Innovator Cranfield University, U.K.: Putting down the toilet lid activates a dry flush. The motion turns a set of gears that drop feces and urine into a pan, where they are separated and either combusted into ash that can be thrown away or filtered into clean water that could be used to water plants, for instance, though not drinking. It was one of the few completely standalone toilets at the expo, able to function without links to water, sewer or electric lines.

The Innovator: Helbling Group, Switzerland: Helbling’s self-contained toilet system
Similar to other models, this toilet is a mostly self-contained system that transforms waste into clean water and a form of charcoal. But its makers, who were contracted by the Gates Foundation to develop this model, also had modern design in mind: A sleek, black-and-white prototype includes a touchpad for the flush and a container that can be detached to dump out excess water. While it doesn’t have to connect to water or sewer lines, one limit is that the model still needs electricity from an outside source

Sedron Technologies makes the Janicki Omni Processor, a small-scale waste-treatment plant that can filter wet fecal matter so thoroughly that the resulting water is not only free of bacteria and viruses but also safe for drinking. At its highest capacity the plant can manage waste for up to 500,000 people, the same range as two other plants featured at the expo. A trial has been running in Dakar, Senegal, over the past three years to identify and fix technical problems.

Excerpts  from Flush With Ideas: Bill Gates Pursues the Toilet of the Future, WSJ, Nov. 9, 2018