Students from the University of Cape Town (UCT) in South Africa have created eco-friendly bricks using human urine. These young scientists have made it through a natural process called microbial carbonate precipitation.
For the production process, they collected urine from specially designed male urinals before adding it to sand and bacteria. Once the urine is mixed with sand and bacteria, an enzyme is formed known as urease. As a result of the chemical reaction, urease breaks down the urea in the urine, producing calcium carbonate, which then combines the sand into solid, grey bricks.
The process of brick-making is essentially the same way that coral is made in the ocean, said Dyllon Randall, their supervisor at the University of Cape Town.
The bio-bricks take almost 4-6 days to grow based on the strength required by the client. If someone wants a brick stronger than a 40 % limestone brick, you need to let the bacteria to make the brick stronger by growing it for a prolonged period. At first, they smell like ammonia, but that odour fades away after almost two days.
From left: Dr Dyllon Randall and his students, Vukheta Mukhari and Suzanne Lambert holding Bio-Brick
As per the researchers, these bio-bricks will cause zero waste as these are developed in moulds at room temperature. Generally, normal bricks are baked in high-temperature around 1,400°C kilns that releases vast amounts of carbon dioxide.
The concept of using urea while growing bricks, was first tested in the US before using any synthetic product. Doctor Dyllon Randall, a senior lecturer in water quality engineering, explains, “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.”
Randall puts urine to side by side of liquid gold. According to him, by volume, it contains 56% of the phosphorus, 63% of the potassium and 80% of the nitrogen and accounts for less than 1% of domestic wastewater. The abundance of phosphorous in the urine can be easily altered into calcium phosphate- one main component in fertilisers, which has been used for commercial farming all over the world. This is essential as the natural phosphate reserves of the world are running dry, as per the scientists.
They say that the urine is first collected in the fertiliser-producing urinals and then used for making rocky hard fertiliser. The leftover liquid is then used in the growing of bio-brick and second fertiliser. The entire process would effectively result in no waste, with the urine completely change into three products.
So, on the whole, this is a groundbreaking scientific invention of truly sustainable construction material.