UCT make world’s first urine bio-brick

From left, civil engineering Masters student, Suzanne Lambert, Dr Dyllon Randall, senior lecturer in civil engineering and, civil engineering Honours student, Vukheta Mukhari.

The University of Cape Town (UCT) has unveiled the world’s first bio-brick grown from human urine.

Dr Dyllon Randall, a senior lecturer in water quality at UCT, conceptualised this project and supervised his students, Suzanne Lambert and Vukheta Mukhari, for the past year as they aimed to perfect the groundbreaking brick.

Dr Randall said the idea for making bio-bricks was started a few years ago by an American company who made bricks using synthetic urea. Urea is a colourless crystalline compound found in urine and excreted by mammals.

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.

Last year Dr Randall requested funding from the Water Research Commission (WRC) to make bio-bricks from urine.

It was granted as a one-year feasibility study and last Wednesday, October 24, UCT launched the bricks from their labs.

Dr Randall said the methodology was developed last year by his Swiss student, Jules Henze, who did his Master’s thesis at UCT.

This year Ms Lambert used the methodology to grow the first bio-brick from human urine.

With the positive results that came from testing this concept last year, Dr Randall applied for additional funding from the WRC which they received for 2018 and 2019 to take this innovation further.

The urine that is used for this bio-bricks comes from the world’s first fertiliser-producing urinal, which is located in selected men’s toilets at the university.

These men’s urinals have removable containers, which house the fertiliser and remaining urine.

The bio-brick ingredients consist of a gravel/sand mix, urine, extra calcium and food for the bacteria.

The bricks themselves are made through a natural process known as microbial carbonate precipitation.

According to Dr Randall, it’s a process where bacteria breaks down the urea present in the urine to produce calcium carbonate, a type of cement.

“The beauty of this is that you can increase the strength by growing it for longer because more cement is made with time,” said Dr Randall.

For the moment, the bio-brick is made in the lab in a rectangular mould made from perspex.

Ms Lambert, a civil engineering Master’s student, said it takes four to eight days for the bio-brick to grow.

Mr Mukhari, civil engineering Honour’s student, said this project is part of his final year thesis.

According to Dr Randall, the major benefit of this process is that it is more sustainable and reuses waste streams.

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 Dr 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.”

In addition, the bio-brick process produces as by-products nitrogen and potassium, which are important components of commercial fertiliser.

All three academics say the project has taken up a lot of their time and energy.

Ms Lambert said it was a learning curve and Mr Mukhari said they sometimes worked until the early hours of the morning.

“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,” said Ms Lambert.