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A straightforward explanation of biodegradable vs. compostable vs. oxo-degradable plastics

Bioplastics, which can lessen our dependency on fossil fuels and lower greenhouse gas emissions, will become increasingly common as customer demand for environmentally friendly products rises. By 2022, it is anticipated that the production of bioplastics will increase by up to 20%, and when that happens, consumer awareness of bioplastics will also need to expand.

The distinction between three terms—biodegradability, compostability, and oxo-degradability—is a significant cause of confusion. These words are not synonymous even though they are frequently used in the same sentence. These and other terms used frequently in the bioplastics industry can be confusing, especially when it comes to how to properly dispose of bioplastic products. To correctly and honestly sell their products, businesses need to be aware of the differences between each category. Additionally, customers must be aware of these words in order to make informed judgments about what to buy and dispose of bioplastic items responsibly after usage.

Understanding bioplastics: Bio-based vs. biodegradable

It is crucial to first comprehend the definition of bioplastics in order to fully comprehend these three terms (biodegradability, compostability, and oxo-degradability). The term "bioplastics" refers to a broad category of plastics that are either initially derived from biomass (bio-based), degrade into organic biomass at the end of their useful lives (biodegradable), or both.

Based on this, bioplastics can be broken down into three distinct classifications:

  1. Non-biodegradable and fully or partially bio-based (e.g., bio-based PET, bio-based PE, Terratek® SC or Terratek® WC).

  2. Biodegradable and petroleum-based (g., PCL).

  3. Both biodegradable and fully or partially bio-based (e.g., PLA or starch blends such as Terratek® BD).

Biodegradation, which is the gradual breakdown of biodegradable plastics into the water, carbon dioxide (CO2), and bio-mass with the aid of microorganisms, is a very tiny subset of bioplastics. Additionally, biodegradable plastics can be either petroleum- or bio-based because the biodegradability of a plastic depends on the chemical characteristics of the polymer, not the source of the feedstock.

Biodegradable vs. compostable vs. oxo-degradable plastics

Almost all substances will biodegrade if given enough time. However, environmental factors like humidity and temperature have a significant impact on how long the biodegradation process takes. For this reason, consumers are misled when plastic is described as "biodegradable" without providing any additional information about how long the process will take and what environmental factors will be present.

Reputable businesses frequently make more precise statements, mainly attesting to the compostability of their bioplastic products. Biodegradable plastics are a subset of compostable plastics, which are identified by the typical circumstances and duration for biodegradation. All biodegradable polymers are compostable, however, not all compostable plastics are biodegradable.

Certified compostable: A more specific claim of biodegradability

Plastics that have undergone independent testing and certification to meet international standards like ASTM D6400 (in the United States) or EN 13432 (in Europe) for biodegradation in an industrial composting facility setting are known as compostable plastics.

In a municipal or industrial composting plant, materials certified in accordance with ASTM D6400 or EN 13432 will disintegrate in 12 weeks and biodegrade at least 90% in 180 days. At the end of the six-month process, 10% of the solid material will still be present and will consist of biomass, compost, or water. These requirements also guarantee that any residual compost won't contain any toxins, ensuring that it won't be harmful when sold by the facility for use in agriculture or gardening.

Unless specified differently, certified compostable items must be disposed of in an approved municipal composting facility rather than at home. To biodegrade sufficiently—or perhaps at all—many certified compostable materials need the higher temperatures of industrial environments.

The best places to use certified compostable products are closed systems, like amusement parks, stadiums, and schools, where compostable and organic waste are carefully monitored and controlled to ensure proper disposal in an industrial composting facility. Few areas in the U.S. have curbside collection for industrial composting. Organizations that use composting to lessen their carbon footprint and keep organic waste out of landfills include San Francisco International Airport and Safeco Field in Seattle.

A quick note on oxo-degradable plastics

Oxo-degradable is a separate category from biodegradable polymers, despite being frequently mistaken for them. They are standard plastic that has been combined with an additive to mimic biodegradation rather than bioplastic or biodegradable plastic. While biodegradable and compostable plastics degrade at the molecular or polymer level, oxy-degradable plastics quickly break down into ever-tinier fragments or microplastics. The resulting microplastics remain in the environment for a very long time before they finally completely decompose.

The importance of clearly and accurately labelling plastic products

In order to effectively advertise products and materials, it is crucial to be transparent about the environmental benefits of bioplastics as they continue to grow in popularity in the coming years. A useful place to look is the Federal Trade Commission's (FTC) Green Guides. In order to ensure that customer expectations are met, the Green Guides establish best practices for clearly labelling and marketing green products.

Transparency will not only help customers make wiser purchases, but it will also guarantee that bioplastics are disposed of properly. Bioplastics' environmental value proposition of keeping organic waste out of landfills, cutting greenhouse gas emissions, and promoting resource sustainability is ultimately strengthened by better end-of-life disposal.

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