August 17, 2010 | General

Industrial Composters Shed Light On Compostable Products

BioCycle August 2010, Vol. 51, No. 8, p. 26
New report provides a snapshot of what composting facilities are currently accepting, processing conditions and experiences with compostable packaging.
Rhodes Yepsen

THIS past spring, the Sustainable Packaging Coalition (SPC), an industry working group, launched its “Industrial Composter Survey Project.” The SPC is a project of GreenBlue, a nonprofit sustainability institute that works with the private sector to enable the positive redesign of industrial systems. The purpose of the project was to gather information about how industrial composting facilities operate – what materials they accept, equipment and systems used, etc. – to gain a better understanding of the fate of compostable packaging and identify possible disconnects between packaging designers and composters. The survey report, “Compostable Packaging: The Reality On The Ground,” provides a snapshot of what composting facilities are currently accepting, processing conditions and general experiences with packaging.
A working group of SPC member companies and composting experts was formed to guide the direction of the survey project and develop questions. Fifty U.S. composting facilities were identified, based on size (annual throughput), composting method and geographic location (Figure 1). This subset was intended to provide a range of experiences with packaging, rather than gauge the total U.S. capacity for processing compostable packaging. Forty facilities completed the survey.


The main outcomes are as follows: 90 percent (36 out of 40) of the facilities surveyed actively accept compostable packaging; 67.5 percent require compostable packaging to have some type of standard or certification before allowing it in the front gate; 82.5 percent want a more universally recognizable label of compostability; 80 percent actively develop food waste programs to increase throughput; and 75 percent would consider promoting or already do promote the use of compostable packaging in their local communities.
The facilities surveyed range in capacity from 1,125 to 1,347,580 tons/year of all incoming materials, with a median of 23,500 tons/year. Some reported actual throughput, whereas others cited permitted capacity. Seventy percent of facilities also reported food waste accepted in 2009, which was converted into tonnages. This ranged from 150 to 75,000 tons of food waste, with a median of 2,142 tons. Most of the facilities accept food waste from commercial and institutional sources (97.5 percent and 95 percent respectively), as well as special events and festivals (87.5 percent). However, only 37.5 percent currently accept residential food waste.
It was difficult for many facilities to accurately determine which sources were actually sending compostable products and packaging in loads of food waste, as haulers often have mixed-business routes. However, using best estimates, the sources diverting the most compostable packaging were special events, schools, restaurants and supermarkets (Figure 2).
A variety of compostable products and packaging are currently accepted at composting facilities (Figure 3). Almost all facilities accept compostable bags and uncoated paper napkins (87.5 percent). While many accept a wide range of compostable packaging, several categories in the survey received low rankings. Paper cups lined with polyethylene were only accepted at three facilities (7.5 percent) because of the noncompostable plastic lining. Mixed paper and clay-coated paperboard also ranked low, accepted at only 18 facilities (45 percent). The primary reason given was that these paper products have a higher value in conventional recycling streams.

The packaging community was concerned that facilities were not following American Society for Testing and Materials (ASTM) standards, and instead were establishing individual facility, state or regional guidelines. Of the surveyed facilities, 67.5 percent require compostable products and packaging to follow some type of specification or certification. Of those, 47.5 percent require products and packaging to meet ASTM specifications, while 37.5 percent require Biodegradable Products Institute (BPI) certification (some indicated both). Twenty percent of facilities checked “other” for specifications and certifications, indicating that on-site testing was conducted prior to accepting compostable products or packaging.
Remaining respondents (32.5 percent) do not require any specifications or certifications. Some facilities have designed expensive screening systems, configuring multiple types of equipment to successfully remove anything from the finished compost that does not fully biodegrade. On the other end of the spectrum, facilities that have a great deal of control over incoming materials can work with food waste generators to quickly identify problematic packaging and remove it, and therefore devote fewer resources to screening equipment.
Another variable is that composting facilities may operate in shorter time frames than allotted by ASTM to meet disintegration and biodegradation tests. For disintegration, no more than 10 percent of the original dry weight of a product may remain after 12 weeks (screened at 2.0 mm). Almost half (19 out of 40) of the facilities surveyed report an active composting time of 70 days or less, which is shorter than the 84 allotted by ASTM. A factor not addressed in the survey, but which bears noting, is that ASTM tests use 140°F as a benchmark, but some facilities operate at much higher temperatures, which can kill off fungi that is beneficial for breaking down fibers (e.g. paper).
The biggest problem reported with compostable packaging was regarding items not breaking down thoroughly or quickly enough. Part of this may be due to items not meeting ASTM standards or being BPI-certified. Many facilities listed compostable plastic cutlery as particularly problematic, with large chunks not breaking down, leading to contaminated screened overs. Another common issue cited was that compostable film and bags create litter at the site. This was most prevalent at facilities with uncovered piles, but not exclusively, and percentages were difficult to ascertain, as compostable film looks similar to conventional plastic film.
An attempt was made to correlate problems with packaging by composting method as well as by region, but the correlations were not very conclusive. While the possibility is significant that composting method and geographic location may impact the performance of packaging at a composting facility, a more targeted set of questions and a larger sample size of facilities would be needed to develop reliable correlations.
Another factor raised in the survey was that compostable packaging may impact the ability of finished compost to be approved for use in organic agriculture (see “Organic Farming And Compostable Plastics” on page 24). When asked whether their compost was approved for use in organic agriculture, 32.5 percent responded “Yes.” Of that group, 23 percent said that compostable products and packaging put that certification at risk, while the rest were either unaware or uncertain whether it was an issue. Also, 31 percent of that group currently processes compostable packaging separately from loads without packaging, due to organic certifications.

Perhaps the most significant area for improvement that composting facilities identified is a standardized labeling system: 33 out of 40 (82.5 percent) of respondents said they would like to see a more universally recognizable label of compostability. Composters suggested a visual cue, such as color-coding, a more prominent and consistent logo, a combination of the two, or other improvements. The SPC suggests that it may be appropriate to codify the label in law to enable government oversight, level the playing field, and limit greenwashing potential.
Benefits of an improved and standardized label include: Assisting composters to identify packaging received at their facility as compostable or as contaminant; Reducing consumer confusion about compostable vs. recyclable/conventional, which in turn would mean less contamination at composting facilities and in recycling bins; and Resolving recycling industry issues on contaminating conventional plastic recycling streams with compostable biopolymer packaging. In general, the results of the survey were positive: 72.5 percent of facilities report that compostable products and packaging allows them to increase food waste tonnage/volume, and 80 percent would consider or already do promote their use.

Rhodes Yepsen worked on the Industrial Composter Survey Project as a contractor to the Sustainable Packaging Coalition (SPC), with assistance and support from SPC staff members Heather Martin and Liz Shoch. More information on packaging at composting facilities can be found in the full SPC survey report, available to non-SPC members for $50.00 purchase at

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