IT IS a common thought that food scraps, considered biodegradable waste, are acceptable to be thrown anywhere, as these are "biodegradable" anyway, meaning they will decompose eventually.
During a random interview with passersby who were mostly students and one mother, all three subjects failed to answer correctly which of the two kinds of waste is admissible for dumping elsewhere: food scraps or plastic refuse. All of them chose food scraps.
However, experts say otherwise
In a huge and populous city like Davao, residential waste covers around 793 tonnes per day (TPD) of waste generated in 2017, according to a study by a Dabawenyo researcher, Kristin Faye Olalo, together with colleagues.
In their study titled Optimal Process Network for Integrated Solid Waste Management in Davao City, Philippines, the researchers said that the biodegradable component accounts for 50% of the total residential waste generated.
Residential waste means any refuse generated on the premises as a result of residential activities. The term includes landscape waste grown on the premises or deposited, but excludes tires, trade wastes, and any locally recyclable goods or plastics.
Breakdown process
Olive Puentespina, CEO of Davao Thermo Biotech Corporation, a company that specializes in a circular, biodegradable waste management system using composting technology with the aid of certain bacteria to transform waste into natural fertilizer, says that although food scraps are biodegradable and easily decompose, it would still take time and a process for them to break down.
"Ang biodegradable waste, ma-decompose na siya via process (Biodegradable waste decomposes via process). Kinahanglan siya ma-mix, aerate, and turn constantly, siguro (It should be mixed, aerated, and turned constantly, maybe) every week, you have to do this process. There have to be all of those elements to decompose biodegradable waste, and by nature, it will take four to six months for this kind of waste to decompose," Puentespina said.
Biodegradable waste and the environment
She added that, even though it may seem "environmentally safe," biodegradable waste, especially those compostable ones, such as food scraps, is not good to add to the ever-growing volume of waste sent to landfills, as numerous studies link biodegradable landfill waste to increasing greenhouse gas emissions into the atmosphere.
One particular study by the US Environmental Protection Agency states that in 2020, food waste was responsible for approximately 55 million metric tons of carbon dioxide equivalents (mmt CO2e) emissions from U.S. municipal solid waste landfills. It added that an estimated 58 percent of the fugitive methane emissions (i.e., those released to the atmosphere) from MSW landfills are from landfilled food waste.
For every 1,000 tons (907 metric tons) of food waste landfilled, an estimated 34 metric tons of fugitive
Methane emissions (838 mmt CO2e) are released.
The study also suggested that reducing landfilled food waste by 50 percent in "2015 could have decreased cumulative fugitive landfill methane emissions by approximately 77 million metric tons of CO2 equivalents (mmt CO2e) by 2020, compared to business as usual."
Food scraps are also not ideal to be thrown into canals or gutters, as these will contribute to the clogging of waterways.
"Some food scraps contain sebo (lard) or animal fat. The lard will form a lining inside our culverts, and then eventually, magiging cause yung lining na yun ng pagbabara, which, as a result, magko-cause din nang pagbabaha," Puentespina said.
This event has been recorded by several studies, including by National Geographic's Huge Blobs of Fat and Trash Are Filling the World’s Sewers. It stated that “Globally, the combination of food fats and debris has produced massive blockages — ‘fatbergs’ — in drainage systems, demonstrating how food-derived fats contribute directly to sewage/overflow problems.”
Puentespina added that runoff food scraps may end up in our seas, which may contribute to algal blooms that cause red tides.
Several local and international studies have also reinforced Puentespina's statement.
In a 2024 study entitled “Harmful Algal Blooms in Eutrophic Marine Environments” by Lan and group, it described how excess nitrogen and phosphorus from runoff, wastewater, and atmospheric deposition fuel marine algal and cyanobacterial blooms and leads to hypoxia or low levels of oxygen in bodies of water.
“Scientific reviews link excess nitrogen and phosphorus from surface runoff and wastewater to harmful algal blooms that can degrade water quality and cause oxygen depletion.”
Additionally, Azanza and group, in their review entitled Transactions of the NAST review on HABs in tropical systems in 2024 states that “Experts in the Philippines warn that nutrient enrichment and local human activities are major contributors to HAB (harmful algal bloom) occurrences, with wide ecological and socio-economic impacts."
Also, Isabelle Caballero and Gabrielle Navarro's Monitoring cyanoHABs and water quality in Laguna de Bay's study in 2021 states that "long-term monitoring of Laguna de Bay shows that nutrient enrichment drives cyanobacterial blooms in Philippine waters, underscoring the link between land-based nutrient inputs and coastal/estuarine algal events." CEA
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