Many only consider the importance of urine when they are facing health disorders that require urine tests. But a University of Cape Town researcher and chemical engineer has shown there is more to this “liquid gold” than meets the eye, using urine to make innovative building material.
Associate professor Dyllon Randall’s work in making bio-bricks from urine is receiving attention after he won a prestigious innovation award – the SA Institution of Chemical Engineers (SAIChE) 2021 innovation award – for developing the environmentally friendly brick, which also produces a fertiliser as its byproduct.
Bio-bricks are produced through a natural process called carbonate precipitation, which involves the collection of urine, stabilising it by keeping the urea in solution, and passing it through a reactor mould. Loose sand, including lime, is colonised with bacteria that produce an enzyme called urease, which breaks down the urea in urine while producing calcium carbonate through a complex chemical reaction. This cements the sand into a solid brick.
Multi-award-winning researcher Randall, a chemical engineer by training and an associate professor in water quality engineering in UCT’s department of civil engineering, will receive the award later this year.
He said of his recognition: “This award means a great deal to the work we are doing in the wastewater and resource recovery space. I have been blessed with incredible students, and our work continues to inspire the next generation of engineers. I hope the award illustrates that we can think differently about systems that we take for granted so that a more sustainable and equitable future is achievable.”
Randall said they were working on optimising the process and using other waste material such as mine tailings.
Process Optimisation and Resource Management chief executive Hamied Mazema, a UCT alumnus who nominated Randall for the award, said: “As a longstanding member of the Institution of Chemical Engineers, I first read about Dr Randallʼs fascinating work, which was truly innovative.
“I was really thrilled to see that one of our UCT alumni had been the first African to win one of the suite of awards, and when (the institution) called for nominations for the innovation award, I promptly called Dr Randall to ask his permission to nominate him.”
Work is proceeding to optimise the production process to improve the bio-bricks’ compressive strength to exceed that of clay-baked bricks and cement bricks. Both have high carbon footprints. The economic feasibility of the bio-bricks is also being investigated as a replacement building material.
Randall was praised for other attractive aspects of the process, and especially the byproducts that consist of an aqueous stream rich in valuable nitrogen, phosphorus and potassium. These are valuable agricultural resources as nutrients for plants.
Phosphorus, a major chemical component of urine, would extend its availability as an ingredient of the fertilisers that are key to meeting the increased demand for food production from a growing world population.
Removing urine from sewage would also reduce the load on sewerage plants. Randall said as such, this zero-waste process “meets multiple Sustainability Development Goals and forms an important element of the circular economy”.
In making their decision, the judging panel noted that the project, backed by a wealth of published and documented evidence, was novel and addressed critical social needs.
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