As more bacteria and algae are getting harder to kill, researchers are looking for new ways to eliminate them in water supplies. One idea is to unleash an electron-starved compound that will rip them apart.

Bacteria swim around in water like they own the place, subdividing and spreading. When that water is heading somewhere important - like down the gullet of a human - they have to be bumped off. There are plenty of ways to do that. Water can be treated with harsh chemicals, filtered, or boiled, but a more compact process could be around the corner. After many years of trying to get iron out of water, the new plan may be to put some in.


Iron comes in a lot of different forms. None of them are too permanent, since iron gives up electrons, changing relatively easily. Minor losses of two or three electrons happen all the time. Occasionally, though, iron will combine with oxygen, calcium, and sodium to form a ferrate. This ferrate is missing six electrons, which means that the compound is extremely positively charged, and hungry.

The electron-starved ferrate will take those electrons just about anywhere it can get them. One place it gets them is organic molecules like bacteria and viruses. It will grab for these electrons and rip the organisms apart to get them. The ferrates also attract other particles dispersed in the water. Water is often contaminated with tiny particles, each of which can float through the water as a suspension when alone. Once these particles are clumped together by the greedy ferrate, they precipitate down to the bottom of the water. The last of these precipitates is the ferrate itself, as any extra particles of the compound glom on to each other, fall to the bottom, and leave clean water behind.

This process is not usually used because of the reactivity of ferrates. They can't be stored for a rainy day. If they sit on a shelf too long, they'll attach themselves to any compound nearby and become useless. The only way to make use of them is to make them fresh. However, companies are working on machinery that can make the ferrates from raw materials at water treatment plants.


[Via Science Daily, General Chemical, and The Economist]