Phys.org [phys.org]:
The world's first bio-brick grown from human urine has been unveiled by University of Cape Town (UCT) master's student in civil engineering Suzanne Lambert, signalling an innovative paradigm shift in waste recovery.
The bio-bricks are created through a natural process called microbial carbonate precipitation. It's not unlike the way seashells are formed, said Lambert's supervisor Dr. Dyllon Randall, a senior lecturer in water quality engineering.
In this case, loose sand is colonised with bacteria that produce urease. An enzyme, the urease breaks down the urea in urine while producing calcium carbonate through a complex chemical reaction. This cements the sand into any shape, whether it's a solid column, or now, for the first time, a rectangular building brick.
If you're been looking for more uses for pee, you're in luck.