Once thrown of biodegradable products - ranging from garbage bags and liners of layers of pens - are designed to decompose relatively quickly and disappear into the natural environment. But these products may not respect their green image, indicates new research.
"The implication is, it is biodegradable, therefore, it is better for the environment-, and our point is: well, not necessarily and not so rapid," said study researcher Morton Barlaz, who heads to North Carolina State University Department of Civil, Construction and environmental engineering.
These biodegradable products release a powerful greenhouse gas, methane, as they decompose in landfills, a problem compounded by the relatively rapid rate at which they decompose.
Barlaz and his colleagues watched what happened when the food waste, paper, newsprint, overall municipal solid waste and a biodegradable polymer called PHBO were buried in the average American landfill. Modelling experience have shown that the materials with higher rates of decomposition, such as food waste and PHBO, issued more than ultimately methane in the atmosphere.
"More slowly that the gas is produced, more it gets collected" to the dump, said Barlaz. "It is a function of how operate landfills." Collectors systems are usually installed after the waste are buried. ?
During the interval, usually about two years, more rapid decomposition, methane is more output.
To improve the environmental benefit of biodegradable products, they should be designed to decompose more slowly and more methane should be collected in landfill, he said. [10 Ways to green your home]
With the technology, the methane can really help the environment. The U.S. Environmental Protection Agency reports that about one third of the waste produced in the United States goes to landfills that capture methane and use it to generate heat and electricity. Another third goes to landfill sites where it is simply burned (and found in the atmosphere), and the rest goes to landfill sites that allow methane to escape into the atmosphere, according to Barlaz.
Stays of methane in the atmosphere for a period of time much shorter that another greenhouse gas, carbon dioxide, but in the meantime it captures heat more effectively.
The research, led by James Levis, Ph.d. at the University of North Carolina student, appeared online on May 27 in the journal Science & environmental technology.
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