Sewage sludge could fuel eco-friendly production of biosolids bricks

Biosolids are a by-product of the wastewater treatment process that can be used as fertiliser, in land rehabilitation or as a construction material.

Around 30 per cent of the world's biosolids are stockpiled or sent to landfill. Now a team at RMIT University in Melbourne has demonstrated that fired-clay bricks incorporating biosolids could be a sustainable solution for the wastewater treatment and brickmaking industries.

Published in the journal Buildings, the research showed how making biosolids bricks only required around half the energy of conventional bricks. Biosolids bricks also had a lower thermal conductivity, transferring less heat to potentially give buildings higher environmental performance.

According to RMIT, the United States produces about 7.1 million tonnes of biosolids a year, the EU over nine million tonnes, and Australia 327,000 tonnes.

The study found there was a significant opportunity to create a new reuse market in the form of bricks.

About five million tonnes of the biosolids produced in Australia, New Zealand, the EU, US and Canada currently go to landfill or stockpiles each year. RMIT maintain that using just 15 per cent biosolids content in 15 per cent of bricks produced could use up surplus biosolids.