Growing bricks from…pee

The world’s first bio-brick made using human urine was unveiled at UCT this week. In picture are (from left) the Department of Civil Engineering’s Dr Dyllon Randall and his students,Vukheta Mukhari and Suzanne Lambert. Credit: University of Cape Town
The world’s first bio-brick made using human urine was unveiled at UCT this week. In picture are (from left) the Department of Civil Engineering’s Dr Dyllon Randall and his students,Vukheta Mukhari and Suzanne Lambert. Credit: University of Cape Town

Being a civil engineer (BSCE ’78) myself, it’s always fun to find out about new building materials. Would you believe that a master’s candidate from the University of Cape Town (UCT), Susan Lambert, has figured out a way to “grow” bricks from human urine?

These bio-bricks are made by a process called microbial carbonate precipitation. Loose sand is colonized with bacteria that produce urease, an enzyme that breaks down the urea in urine while producing calcium carbonate. The calcium carbonate cements the sand into any shape, like a brick or column. Natural limestone is made up primarily of calcium carbonate, by the way.

Even more amazing, the bio-bricks don’t need to be fired in a kiln. Regular bricks require kiln firing that uses a lot of energy.

The entire process is pretty incredible: they collect the urine from fertilizer-producing urinals (yep, it’s all male pee for now) that make a solid fertilizer. The remaining liquid is used to create the bio-brick. The final liquid left over from the bio-brick production can make a second fertilizer. The ultimate goal is to have zero waste from urine with fertilizers and bricks — good for helping food production and building structures — as the products.

 

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