How long things take to decompose in landfill

If there's one thing we know for sure, it's that recycling can be confusing by nature. With a number of rules, bins, materials, and codes to sift through, correctly recycling can be a more involved process than it seems.

Additionally, the lack of education around recycling often results in individuals sending the majority of their waste to landfills instead of taking the time to understand what can be separated out for reuse or recycling.

Unfortunately, this behavior has consequences that will impact our environment for years to come—The most obvious being the length of time it takes certain materials to decompose in a landfill.

An estimated million pairs of shoes are thrown away every year. Leather shoes are specifically problematic in landfills because of the harmful chemicals used during the tanning process. Plastic bags have only been around for about 50 years, so how do the scientists know how long they take to degrade?

To make long-term estimates, scientists often use respirometry tests. The experimenters place a solid waste sample — like a newspaper, banana peel or plastic bag — in a container with microorganisms and soil, and then they aerate the mixture.

Over the course of several days, microorganisms digest the sample bit by bit and produce carbon dioxide — the resulting amount of CO 2 serves as an indicator of degradation. Sometimes scientists use estimates to give data on biodegradability. These are usually based on known quantities and extrapolated to take account of time or other environmental factors.

Respirometry tests work well for newspapers and banana peels, but when scientists test plastic bags, nothing happens — there's no CO 2 production and no decomposition. The most common type of plastic shopping bag — the kind you use to get at supermarkets — is made of polyethylene, a person-made polymer that microorganisms don't recognise as food.

So, if there is no CO 2 production for plastic in respirometry tests, where does the year estimate come from? Although polyethylene bags don't biodegrade, they do photodegrade. When exposed to ultraviolet radiation from sunlight, polyethylene's polymer chains become brittle and start to crack.

This suggests that plastic bags will eventually fragment into microscopic granules. Scientists do know that many plastic break down into microplastics, as of yet, however, scientists aren't sure how many centuries it takes for plastics to completely break down and 'disappear'. That's why some people give a year estimate, while others prefer a more conservative year lifespan. United States Environmental Protection Agency. ACS Publications. Download PDF. Accessed Jan. Real Diaper Association.

The Aluminum Association. Commercial Aircraft Fleet From to Smithsonian National Air and Space Museum. Waste Advantage Magazine. Susquehanna University. Actively scan device characteristics for identification.

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