Nature
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A team of researchers from the University of Cape Town (UTC) is changing how we treat our waste, and we’re not talking about taking out the recycling. Rather, this crew is growing building bricks from human urine.
The innovative bio-brick building material comes in various shapes and strengths meant to suit a person’s specific design needs. Created in the same way seashells are, the edgy technology employs a natural process called microbial carbonate precipitation. Urine from specially designed fertilizer-producing male urinals and is mixed with loose sand that is colonized with bacteria, producing urease. This enzyme breaks down the urea in urine to produce calcium carbonate by way of chemical reaction, cementing the sand in its mold at room temperature. By comparison, traditional bricks are kiln-fired at around 400°C, creating carbon dioxide in the process. Even cooler is the fact that the strength, size, and shape of a bio-brick can be tailored to individual 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 civil engineer Dyllon Randall in a statement. “The longer you allow the little bacteria to make the cement, the stronger the product is going to be. We can optimize that process.”
The bio-brick builds on previous US research that used a similar process but with synthetic solutions meant to mimic urine. UTC’s work is the first to use actual human urine which, as it turns out, produces nitrogen and potassium as a by-product that can be used in commercial fertilizers.
That’s right. Urine is literally liquid gold. Although our pee accounts for less than 1 percent of domestic wastewater by volume, it contains 80 percent of nitrogen and more than half of phosphorus and potassium in wastewater systems. Almost all of the phosphorus found in urine can be converted into calcium phosphate, a key ingredient in commercial farming globally.
In short, urine is collected in special fertilizer-producing urinals that create a solid fertilizer. From there, the leftover liquid is then used to grow the bio-bricks using calcium and carbonate ions not extracted from the urinal. After the bricks are made, any excess products are made into a second fertilizer. So, our pee is made into three useful products essentially leaving zero waste behind.
But not everyone is as stoked about pee bricks as we are. At least, not yet. Randall says logistics are an issue (collecting and transporting pee is sort of icky). Plus, people are weird about human waste, so researchers need to create a culture that accepts pee-bricks from both male and female sources.
