The world’s first bio-brick grown from human urine has been unveiled by researchers at the University of Cape Town (UCT)
Dyllon Randall, a senior lecturer at UCT, said the bricks were created using microbial carbonate precipitation, a process similar to the way seashells are formed.
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.
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 concept of using urea to grow bricks was tested in the United States some years back using synthetic solutions, but Lambert’s brick uses real human urine for the first time, with significant consequences for waste recycling and upcycling.
The development is also good news for the environment and global warming as bio-bricks are made in moulds at room temperature.
For the past few months, Lambert and civil engineering honours student Vukheta Mukhari have been hard at work in the laboratory testing various bio-brick shapes and tensile strengths to produce an innovative building material.
Chemically speaking, urine is liquid gold, according to Randall. It accounts for less than 1% of domestic wastewater (by volume) but contains 80% of the nitrogen, 56% of the phosphorus and 63% of the potassium of this wastewater.
Some 97% of the phosphorus present in the urine can be converted into calcium phosphate, the key ingredient in fertilisers that underpin commercial farming worldwide. This is significant because the world’s natural phosphate reserves are running dry.
The fertilisers are produced as part of the phased process used to produce the bio-bricks.
The overall scheme would effectively result in zero waste, with the urine completely converted into three useful products.
Randall said the work is creating paradigm shifts with respect to how society views waste and the upcycling of that waste.
“In this example you take something that is considered a waste and make multiple products from it. You can use the same process for any waste stream. It’s about rethinking things,” he concluded.