Johannesburg: Researchers say they have developed the world’s first bio-brick grown from human urine, an advance with significant consequences for waste recycling and upcycling. The bio-bricks are created through a natural process called microbial carbonate precipitation, said researchers from the University of Cape Town in South Africa. Loose sand is colonised with bacteria that produce urease enzyme which breaks down the urea in urine while producing calcium carbonate through a complex chemical reaction.

This cements the sand into any shape, whether it is a solid column or the rectangular building brick described in the Journal of Environmental Chemical Engineering. Regular bricks are kiln-fired at temperatures around 1400 degrees Celsius and produce vast quantities of carbon dioxide. The strength of the bio-bricks would depend on client needs, the researchers said. “If a client wanted a brick stronger than a 40 per cent limestone brick, you would allow the bacteria to make the solid stronger by ‘growing’ it for longer,” said Dyllon Randall, a senior lecturer at UCT. “The longer you allow the little bacteria to make the cement, the stronger the product is going to be.