A coating that lets toilets ‘self-clean’ by preventing unsightly stains from sticking to the inside of the pan could save 70 billion litres of water a day worldwide.
Not only does the treatment dispense with the need for unpleasant scrubbing, but the two-layered slippery surface it forms cuts a toilet’s water use by half.
The coating — which can be sprayed on, sets in five minutes and lasts up to 500 flushes — also repels bacteria and can be applied to urinals as well.
More than 141 billion litres of water are used to flush toilets across the globe every day.
‘With millions of global citizens experiencing water scarcity, what if that amount could be reduced by 50 per cent?’ said paper author and mechanical engineer Tak-Sing Wong of the Penn State University in the US.
‘Our team has developed a robust bio-inspired, liquid, sludge and bacteria-repellent coating that can essentially make a toilet self-cleaning.’
The new method — dubbed the liquid-entrenched smooth surface, or ‘LESS’ — is a two-step spray that lasts up to 500 flushes before needing to be reapplied.
It first covers the ceramic bowl in an ‘extremely smooth’ liquid repellent and then adds a layer of lubricant to make the toilet pan even slippier.
When it dries, the first spray grows molecules that look like little hairs, with a diameter of about 1,000,000 times thinner than a human’s,’ said Professor Wong.
‘The second spray infuses a thin layer of lubricant around those nanoscopic “hairs” to create a super-slippery surface.’
The researchers tested the spray against synthetic excrement and found that it left the bowl, in their words, ‘spotLESS’.
‘When we put that coating on a toilet in the lab and dumped synthetic faecal matter on it, [the waste] just completely slid down and nothing sticks to [the toilet],’ explained Professor Wong.
The team hopes that their latrine treatment will make waterless toilets and urinals more pleasant — while allowing any saved water to be directed towards drought-stricken areas.
‘Poop sticking to the toilet is not only unpleasant to users, but it also presents serious health concerns,’ added Professor Wong.
‘If a waterless toilet or urinal used the LESS coating, these types of fixtures would be more appealing and safer for widespread use.’
The coating takes just five minutes to set, unlike other surface-sprays which can take hours.
The researchers have set up a company called spotLESS Materials, which aims to bring their slippery spray to market and has already attracted a lot of interest.
‘As a researcher in an academic setting, my goal is to invent things that everyone can benefit from,’ said Professor Wong.
The full findings of the study were published in the journal Nature Sustainability.
What is China’s ‘toilet revolution’?
The ‘toilet revolution’ is an initiative launched by Chinese President Xi Jinping in April 2015 to improve sanitary conditions in mainland China, especially in rural areas and tourists attractions.
Overseas visitors have long complained about poorly maintained or primitive open-pit and squat toilets in the country.
In rural areas, some toilets were little more than makeshift shelters surrounded by bunches of cornstalks, and some were open pits next to pigsties, leading to unhygienic living conditions.
Most importantly, the poor sanitary conditions contributed to the spread of diseases such as dysentery, cholera, hepatitis and infectious diarrhoea, according to state broadcaster CCTV.
The overhaul was backed by more than 1 billion yuan (£110 million) in central government funding and over 20 billion yuan (£2 billion) from local authorities.
By Octover 2017, more than 68,000 public bathrooms were reconstructed and upgraded across various tourist destinations in the country – 19 per cent more than the target number, according to Xinhua News.
In several bigger cities, such as Beijing, Haikou and Taiyuan, plusher public toilets have been built, offering bank ATMs, snack machines, Wi-fi and recharging stations for mobile phones and electric cars, according to South China Morning Post.
Some toilets have also been expanded to include bigger unisex cubicles for the disabled, elderly and adults with young children.
Last year, authorities announced plans to expand the campaign to cover more rural areas.
Another 64,000 public toilets are set to be installed or upgraded at tourist spots from 2018 to 2020, according to an action plan released by the China National Tourism Administration.
The construction of clean toilets is an important part of pushing urban and rural civilisation, and more efforts should be made in both cities and rural areas to upgrade toilets, Xi previously said.
Along with the toilet revolution, China should construct better public facilities and services to boost the tourism industry, Xi added.
Source: dailymail
