The by-product of the sewage treatment process is a substance known as biosolids. After being treated and air dried, biosolids are stockpiled at water treatment plants for three years under health and safety guidelines.
Melbourne Water is responsible for treating about 92 per cent of Melbourne’s sewage, and from this produces over 67,000 tonnes of dried and treated biosolids a year.
With a growing population, Melbourne’s water treatment plants are being left with an equally growing stockpile of biosolids. Finding innovative uses for biosolids is a key challenge facing the water industry.
Melbourne’s Swinburne University is conducting research into an innovative use for biosolids that could help reduce these stockpiles.
Swinburne University researchers have undertaken a project to determine the suitability of biosolids as stabilised fill in road embankments.
The project involves conducting tests on the strength and durability of ‘pure’ biosolids, as well as biosolids stabilised with other additives such as cement, crushed brick and lime.
Based on the test results a technical note for the use of ‘pure’ biosolids as stabilised fill will be created, the first of its kind in Australia.
Field testing, laboratory testing and finite element modelling works have been completed and provided promising results, demonstrating that biosolids can be used as a suitable stabilised fill material in road embankments.
A technical note is presently being prepared for the usage of biosolids in road embankments. The project is scheduled for completion in late 2009.
Enhancing our understanding of the geotechnical properties of biosolids may increase the range of alternative uses of the product.
With Melbourne continuing to grow rapidly, biosolids could provide a sustainable resource for road embankment construction in new housing estates, or in the repair of expansion of existing roads.