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The Department of Civil Engineering at the University of Cape Town in South Africa has revealed their work to the world for the first time – the world’s first human urine brick. The research and development team includes master’s student Suzanne Lambert of the Department of Civil Engineering, college student Vukheta Mukhari and their teacher Dr Dyllon Randall.

The world's first human urine brick

How to make human urine biobricks?

Human urine biobricks are made through a process called “microbial carbonate precipitation,” Randall explained. After they collected the men’s urine, they used it to make fertilizer, and the remaining urine was mixed with loose sand and bacteria to make urease.

After a complex chemical reaction, urease can decompose urine to produce calcium carbonate. The calcium carbonate then joins the sand together to complete a human urine biobrick.

In addition, the entire manufacturing process can be carried out at room temperature, unlike ordinary bricks which must be fired in a kiln at a temperature of about 1,400 degrees Celsius. During the high-temperature firing process, a large amount of carbon dioxide is often produced, causing harm to the environment.

How much urine does it take to make a brick?

However, how much human urine is needed to make a standard-sized biobrick? A human urine bio-brick requires about 25-30 liters of human urine. If the average human urine is 300 ml per soak, it would take 100 soaks of human urine to make a standard-sized brick.

At first glance, this seems to require a lot of human urine. However, most of the human urine used to make bricks has been used as fertilizer first, and this amount can make about 1 kilogram of solid fertilizer.

Therefore, Randall calls human urine “liquid gold” because human urine accounts for less than 1% of household wastewater, but in these household wastewaters, 80% of the nitrogen and 63% of the potassium come from human urine, while nitrogen and potassium Exactly what fertilizer is made of.

The strength of human urine bio-bricks is about 40% that of limestone bricks. However, after a few months, it was discovered that as long as the materials put into the mold are changed and the bacteria are given a longer time to adhere to the particles, the strength of the bio-bricks can be doubled, and The whole process is done at room temperature without heating.

Human urine bio-bricks take about 4-6 days to generate. If you want stronger bricks, you have to leave them longer.

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