Toilets in their current form are little different to that devised by Mr Thomas Crapper, that famous purveyor of Victorian sanitary wares. Indeed Mr Bill Gates himself, one of the world’s foremost billionaire philanthropists and businessmen, has questioned whether the artefact that is the flushable toilet should remain in its current, wasteful form for much longer.
“If Thomas Crapper were around today, he would find our toilets quite familiar,” says Bill Gates, “They haven’t seen many advances apart from handles and paper toilet-rolls.” There have also been the addition of S-bends to trap smells, but regardless the concept is the same and Mr Gates has decided it is time for a change.
On August 14th his charity, the Bill & Melinda Gates Foundation, announced the gold, silver and bronze medal winners in its ‘Reinventing The Toilet Challenge’. The aim of the Challenge is to bring safe, affordable and “sustainable” loos to the 40% of the world’s population who lack access to basic sanitation. Up to 1.5m deaths from diarrhoea a year could be prevented.
The specification of the innovative toilets is quite, well, specific. The winning device must cost less than five cents per user per day to operate, require neither a supply of clean water nor sewerage infrastructure to take the waste away, and generate energy and recover salts, water and other nutrients, producing no untoward by-products.
Nevertheless, with just 1 year in operation, the challenge has produced some remarkable results, achieving all of those things and more.
In fact, one of the medal winners, silver in this case, was from Loughborough University in Britain, proving that we must still be considered amongst the world’s foremost toilet experts.
A tank feeds mixed urine and faeces through a rig that heats it to 200°C under high pressure, killing pathogens. Returning the superheated mixture suddenly to atmospheric pressure causes it to separate into its liquid and gaseous components. The gas is used to heat the feed tank. The liquid is fed into a digester that produces enough methane to power the system—and some to spare.
If you think that’s clever, the gold medal winner was developed by Michael Hoffman of the California Institute of Technology, earning him the $100,000 first prize. His toilet uses solar panels to power an electrochemical system that turns waste into useful things. One is a compound which oxidises the salts in urine to generate chlorine, creating a mildly disinfecting solution that can be used to flush the toilet. The second is hydrogen, which is suitable for cooking or for powering a fuel cell to produce electricity. The residue from the process can be used as fertiliser.
The innovative products are being developed into a number of prototypes to test in the field, with the hope that they will become commonplace in the future. The aim is to assist in one of the UN’s most challenging, and thus far failing, Millennium Development Goals: to halve by 2015 the proportion of people without sustainable access to basic sanitation.
Dr Hoffman claims that treating faeces just ‘isn’t sexy enough’ making it hard to get a scientific grant. Frankly, we ask, who has been saying that oxidising urine salts isn’t sexy?