One day, when nature calls, your urine can be used better than being doused into the toilet.
Instead, it can be the main ingredient in building greener offices or new homes.
In one of the latest innovations in the search for environmentally friendly building materials, South African university researchers have made bricks using human urine.
The first of its kind in the world, the coal has a sustainable alternative prospect of standard concrete bricks and bricks, they hope.
The prototype has "grown" from urine using a technique that is somewhat similar to the natural formation of sea shells, taking six to eight days to form.
Innovative discovery is the idea of two University of Cape Town students and a lecturer.
With a grant from the government-run Water Research Council, a feasibility study was launched last year using synthetic urea. And then research increased to use human urine.
"I always want to know why we don't use urine to do the same thing," Dyllon Randall, a lecturer who oversees one of two students, told AFP.
"The simple answer is:‘ Yes, we can. '
A year later they succeeded in producing their first bio-brick in the laboratory.
Using a natural process known as microbial carbonate precipitation, they mix urine, sand, and bacteria to make bricks.
This research is still in the early days. So far, it takes up to 30 liters (eight US gallons) of urine to make only one brick with urine provided by male students at the university via a special urinal.
"We basically make the first biotech from the actual urine," Randall said.
"This process is amazing because basically what we have done is we grow bricks at room temperature."
The first three bricks are on display. They are gray weighted blocks and indistinguishable from standard limestone.
Copying natural processes
Suzanne Lambert, a Master of civil engineering student, admired how the team mimicked "natural processes of nature" to create sustainable ways of building.
"This process mimics the way coral is formed and natural processes produce cement," he said.
Conventional brick or brick fired clay is produced in the kiln, where they are dried at 1,400 degrees Celsius (2,500 degrees Fahrenheit), a process that causes large carbon dioxide emissions.
In contrast, bio-brick "grows" through loose sand that is seeded with bacteria that produce an enzyme called urease.
Urease reacts with urea in urine to produce compounds such as cement which bind with sand.
These products can be formed into various shapes and dry at room temperature – no oven, no greenhouse gas emissions.
"We take something that is considered a waste stream like urine and use it in a truly sustainable process," Randall said.
And for those concerned about the smell of urine seeping from the wall, the good news is that the brick doesn't smell. The smell of strong ammonia from urine disappears after several days of drying.
Fellow researcher Vukheta Mukhari said the strength of bricks can be adapted to the needs of certain buildings but what they produce so far is "as strong as ordinary bricks you find on the market"
Bio-bricks have been produced in the US, but they use synthetic forms of urine.
This, though, is the first to use natural human excrement.
Is bio-brick one day replacing standard or concrete clay?
The key factor is price, but in the initial stages of this development there have been no attempts to examine costs.
"We are still far from actually commercializing this as a full-scale system," Randall warned, but said there was plenty of room for efficiency.
"We currently need between 20 and 30 liters to make one standard brick. That does sound like a lot, but remember that about 90 percent of urine is actually water, "Randall said.
"We want to reduce the amount of urine we need to make one brick, and I'm sure in the next few years it will have far better results." NVG
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