“Waste Zapper,” Caltech's Solar-Powered Toilet - a waterless sanitation solution

Tuesday, November 19, 2013 |

Some 2.5 billion people—more than a third of the world's population—lack clean toilet facilities. Such poor sanitation causes diarrhea, which kills 800,000 children each year. A Caltech team led by Michael Hoffmann, a professor of environmental science, is creating a new toilet to solve the problem. This design, which recently won a grant from the Gates Foundation, costs less than a nickel per person per day to run, while requiring minimal maintenance.
How It Works:

To minimize transport costs, the toilets are housed in shipping containers. In December, two units will be shipped to India for field-testing.
The toilet has to work in areas without electricity. But to be sustainable, it also needs a water-recycling pump. The requisite juice comes from solar panels, which also power the sterilization process. To prevent theft, the assembly is cemented in place.
Water Spray
When toilet paper is available in Southeast Asia, it's customary to throw it in a wastebasket to prevent pipes from clogging. The wastebasket thus becomes a disease vector. These washrooms reject TP in favor of a purified-warm-water spray and blow-dryers.
Electrochemical Treatment
Remaining water is sterilized electrochemically and ready for another flush within four hours. By that time, it's also clean enough to be used for irrigation—creating revenue for the toilet's  manager on top of per-use fees.