Waste Wise

Recycling’s Challenge: Plastic Bags

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For every retail item you buy, chances are you bring it home in a plastic bag. Cheap to produce, lightweight yet strong, plastic bags are among the unsung heroes of convenience in our society. Yet this convenience is short-lived. The average plastic bag has a duty cycle on the order of minutes to hours from its initial use to being discarded, although some of the lucky ones might be stored temporarily by consumers for later use. 

Once discarded, roughly 13 percent of plastic bags are actually recycled. The rest are landfilled or wind up as litter. One reason plastic bags wind up as litter is not that people fail to throw them into a waste receptacle, but that they easily blow away. Once in the environment, plastic bags are problematic. They can clog up stormwater drainage systems and contribute to man-made debris in rivers, lakes and oceans. Plastic bags comprise a significant portion of the Great Pacific Garbage Patch, and now have been found as far as the North and South poles. 

Although plastic bags are recyclable, a large number of recycling programs do not accept them. The larger philosophical reason for this is that plastic bags have been designed and manufactured with little regard as to their recyclability and end-of-life management. However, this is a larger discussion for a different time. From a practical standpoint, the reasons for limited recycling of plastic bags are that they can clog recycling equipment and are difficult to separate from other materials; plus, if they are contaminated or dirty, plastic bags can detrimentally affect the quality of the recycled end-product. The plastic bag that has stuff in it (like food scraps or dirty disposable diapers) and gets thrown into a recycling bin is much more common than you might think. 

To minimize the challenges with collection and at the materials recovery facility, one strategy is to manage plastic bags separately from other recyclables. For example, many grocery and retail stores have drop-off locations for this purpose. Similarly, many policymakers have recognized plastic bags’ potential environmental issues and have begun enacting legislation to require recycling. Yet the larger challenge of what to do with these bags after collection remains. 

Researchers at the University of Illinois (Urbana-Champaign) are evaluating the ability to convert plastic bags to a diesel fuel alternative using a waste conversion technology called pyrolysis. The development of large-scale technologies using mixed municipal solid waste has been slow to materialize; such technologies have a better track record at smaller scale and using one material as a feedstock.

Results thus far have shown that pyrolysis of plastic bags produces a fuel that consists of 74 percent crude oil, 17 percent solid residue and 9 percent gases. The quality of the product is comparable to conventional petroleum diesel fuel and the research team has thus far demonstrated that the product from the pyrolysis of plastic bags can be satisfactorily blended with petroleum-based fuels. While some questions remain—such as what levels of contamination can be accepted while still creating a high-quality fuel—this represents a first step towards a potential next-generation technology to deal with problem materials like plastic bags.

Of course, the larger challenges for a technology like this rely more on taking it from lab scale to field scale and implementing it in a way that works within the existing societal and waste management infrastructure, yet this cannot be done without first demonstrating a viable technology. A full description of this research can be found in the journal Fuel Processing Technology (2014, Issue 122, p. 79-90).

Discuss this Blog Entry 2

on Apr 16, 2014

It seems to me it would be best to go back a step and focus on reducing our plastic bag use versus trying to recycle, which requires time, energy and money with an uncertain outcome.
The best option is here is prevention/reduction, not recycling.

on Sep 19, 2014

I agree with greater emphasis on reduction and reuse but I'd also like for folks to consider recyclable film beyond bags and why it's in every household and business. Our primary objective is resource efficiency (reducing fossil resource use). Given the impact of transportation, making things lighter is critical (along with buying local and avoiding packaging all together). Companies choose packaging based on performance and cost. Bathroom tissue is wrapped in polyethylene film because it's super light weight and protects the product. Why not let folks know they can recycle that along with case wrap, bread bags, food storage bags, dry cleaning bags, air pillows, and bubble wrap in bag recycling bins available at most large grocery stores across the country? There is not a problem finding a buyer (domestic reclaimer) for this material provided it's clean and dry. This material travels with the grocers' commercially generated plastic film therefore maximizing efficiency. The scrap value for this material is far greater than other common commodities and has been for years. Finding a market is not a barrier to film/bag recycling.

To find film markets, where to recycle, and what to recycle visit PlasticFilmRecycling.org. If you are willing to help get info out about recycling film beyond bags you can sign up as a WRAP champion in the WRAP section.

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Bryan Staley

Bryan Staley, P.E., is president of the Environmental Research and Education Foundation, a non-profit foundation that funds and directs scientific research and educational initiatives to benefit...
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