Your Poo is Saving the Planet… and Building Houses

Australians may soon be “shitting bricks” after researchers at RMIT University unveiled a sustainable alternative to the classic brick, made from recycled sewage.

Currently 30 per cent of the world’s biosolid waste, a by-product of treated sewage sludge, is thrown into landfill and is emitting harmful levels of greenhouse gases. These bricks can help reduce that waste by reusing the biosolids.

Lead investigator Associate Professor Abbas Mohajerani, said making a biosolid brick required half the energy of a conventional brick, which could considerably slash the carbon footprint of brick manufacturing companies, and the cost of the brick.

“The biosolid bricks have a good level of organic content, which is a source of energy. So if you add 25 per cent of biosolids to the brick clay mix, you can save around 50 per cent of the energy we require for firing and making the bricks,” Mohajerani told Pro Bono News.  

“Because of that substantial saving, the bricks will be cheaper.”

He said by using up the stockpiles of biosolids, it would also reduce the excavation of soil required for conventional brick production.

“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,” he said.

“It’s a practical and sustainable proposal for recycling the biosolids currently stockpiled or going to landfill around the globe.”

The brick industry has shown great interest in using biosolids as a cheaper and more sustainable option, and Mohajerani said there was a possibility the bricks could be used for projects such as social and affordable dwellings, or public housing.  

“The brick industry are very interested to use biosolids in the production of brick, and I definitely think the future of bricks are biosolid, clay bricks,” he said.

The biosolid bricks have passed strength tests and analysis demonstrated heavy metals were largely trapped within the brick.

But researchers have recommended further testing before large-scale production of the bricks takes place, as biosolids could have significantly different chemical characteristics.

The EU produces over 9 million tonnes of biosolids a year, while the United States produces about 7.1 million tonnes. In Australia, 327,000 tonnes of biosolids are produced annually.

Mohajerani said the issue of biosolid waste had been “out of sight, and out of mind” for many years, but now after extensive development globally, he was excited the bricks were nearly ready for release.

“We have been developing this for five years, not just in Australia, but other countries like America too. I think people are really starting to take it seriously now, so we are very happy,” he said.  

“Obviously everything takes time to get exactly right, but it will happen in the near future.”