Published by the Students of Johns Hopkins since 1896
January 21, 2022

Miracle tree produces cleaner water

By Mo-Yu Zhou | February 8, 2012

What makes a tree a ‘miracle tree'? The plant known as Moringa oleifera, or drumstick tree (due to the shape of its seedpods), has been dubbed miraculous by some who are optimistic about its ability to increase the availability of clean water to areas susceptible to drought and contamination. This thin-branched tree has seeds that attract and destroy bacteria in water. These intriguing properties have led several teams of researchers to investigate the Moringa tree's applications to cleaning water.

Many regions in Asia, Africa and South America that face shortages in potable water also happen to have an abundant supply of Moringa trees. In turn, a single tree can produce a large amount of seeds — up to 15,000. This makes using Moringa trees a relatively sustainable solution to the problem.

A group of researchers from Pennsylvania State University, led by chemical engineer Stephanie Velegol, is one of several teams developing methods to clean drinking water using the Moringa tree. Veleogol's method involves developing a kind of filter that could be easily replicated by people at home. The filter would simply consist of some ordinary sand and Moringa seeds. The team's findings were published last November in Langmuir.

Veleogol's method involves crushing Moringa seeds and mixing them with water. After an hour has elapsed, the water is poured onto some ordinary sand, while the solid pieces of Moringa seed are discarded. The sand is then rinsed after another hour. As a result of this process, the pieces of ordinary sand become coated with the active antibacterial protein from the Moringa seeds.

Using such a filter is superior to simply stirring crushed Moringa seeds into water. This is because the latter method causes water to become contaminated after a while. The seed, while antibacterial at first, will attract new bacteria after a certain amount of time. In fact, according to Habauka Kwaambwa, a chemist at the University of Botswana, water that is treated only with crushed Moringa seeds can only be stored for a maximum of 24 hours. Veleogol's method bypasses this concern by making use of the protein inside the seeds, rather than the seeds themselves.

Currently, many governments distribute chlorine to people who use wells, rivers and ponds as sources of water. However, Moringa seeds may prove to be an attractive alternative. For instance, the taste of chlorinated water is not very pleasant. Research led by Philip Makutsa of CARE Kenya has found that half or fewer of people who have tried chlorinating water continue this method, even though doing so is effective in preventing diarrhea. In addition, locals may find it more appealing to use materials that are readily available.

The team has confirmed that the Moringa filter is effective against E. coli bacteria in water, and muddy water is made clearer by the process. However, the researchers still need to test the filter's effectiveness when in contact with other bacteria. Further research also needs to be done on how much seed is necessary to filter a given amount of water. If it transpires that the Moringa seed method is insufficient in both cases, it may be used alongside chlorine.

If all goes smoothly, the sand filter could be tested in an actual village or town in about a year. While lab studies have confirmed the antibacterial capabilities of the Moringa seed, few field tests have been performed. Jacqueline Firth of the Warren Alpert School of Medicine at Brown University led one such field tests in 2010, but found that the seeds were not very effective.

It remains to be seen whether further tests, both in the lab and in actual villages and towns, will yield positive results. In the meantime, other research teams are working on alternative methods of using Moringa seeds to clean water.

 

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