Thursday, September 6, 2007

What happens to plastic when we throw it away?

Ideally, there are two ways to dispose of plastic: landfills or recycle centers. (Burning and dumping in the environment will be discussed in a later post.)

My preferred method to dispose of plastics is by recycling them. Seattle currently recycles about 44% of it's solid waste, with an official goal of 60% by 2010. With new proposed legislation, Seattle hopes to reach 72% by 2025. (Seattle PI article)

I found a great slideshow link on demonstrating what happens to recyclables after you toss them in your blue bins. The short version: recycling trucks from Rabanco sort recyclables into two bins; glass and "commingled". The truck dumps the "commingled" recycling inside the 80,000 square foot facility. Glass is unloaded outside in a separate area. For the next 24-48 hours, the "commingled" recycling is sorted into cardboard, mixed paper, newspaper, plastic bags, metal, aluminum, and finally, plastic. The different materials are then baled and sent onto additional facilities for processing.

Recycled plastic can be converted into new materials. Plastic bags are remade into plastic lumber, and siding for houses. Plastic containers are made into fleece clothing, carpet, and new containers. Seattlites love their fleece.

Some of the downsides to recycling can be avoided by an informed public. Different cities have different recycling capabilities and can't handle all the materials that other facilities can. For example, Rabanco asks customers to remove all caps/lids from plastic and glass containers. "Contamination" of non-recyclable or improper materials can also cause delays, injuries to workers, and/or add delays to the recycling process. These materials are then diverted to the Roosevelt Regional Landfill.

Americans generate trash at an astonishing rate of four pounds per day per person, which translates to 600,000 tons per day or 210 million tons per year. (source) According to How Stuff Works, a landfill is a "carefully designed structure built into or on top of the ground in which trash is isolated from the surrounding environment (groundwater, air, rain). This isolation is accomplished with a bottom liner and daily covering of soil."

  • Sanitary landfill - landfill that uses a clay liner to isolate the trash from the environment.
  • Municipal solid waste (MSW) landfill - uses a synthetic (plastic) liner to isolate the trash from the environment.
"The purpose of a landfill is to bury the trash in such a way that it will be isolated from groundwater, will be kept dry and will not be in contact with air. Under these conditions, trash will not decompose much. A landfill is not like a compost pile, where the purpose is to bury trash in such a way that it will decompose quickly." (source)

How long does it take garbage to break down in a landfill? A quick Google search with the terms "landfill garbage break down" does not produce many positive results. Without microorganisms and oxygen to break down garbage, even the most biodegradable items, such as an apple core, will remain for years longer than it would in an ordinary compost bin. Add in the additional problems of toxic waste leaking into the surrounding environment (Roosevelt Regional Landfill is located close to the Columbia River) and landfill fires.

With the millions of plastic items manufactured each year all over the world, how many end up in landfills? How many end up littering the environment, never fully breaking down into non-toxic substances? In the environment, the evidence from plastics linger years after disappearing from view. An article from Sustainability Institute reports:

Degradable plastics come in two forms: biodegradable and photodegradable. The biodegradable kind mixes the long plastic molecules, which nothing in nature can digest, with starch, which micro-organisms will happily munch away. Depending on the material strength required and the rate of degradation, the starch percentage varies, but it's usually something like six percent starch to 94 percent plastic.

On the side of the road a bottle or bag made of biodegradable plastic slowly falls apart -- into tiny shards of undegradable plastic. The bottle or bag disintegrates, but the plastic is still there. Presumably it is inert and harmless, but no one really knows the implications of a world filled with plastic sand.

We can cut back on the amount of plastics we manufacture and purchase, reduce the amount of packaging on consumer goods, and work to recycle almost all of the plastics that we use.

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