Who would have expected a toilet to one day filter water, charge a cellphone or create charcoal to combat climate change?

 

These are lofty ambitions beyond what most of the world’s 2.5 billion people with no access to modern sanitation would expect. Yet scientists and toilet innovators around the world say these are exactly the sort of goals needed to improve global public health amid challenges such as poverty, water scarcity and urban growth.

 

Scientists who accepted the Bill & Melinda Gates Foundation’s challenge to reinvent the toilet showcased their inventions in the Indian capital Saturday. The primary goal: to sanitize waste, use minimal water or electricity, and produce a usable product at low cost.

 

To be successful, scientists said, the designs being exhibited at Saturday’s Toilet Fair had to go beyond treating urine and feces as undesirable waste, and recognize them as profit-generating resources for electricity, fertilizer or fuel.

 

The designs are mostly funded by Gates Foundation grants and in various stages of development, though others not created as part of the Gates challenge were also exhibited on Saturday.

 

Some toilets collapsed neatly for easy portability into music festivals, disaster zones or illegal slums. One emptied into pits populated by waste-munching cockroaches and worms.

 

One Washington-based company, Janicki Industries, designed a power plant that could feed off the waste from a small city to produce 150 kilowatts of electricity, enough to power thousands of homes.

 

The University of the West of England, Bristol, showcased a urine-powered fuel cell to charge cellphones overnight.

 

Another team from the University of Colorado, Boulder, brought a system concentrating solar power through fiber-optic cables to heat waste to about 300 degrees Celsius. Aside from killing pathogens, the process creates a charcoal-like product called biochar that can be used as cooking fuel or fertilizer.

 

A team from Beijing Sunnybreeze Technologies Inc. also brought a solar-biochar system, with the solar panels heating air that dries sludgy human waste into nuggets that are then heated further under low-oxygen conditions to create biochar.