Compostable materials go a step beyond biodegradable materials by breaking down into natural components and becoming a part of healthy soil. Industrially compostable products require the high heat (over 136°F) of industrial compost systems to properly biodegrade. These higher temperatures speed up microbial action and accelerate the degradation process. In contrast, home compostable materials are still industrially compostable, but can also break down in the lower temperatures (68-86° F) of a home compost pile/bin1.
Industrial compost systems collect large amounts of food, yard, and otherwise biodegradable waste. The material is mixed, sometimes shredded or ground, and then formed into long rows that are aerated to increase microbial activity2.
Home compostable materials, in contrast to those that are industrially compostable, biodegrade in the lower temperatures of backyard compost. Many materials are classified as industrially compostable but not home compostable.
Why choose it?
If packaging is soiled with food or grease, particularly fiber based packaging, it can be difficult to recycle4. Composting is an effective end-of-life strategy for applications where oil contamination is inevitable.
By and large, access to industrial compost is limited4. If your customer base is concentrated in areas with access to curbside compost collection that accept all industrially compostable materials (including plastic), then industrial compost can be an effective property to consider.
Why not choose it?
Unfortunately, building new composting facilities is a bit of a catch 22. Municipalities are reluctant to collect compostables without processing plants in place, and private companies are hesitant to build processing plants until they can be guaranteed a reliable source of contaminant-free collection — the main concern here being plastic7.
When it comes to compostable plastics, they’re often designed to look and feel like traditional plastics, creating consumer confusion when it comes to the end-of-life disposal. This leads to a lot of contamination of the final compost. Even well designed composting infrastructures can see contamination rates of 1.9%2.
Frequently asked questions
J.H. Song, R. J. Murphy, R. Narayan, G. B. H. Davies. Biodegradable and compostable alternatives to conventional plastics (NCBI, 2009)
Gaurav Kale, Thitisilp Kijchavengkul, Rafael Auras. Compostability of bioplastic packaging materials: An overview (Macromolecular Bioscience, 2007)
Adele Peters. Will compostable packaging ever be able to solve our waste problem? (Fast Company, 2019)
Alexis Shulman, Judith A. Layzer. Municipal Curbside Compostables Collection: What Works and Why? (MIT, 2014)
AU Standards: Biodegradable plastics suitable for home composting (Standards Australia)
Katelan Cunningham. Ask Lumi: Is Compostable Plastic Better for the Planet? (Lumi, 2019)