Biosolids have traditionally been processed into things such as fertilizer, compost, and biogas. But a new study has looked into converting biosolids into bricks. It would become an ideal solution for developing renewable materials for construction making it affordable and readily available.
The United States produces about 7.1 million tonnes of biosolids, the EU over 9 million, Australia approximately 327,000 tonnes and Canada around 660,000 tonnes.
It is estimated that around 30% of the world’s biosolids end up either being stockpiled or used for landfills which could emit greenhouse gases. About 5 million tonnes of biosolids produced in Australia, New Zealand, the EU, US and Canada that would’ve gone into landfill or stockpiles could be used for brick making instead.
The potential to use biosolids in creating bricks would not only revolutionize low-cost construction but also reduce the harm it may cause the environment.
A team from RMIT University in Melbourne, Australia, has taken on the challenge of providing a sustainable solution for both the wastewater treatment and brickmaking industries by incorporating biosolids into fired-clay bricks.
Their research showed that making bricks from biosolids only required around half the energy of conventional bricks. This is just one of the findings that were published in the journal Buildings. They also discovered that biosolids bricks are more porous than standard bricks, giving them lower thermal conductivity. This would give buildings higher environmental performance because of the reduced heat transfer.
Abbas Mohajerani, the Associate Professor leading the research has sought to tackle two environmental issues—the stockpiles of biosolids and the excavation of soil required for brick production.
Mohajerani, a civil engineer in RMIT’s School of Engineering, said that “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.”
The physical, chemical and mechanical properties of fired-clay bricks were examined with different proportions of biosolids, ranging from 10 to 25%. It showed that the biosolid-enhanced bricks passed compressive strength tests and analysis and demonstrated that heavy metals are largely trapped within the brick.
The organic content of the biosolids has been show to cut the firing energy needed by up to 48+% for bricks that incorporated 25% of biosolids. This means that biosolid bricks could considerably reduce the carbon footprint of brick manufacturing companies.
A comparative Life Cycle Assessment and emissions study conducted as part of the research confirmed that biosolid bricks offered a sustainable alternative approach to addressing the environmental impacts of biosolids management and brick manufacturing.
More testing still needs to be done however before it can be recommended for large-scale production because biosolids exhibit significantly different chemical characteristics that still merit further study. The results so far look promising.
If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us on 1 (877) 479-1388