Muck not yuck: Fly larvae could be solution to the Philippines’ landfill, food waste woes
- The black soldier fly’s larvae can break down food waste which accounts for a large chunk of the city of Davao’s daily landfill; plus, larvae excrement can be used as a fertiliser
- However, officials are mulling building an expensive waste-to-energy plant, aware that the city’s sole rubbish dump will be full by 2023; there’d be even more pollution if the plant goes ahead, say environmentalists
Davao city in the Philippines is in a race against time for a solution to its landfill issues. Rapid urbanisation and poor separation of waste are taking a toll on the city’s only landfill, which will be full by 2023.
Enter the black soldier fly, whose larvae break down biodegradable waste with their strong mouthparts and powerful digestive enzymes, and effectively decompose matter like the debris of rotten animals and plants.
LimaDOL, a start-up in Davao, is using the flies to handle food waste and develop a chemical-free insect protein that can be fed to poultry.
Global environmentalists oppose this as WTE incinerators “produce very little energy while emitting large quantities of climate pollution”, according to international environmental network Gaia.
Carmela Marie Santos, Director of Ecoteneo, Ateneo de Davao University’s environmental organisation, called the WTE project a “false solution” as the problem could be rectified by proper waste segregation instead of constructing a WTE plant.
“By source, 60 per cent of Davao’s waste is from households, and by site, 60 per cent from compostables. This means that the problem is not the growing population and its waste, but that we’re not doing what we’re supposed to be doing, which is diverting compostables and recyclables,” said Santos.
She said that some 80-90 per cent of waste would not reach landfills if there was stricter implementation of the law for waste separation.
About half of Davao’s waste is biodegradable, with food waste accounting for 200-300 tons of its daily landfill waste.
Food that ends up in landfills also creates methane. After carbon dioxide, methane is the second most abundant greenhouse gas emitted through human activity, accounting for 17 per cent of global greenhouse gas emissions.
“If global food waste was measured as a country, it would be the world’s third-worst emitter of greenhouse gas,” according to the international Commission for Environmental Cooperation.
Davao environmentalists, part of the Sustainable Davao Movement that advocates sustainable living in Davao city, said there are zero-waste solutions to address the city’s pressing waste problem which can be jump-started by tackling how a city handles food scraps.
How the flies ‘work’
Black soldier flies are a relatively new form of biowaste treatment. They come from the same family as house flies but do not harm humans, spread diseases, or infest crops.
They help in composting food waste and the larvae can be fed to poultry for protein. They only live an average of 45 days and undergo five main stages: egg, larval, pre-pupal, pupal, and adult.
LimaDOL’s founder, agronomist Peter Damary said: “We started this facility in 2019 because I came across a report from the UN’s Food and Agriculture Organization and realised how useful black soldier flies are in zero-waste composting.”
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LimaDOL is derived from the Filipino word Lima, which means five, and day-old larvae (DOL), the age larvae are when added to food waste.
The start-up collects more than 150 kilograms of food waste from over 200 households and five restaurants, three to four times a week. The waste is fed to the black soldier flies at its facility.
At the facility, food waste is first shredded and dehydrated to ensure proper decomposition.
“We feed the numbers we have with enough food but we could, and should, increase the number. Our aim is to collect and compost much more as it would reduce more food waste in the landfill, and reduce methane,” said Damary.
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After 20-24 days, the larvae, if not harvested, transform into pre-pupae and then pupae, stop eating, go into dormancy, then emerge in their adult form - the fly. Soon after mating and laying 500-900 eggs, the female black soldier fly dies.
“Black soldier flies are in nature, so there is no risk of introducing this into the environment. As adults, they only live for a few days, they do not have a mouth, so they do not bite, nor carry any illnesses,” explained Damary.
“They reduce food waste, eliminate the smell of decomposing food, and reduce the presence of houseflies,” he added.
Ensuring food sustainability
Frass, the flies’ excrement, can also be a useful tool in agriculture. “We sift through 18-day old larvae using a screen and we harvest the frass, which becomes an organic fertiliser. The larvae are rich in protein and fats, and can be used as animal feed for poultry and fish,” said Damary.
Santos said the initiative works because it is based on how nature operates.
“There are species who break down compostables. From vermicomposting (worm composting) to natural composting, and, for this one, they’re using black soldier flies. It’s organic, it doesn’t require burning. And it addresses the big problem of compostables.”
She added: “I think it should be adapted citywide. I’ve been recommending it to the local government because a nature-based production or process naturally feeds into another cycle. For this one, it could be food production.”
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Damary said black soldier flies “are central to circularity by transforming the ‘energy’ embedded in food waste to compost and animal feeds” and, while using the insects remains a foreign concept to most Filipinos, he is hopeful they will become open to the idea.
“If the price is right, Filipino farmers will adapt the insect protein and pet owners will feed their fish and birds with them,” said Damary.
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He added that local governments can also observe how the flies are more efficient than other forms of composting.
“The biggest obstacles are the disincentives for local governments to collect segregated food waste. But these can be changed since these are policy or interest-driven.”
