BioCycle May 2006, Vol. 47, No. 5, p. 46
Over a decade after their introduction, compostable plastic products made from biodegradable polymers are gaining a foothold in the commercial and consumer marketplaces.
Nora Goldstein

IT’S BEEN well over a decade since BioCycle tackled the complex subject of biodegradable polymers and their use in products that were ultimately destined for the compost pile. Since that time, we have seen the adoption of ASTM specifications for compost products, the creation of the Biodegradable Products Institute (BPI) with its certification program, and the introduction of a range of products designed to facilitate diversion of organics to composting. Furthermore, production capacity has grown significantly for some biodegradable resins, which creates the potential for lower product unit costs.
The Compostable Plastics Update section in this issue of BioCycle is the beginning of more regular coverage of the market inroads being made in the biodegradable plastics industry – primarily as they relate to increased diversion of organic feedstocks to composting. Without a doubt, there is intense interest on the part of composting program coordinators to see the price of compostable products decrease so that their use can be expanded in local and regional diversion programs. Composters are getting more confident in the degradability of the polymers in their composting systems. While it is naíve to say there is smooth sailing ahead, we have seen definite progress in addressing hurdles. It is also exciting to see major companies starting to use biodegradable polymers in their industrial and consumer products. The article by Connie Hensler of Interface Corporation in this section is a case in point.
This article highlights some trends and developments that we have seen over the past year or two. In the next issue of BioCycle, we will continue our industry overview, as well as profile several composting programs that are incorporating compostable bags and other products.
THE BIOLOGICAL DEGRADATION TEST
Cedar Grove Composting operates two large-scale facilities in the Seattle, Washington region that process yard trimmings and commercial and residential source separated organics. When Cedar Grove initially began receiving food residuals, it was limited to preconsumer vegetative materials. Installation of the Gore Cover System technology at its original Maple Valley site and its new facility in Everett, Washington allowed Cedar Grove to accept postconsumer food residuals as well. As with most organics diversion programs, the desire to continue use of plastic bags to line collection containers arose. Cedar Grove would not allow conventional plastic bags, but did agree to test the use of the biodegradable variety. The company bags a considerable amount of compost, and in general, sells to higher value end markets. It was not willing to compromise the quality of its compost product by accepting bags and other biodegradable items such as cups and cutlery that would not biologically degrade in its Gore composting system.
At BioCycle’s recent West Coast conference in Portland, Oregon, Denise Foland of Cedar Grove explained the protocol used to evaluate the biodegradability of commercially available products. First, all items submitted must be BPI-certified or pass the ASTM D6400 test for biodegradability and compostability (see sidebar with accompanying article by Diane Greer). Products without this certification or confirmation of passing the test will not be tested. The items Cedar Grove is willing to test range from bags and bin liners to food service items such as utensils and plates. Companies submitting biodegradable items for testing must include three to five samples of each item submitted with an identification number written on at least one of the samples. A profile sheet that provides a description of the samples being submitted, their composition and the manufacturer must be filled out. Cedar Grove charges a testing fee of $250 for all groups of items submitted (maximum 10 different items per group).
“We take utensil and plate materials all the way through the third phase of our composting process,” said Foland. “The first phase is 28 days, where temperatures can get as high as 180° to 190°F, starting off with a moisture content of 60 percent. After four weeks, the piles are uncovered and moved. Phase 2, where the piles are covered and aerated, is 15 days. In Phase 3, the piles are uncovered and aerated for another 15 days.”
The samples are put in mesh bags and typically placed between two aeration trenches about two feet above the ground in the first quadrant of the pile. Duct tape is put on all the items tested so they can be identified. For items other than bags, e.g., cups, utensils and plates, the sample is cut so that the pieces are uniform, and layered with some of the feedstocks to simulate the conditions as when it would be disposed with the food residuals. “Our criteria for passing products other than bags is that there is less than five to 10 percent of the original sample left after the two phases of composting,” explained Foland. Bags are put in the piles whole and are filled with the feedstock materials they would typically contain. “Our criteria for the bags is that less than 20 percent can remain after Phase 1 of composting,” she said.
