The
new method for producing hydrogen can also convert the carbon found in biogas
and biosolids into advanced carbon nanomaterials, pictured here magnified
50,000 times. Courtesy: RMIT University.
Researchers
have used biosolids to produce hydrogen from wastewater, in new technology that
supports the comprehensive recycling of one of humanity’s unlimited resources —
sewage.
The
innovation focuses on the advanced upcycling of biosolids and biogas,
by-products of the wastewater treatment process.
Developed
by researchers at RMIT University in Melbourne, Australia, the patented
technology uses a special 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.
Lead
researcher Associate Professor Kalpit Shah said 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,†said Shah, Deputy Director
(Academic) of the ARC Training Centre for Transformation of Australia’s
Biosolids Resource at RMIT.
“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. 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 fertilizer and soil amendment in agriculture, but around 30% of the world’s biosolids resource is stockpiled or sent to landfill, creating an environmental challenge.
Lead researcher Associate Professor Kalpit Shah, with the novel reactor
developed and patented by RMIT University. Courtesy: RMIT University
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. 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.
Patented
reactor technology
Shah said
the unique reactor developed by the RMIT School of Engineering team was at the
heart of this innovative recycling approach.
We’ve
radically optimized heat and mass transfer in our reactor, while shrinking the
technology to make it highly mobile, he said. 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.
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 South East Water, which will be trialing the
biosolids and biogas conversion technology in a pilot plant currently under
fabrication.
Dr. David
Bergmann, Research and Development Manager at South East Water, said 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, Bergmann said.