The world’s first ‘bio-brick’ grown from human urine has been unveiled by the University of Cape Town (UCT) master’s student in civil engineering Suzanne Lambert, signalling an innovative paradigm shift in waste recovery.
Lambert’s supervisor Dr Dyllon Randall, a senior lecturer in water quality engineering, said that the bio-bricks were created through a natural process called microbial carbonate precipitation, that is ‘not unlike the way seashells are formed’.
The brick is made by mixing sand with bacteria that produces urase – an enzyme that 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.
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.
The development is also good news for the environment and global warming as bio-bricks are made in moulds at room temperature, while regular bricks are kiln-fired at temperatures around 1 400°C and produce vast quantities of carbon dioxide. Dr Randall said that the strength of the bio-bricks could also depend on the client’s needs.
“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 Randall, “the longer you allow the little bacteria to make the cement, the stronger the product is going to be. We can optimise that process.”
The concept of using urea to grow bricks was tested in the United States a few years ago using synthetic solutions, but Lambert’s brick uses real human urine for the first time. Her work builds on foundational research by Jules Henze, a Swiss student who spent four months working with Randall on this concept in 2017.
“It’s what I love about research. You build on the foundations of other work,” he commented. In addition to this, the bio-brick process produces nitrogen and potassium as by-products, which are important components of commercial fertilisers.
Could ‘bio-bricks’ become a zero waste solution?
Urine is first collected in novel fertiliser-producing urinals and used to make a solid fertiliser, then the remaining liquid is used in the biological process to grow the bio-brick.
“But in that process, we’re only after two components: carbonate ions and the calcium. What we do last is take the remaining liquid product from the bio-brick process and make a second fertiliser,” he explained. The overall scheme would effectively result in zero waste, with the urine completely converted into three useful products.
In the lead-up to unveiling the bio-brick, both students expressed optimism about the potential of innovation in the sustainability space.
“This project has been a huge part of my life for the past year and a half, and I see so much potential for the process’s application in the real world. I can’t wait for when the world is ready for it,” Lambert said.
“Working on this project has been an eye-opening experience. Given the progress made in the research here at the University of Cape Town, creating a truly sustainable construction material is now a possibility,” Mukhari added.
Lastly, Randall said that 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 said.
The full release by the University of Cape Town can be found here.