https://phys.org/news/2018-06-seed-millions.html

"F-sand" uses proteins from the Moringa oleifera plant, a tree native to India that grows well in tropical and subtropical climates. The tree is cultivated for food and natural oils, and the seeds are already used for a type of rudimentary water purification. However, this traditional means of purification leaves behind high amounts of dissolved organic carbon (DOC) from the seeds, allowing bacteria to regrow after just 24 hours. This leaves only a short window in which the water is drinkable.

Velegol, who is now a professor of chemical engineering at Penn State University, had the idea to combine this method of water purification with sand filtration methods common in developing areas. By extracting the seed proteins and adsorbing (adhering) them to the surface of silica particles, the principal component of sand, she created f-sand. F-sand both kills microorganisms and reduces turbidity, adhering to particulate and organic matter. These undesirable contaminants and DOC can then be washed out, leaving the water clean for longer, and the f-sand ready for reuse.