Researchers from the University of Cape Town have produced the world’s first bio-brick from human urine.
Dyllon Randall, a senior lecturer at the university, said the bricks were created using microbial carbonate precipitation, a process similar to the way seashells are formed.
The process involves mixing loose sand with urease, a protein that breaks down the urea in urine while producing calcium carbonate, which can cement the sand into any shape.
Suzanne Lambert, a master’s student in civil engineering, added that the strength of the bio-bricks could be adjusted. "If a client wanted a brick stronger than a 40% limestone brick, you would allow the bacteria to make the solid stronger by growing it for longer," she said.
The bio-bricks are made in molds at room temperature, as opposed to traditional bricks, which are kiln-fired at temperatures around 1,400°C and produce vast quantities of carbon dioxide.
Synthetic urea has been used to grow bricks previously, but the research is the first time human urine has been used as a source for it.
The process of making the bricks produces nitrogen and potassium as by-products, which are used in commercial fertilisers.
Images courtesy of the University of Cape Town