About this Article
Written by: Samantha Huyhua
Written on: April 26th, 2010
Tags: material science, energy & sustainability
Thumbnail by: Streetwise Cycle/Wikipedia
About the Author
Samantha Huyhua is a senior at the University of Southern California majoring in environmental engineering. She hopes to be able to implement the knowledge gained at USC back in her home country of Peru.
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Volume XII Issue I > Recycling Plastics: New Recycling Technology and Biodegradable Polymer Development
Plastics are usually disposed of in one of three ways: discarded, combusted, or recycled. Of the three options, recycling is least implemented. Because the disposal or combustion of plastics leads to detrimental health and environmental effects, short and long term solutions need to be established. A potential short-term solution would be the development of new technology to boost recycling rates. The current recycling system requires a labor-intensive sorting step which contributes to the low amounts of plastic being recycled. Technology that eliminates the sorting process could potentially increase recycling rates. However, because all plastics cannot be recycled indefinitely, a long-term solution is also needed. The advancement of biopolymers that will degrade faster than regular plastic polymers that end up in landfills would decrease environmental pollution while providing compost for plant nutrition.

The High Cost of Plastic Convenience

Streetwise Cycle/Wikipedia
Figur​e 1: Plastics that are discarded into landfills release toxic chemicals that pose risks for human and wildlife health.
Since their creation, plastics have been an indispensable ingredient in consumer lifestyles. They have found their way into various household and commercial products, such as water bottles, food containers, packaging materials, or disposable utensils. Plastic materials are convenient and inexpensive, but their disposal poses an environmental dilemma (Fig. 1). Although plastics only accounted for 12% of total municipal solid waste generation in the United States in 2008, they steadily increased since the 1960s and now constitute the greatest amount of discarded material with a low rate of biodegradation [1]. Furthermore, of the 30 million tons of plastic that ended up in municipal solid waste centers in 2008, over 75% was discarded into landfills [1]. The problem with plastic material in landfills, besides the space they occupy, is that they contribute a barrage of toxic chemicals to the fluids that drain and percolate through the landfill (known as leachate). Toxic chemicals that are derived from plastics (for example, phthalates) have been found in ground water due to leachate infiltration, posing a great concern to human and wildlife health [2].

Dealing with Different Plastics

Although most of the discarded plastic finds its way into landfills, about 16% is combusted to produce energy [2]. Since plastic is derived from petroleum products, its energy yield is almost as high as fuel oil; plastic yields 19,900 BTU/lb whereas oil yields 20,900 BTU/lb [3]. However, the incineration of plastics produces air pollution by releasing chemicals such as hydrogen chloride, dioxin and fine particulate matter [2]. Another way of dealing with plastics is recycling, but this only accounts for about 7% of the plastics encountered in municipal solid waste centers [1]. Because plastics pose a threat to human and wildlife health when disposed of in landfills or through incineration, engineers are working to increase recycling rates by improving current recycling technologies while also developing biodegradable polymers for future use.