Last updated September 21, 2020 at 11:51 am
Researchers have used biosolids to produce hydrogen from wastewater, in new technology that makes use of one of humanity’s unlimited resources – sewage.
The new approach means all the materials needed for hydrogen production could be sourced on-site at a wastewater treatment plant. Credit: RMIT
Human waste, also known as biosolids and biogas, is the driving force behind a sustainable new method for producing hydrogen from wastewater, say Australian researchers.
Developed by researchers at RMIT University, the technology uses a material derived from biosolids to spark chemical reactions for producing hydrogen from biogas.
The approach means all the materials needed for hydrogen production could be sourced on-site at a wastewater treatment plant, without the need for expensive catalysts.
The method also traps the carbon found in biosolids and biogas, which could in future enable a near zero-emission wastewater sector.
Technology to aid a transition to a circular economy
Associate Professor Kalpit Shah, who oversaw the research, says existing commercial methods for producing hydrogen were emission and capital-intensive, and relied heavily on natural gas.
“Our alternative technology offers a sustainable, cost-effective, renewable and efficient approach to hydrogen production,” says Shah.
“To enable the transition to a circular economy, we need technology that enables us to squeeze the full value from resources that would ordinarily go to waste.”
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“Our new technology for making hydrogen relies on waste materials that are essentially in unlimited supply.
“By harnessing the power of biosolids to produce a fully clean fuel from biogas – while simultaneously preventing greenhouse gas emissions – we can deliver a true environmental and economic win.
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.
Kalpit Shah, with the novel reactor developed and patented by RMIT. Credit: RMIT
Dr Aravind Surapaneni says 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 says.
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.
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.
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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.
The method for producing hydrogen can also convert the carbon found in biogas and biosolids into advanced carbon nanomaterials, pictured here magnified 50,000 times. Credit: RMIT
Shah says the unique reactor was at the heart of this innovative recycling approach.
“We’ve radically optimised heat and mass transfer in our reactor, while shrinking the technology to make it highly mobile,” he says.
“There are no reactors available that can achieve such phenomenal heat and mass integration, in such a small and cost-effective package.
“And while it’s already energy efficient, with further integration, this reactor could turn biosolids and biogas conversion into a process that actually produces energy instead of consuming it.”
Novel reactor could be easily adopted by industry
As well as being used in wastewater treatment, the novel reactor has potential applications in the biomass, plastics and coating industries.
The research was supported by Victoian Government water supplier South East Water, which will be trialling the biosolids and biogas conversion technology in a pilot plant.
South East Water’s Dr David Bergmann says the technology had potential for adoption by the industry.
“Supporting these kinds of innovative emerging technologies is an important part of our commitment towards reduced emissions and a circular economy approach involving wastewater.”
