MIT engineers make filters from tree branches to purify drinking water | Xylem Water Filter

Summary

MIT engineers have advanced the use of xylem, the sapwood in nonflowering trees like pine and ginkgo, as a natural water filter. They demonstrated that xylem effectively removes pathogens such as E. coli and rotavirus from contaminated water. The team developed affordable, easy-to-make filters that could provide clean drinking water in areas with limited resources. These filters are sustainable, using abundant materials, and can be easily fabricated and distributed locally. After testing in India, the team has explored scalable solutions to improve global access to safe drinking water.

Takeaways

• 😀 Xylem, the sapwood in nonflowering trees like pine and ginkgo, acts as a natural filter by drawing water up through the tree and filtering out bubbles, bacteria, and pathogens.
• 😀 MIT engineers have successfully used sapwood's natural filtering abilities to create low-tech filters that effectively remove harmful bacteria, including E. coli and rotavirus.
• 😀 Xylem filters can purify water from contaminated sources like spring, tap, and groundwater, showing promise for improving public health in areas with limited access to clean water.
• 😀 Simple techniques have been developed to extend the shelf-life of xylem filters, allowing them to remain effective for up to two years, even in dry storage.
• 😀 A field test in India demonstrated the viability of xylem filters, with the researchers tailoring designs based on local water contamination and user feedback.
• 😀 The researchers created a prototype filtration system that can filter water at a rate of one liter per hour, using easily replaceable xylem filters that meet World Health Organization water safety standards.
• 😀 The filters are made from inexpensive, widely available materials, allowing for low-cost production and local distribution, which could be integrated into community water purification efforts.
• 😀 The team has launched an open-source website with guidelines to support entrepreneurs and organizations in fabricating xylem filters from various tree types and introducing the technology to broader communities.
• 😀 Xylem filters are particularly well-suited for areas where unfiltered water has been the only option, as they improve water quality and help reduce waterborne diseases.
• 😀 The filters show potential for large-scale production and distribution, enabling users to pay for filters on a daily basis rather than committing to expensive, long-term filter replacements.
• 😀 Although xylem filters have proven effective at removing bacteria and viruses, further research is needed to determine their effectiveness against chemical contaminants like arsenic and fluoride.

Q & A

What is the primary function of xylem in nonflowering trees like pine and ginkgo?

Xylem in nonflowering trees functions as a conduit that draws water up through the tree’s trunk and branches. It contains straw-like structures that are interconnected via thin membranes that filter out bubbles from water and sap.

How have MIT engineers advanced the technology of xylem filters?

MIT engineers have fabricated new xylem filters that can effectively filter out pathogens such as E. coli and rotavirus. These filters have been tested in lab environments and on contaminated spring, tap, and groundwater.

What was the significance of MIT's development of xylem filters in real-world situations?

The significance lies in the successful application of the technology to purify water in real-world situations, such as using xylem filters to remove bacteria from contaminated water sources like spring, tap, and groundwater.

How long can xylem filters be stored while still maintaining their effectiveness?

Xylem filters can be stored for up to two years in a dry form and still maintain their ability to purify water effectively after being rehydrated.

What was the researchers' approach to testing xylem filters in India?

In India, the researchers made xylem filters from native trees and tested them with local water sources. They also conducted interviews, focus groups, and design workshops to understand the water practices, challenges, and preferences of local communities.

How did the local community in India respond to the xylem filter design?

The local community appreciated the use of a natural material, as it was something they could easily recognize. They also preferred a low daily cost for water filtration instead of a larger upfront payment for replacement filters.

What is the filtration rate of the xylem filter prototype developed by the researchers?

The prototype developed by the researchers purifies water at a rate of one liter per hour.

What challenges were identified regarding the natural filtering ability of xylem wood?

The natural filtering ability of xylem wood comes with limitations, including a reduction in permeance as the wood dries and the tendency of the branches’ sieve-like membranes to clog up over time.

What simple treatments improved the performance of xylem filters?

The performance of xylem filters was improved by soaking small cross-sections of sapwood in hot water for an hour, then dipping them in ethanol and allowing them to dry. These treatments helped maintain the filter’s permeance and prevent clogging.

How effective were the xylem filters in removing pathogens like E. coli and rotavirus?

The treated xylem filters successfully removed more than 99 percent of both E. coli and rotavirus, meeting the 'two-star comprehensive protection' category set by the World Health Organization for water treatment.

What is the potential impact of xylem filters on global water purification efforts?

Xylem filters have the potential to significantly improve water purification in areas with limited access to clean water, particularly in regions where waterborne diseases are prevalent, as they are inexpensive, made from locally available materials, and easy to fabricate.