Chemical engineers on the toilet (Day 254)

Chemical engineers on the toilet (Day 254)

5th February 2015

There was a great news story in January about Bill Gates drinking a cup of clean water that, five minutes earlier, had been raw sewage.

It was a fantastic PR stunt that drew attention to how engineers can change the world in all sorts of ways.

It was also a good illustration of how trust is important to get our engineering ideas off the ground.

The 'Omni Processor', which processes the sewage into drinking water, was created by Janicki Bioenergy; a company which received funding from the Bill and Melinda Gates Foundation.

This project reminded me of a similar but separate Gates Foundation initiative called the 'Reinvent the Toilet Challenge.' This initiative sought to develop a waterless, hygienic toilet that doesn't have to be connected to a sewer.

You may think that this blog seems to feature waste a lot; both human ('The original natural gas - poo power') and manufactured ('Plastic waste and oceans of opportunity') - but that's because it's a huge issue! We create vast quantities of both sorts, and chemical engineers are trying to find ways to use it rather than lose it.

In the case of the humble toilet, it's even more important than that. Around 2.5 billion people around the world do not have access to decent sanitation facilities. So since 2011, the 'Reinvent the Toilet Challenge' has awarded grants to teams around the world to find more sustainable ways to deal with human waste.

I thought I would highlight some examples where chemical engineers are playing a crucial role in reinventing the toilet.

UV-ray disinfecting chamber and sand filter toilet. Image credit: University of Toronto

A team from the University of Toronto, Canada, led by a chemical engineer, Professor Yu-Ling Cheng, designed a simple solution that only leaves behind ash as a waste product.

The process first separates the solid and liquid waste, then dries and flattens the solid waste before dropping it into a smolder chamber. The smolder chamber incinerates the flattened solid waste, killing any bacteria and converts it to harmless ash.

Simultaneously, the liquid waste passes through a sand filter and then sterilised in a UV-ray disinfection chamber. The most polluted sand is also fed into the smolder chamber with the other solid waste to be incinerated into ash.

Another example comes from South Africa; Professor Chris Buckley of the University of Kwazulu-Natal, and his Pollution Research Group has taken on the unenviable, yet crucial task of understanding the physical and chemical properties of excreta streams from sanitation systems.

This type of research will be vital in enabling other teams to develop solutions that will actually work when put into practice.

Process and chemical engineers at Cranfield University, UK, have also been working on the 'Nano Membrane Toilet'. This toilet won't required any external energy or water supply, but instead makes use of high-tech nanostructured membranes to clean liquid waste completely. Solid waste will then be fed into a gasifier which will create enough energy to power the membrane process.

Engineering research around the world takes all sorts of forms and is funded in many different ways. The grants that the Gates Foundation awards have the benefit of driving exploration of real-world solutions that make a difference to people's lives.

Chemical engineers, as ever, are playing a key role in developing these solutions.