Bio-bricks grown from human urine

Researchers from the University of Cape Town developed the world’s first bio-brick grown from human urine.

The bio-bricks are created through a natural process, known as microbial carbonate precipitation. According to the researchers, the process is similar to the way seashells are formed.

To make the bricks, bacteria that produce the enzyme urease colonise loose sand mixed with urine. The urease breaks down the urea in urine, while producing calcium carbonate through a complex chemical reaction. The calcium carbonate binds the sand into any shape, in this case a rectangular building brick. In August, researchers used the same method to create a column. The bio-bricks do not need to be fired in a kiln like regular bricks, saving a lot of CO2 emissions.

For the past few months, the researchers have been testing various shapes and tensile strength of the bricks. The overall strength depends on how long the brick is ‘grown’, or rather, how long the bacteria are allowed to make calcium carbonate.

A few years ago, the process of making bricks with urea was pioneered in the United States, but according to the University of Cape Town, this is the first time real human urine was used, with significant consequences for waste recycling and upcycling.

The bio-brick produces nitrogen and potassium as by-products, which can be used in commercial fertilisers. To make this process easier, the necessary urine is collected in fertiliser producing urinals, which first make a solid fertiliser. The remaining liquid is used to grow the bio-bricks. The liquid that is left after making the bricks is used to make a second fertiliser, making the bricks zero waste.

Photos: University of Cape Town