What is the difference between compostable and biodegradable?
Biodegradable
Biodegradable means being able to decompose into carbon dioxide, water and biomass by the natural action of microorganisms within an unspecified time and under undefined conditions.
Compostable
Compostable means being able to decompose into carbon dioxide, water and biomass within a specific time frame and under specific conditions. This specific condition can also be understood as home composting (at room temperature and natural microbial communities) or industrial composting (under increased temperature, humidity and specially formulated microbial conditions).
Compostable materials can be made from bio-based or petrochemicals. Compostable packaging is certified in North America, Japan, and Europe.
So how are these materials made?
Bio-based plastics
Bio-based refers to where the material comes from, not what happens to it after use. Traditional fossil-based plastics are mainly based on petroleum. Bio-based plastics can be made entirely or partially from organic materials, such as polymers extracted from plants, microorganisms, and greenhouse gases (such as corn, algae, yeast, and CO2).
1. Bio-based and biodegradable plastics: Among biodegradable bioplastics produced from natural sources, we can find thermoplastic starch (TPS), cellulose acetate, and polyhydroxyalkanoates (PHA). In addition, there are synthetic plastics like polylactic acid (PLA) and polybutylene malonate (PBS), which can be produced by microbial fermentation and chemical polymerization.
2. Fossil-based and biodegradable plastics: Polycaprolactone (PCL) polysuccinate terephthalate (PBAT) are biodegradable plastics, but they are produced from fossil-based resources.
3. Traditional plastics: Fossil plastics, non-degradable.
4. Bio-based non-biodegradable plastics: The most important of these are polypropylene carbonate (PPC), polyethylene plastic (PEP), bio-polyethylene (Bio-PE), bio-terephthalate (Bio-PET) and bio-polypropylene (Bio-PP).
