SA inventor turns waste plastic into fertiliser and energy

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Plastic in landfill Plastic in landfill

The first systems to use anaerobic digestion technology to turn waste plastics into energy and fertiliser are being developed in South Australia.

POET Systems expects to have its first two machines – each capable of processing 20 tonnes of plastic a week – operating commercially in about 12 months.

More than 1 million tonnes of contaminated plastic deemed unfit for recycling is sent to landfill in Australia each year. In the United States the figure is almost 10 million tonnes.

Inventor David Thompson says his plastic to energy technology has so far successfully been applied to polyethylene, polypropylene, polystyrene and expanded polystyrene.

He says the anaerobic digestion process varied on disposal feedstock and also depended on temperature and system set up.

"The POET system – which is an acronym for Polymer-Organic-Energy-Treatment – prepares waste plastic in a way that microbial digestion can take place quickly and I think that’s really the key to making it a commercial opportunity," Thompson says.

"I have already got inquiries from overseas including a large consortium in South America that is really quite interested to get involved and take the technology over there."

The first two POET machines will be built at wastewater treatment plants in regional areas of Victoria.

The same microbes will treat the plastic and the water simultaneously. The microbes then die and leave behind liquid and solid biomass, which can be used as fertiliser, and biogas, which can be separated into methane and carbon dioxide.

Thompson, who is based in Adelaide, says the methane could be used to create heat and energy, possibly to power the wastewater plant, while there was also potential for the carbon dioxide to be captured and reused.

"So basically the plastics go into an anaerobic situation in wastewater where the microbes digest the plastic and create energy," he says.

"This client in Victoria is big on wastewater treatment plants and after thinking about his methodology – there’s over 550 wastewater treatment plants in Australia and at least half of those would have anaerobic digestion facilities attached so it’s a good opportunity to go down that path."

Thompson plans to lodge provisional patent documents for the technology in the coming weeks.

He says the system does not impact on existing recycling practices as it targets plastics destined for landfill and would add a new revenue stream for companies in the waste industry.

"People in the waste industry have already invested heavily in infrastructure so they know how to do the business," he says. "If this gives them an additional opportunity to make money and take on a segment which hasn’t been handled before then I’m happy with that.

"We’ve had a look at a number of scenarios and where it actually works as a business model is at a starting point of 20 tonnes a week.

"So everything I’ve designed ready for manufacture here in Australia is based on 20 tonnes a week and I can scale it up larger from there."

POET Systems is one of 32 semi-finalists in the 2017 Australian Technologies Competition, which assesses, mentors and promotes companies providing a uniquely Australian take on the future and is open to technologies that have global potential in a range of industries.

This year’s 122 entries have jointly spent $94 million to date developing their technologies and have over 400 employees. While many of the Semi Finalists are already selling solutions, they are jointly seeking an additional $45 million to bring all the solutions to market.

​"The companies are developing a range of incredible innovations that address the big growth opportunities and challenges of the future," the competition organisers say.

"Solutions for food, agriculture, energy, mining, cities, medicine and cyber security will create new knowledge and skills intensive industries that will be Australia’s future."

This year's semi-finalists include electric vehicle charging, geo-fencing solutions for share-bikes, graphene materials for dam-liner monitoring, a foetal monitoring probe, wearable sensors for injury rehabilitation and a secure online voting system.

​"This year we have again partnered with the Federal Government’s Industry Growth Centres to identify and work with technologies from the Government’s priority sectors," competition organiser John O'Brien says. "The semi-finalists will have unmatched profiling opportunities with industry and investors that will help them get to market and realise their potential in Australia and globally."

The winners will be announced at Technology Showcases in Melbourne and Sydney in October and November.


Republished with permission from The Lead South Australia

 

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