Human waste has given a new meaning to ‘man-made’ bricks – after research group devised a way of using it to build houses
I know what you're thinking, they must be crappy bricks. But you would be wrong. These bricks are as strong as any other brick, if not stronger.
In the search for more sustainable building materials, scientists have discovered a way to transform human waste into bricks that can be used for building.
However, human feces only accounts for 25% of the material in the bricks, the remaining 75% is made out of traditional clay. Even with using mostly clay, this process would still cut down on 30% of the biosolid material that is sent away to landfills, according to a recent study conducted by researchers from RMIT University in Australia.
Associate Professor Abbas Mohajerani with a biosolids brick. Image credit: RMIT University in Australia
Lead investigator Associate Professor Abbas Mohajerani said the research sought to tackle two environmental issues – the stockpiles of biosolids and the excavation of soil required for brick production.
“Millions of tonnes of leftover biosolids are increasingly stockpiled every year around the globe. Biosolids are a product of the wastewater sludge treatment process. Stockpiles necessitate the use of large areas of increasingly valuable land. Biosolids have many beneficial uses and are currently utilised in agricultural and land rehabilitation applications. However, it is estimated that 30% of biosolids are unused and stockpiled.”
These bricks were tested against traditional bricks and were found to be sturdy and able to hold up to any existing stringent building regulations. I sh*t you not.
In the study, prototypes of these bricks were made and tested to compare with traditional building materials. The tests found that the bricks were sturdy and would hold up to the most stringent global building regulations. The creation of the bricks also uses less energy than traditional building materials, and they are better for insulation as well.
The biosolids bricks are are less energy intensive to create as well as more porous than standard bricks, giving them lower thermal conductivity.
Bricks were produced from three different biosolids samples collected at Melbourne’s Eastern Treatment Plant (left) and the Western Treatment Plant (middle and right)
Adding this extra material would also cut down on the amount of clay and sand that is used for building. According to the study, published in the journal Buildings, explained that :
“A second and seemingly unrelated environmental issue is the massive excavation of virgin soil for brick production. The annual production of 1500 billion bricks globally requires over 3.13 billion cubic metres of clay soil—equivalent to over 1000 soccer fields dug 440 m deep or to a depth greater than three times the height of the Sydney Harbour Bridge.”
They were also more porous and better insulators. The bricks are able to stand up to the strictest building regulations and have added thermal benefits but are also less energy thirsty to make
In last year’s book, The World in a Grain: The Story of Sand and How It Transformed Civilization, author Vince Beiser makes the case that the world is actually running out of sand to keep up with the current demand of products from concrete to computer chips.
The massive dredging projects to harvest sand and clay also has an incredibly detrimental impact on the environment as some of the best clay for building is taken from beneath waterways, causing significant damage to the local wildlife and ecosystem.
Professor Abbas Mohajerani, a civil engineer in RMIT’s School of Engineering and one of the lead researchers in the study, pointed out that this new process could help alleviate two seperate environmental issues at the same time, both the overabundance of biosolid waste, and the unsustainable soil evacuation required for traditional building materials.
“More than 3 billion cubic metres of clay soil is dug up each year for the global brickmaking industry, to produce about 1.5 trillion bricks. Using biosolids in bricks could be the solution to these big environmental challenges. It’s a practical and sustainable proposal for recycling the biosolids currently stockpiled or going to landfill around the globe,” Mohajerani says.
More research is needed before the bricks are thrown into production but early indications are promising.
Previous research has looked into similar avenues and found it is also possible to turn human urine into bricks.
Students in Cape Town collected the human waste from urinals in their university department and mixed it with sand and bacteria.
The process, known as microbial carbonate precipitation, allows the building materials to be created at room temperature, far more energy efficient that firing clay bricks.
The new method instead produces nitrogen and potassium which can be used as commercial fertilisers.
Urine is collected in novel fertiliser-producing urinals and used to make a solid industrial product, with the remaining liquid used to make the brick.
Bacteria in the form of urease breaks down the urea in the liquid urine while producing calcium carbonate through a chemical reaction.
That cements the sand into the desired shape, which could be a column as well as a rectangular building brick.
Previous research has looked into similar avenues and found it is also possible to turn human urine into bricks (pictured)
Hemp has also been proven as a sustainable building material. A relatively new composite material made from wet-mixing hemp shiv with a lime binder, Hempcrete provides a natural, vapour-permeable, airtight insulation material which also has great thermal mass, giving it a uniquely effective thermal performance.