As concerns grow about dwindling landfill space and petroleum scarcity (and therefore the future availability of plastics and other petroleum based products) manufacturers have begun to explore alternatives to traditional resins. With climate change and zero waste initiatives at the forefront of environmental concerns, industry is reacting by designing new products that are petroleum content free and compostable, thus seemingly reducing environmental impacts through consumption choices. These choices provide consumers with the opportunity to be part of the solution.

There are two main types of biodegradable plastics or bioplastics. The first is polylactic acid (commonly referred to as PLA) which is a completely new resin. The second type of biodegradable plastic is standard resin with additives to promote biodegradability. These bioplastic resins are made from corn, potatoes, sugarcane, or other plant cellulose sources. It is the organic nature of these manufactured polymers that increases end use biodegradability. It should be noted that besides petroleum, which is also plant based, traditional plastic resins also commonly contain additional plant based additives such as cellulose.

The main benefit of PLA containers is that they can be composted and therefore should not take up landfill space if disposed of properly. PLA containers also use less petroleum through manufacturing processes than conventional plastic containers. According to Natureworks LLC, a leader in biopolymer manufacturing, the corn based products created by the company use 65% less petroleum and contribute 68% fewer greenhouse gas emissions to the atmosphere than traditional resins. [27]

Despite the potential environmental benefits of PLA containers and other biodegradables, they are not an end all solution to waste. To the contrary, bioplastic manufacturing processes are energy intensive and bioplastic products are generally designed for single use rather than durability. When working towards campus sustainability, it is important maintain a broad view of waste management and remember: “Reduce, Reuse, Recycle,” when making decisions. PLA products fit into the recycling/composting category, but do not address issues of consumption and if single use containers are necessary in the first place.  

It is important to comprehend a product's properties in order to determine how best to deal with it at the end of its life cycle. Generally, only bioplastics that are 100% PLA are compostable through industrial composting processes. Bioplastics made from mixed resins (such as a combination of PET and PLA) are frequently touted by manufacturers as recyclable, but are typically viewed by recycling companies as contaminants. As new products appear on the market, be in continuous communication with local recyclers and composters in order to determine what can and cannot be collected for reprocessing. Otherwise, items that are collected with no available market become waste.     

If bioplastic containers are collected with other compostable materials (such as food scraps), ensure that the materials are collected in biodegradable bags. A typical plastic bag will contaminate the composting process. The Biodegradable Products Institute (BPI) lists products that are generally accepted at industrial composting facilities. There are a variety of bioplastic items that contain plastic polymers that are not compatible with industrial composting processes. As specifications may vary, make sure to double check with the local industrial composting facility before choosing a product, even if BPI lists it as biodegradable.    Be aware that biodegradable bags and containers will degrade over time and cannot be stored indefinitely, especially at higher or continually fluctuating temperatures. Such products should be utilized within eight months of purchase for best results.     

While bioplastics will biodegrade over time, they require special handling procedures in order to fully decompose back into a useful end product and will not readily decompose if placed in a landfill or basic home composting system. Industrial composting processes are required to melt PLA plastic back into reusable components because typical home composting systems do not reach high enough temperatures to break the polymer chains. PLA generally requires temperatures of at least 150° C in order to break down. [28] While industrial composting facilities with these capabilities exist, they may not be readily accessible to local recycling and composting programs or may not have the capacity to handle the amount of PLA waste generated by a large institution such as a university. As with any recyclable item, an existing market is required before the Campus Recycling Program starts collecting. Assess the feasibility of collecting and processing PLA containers before purchasing such items for use on campus. Use durable foodware whenever possible, or items that are inherently biodegradable, such as paper plates or food boats without plastic coatings.   

If the campus does decide to begin purchasing bioplastic products as replacements for traditional plastic items, be selective in the types of containers that are purchased and establish clear collection and disposal guidelines. Work with the campus Purchasing Department to choose compostable containers (100% PLA) that are easily distinguishable from non-compostable containers. This will make composting guidelines far easier to explain to consumers. For example, containers with a bright green stripe or that read, “Biodegradable” will be easily identifiable in the waste stream. Currently, many bioplastic containers look very similar to conventional plastic containers. However, PLA is different from conventional plastics with respect to both physical and chemical properties. If not properly separated, PLA will act as a contaminant to PET, HDPE, and other resins, and will undermine the integrity of the new products created with these plastics. Similarly, standard resins, or mixed PLA/PET blends, easily mistaken for 100% PLA, will contaminate composting processes. This can result in major health and safety concerns as well as significant financial losses on the part of the recycling and composting facilities processing the materials. Therefore, PLA containers should be used only as a last resort in a highly managed waste stream. Otherwise, contamination occurs, and highly recyclable plastics are replaced with a material that becomes a lasting burden in a landfill despite its claim to biodegradability.

Consider staffing waste stations in order to educate the campus community regarding what is acceptable for composting, what can be recycled, and what is considered trash. Be available to answer questions. This is especially important when new biodegradable products are introduced into the campus waste stream as it will significantly decrease contamination.

Be aware of a product's entire life cycle before introducing it into the campus waste stream. While PLA products use less petroleum than conventional plastics, they do not have the durability or recyclability of PET or HDPE. Identify which sectors of campus would benefit from PLA products and which would benefit more from traditional plastics recycling. In addition to low-durability, there are other factors to consider in assessing a PLA product's life cycle. Was it made with genetically engineered corn which increases soil erosion, contaminates air, water, and soil with biocides, disrupts local ecosystems, and cross-contaminates nearby non-GMO crops with new biological material? What sort of energy source was used to manufacture the product? How much energy will be required to heat the product in the industrial composting process in order for it to biodegrade? The same types of questions need to be asked more frequently with regards to PET and any other materials, but are especially important when deciding whether or not to replace an existing waste management system with a new one.

The best application for bioplastic is as a replacement material for single use trash items. Consider all implications of replacing a highly recyclable item such as PET plastic bottle with a bioplastic container. This may lead to consumer confusion and can promote the misconception that traditional plastic is compostable or that bioplastic is recyclable within existing processes. If previously recycled items are replaced by bioplastics, be certain of the new product's chemical composition. For example, if a product is marketed as a bioplastic, make sure all components are PLA (instead of a mix of PLA and traditional resins) before composting. Thoroughly research the benefits and drawbacks of any product or process before introducing it on campus.

Resources

The Association of Postconsumer Plastic Recyclers
Factsheet: A Recycling Coordinator's Guide to Managing Compostable and Bio-based Plastic
http://www.plasticsrecycling.org/article.asp?id=57

 The Biodegradable Products Institute
http://www.bpiworld.org 

Federal Trade Commission's “Guides for the Use of Environmental Marketing Claims.”
http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=b2333ddf96abf25788ef3037ffcfb40a&tpl=/ecfrbrowse/Title16/16cfr260_main_02.tpl        

Natureworks, LLC
http://www.natureworksllc.com/ 

Royal Science of Chemistry- “Using Polylactic Acid”
http://www.rsc.org/education/teachers/learnnet/inspirational/resources/3.1.11.pdf

 Related Articles  

Scientific American. “The Environmental Impacts of Corn-Based Plastic”
http://www.scientificamerican.com/article.cfm?id=environmental-impact-of-corn-based-plastics 

Smithsonian Magazine. “Corn Plastic to the Rescue”
http://www.smithsonianmag.com/science-nature/plastic.html 

Tree Hugger. “Canadian Water in Corn-based Bottles”
http://www.treehugger.com/files/2007/01/canadian_water_1.php

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