Vietnam has started producing biodegradable plastic bags that can break down in less than three years into CO2 and water when buried.
The Vietnam Academy of Science and Technology’s Institute of Chemistry is partnering with Lac Trung Technology; a Hanoi company that imports and exports machinery and industrial chemicals, to produce the bags at a rate of 30 kg per hour.
Nguyen Trung Duc, head of a research team at the institute, said the bag does not shred into small pieces like other plastic bags; but is converted into water and CO2, bringing nutrients to plants.
The bags are durable and have an elasticity rate 5 percent higher than plastic bags currently available on the market. They will be manufactured in various thicknesses to carry heavy items and for daily use. The team, after two years of research, created the bags in 2018 from high-density polyethylene; which is commonly found in plastic waste such as bottles.
This resin is treated, mixed with additives including salts and metal compounds; that promote oxidation and other composites to break down the original structure of the waste plastic and weaken the carbon bonds.
It then goes through other processes like extrusion, blowing, pressing, and pulling to make the bags. They tested its decomposition by burying samples in the ground, and discovered 70-100 percent of it decomposed. It can take less than three years for the bag to biodegrade depending on its thickness.
If soaked in activated sludge and compost media, the decomposing time is shortened to seven or eight months. But according to a study by British scientists, biodegradable bags do not fully break down after three years and could still be used.
In an interview with National Geographic, Richard Thompson, a British marine biologist; said: “They didn’t have the same strength as they had when they were brand new. But they hadn’t degraded to any meaningful extent.”
But the study should not be read as an argument against development of biodegradables or compostables; he said, suggesting that manufacturers should focus on durability so that “a bag that can and is reused many times presents a better alternative to degradability.”
Duc said the biodegradable bags cost more than conventional plastic bags. “We will continue to research and improve the production method to make it more affordable.” His team is studying how to turn polyethylene waste into degradable seeding pots and plastic mulch.
According to a report by Ipsos Business Consulting, a global growth strategy consulting firm based in Paris; Vietnam’s per capita plastic waste is the third highest in Southeast Asia after increasing more than 10-fold in the last three decades. The country generates 1.8 million tons of it annually, but recycles only 27 percent, the report said. The government has been making increasing efforts to combat the plastic waste epidemic; with Prime Minister Nguyen Xuan Phuc calling for action to achieve zero disposable plastic use in urban shops; markets and supermarkets by 2021 and nationwide by 2025.
Source: e.vnexpress.net | biodegradable plastic bags
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