The road to using biosolids

Reducing Melbourne’s growing stockpile of biosolids is a step closer to reality after research finds that they are suitable for use as fill material for road embankments.

Researchers from Swinburne University of Technology undertook the study on biosolids, a by-product of the sewage treatment process, to determine their suitability as stabilised fill in road embankments. 

Biosolids are stockpiled at water treatment plants for three years after being treated and air-dried, with Melbourne producing more than 67,000 tonnes of biosolids a year. The biosolids tested in the research were from the Western Treatment Plant in Victoria.

“We conducted tests on the shear strengths and compressibility of untreated biosolids, as well as biosolids stabilised with additives such as cement, crushed brick and lime,” says Swinburne’s Dr Arul Arulrajah. 

“Biosolids stabilised with the required proportions of various additives are suitable for carrying the embankment and traffic load, and can be used as fill material for road embankments. Untreated biosolids are not suitable.”

Finding innovative uses for biosolids is a key challenge facing the water industry, as the volume of biosolids produced by Melbourne’s growing population increases. Using crushed brick as an additive has additional environmental benefits, as it is traditionally considered a waste material. 

With Melbourne continuing to grow rapidly, this research, supported by the Smart Water Fund, indicates that biosolids can provide a sustainable resource for road embankment construction in new roads, or in the repair or expansion of existing roads.

About the Smart Water Fund: 

The Smart Water Fund is an initiative of Melbourne’s water businesses including City West Water, South East Water, Yarra Valley Water and Melbourne Water in partnership with the Victorian Government. The Smart Water Fund encourages innovation in water recycling, water conservation and bio-solid management to help secure Victoria’s water supplies now and in the future. For further information, visit: http://www.smartwater.com.au