The University of Cape Town (UCT) in South Africa rated amongst the best in the world is leading the way in innovation in waste recovery. The university has cemented its place as a top teaching and research institution, recently recording a significant increase in the research category in the latest 2019 Times Higher Education (THE) World University Rankings results.
Researchers from the university have been involved in ground breaking studies in various areas including malaria prevention and treatment, HIV/AIDS, cardiology, and waste recycling. Early this year, Civil Engineering graduate Tinashe Chipako won an award for his recycled urine project that could lead to less flushing and more water conservation. The project investigated the feasibility of implementing waterless urinals on UCT’s upper campus, and also revealed that tons of fertiliser could be made from urine collected on campus.
Following Chipako’s innovative and award-winning study, Suzanne Lambert, a master’s student in Civil Engineering at UCT recently unveiled the world’s first bio-brick grown from human urine a major step in waste recycling. Lambert and civil engineering honours student Vukheta Mukhari have been testing their idea to produce this unique building material with guidance and supervision of Professor Hans Beushausen.
“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.
The development is also good news for the environment and global warming as bio-bricks are made in moulds at room temperature, newsuct says. Regular bricks are kiln-fired at temperatures around 1 400°C and produce vast quantities of carbon dioxide.
The strength of the bio-bricks would depend on client needs.
“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,” said Randall.
Fertilisers as by-products
In addition, the bio-brick process produces as by-products nitrogen and potassium, which are important components of commercial fertilisers. Chemically speaking, urine is liquid gold, according to Randall. It accounts for less than 1% of domestic waste water (by volume) but contains 80% of the nitrogen, 56% of the phosphorus and 63% of the potassium of this waste water.
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. First, urine is collected in novel fertiliser-producing urinals and used to make a solid fertiliser. The remaining liquid is then used in the biological process to grow the bio-brick.
Social acceptance: a consideration
At the moment, the researchers are only collecting urine from male urinals because that’s socially accepted. In the run-up to unveiling the bio-brick, both students expressed optimism about the potential of innovation in the sustainability space, according to newsuct.
“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 UCT, creating a truly sustainable construction material is now a possibility,” Mukhari added.