Eat, Poop, Brick, Building… What You Eat Is What You Live In
By turning biosolids into bricks you can recycle the world’s stockpiles of treated sewage sludge and boost sustainability in the construction industry, both at the same time! What are biosolids? They are a by-product of the wastewater treatment process that can be used as fertilizer, in land rehabilitation, and now even as a construction material. A team at RMIT University has found a way to turn it into bricks for building.
Statistics show that about 30% of the world’s biosolids are stockpiled or sent to landfill, using up valuable land and potentially emitting greenhouse gases. These clever researchers demonstrated that fired-clay bricks incorporating biosolids could just be one big approach to a sustainable solution for both the wastewater treatment and brickmaking industries. Thus, taking care of one of the worlds ever-growing environmental challenges.
Their research reveals how making biosolids bricks only required around half the energy of conventional bricks. Not only are they cheaper to produce, but they also had a lower thermal conductivity, transferring less heat to potentially give buildings higher environmental performance. They published their findings and study in the “Green Building Materials Special Issue” of the journal Buildings.
Roughly 16,427,000 tons of biosolids are produced annually by the USA, EU, and Australia alone. Of that, 5,000,000 tons goes to landfill to pile up year after year. All of this – the whole 5,000,000 tons – could be used up by using a minimum 15% biosolids content in 15% of bricks produced for construction.
However, this research tackles more than just the environmental issue of the stockpiles of biosolids humans are producing. It also helps alleviate the requirement to excavate soil for brick production. Lead investigator Associate Professor Abbas Mohajerani and a civil engineer in RMIT’s School of Engineering said:
“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.”
Different prototype bricks were tested out to examine their physical, chemical and mechanical properties. The variety of bricks contained different proportions of biosolids, from 10 to 25%.
- All types passed compressive strength tests.
- They have lower thermal conductivity rates than standard bricks because they are more porous.
- When the bricks incorporate 25% biosolids, the brick firing energy demand was cut by up to 48.6%. This is due to the organic content of the biosolids. It could considerably reduce the carbon footprint of brick manufacturing companies.
They conducted a Life Cycle Assessment and an emissions study as part of the research. These tests confirmed that biosolids bricks offered a sustainable alternative approach to addressing the environmental impacts of biosolids management and brick manufacturing.
If you are interested in eco-friendly construction, hemp and soft rush have also been proven to be sustainable building materials. You can read about an old 1960’s home that was renovated with hempcrete here; And you can read about a designer in the Netherlands transforming an invasive weed into furniture and packaging materials here.