The Challenge
The image of the toilet hasn’t changed much in over a hundred years. Determined to shake this up, the Bill & Melinda Gates Foundation challenged scientists around the world to reinvent this concept. The toilet would have to cost less than 5 cents a day and be smell free. A team from Loughborough University, headed by M. Sohail (Khan), Professor of Sustainable Infrastructure, responded with a standalone toilet system, which converts human waste into carbonised material that can be used as a fuel or fertiliser. The only UK team awarded a grant in the competition, their prototype won second prize, acknowledging its status as an innovative eco friendly and affordable sanitation solution.

Carbonising the waste
Drawing on their extensive experience in the area of water and sanitation, their principle is simple. Using a process called continuous hydrothermal carbonisation, which heats the waste material to 200 °C under 20 Bar pressure and converts the waste material into a substance that smells like coffee and can be used for energy harvesting or other purposes.

Sohail points out, ‘when you eat food you know its calorific value. What comes out of our body still has energy, which we don’t use. We use 4.5 litres of water, which is purified just to flush out the toilet. We take the waste for miles and then in many countries it doesn’t even get treated. So it seems pretty daft that we are not using the natural energy that is available. Basically, what we are trying to do is to make it so there is more energy coming out of the process.’

Improving the toilet experience
The process behind their toilet is totally different. As Sohail explains, it doesn’t involve the cost of miles of pipes and treatment plants and chemicals. The project designers are also finding ways to enhance the ergonomic design of the toilet itself, taking advantage of latest technology, to improve the toilet experience for everyone.

Their next challenge is to make the unit smaller and experiment with the waste, which in practical terms will vary depending on the diet of its users. The first field test will be on the university campus where the variety of users will be a good test. Like the car, Sohail foresees different models for different countries.