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CMU Team Finds The Seed Of A Tropical Plant Filters Water When Mixed With Sand

Carnegie Mellon University
The Moringa oleifera's seed unshelled (left), shelled (middle) and crushed (right). Special proteins in the seed make it an effective water filtration system when mixed with sand.

The seed of a tropical plant and run-of-the-mill sand is all researchers needed to create a powerful water filtration system, according to a team from Carnegie Mellon University refining the process.

The Moringa oleifera tree is native to India and found in many developing countries in tropical and subtropical regions. Proteins inside the tree's seed kill bacteria, and the ground up seed is sometimes used as a rudimentary filtration system.

"But the problem with using it in this traditional way is that eventually bacteria would start growing again," said biomedical engineering professor Bob Tilton.

Bacteria begins to regrow within 24 hours, he said, but when the seed's proteins are absorbed into sand, that mixture is more effective for a longer period of time.

"And now you've got this active filter that's really good at removing solid particles and removing bacteria," Tilton said.

The filtration system looks like a tube filled with average looking, protein-powered sand. When water runs through, bacteria dies and it catches dust and other particles.

"You can use it for a long time, and the water stays safe to drink for a long time," Tilton said. "You don't have to worry about the regrowth of bacteria."

Chemical engineering professor Todd Przybycien said the system is also renewable. Seeds are abundant where they're grown, and the process can be applied more than once.

"It's really easy to regenerate when needed, just adding a little bit of salty water will strip the remaining proteins off the sand and then you can start again with a fresh batch of extract," Przybycien.

The researchers plan to test how dirty water affects the seed-sand combo next.