We Talked to the Graduate Student Who Made Bricks From Human Pee

Pee contains some pretty amazing stuff. Scientists have known for nearly a decade that it’s possible to produce bricks from bacteria, sand, and urea—a chemical found in urine. Researchers have gone ahead and produced those bricks, now for the first time with human pee.

South African engineer Dyllon Randall from the University of Cape Town, who refers to urine as “the liquid gold of wastewater” due to its chemical contents, has been studying various uses for pee and its components. A graduate student in his lab, Suzanne Lambert, has now unveiled bricks about as strong as clay bricks, produced with human pee through a process called “microbial carbonate precipitation.” Basically, they begin with sand containing bacteria that produce an enzyme called urease. Urease eats the urea in the pee and produces calcium carbonate, gluing the sand in place.

But why pee bricks? According to the University of Cape Town press release, they’re better for the environment because they can be formed at room temperature. By contrast, kiln-fired bricks must be heated to 1,400 degrees Celsius and produce lots of carbon dioxide. Plus, it’s surely a better use for your pee than whatever you’re currently doing with it. 

We chatted with Lambert about what it’s like to make pee bricks.

Gizmodo: Where did you get this idea?

Suzanne Lambert: My supervisor came up with it while he was researching how to make fertilizers out of urine… But he found that the urea was not hydrolizing [breaking down with the help of water]. He was researching what to do with the urea and found a company that uses synthetic urea to produce bricks. So why not use the urea in urine to do the same thing?

G: How do you collect the urine?

SL: There’s a boys’ bathroom opposite the lab. We have a makeshift urinal—a can with a urinal attachment on top. You can detach the urinal to store the urine. I just asked the boys at the university to please donate to me.

G: And what’s the texture of the bricks like? Are they as strong as normal bricks?

SL: The texture is similar to normal bricks. They’re kind of grey. And they’re as strong as bricks. The last test I did, I brought them to 2.5 megapascals. There’s an undergraduate who’s been doing tests and he got one up to 5 megapascals. a clay brick can withstand around 3 megapascals. It’s pretty good. [Author’s note: A military submarine would need to withstand 5 megapascals at 500-meter depths.]

 
G: How does it get so solid?

SL: The idea is mimicking something that happens in nature. Let’s take the way coral is formed. Coral has bacteria on it. The bacteria produce an enzyme that makes a reaction to produce calcium carbonate. I grow bacteria and put it in a sand mixture then the bacteria colonizes within it when you pump the urine through. The bacteria produces an enzyme that converts the urea into carbonate and ammonia.

G: Do people think this is weird?

SL: Some people do. Mostly people are just interested. You can change people’s concept of waste and how we reuse our waste that would otherwise get incinerated in a wastewater treatment plant. It’s pretty great.

G: Do you think people will buy into this? How do you plan on changing their perceptions?

SL: First, these kind of things require putting an idea into people’s brains, and showing them that the bricks don’t smell. It’s an interesting process, and there are so many other applications of these bacteria. It could be cheaper than most methods today. Hopefully the need will supply the change. It may be a little while until it’s something that can be applied in our real world, but it’s not that far away. Maybe it can absorb some of the market. I’m not sure. You can only hope.

[University of Cape Town]