CLEMSON — There’s a lot of waste in the world — literally and figuratively — but thanks to a harmless little fly, some of this waste is being recycled and turned into a slew of beneficial products.
Shawn Jadrnicek, farm manager for the Clemson University Student Organic Farm, has helped develop a project that is using food waste from the university cafeterias to attract a species of fly that is rapidly gaining fame among fans of sustainability.
Common throughout most of the world, the black soldier fly does not bite or spread disease. What it does do is feed on waste with the same zest as moviegoers munching popcorn. And the results have the scientific community abuzz.
Jadrnicek’s project was developed in collaboration with Clemson University recycling organics and biofuels project coordinator C. David Thornton. Here’s how it works:
Food waste is placed into grub composting systems called ProtoPods.
The adult flies, which are abundant in the wild and live only five to eight days, lay their eggs at the edge of the waste.
The eggs hatch into larvae and fall into the waste.
The larvae then eat the waste. And eat it. And eat it. Pound upon pound.
After a few weeks, the fully stuffed larvae reach maturity, wherein they go in search of a drier place to eventually hatch into adult flies. Like a slow-moving army of Gummi Worms, the larvae crawl up a ramp in the ProtoPod and then fall through a hole into holding bins.
“We can get two to three pounds of larvae a day,” Jadrnicek said. “If you have a food waste that you need to get rid of, this is a great way to do it. We’re saving the cafeterias money because now we don’t have to throw that waste away at a landfill.”
That’s not the only reason to cheer the flies. In addition to disposing of waste, the larvae become bloated with protein and fat that can be used as a food-source for livestock and fish. They also are soaked with oils that can be turned into biofuel.
“This has a lot of applicability for small-scale, diversified farming operations,” says Geoff Zehnder, coordinator for Clemson University’s sustainable agriculture programs. “Farmers can process their waste while also getting some value-added products.”
Large-scale applications are also in the works throughout the nation and world. Huge hog farms in Texas have been using the fly larvae to process swine manure.
And more isolated places — where waste removal can be extraordinarily expensive — are paying special attention to this tiny, yet voracious recycler. In Hawaii, for instance, scientists are feeding the larvae to shrimp. And the shrimp really seem to like it.
Though black soldier flies might seem like the super-heroes of sustainability, the innocuous insects do have one weakness: Cold tends to kill them. So Jadrnicek has been experimenting with ways to raise the flies inside greenhouses, thereby allowing them to survive and lay eggs even during winter.
This goes hand in hand with another Jadrnicek/Thornton project that also uses food waste, only this time to create heat, not fly larvae. Using a mixture of waste and wood chips, Jadrnicek and Thornton have built long, thick piles of mulch that slowly decay and in the process get surprisingly hot, reaching internal temperatures of up to 160 degrees. When water is piped through the mulch piles, it is naturally heated — free of charge — and then used for a variety of purposes at the organic farm.
“It’s pretty much free heat,” Jadrnicek said. “And when the piles decompose at the end of the year, we use all the leftover nutrients in our fields. It’s all integrated together.”