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Add Value–Add Larvae

By Office of Communication Services    Published on 04/30/2015 More stories >>

Samir
Khanal, Robert Olivier, and graduate student K.C. Surendra show the products of
larval composting.

Samir Khanal, Robert Olivier, and graduate student K.C. Surendra show the products of larval composting.

Most people are familiar with vermicomposting, using worms to break down garden and kitchen waste and boost the fertilizer content of the resulting compost. But as Molecular Biosciences and Bioengineering researcher Samir Khanal explains, larvae generate a similar high-quality soil amendment while eating more, and more diverse, waste. And they also create two further products: fuel and feed.

Food scraps, including fats and meat that can’t go into ordinary compost, are placed in a BioPodTM, an ingeniously designed compost-type bins, to be eaten by black soldier fly grubs. These voracious eaters become very fat, and this fat is a valuable source of fuel. The grubs are heat-dried to reduce moisture content, then pressed for oil. “There’s nothing more valuable than a liquid fuel source,” avers Robert Olivier, Dr. Khanal’s collaborator and BioPodTM creator; it’s far more versatile and easy to use than a gas.

Desirable as it is, the fuel may not be as important as the other end-product, the feed. After dried larvae are pressed, the resulting meal is the perfect blend of protein and fat for feeding chickens and fish. Mr. Olivier is running a trial with 120 chickens on a Maui farm now; final results aren’t in, but he confirms, “They love it. And the eggs are phenomenal!” Tilapia and other fish used in aquaponics also thrive on the meal, providing a much-needed solution to the conundrum of trying to promote food sufficiency through aquaponics when feed is largely imported from the Mainland.

Dried larvae can be turned into larval protein meal and oil.

Dried larvae can be turned into larval protein meal and oil.

Larval farming is potentially a self-perpetuating cycle on both large and small scales. Self sufficiency-oriented homesteaders can use their own scraps to feed their own BioPodTM of larvae, using the pressed oil in oil lamps or oil-fueled heating devices and feeding small flocks of poultry and tanks of fish. But Dr. Khanal and Mr. Olivier envision the citywide implications: Trucks bringing food waste from restaurants and supermarkets to facilities with much huger BioPodTM bins could be powered by larval biodiesel—the oil, amended for consistency and stability. This biodiesel, they calculate, would easily power the machines pressing the dried larvae—and the heat generated by the pressing is just the temperature needed to dehydrate the next batch. And commercial-grade feed, pressed into pellets, could be trucked to feed-supply stores all over the state, again in trucks fueled by larvae. It’s an exciting vision…one they’re already working to bring to reality.