Adelaide, Australia — An Australian inventor has developed a technology he says can convert waste plastic into energy and fertilizer using anaerobic digestion.
David Thompson, based in Adelaide, said his plastic-to-energy technology, which he calls "poet," an acronym for polymer organic energy treatment, has been used successfully for polyethylene, polypropylene, polystyrene and expanded polystyrene.
He said in an article published on The Lead, a promotional website for South Australia, the poet system "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 expects to have the first two machines, each capable of processing 20 metric tons of plastic a week, operating commercially in mid-2018. The machines will be built at wastewater treatment plants in the state of Victoria.
The same microbes will treat plastics and water simultaneously. The microbes then die and leave behind liquid and solid biomass, which can be used as fertilizer, and biogas, which can be separated into methane and carbon dioxide.
Thompson told The Lead the methane could be used to create heat and energy, possibly to power the wastewater plant, and there was potential for the carbon dioxide to be captured and reused.
"Basically, plastics go into an anaerobic situation in wastewater where the microbes digest the plastic and create energy," he said.
Thompson said Australia has more than 550 wastewater treatment plants: "At least half would have anaerobic digestion facilities attached so it's a good opportunity to go down that path.
"I have already got inquiries from overseas, including a large consortium in South America that is quite interested to get involved and take the technology over there," he said.
Thompson said the poet system did not impact existing recycling practices because it targets plastics destined for the landfill and will add a new revenue stream for waste industry companies. He said more than 1 million metric tons of plastics unfit for recycling goes to landfill in Australia annually.
Poet is a semifinalist in the 2017 Australian Technologies Competition, which promotes startup technologies with global potential. Winners will be unveiled in October and November.
