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South East Water’s Research and Development team works to identify emerging trends and technologies to help solve problems presented by wastewater management and treatment, particularly in relation to sustainability and the circular economy. In this interest, South East Water has partnered with engineers from RMIT University and Manipal University, India, to trial pyrolysis, a groundbreaking technology that revolutionises how the biosolids produced through wastewater treatment be reused and recycled.

Wastewater offers huge potential for renewable initiatives. With Australians producing more than 300,000t of wastewater

Image/South East Water

every year, there is no shortage of material to work with. Treated wastewater produces two materials: treated water and biosolids. Treated water is reused and recycled in a number of ways – but reusing biosolids is a more difficult task.

A pioneering technology, pyrolysis, opens up a whole new world of uses for biosolids by turning the material into biochar. Biochar is a solid carbonaceous material of organic feedstock, which contains stable and porous structures, and possesses desirable physicochemical and morphological attributes for many applications.

Introducing Pyroco
RMIT University Professor and Group Leader for Innovative Resource and Waste Conversion Technologies, Kalpit Shah, has developed a specific pyrolysis technique, called PYROCO, which uses a process called fluidised bed pyrolysis. Fluidised bed pyrolysis heats biosolids to a high temperature (approximately 500–700°C), keeping the temperature stable to ensure high quality product.

Fluidised bed pyrolysis can be used for sustainable and cost-effective upcycling of contaminated wastes, with a reactor used to convert biosolids to biochar.

Professor Shah explained that, “PYROCO is a first-of-its- kind fluidised bed pyrolysis technology that can be used for sustainable upcycling of waste into energy and high-value products. PYROCO is essentially a fluidised bed heat
exchanger device that significantly improves heat and mass transfer in the process, resulting in huge savings in capital and operating costs as well as generating the highest quality biochar product.

“We believe that PYROCO can achieve the high throughput per unit cost compared to other technologies. Unlike other technologies such as auger or rotary kiln-based systems, PYROCO (a fluidised bed heat exchanger) is simply made up of tubes and pipes, which is far easier to fabricate and maintain. Also, unlike other technologies, PYROCO has minimal moving parts and, therefore should achieve the high plant availability. PYROCO’s innovative process design also
offers flexibility to deal with feedstocks with varied quality, where other technologies will struggle,” Professor Shah said.

Trialling the technology
The fluidised bed pyrolysis technique is currently being trialled by South East Water, Intelligent Water Networks and Greater Western Water at the Melton Recycled Water Plant.

South East Water Research, Development and Innovation Manager, David Bergmann, said, “The key is in the absence of oxygen. You take whatever you started with, and you turn it largely into forms of carbon. And it turns out carbon actually has a lot of uses. If we can take that from a waste product that otherwise has no value, then that’s a great outcome.”

The circularity concept is to keep valuable nutrients in biosolids – such as carbon, nitrogen and phosphorous for reuse in applications such as agriculture, construction, energy, batteries etc.

Image/South East Water

For South East Water, the potential benefits are significant.

Mr Bergmann explained that, “The volume reduction for us, distribution cost reduction, creating material of value, destruction of contaminants are the core benefits for us. We believe this technology is going to be able to make that conversion with lower carbon emissions, lower greenhouse gas emissions, than our traditional processes would. So it’s going to help us achieve our greenhouse gas emissions targets as well.

“Further to that is carbon in its most basic form, so effectively, it’s inert. It can no longer have any greenhouse
gas emissions, so by then using it in agriculture or construction, we are locking it down. We’re taking it out of that carbon emission cycle. And so that’s a great thing for our climate targets that we’re all trying to achieve,” Mr Bergmann said.

Mr Bergmann believes one of the key factors to increasing uptake of this technology in water utilities is changing the way we see wastewater treatment facilities.

“We really need to start seeing our water recycling plants, not as waste processing facilities but as manufacturing facilities. A facility that manufactures, yes, water, but also a quality sludge or biosolids product that we then convert into a quality carbon product. It’s a manufacturing production plant that produces consistent materials for an end user that can put it into batteries, electronics and other high end applications.

“That’s quite a shift in how we’re running. When you’re running a waste treatment plant, it’s about focussing on volume throughout. When you run a factory for carbon, it needs to be an optimised operation focussed on tight end user specification and requirements, it’s a mindset change, and you’re thinking about producing good quality products at the end of the day. I think that’s the shift that we need actually in the way we run our operations and our treatment plants.”

Featured image/South East Water

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