Biosolids are commonly used as fertiliser and soil amendment in agriculture, but around 30% of the world’s biosolids resource is stockpiled or sent to landfill, creating an environmental challenge.

Dr Aravind Surapaneni, Senior Research and Planning Scientist at South East Water and Deputy Director (Industry) of the ARC Training Centre for Transformation of Australia’s Biosolids Resource, said research into new and valuable uses for biosolids was vital.

“The wastewater sector is constantly looking to develop new ways to transform biosolids into high-value products, in environmentally sustainable and responsible ways,” Surapaneni said.

How the tech works

In the new method, published in the International Journal of Hydrogen Energy, biosolids are first converted to biochar – a carbon-rich form of charcoal used to improve soil health.

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The biosolids-derived biochar contains some heavy metals, which makes it an ideal catalyst for producing hydrogen out of biogas.

As part of the experimental bench-scale study, researchers tested the process with a methane-rich gas that resembles biogas.

They showed the biochar made from biosolids is highly effective for decomposing the gas into its component elements – hydrogen and carbon.

The decomposition process can also be conducted in a specially designed and hyper-efficient reactor developed and patented by RMIT, which can produce both hydrogen and a high-value biochar that is coated with carbon nanomaterials.

By converting the carbon found in biogas and biosolids into advanced carbon nanomaterials, their method can also capture and sequester the greenhouse gas to prevent its release into the atmosphere.

The carbon nanomaterial-coated biochar produced through the novel technique has a range of potential applications including environmental remediation, boosting agricultural soils and energy storage.