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Drop-off compostable

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Definition

Breaks down to become part of healthy soil in an industrial composting facility.

Overview

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.

Common industrial compostability standards include ASTM 6400 and EN13432, and these standards both use a benchmark of 58°C (136°F) as a proxy to represent the heat of industrial compost systems3 6.

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.

Top 10 US States by Weight of Compost

Why not choose it?

Access to industrial compost is limited at best. Many cities do not offer municipal compost collection, because setup can be challenging and costly5.

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

Generally, paper and plastics made from biodegradable polymers can be compostable.

Industrially compostable products can be marked with the BPI certified logo, OK Compost Industrial, or the Seedling logo given by TUV Austria. These marks ensure packages were tested to either ASTM 6400 or the EN 12432 Industrial Compost Standards.

It depends on how the material is disposed. If landfilled, compostable plastic decomposing in an anaerobic environment (without oxygen) can produce methane, a powerful greenhouse gas. Paper-based materials, while compostable, are fiber based and can be easily recycled.

Industrially compostable plastic (PLA) will not break down in the ocean. Other home compostable polymers, starches, and paper will break down over time. ISO 18830 is the standard test to determine compostability in marine environments, but the test is not commonly performed by packaging manufacturers.

Compost (also called humus) is usually sold in bulk to farms in the immediate area surrounding a municipal compost facility. Sometimes the compost is used in construction projects on steep embankments because it is more effective than dirt at reducing erosion and establishing plant growth2.

Industrially compostable packaging is ideal in scenarios where dedicated processing is arranged. Given the current infrastructure and uncertainties around collection and processing, the best use of industrially compostable packaging is in closed systems such as restaurants, office campuses, and sports stadiums, all places where collection can be ensured.

References

  1. J.H. Song, R. J. Murphy, R. Narayan, G. B. H. Davies. Biodegradable and compostable alternatives to conventional plastics (NCBI, 2009)

  2. Gaurav Kale, Thitisilp Kijchavengkul, Rafael Auras. Compostability of bioplastic packaging materials: An overview (Macromolecular Bioscience, 2007)

  3. Packaging waste directive and standards for compostability EN 13432 (BPF)

  4. Adele Peters. Will compostable packaging ever be able to solve our waste problem? (Fast Company, 2019)

  5. Alexis Shulman, Judith A. Layzer. Municipal Curbside Compostables Collection: What Works and Why? (MIT, 2014)

  6. AU Standards: Biodegradable plastics suitable for home composting (Standards Australia)

  7. Katelan Cunningham. Ask Lumi: Is Compostable Plastic Better for the Planet? (Lumi, 2019)