Microrecycling science: revolutionising recycling and manufacturing

Pioneers of ‘microrecycling science’ at UNSW’s Centre for Sustainable Materials Research and Technology (SMaRT) have developed a technology that is set to propel advanced manufacturing in Australia while also addressing the nation’s waste management challenges.

Developed by Professor Veena Sahajwalla and her team, the novel ‘material microsurgery’ technique can extract valuable materials and elements from complex waste items and reform them into strengthening layers for steel and other applications. The technique is outlined in a paper published in ACS Omega, which complements their ‘Science of Microrecycling’ paper, published in Materials Today Sustainability.

The SMaRT Centre created the phrase microrecycling science to describe its novel approach to researching innovative approaches and technologies to reform various waste streams into value-added materials and products.

“Australia’s governments have agreed to ban the exporting of glass, plastic, paper and rubber tyres from January 2021; therefore, we need to start treating these waste items as the ‘renewable resources’ they really are,” Professor Veena Sahajwalla said.

“Ever-increasing population, technological advancement, variable consumption trends and lack of efficiency in using materials are forcing us near a crisis point in terms of waste management.

Professor Veena Sahajwalla explained that Australia’s manufacturing has come into sharp focus since COVID-19 disrupted global supply chains.

“We can start a whole new ‘green materials’ movement where we use waste as renewable resources for decentralised manufacturing to supercharge our economy, which is going into the biggest recession and depression since the 1930s,” Professor Sahajwalla said.

“The problem of countries now being affected by unreliable global supply chains for certain materials and goods has sparked questions around how to produce the goods they need.

“We are scientifically developing new technologies to not reform complex waste items into new, value-added materials to help address this ‘sovereign capability’ issue, but to do so through decentralised manufacturing,” she said.

“A key challenge is that existing, centralised recycling and waste treatment methods at scale often just turn things like PET bottles back into PET bottles.

“What we need is a recycling and manufacturing system that can innovate to reform waste for more diverse and value-added end uses. Recyclers traditionally haven’t seen themselves as manufacturers and manufacturers haven’t seen themselves as recyclers, but we need them to. So, if we accept that we need plastic and want to keep it out of landfill, we need a system that treats it as a renewable resource.”

Material microsurgery

Material microsurgery is the latest innovative technique from the SMaRT Centre, which has pioneered the technological concept of Microfactories to reform different waste streams that mostly end up in landfill or stockpiles by turning them into value-added ‘green' materials and products, thus able to revolutionise the recycling and manufacturing sectors.

Material microsurgery uses the foundational selective thermal transformation techniques developed in the microrecycling science by the SMaRT Centre to extract valuable core elements from electronic waste that can be used in a novel way as a high-performance hybrid layer to improve performance of the surface of steel. This means that regular steel can be enhanced to have a ‘super surface’ via the modification.

The method could be a suitable alternative to conventional surface coatings and reduce the burden on raw material feedstocks. In the material microsurgery study, glass and plastic from spent computer monitors and copper from waste printed circuit boards were used to produce a hybrid thin film layer on a steel substrate to provide a protective layer over the base material at the microscale to alter the overall performance of the material.

This high-performance advanced material is a hybrid layer chemically bonded in situ on steel to produce a super surface with enhanced mechanical properties compared with uncoated steel.

“We use the term material microsurgery because we were inspired by the processes medical surgeons use in microsurgery where they apply targeted and selective solutions to problems,” Professor Sahajwalla said.

“Existing waste and recycling technology doesn’t do this for our traditional waste treatments. We need to step up to do the things that were thought unimaginable for waste management so it can be cutting edge.”

The SMaRT Centre’s Microfactorie technologies use various discreet modules to transform problematic waste materials, such as glass, textiles and plastics, into new value-added materials and products such as engineered green ceramics for the built environment and plastic filament as a renewable resource for 3D printing. This modular technology is capable of harnessing value from waste resources to deliver high-value materials and products.

Image caption: Professor Veena Sahajwalla. Photo: Anna Kucera