Washington: A new "eco-vapour" toilet system being tested in India uses a breathable fabric that traps human waste and allows only water vapour molecules to escape, rendering sewage less hospitable to bacteria and other disease-causing organisms.
A team of researchers led by Steven K Dentel, professor of civil and environmental engineering at the University of Delaware in the US, has been working for several years on a breathable fabric that can be used to line pit toilets and other basic sanitary facilities in developing nations.
The fabric Dentel and his team are developing is similar to that used in sports jackets and raincoats; it only allows tiny water vapour molecules through.
Dentel said this could be a valuable way to filter out liquid water from human waste, letting the pure water escape while retaining everything else.
Sewage placed in a container of this fabric would become dehydrated and therefore less hospitable to bacteria and other disease-causing organisms.
Funded by the Bill and Melinda Gates Foundation, researchers have been working on the project for some time now.
On December 28, a small group led by doctoral student Shray Saxena headed to India to begin the first field test of the new fabric.
"A lot of people in India right now don't have improved toilet systems. Even in cities like Kanpur (UP), which are really quite developed, people do not have these facilities available to them," Saxena said.
Families in two cities, Kanpur and Puri in Odisha, are trying out the new "eco-vapour" toilet system, with sewage collected in 55-gallon drums lined with the breathable fabric, allowing water vapour to evaporate.
The researchers are observing how the fabric performs under varying conditions of heat and humidity, which affect the rate at which water diffuses through the membrane.
If external humidity is high, the lined drums may fill up before enough of the water can evaporate.
A nongovernmental organisation WaterAid India is partnering with the research group on site selection and implementation of the pilot project.
Approximately 2.5 billion people around the world are still without adequate sanitation, which leads to water contamination responsible for hundreds of thousands of deaths each year.
About a billion people still have to defecate in the open, without any privacy or sanitary facilities.