We're Not the Only Ones Using Dirt to Clean!


Some time back I wrote how we are using soil to clean in the kitchen. Well it turns out that lots of other folks are using dirt to clean things too--in this case--water!

Thirst Relief International is building bio sand filters and teaching households how to use and maintain them, greatly improving the cleanliness of drinking water and all but eliminating diseases caused by contaminated water. Bio sand filters are built with the help of an iron mold. Concrete forms the base of the filter and its center is filled with layers of differently-sized, crushed rock. Two layers of gravel and then fine-grained sand create three levels through which water is poured over the course of three weeks. Slowly on the very top forms what is called a biolayer. Once that final layer has formed, the filter removes 99 percent of the bacteria in water that passes through it and is ready to use.

The drinking water slowly filters through the layers of naturally formed bacteria and sand at a rate of about 1 liter per minute and comes out clean and ready for consumption from a pipe that’s connected through the concrete from the bottom to the side top outlet of the filter. If properly maintained a biosand filter can be used for up to 12 months without the need for much maintenance.

This story is from the Worldwatch blog. Read the entire article here.