From left, civil engineering Master’s student, Suzanne Lambert, Dr Dyllon Randall, senior lecturer in civil engineering and, civil engineering Honour’s student, Vukheta Mukhari.
From left, civil engineering Master’s student, Suzanne Lambert, Dr Dyllon Randall, senior lecturer in civil engineering and, civil engineering Honour’s student, Vukheta Mukhari.

Proving that sometimes ‘taking the ****’ is a good thing

By LIZ CLARKE Time of article published Feb 23, 2020

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Cape Town - Few would think there was any connection between a sea shell that you find on the beach and a brick used to build a house.

And just to be more outlandish, who would have dreamt that human waste would one day be a part of the construction industry.

The person who knows exactly what you’re on about is Vukheta Mukhari, a master’s candidate in civil engineering at UCT, who with fellow science boffins, has managed to produce a brick that looks and feels like any other brick, but is made from human urine.

Next week at the 25th Design Indaba in Cape Town, he and his eco brick-making team, will be letting the public into their secret and asking industry to support and back their “green” ideas.

They are more than “ideas”, he said. This world-first innovation is the prototype for transforming the building and fertiliser industry and offers enormous opportunities for the recycling of human waste.

He explained the shell concept is nature’s way of showing that hard substances can be made naturally using a mixture of sand, microbes and certain organic elements, in this case ones found in human urine.

Some may be concerned about building a house out of urine - when it rains or the sun brings out bacteria that crawls around the bricks.

Mukhari is quick to dampen that one. “The process we use in stage one kills all harmful pathogens and bacteria. We operate at an extremely high pH level that has been shown to kill, well, pretty much everything.”

Dr Dyllon Randall, a senior lecturer in water quality engineering, says his team, comprising Mukhari and fellow student Suzanne Lambert, use a natural process known as microbial carbonate precipitation to produce the planet’s first bio-bricks.

Tiny blobs of bacteria are let loose in a mixture of sand, producing a busy enzyme that breaks down the urea in urine which by some chemical miracle results in a cement that turns to stone, or in this case shaped into bricks.

The extra benefit is that the process doesn’t require heat or energy, so no damage to the environment. The bricks start to form naturally, within about 48 hours and take between four and six days to “grow” to maturity - or longer if stronger bricks are required.

Mukhari said the sustainability of the project is what interests him most, plus the environmental impact, if any.

The material can also be used to make fertiliser. A typical scenario would involve the collection of urine from a men’s urinal.

Mixed with a lime compound, this would result in the production of calcium phosphates, a key ingredient of agricultural fertiliser and would solve the potential problem of running out of natural phosphorous. It would also solve the issue of algae formed by human waste contaminating dams and rivers and would help save millions of litres of water.

The next question is where would you find large quantities of urine?

“We are conducting our research using urine collected from the campus. However, if the process was to be rolled out, there would need to be a more integrated approach to collection.”

At a recent Sevens rugby tournament in Cape Town it was estimated that the predominantly beer drinking fans managed to produce more than 250000 litres of waste liquid in three days. That could build 30 houses, or maybe a school or a clinic.

Could it be a case of “waste not, want not?”

Weekend Argus

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