Veolia has installed a Bioreactor in Ipswich - a responsible alternative to polluting landfills. Biogas produced as the waste ferments is recovered and turned into green electricity.
Ti Tree produces enough green electricity to power 2,500 households every day.
Waste management is one of the major environmental issues of the 21st century. At the moment most of our garbage ends up in open dumps, where it contributes to global warming. In fact, as it decomposes, waste naturally releases biogas - a mixture of methane and carbon dioxide, two substances that have a powerful heating effect. Now it’s possible to recover this biogas in order to produce renewable energy. It’s a process Veolia has been using in Australia since 2008!
The "Ti Tree" bioreactor
On the outskirts of Ipswich, not far from the city of Brisbane, Veolia built a bioreactor. The facility was dubbed "Ti Tree Bioenergy", and is a joint-venture between Veolia (Australia NZ) Pty Ltd and JJ Richards & Sons Pty Ltd. It is an environmentally friendly waste disposal facility that offers a sustainable alternative to conventional landfills. The facility utilises the 37 million m3 void left over from a previous open cut coal operation in the Willowbank area of Ipswich.
The bioreactor provides a favourable environment for the biological decomposition process – known as anaerobic digestion – to occur. This process requires that waste reaches its optimum moisture content followed by a decrease in the oxygen content. This is achieved through precise management of the water balance within the system. Waste typically consists of 10-30% moisture, which is well below the optimum level of 40 - 45% required for active biological decomposition. The bioreactor maintains optimum moisture levels by recirculating leachate (nutrient rich water produced by decomposing waste) and other liquids, such as storm water, through an extensive network of pipes.
In total, Ti Tree Bioenergy produces enough green electricity to supply 2,500 households daily, of which is projected to increase up to 4,000 homes by 2020.
Circular waste management
Over a period of 10 years the facility has avoided the emission of more than 3 million tons of greenhouse gases (those that would have been released had the waste ended up in conventional landfills).
And because the bioreactor accelerates the decomposition of waste, it will enable Ipswich to quickly rehabilitate the old mining site on which has been built. Estimates suggest that a bioreactor is able to stabilize the waste within fifteen years, whereas it takes more than a hundred years in a classic dump.
To sum up, Ti Tree Bioenergy has allowed Ipswich to create a circular economy by turning its waste into a resource. An initiative that could well serve as a model for other Australian cities that want to tackle their waste more responsibly.
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Main picture: ©Rod Tamlyn / Andrew Robertson