scientists make world's first bio-brick using human urine

students from the university of cape town have made the world’s first bio-brick made using human urine. the young scientists developed the new building material by collecting urine from specially designed male urinals before mixing it with sand and bacteria.

the bio-bricks are created through a natural process called microbial carbonate precipitation. this process sees the production of an enzyme called urease once the loose sand is colonised with bacteria. 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 in this case, a rectangular building brick.

all images courtesy of the university of cape town

the use of these bio-bricks would effectively result in zero waste as they are made in moulds at room temperature. regular bricks are kiln-fired at temperatures around 1,400°C and produce vast quantities of carbon dioxide. 

the concept of using urea to grow bricks has been tested in the united states before using synthetic products, but UCT master’s student suzanne lambert is the first to use real human urine to make a brick, according to the university. the urine is collected from fertiliser-producing urinals, which are also used to make a solid fertiliser. the remaining liquid is used to grow the bio-brick.

‘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,’ dr dyllon randall, a senior lecturer in water quality engineering, explains.

according to the scientists the strength of the bricks can be optimized to suit the client’s specific needs by prolonging the growing process. ‘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, likening the process to the way seashells are formed.

randall compares urine to liquid gold. by volume, it accounts for less than 1% of domestic waste water but contains 80% of the nitrogen, 56% of the phosphorus and 63% of the potassium of this waste water. the vast majority of the phosphorus present in the urine can be converted into calcium phosphate, a key ingredient in fertilisers that supports commercial farming worldwide, but one that is running dry.

despite the positive result of real life applications the students behind the development forecast some logistics that would need to be considered, including urine collection and transport to a resource recovery. still, they express optimism about the potential of innovation in the sustainability space: ‘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,’ said vukheta mukhari, a civil engineering honours student who worked with lambert.