Linda Norris Waldt
US Composting Council
Compostable bioplastics are becoming ever more present in the marketplace. From food packaging in the grocery store, to produce bags, to disposable dishware and cutlery at restaurants, to agriculture-related products, compostable bioplastics are becoming a more frequent purchasing choice. Ultimately, the goal for these products —when they meet compostability standards such as BPI certification or field-testing standards—is successful composting at a commercial composting facility alongside the organics with which they are associated.
Compostable bioplastics have the opportunity to not only lessen the amount of waste being sent to landfills, but to bring much needed nitrogen from the food scraps traveling with them to the compost manufacturers’ recipe for quality compost.
However, with compostable products often comes an unfortunate ride-along of non-compostable contaminants, such as metals, glass, and non-compostable plastic. These tend to slip through due to unclear labeling and confused waste generators (e.g., consumers, restaurants, and others). Compost manufacturers are faced with the cost of sorting out these contaminants and/or facing a lessened value of their compost when they make their way into the mix.
Due to this risk of contamination, the rate of acceptance for compostable bioplastics is low. Of the 2,700 compost facilities in the U.S., fewer than 5% accept compostable products.
The challenge for the bioplastics industry? How to address the obstacles compost facilities face. Here are the top 5 things composters need in order to feel confident in accepting compostable products.
#1. It must be food-associated.
Food waste brings compost manufacturers the nitrogen they need to balance their recipes for quality compost. With a recommended 25:1 ratio of carbon to nitrogen, the nitrogen provides the fuel (microbes) needed to break down carbon feedstocks (e.g., wood chips, paper, and other carbon-based feedstocks). Some compost manufacturers having trouble finding carbon sources may use controlled amounts of compostable packaging to help balance their recipes.
There’s a double-shot benefit from wasted food scraps: EPA estimates 24% of the municipal solid waste we throw away is wasted food, generating 58% of landfill methane emissions, contributing to high levels of greenhouse gas emissions. The food scraps used in composting also convert to soil carbon, a plus for stabilizing the amount of carbon in the atmosphere. Compostable packaging that is DIRECTLY associated with food being discarded (e.g., produce bags, condiment packets, plates etc.) are what composters look for in the assumption they will be carrying nitrogen-rich food scraps along with them.
#2. Meet the U.S. standards.
Composters want to be assured that materials meet ASTMD6400 and ASTMD6868 standards for lab degradability as well as BPI (Biodegradable Products Institute) limits on fluorine content. It’s even better if product managers can arrange to have materials field-tested in regions where products are being accepted to ensure that breakdown is likely. Composting conditions are extremely variable based on system, process, geography (soil makeup and weather). Another standard coming from Europe is the TUV standard. Most composters do not require TUV, but it is helpful since it indicates home composting breakdown capability for optimized home piles, which makes it even more likely to break down in commercial composting environments.
#3. Make it obvious.
It makes the compost industry extremely happy when product manufacturers take care to use proper labeling, such as the BPI logo, the word “compostable,” and green tinting; these are all markings in conjunction with BPI-recommended practices. Interestingly, such labeling is not necessarily for the benefit of the composter. More importantly, it is helping the consumer or kitchen employee make quick and easy choices to put the right items in the compost receptacle. Products should be well marked, labeled with BPI, and preferably have green tinting. Composters have always said that it is consumers and haulers who need to get it right— by the time materials arrive at the composter, it’s too late.
#4. Educate. Educate. Educate.
Generators—such as restaurants, institutional kitchen managers and facilities directors—and the communities must be doing a good job of educating people about what is and isn’t compostable. Compost manufacturers love to work with haulers and generators to make sure the education they are providing adequately conveys the message regarding which materials the composter will accept. Compost is local in many ways—both in what is accepted, because conditions vary so much, and in the quality of compost that is generated later. Taking the time to do regional and local research and education pays off for everyone in the end. Many composters have a contamination fee or “three-strikes and you’re out” policy for high contamination—and for good reason.
The flip side of this coin is more pertinent to municipalities than compostable product manufacturers but is still important: it’s better to start municipal programs with people who truly want to compost. If a municipality institutes mandatory instead of opt-in composting, contamination of the composting stream is guaranteed. It is better to phase in programs once early adopters have time to succeed and educate their neighbors and friends.
#5 Compostable bags make life easier.
Just as plastic film is problematic for mechanical recycling, it can be problematic for composting as well —specifically, when it comes to non-compostable bags. These materials can make it difficult to reach the goal of making and/or selling quality compost because they are difficult to sort out of the compost pile. Plus, due to their thin nature, films pose a high risk of creating microplastics. The more certified compostable bag choices municipalities offer for consumers, the better. More options results in better pricing and access to supply. Produce bags and other bags used with food should be compostable as well, and easy to find in major retail outlets.
In 2021, the U.S. Composting Council (USCC) held a series of virtual panels around composting and compostables. Two informative documents came out of that process. Both can be found at compostingcouncil.org/compostable products:
In 2022 USCC, BPI, and composting and packaging stakeholders developed a set of compostable packaging/labeling principles that would be helpful as part of state and national labeling bills. See more about that here: www.compostingcouncil.org/truth-in-labeling.
As the plastics industry responds to increasing demand for plastics, despite low labor supply, it…
