RMIT professors push for industry input on circular economy

Academics engaged to provide comment on Victoria’s draft Circular Economy Policy have warned that without industry input, the strategy’s success could be limited.

The Victorian Circular Economy Policy draft was opened to public comment earlier this year.

According to the official document, the policy aims to re-define growth by decoupling economic activity from the consumption of finite resources and design waste out of the system.

According to RMIT professors Usha Iyer-Raniga and Scott Valentine, the strategy needs to involve a rethinking of resource efficiency across the economy, and extend its focus beyond Victoria’s waste and recycling crisis.

Ms Iyer-Raniga said while environmental ministries have an important role in circular economy strategic development, business model innovation and corporate buy-ins are needed to foster results.

“As the Danish and Dutch experiences in circular economy planning show us, it is not only about diverting tins of soda away from landfills, it is about new innovations and new strategies for producing and consuming goods and services,” Ms Iyer-Raniga said.

Both Ms Iyer-Raniga and Mr Valentine are members of RMIT’s CE Hub, which helps businesses find profitable resource efficiency strategies.

“If implemented correctly, a circular economy strategy will enhance corporate profitability, reduce resource costs, make Australian industry more competitive and create new business and jobs,” Mr Valentine said.

“In short, the circular economy needs to be approached as an economic development strategy, and connections need to be made with research and development hubs like we have at RMIT. Failure to do so will discourage corporate buy-in and the initiative will underperform.”

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Tracking sludge flow for better wastewater treatment

A new way of tracking how sewage sludge flows during thermal treatment could help engineers design better wastewater treatment plants and boost the production of biogas.

Researchers at RMIT University have demonstrated how the flow behaviour of sludge can be used as a tool to gauge how quickly organic matter is dissolving at high temperatures, suggesting the potential for online monitoring.

Traditional methods of assessing thermal treatment performance require time-consuming sampling and chemical analysis,  rheology calculations however – which measure and detail how liquids flow – can be done in real time online.

The study, published in Water Research, found a correlation between how sludge dissolves and changes in its flow behaviour, indicating it may be possible to monitor thermal treatment performance simply by tracking flow.

Lead investigator Associate Professor Nicky Eshtiaghi said correctly estimating the rheological parameters of sludge is critical to efficient process design.

“Our technique enables engineers and plant operators to conveniently obtain these parameters without having to perform the measurements at high temperatures themselves,” Ms Eshtiaghi said.

“We hope the research encourages more serious consideration of flow behaviour in optimising and designing high pressure and high temperature sludge-handling processes.”

The new technique can measure flow behaviour without destroying samples, often a big challenge for concentrated sludge data collection.

The study also shows that varying the thickness of sludge has little impact on the effectiveness of thermal treatment, meaning plant operators could potentially increase biogas production by increasing the solid content of sludge during initial treatment processes.

“Thicker sludge can be beneficial for both optimising efficiency overall, and for producing more biogas,” Ms Eshtiaghi said.

“With our discovery that the thickness of sludge makes no difference, this research gives plant operators more flexibility in designing processes that can better exploit the renewable energy potential of wastewater sludge treatment.”

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Recycling biosolids into bricks

Image Credit: RMIT University

New research has found a way of turning biosolids from sewage into cheaper, higher performing bricks suitable for the construction industry.

A research team from RMIT University has developed a fired-clay brick as a sustainable solution for the wastewater treatment and brickmaking industries.

The bricks are made up of biosolids, a by-product of the wastewater treatment process, and were found to have a lower thermal conductivity than other bricks, meaning they will transfer less heat and potentially give buildings higher environmental performance.

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The research examined the physical, chemical and mechanical properties of fired-clay bricks incorporating different proportions of biosolids, from 10 to 25 per cent.

Researchers found brick firing energy demand was cut almost in half for bricks that incorporated 25 per cent biosolids, due to the organic content and could considerably reduce the carbon footprint of brick manufacturing companies.

Around five million tonnes of the biosolids in Australia, New Zealand, the EU, US and Canada currently go to landfill or stockpiles each year. By using a minimum of 15 per cent biosolids content in 15 per cent of the bricks produced, the research team estimates around five million tonnes could instead be used for construction.

The bricks have passed compressive strength tests and analysis demonstrated heavy metals are largely trapped within the brick. Biosolids can have significantly different chemical characteristics, so the researchers recommend further testing before large-scale production.

Lead investigator Associate Professor Abbas Mohajerani said the research sought to tackle two environmental issues – the stockpiles of biosolids and the excavation of soil required for brick production.

“More than 3 billion cubic metres of clay soil is dug up each year for the global brickmaking industry, to produce about 1.5 trillion bricks,” Mohajerani said.

“Using biosolids in bricks could be the solution to these big environmental challenges.

“It’s a practical and sustainable proposal for recycling the biosolids currently stockpiled or going to landfill around the globe,” he said.

The results of a comparative Life Cycle Assessment and an emissions study conducted as part of the research confirmed biosolids bricks offered a sustainable alternative approach to addressing the environmental impacts of biosolids management and brick manufacturing.

The research, funded by RMIT University, Melbourne Water and Australian Government Research Training Program scholarships, is published in the “Green Building Materials Special Issue” of Buildings.

Pictured: Associate Professor Abbas Mohajerani. Image Credit: RMIT University

Experts react to single-use plastic ban

Plastic bottles dumped

A senate inquiry into Australia’s recycling industry has recommended that all single-use plastics should be banned by 2023.

The decision could potentially include products like takeaway coffee cups, chip packets and takeaway containers.

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Professor Sankar Bhattacharya from Monash University’s Department of Chemical Engineering said time is of the essence to find a new home for recyclate stockpiles.

“Now that China has stopped taking our trash, we’re scrambling to figure out how to keep all those good intentions out of the landfill,” he said.

“The majority of the plastics we use in our daily life – different grades of polyethylene, polypropylene, polystyrene and even polyvinyl chloride, to some extent – can be processed into liquid fuel.

“That’s what China was doing with the plastic recyclables it bought from us. They’re now realising that their domestic production of waste products is so large that they cannot process any more by bringing in waste plastics from other countries,” he said.

Katherine Gaschk, a Research Masters from Murdoch University said she was pleased with the Senate inquiry’s findings.

“The sooner we accept the need to stop using plastics and change from our current mode as a throw-away society, the better for the future health of our planet,” she said.

“Ultimately it is human behaviour that is responsible for plastic pollution. Removing the plastics will certainly help to reduce pollution, but there is also a need to educate retailers, consumers and manufacturers about the impacts of plastic pollution and how we can reduce our dependence on plastics.”

Simon Lockrey, a Research Fellow from RMIT University’s School of Design warns that while the ban would be great in theory, there may be rebound effects.

“For instance in food systems, packaging can save food waste in the supply chain, from farm to plate,” he said.

“Without acknowledging other changes to that system when taking away single-use packaging, we may move the waste burden, sometimes to more impactful levels. For example, packaging can be a low impact compared to food waste impacts.

“Therefore, it would be good with this senate initiative to see the complimentary strategies for industries using single-use packaging to make sure we are in a waste reduction winner all around,” Mr Lockrey said.

Thavamani Palanisami, a Senior Research Fellow at the University of Newcastle’s Global Centre for Environmental Remediation said what should be the next step.

“Tags such as ‘biodegradable’, ‘bio-based’, ‘100 per cent degradable’ need to be regulated,” he said.

“We need to create public awareness about types of plastic and their individual behaviour.

“We need to set standard testing methods to verify the biodegradability of the plastic items tagged as ‘biodegradable’,” Dr Palanisami said.

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