The categories of composting

Industrial compostable? home compostable? or biodegradable?

On this page, we provide an overview of the different categories of composting and explore the key differences between:

  • Industrial compostable packaging
  • Home compostable packaging
  • Biodegradable packaging
  • bio-based packaging, and
  • Oxo degradable packaging
Cateogires of compostability.v1

What is industrial compostable?

  • Unless expressly stated otherwise, certified compostable products must be disposed of in a designated industrial composting facility as the materials require higher temperatures (above 55 degrees) to biodegrade
  • Biodegradable plastic for example, doesn’t fully decompose in landfill because the necessary oxygen to decompose  is too low, it can’t be composted from home either due to lack of heat and can only be composted from a commercial facility
  • The environments in commercial facilities are designed to optimise the degradation process as industrial composting more rigorously sustains the temperature and stability of the compost
  • Compostable plastics are those plastics which have been tested and certified by a third party to adhere to international standards such as EN 13432 for biodegradation in an industrial composting facility environment
  • Compostable materials will disintegrate within 12 weeks and biodegrade at least 90% within 180 days in a municipal or industrial composting facility
  • The problem is that industrial composting facilities are rare and most not located near cities
  • Eco-friendly plastic and other materials aren’t sustainable if they aren’t disposed of properly in a commercial composting facility

 

  • Items that should only be industrially composted:
    • Meats
    • Avocado
    • Bones
    • Animal manure
    • Food scraps
    • Dairy products

 

What is home compostable?

  • Home composting involves the collection of organic, plant-based materials that are either piled in an area of the backyard or collected in a compost bin
  • All components and materials used in the packaging including the printing ink, and the adhesives will decompose into organic soil
  • All manufactured products certified by the AS5810 (2010) standard are safe to go into the home compost as they have been verified by the Australasian Bioplastics Association
  • If compostable plastics and other materials break down in  landfill with low levels of oxygen, the production of methane could occur leading to powerful greenhouse gas emissions

 

  •  Items you can’t compost at home:
    •  Meat, fish or dairy as the smell attracts vermin
    •  PLA bioplastic products
  • Items you can compost at home:
    • Paper towels, bags, plates
    • cardboard
    • Corks
    • Tea and coffee grounds
    • Old herbs and spices
    • Fruit and vegetable scraps and all other organic matter

Biodegradable

  • Biodegradable means that a product can break down without oxygen and turn into carbon dioxide, water and biomass within a set time period
  • All compostable plastics are biodegradable, but not all biodegradable plastics would be considered compostable
  • Compostable products require a specific setting in order to break down whilst biodegradable products break down naturally

Bio-based

  • Bio-based materials are materials sourced from biomass at the beginning of their life
  • Bio-based plastic for example, is produced from renewable sources such as plants (such as sugarcane, corn, potatoes, rice, soy, wheat and vegetable oil) 
  • Because these are renewable sources, they contribute to a lower carbon footprint as opposed to traditional polymers which are made from fossil fuel resources, contributing to the overall scarcity of the planet’s resources
  • Bio-based materials include:
    • PLA
    • Bio-PET
    • Bio based PVC
    • Bio based PE (which is also fully recyclable but not necessarily biodegradable)

Oxo-degradable

  • Oxo-degradable plastics are not compostable as defined by international standards EN 13432, ISO 18606, AS 4736 and ASTM 6400 as the biodegradation takes too long and plastic fragments can remain in the compost
  • Oxo degradable materials are conventional plastics mixed with an additive in order to promote oxidation and imitate biodegradation
  • The plastics quickly fragment into smaller pieces called microplastics, but don’t break down at the molecular or polymer level like biodegradable and compostable plastics
  • These small fragments remain in the environment, are more challenging to clean up and affect nearby organisms 
  • There is currently insufficient evidence to suggest that oxo-degradable plastics biodegrade fully or within a reasonable time
  • The pro-oxidant additives can also cause toxic effects in soil 
  • You also cannot reuse oxo-degradable plastics as they are designed to start fragmenting within a few months or years and thus is not suitable for long-term reusable applications
  • Oxo-degradable plastics also negatively impact the quality and value of plastic recyclates as they cannot be detected by current technology at a sufficient scale to be sorted from conventional plastics
  • In March 2019 the European Parliament approved measures prohibiting the selling of oxo-degradable plastic on the EU market by July 2021