Four brands of biodegradable bags have met Cedar Grove’s criteria. They include BioBag, BioTuf by Heritage Bag, Eco Film/EcoWorks from Cortec Corporation and Nat-Ur, Inc. The BioBag brand is made of Mater-Bi, a blend of cornstarch and biodegradable and compostable polyesters, and vegetable oil. Heritage Bag’s BioTuf brand is made from a proprietary mix of organic materials, including PLA and EcoFlex (from BASF). Cortec’s EcoFilm/EcoWorks contains biobased polyester made from corn (no polyethylene or starch is used). The Nat-Ur bags are made from Cereplast biobased resins that include various starches and PLA.
To date, no other categories of biodegradable products (e.g., cutlery, cups) have been approved through the testing process. While Cedar Grove receives source separated organics from commercial and residential collection programs, only commercial organics generators are allowed to use biodegradable bags. There is a concern that allowing use of the biodegradable bags in residential programs could lead to inclusion of noncompostable bags (e.g., grocery store sacks) in curbside setouts, something that is more difficult to control and monitor than with commercial diversion programs.
HIGH PROFILE DEVELOPMENTS
Sustainability “speak” on the part of major corporations is leading to some significant commitments on the environmental front, which also could blow the market wide open for biodegradable resins. One of the more dramatic corporate announcements came from Wal-Mart. In November 2005, the company announced that Sam’s Club stores would begin using containers made from PLA produced by NaturWorks, LLC. According to an article in SustainableBusiness.com, the stores started with packaging for cut fruit, strawberries, herbs and brussel sprouts, which together account for over 100 million containers a year. In general, Wal-Mart CEO Lee Scott set a corporate goal of reducing its solid waste generation by 25 percent by the end of 2008.
In 2003, the Sustainable Packaging Coalition was formed, an industry working group “inspired by cradle to cradle principles and dedicated to creating a more robust environmental vision for packaging,” according to its website. Corporate members include biodegradable resin manufacturers, packaging and consumer product manufacturers and retailers. Packaging Strategies, a publisher and market analysis firm for the packaging industry, sponsored its first Sustainable Packaging Forum last fall, with a second event planned for this coming September. Biodegradable plastics are a primary area of coverage.
Along with this high profile being given to biodegradable packaging must come a dose of reality – achieving the “cradle to cradle” goal requires having the final “cradle” available and accessible. In BioCycle “speak,” that final cradle is a composting facility that provides the controlled aerobic environment for these products to biodegrade. An article in the April 30, 2006 edition of Packaging Strategies on biodegradable and compostable package claims, opened with the following statement: “While biodegradable packaging continues to make market inroads, certification specialists have expressed concern that few standards are being followed by marketing departments that are making exaggerated, undefined, or even uncertified claims regarding their packaging’s biodegradability and compostability. Corn-based PLA resins in particular will not degrade unless products are placed in a controlled industrial compost that contains the right mix of moisture, heat and microbes. Minneapolis-based NatureWorks specifies on its website that its PLA materials will be transformed and deteriorate in about 47 days if composting conditions meet global testing standards.”
The article cites the Biodegradable Products Institute’s certification program, which asks that items with a BPI label state their products can only degrade under specified conditions. “To comply with (Federal Trade Commission) guidelines, companies must talk about the fact that biodegradability can only take place in large-scale composting facilities,” Steve Mojo, Executive Director of BPI, told Packaging Strategies. “There are many claims that are misleading; companies talk about biodegradability but not where it is supposed to take place.”
Over the next several months, BioCycle will be updating its database of composting facilities in North America that accept bags, packaging and products made from biodegradable resins. Compost operations are encouraged to contact us (see sidebar for details) in order to be included.