Turning bio-solids into bricks

A research team at RMIT University in Melbourne, Australia, has found a method to turn bio-solids into sustainable bricks.

Bio-solids are nutrient-rich organic materials that derive from domestic sewage. If they are properly treated, they can be used for productive purposes (e.g. as a fertilizer to improve soil's production). Currently, about 30% of bio-solids worldwide are not recycled ending up in landfills. When Europe, United States and Australia produce annually over 9, 7.1 and 0.3 million tons of bio-solids, respectively, it is certain that this environmental challenge has to be addressed.

Researchers have found a reliable solution which will deal with the aforementioned issue and will also benefit construction industry. According to their study, fired-clay bricks can be manufactured using bio-solids, a procedure which needs half the energy of conventional brick production and therefore, is cost-effective. Moreover, bio-solids will provide the bricks with lower thermal conductivity, improving building's environmental performance.

The team investigated the physical, chemical and mechanical characteristics of the bricks produced using 10% to 25% bio-solids. Those bricks performed well under uniaxial compression tests but the analysis showed that their chemical behavior is much different from conventional bricks and thus further investigation is needed.

Abbas Mohajerani, leader of the research and Associate Professor of RMIT University, said that their attempt will also resolve the issue of large soil excavations needed to produce bricks. "More than 3 billion cubic meters 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."