what the MIT team focused on, adding to previous research carried out in 2014.
To keep the wood filters from drying out or self-blocking over time, the team soaked small sections of the wood in hot water for an hour, then dipped them into ethanol before letting them dry. This allows the filter to keep its permeance and prevents the filter from clogging up.
New prototypes were created and tested in real-world situations in India, where over 160 million people lack access to safe and reliable drinking water. It turns out MIT’s xylem filters are capable of removing bacteria such as E. coli and rotavirus — one of the most common causes of diarrhea.
To be precise, the treated filters removed 99 percent of both the aforementioned contaminants — which meets the WHO’s two-star comprehensive protection category.
By simply adding one of these wooden disk filters to a tap, the quality of life can drastically improve.
What’s also great about these filters is that they can be sourced locally from native trees, which is precisely what the team did during the research phase in India.
In the end, the filters tested on-site with the local tap water could reliably remove bacteria, filter purified water at a rate of one liter per hour, and process around 10 to 15 liters of water a day.
Ultimately, these filters show the potential for use in community settings to remove bacteria and viruses from contaminated drinking water.
To help communities quickly, the team has already shared its guidelines for designing and fabricating its xylem wood filter on an open-source website. Now, anyone who is willing to help introduce the system to broader communities can draw upon these safe parameters.
The team’s next steps are to carry out more on-site tests and studies to keep finding the most effective method for everyone involved.