What exactly is compostable or biodegradable plastic? 3 points to understand its definition and principle
Biodegradable plastics made from organic materials such as corn and barley can be converted into organic compost or decompose after being discarded. Will it become an easy solution to plastic pollution in the 21st century?
The truth is, it's more complex.
1. The material of biodegradable plastic is
At present, biodegradable materials have been commercially produced, mainly including polyvinyl alcohol (PVA) and polylactic acid (PLA), as well as starch-based (Starch Blends), polybutylene terephthalate (PBAT), Polybutylene succinate (PBS) and polyhydroxyalkanoates (PHAs), etc. [1].
2. The principle of biodegradation
With the help of microorganisms, it can be converted into water, carbon dioxide, and biomass. This conversion is called biodegradation. However, there are different definitions of biodegradable plastics in the world, and whether degradable plastics can be completely degraded depends on many factors, including the type of additives in the degradable plastics, the thickness of the material, and, more importantly, whether there are favorable conditions in the disposal environment. Degradation conditions, etc.
Compostable plastics are also included in the name of biodegradable plastics. At present, the international market has different certifications for compostable plastics, but generally, they all point to the fact that the product will decompose within 180 days, compost is non-phytotoxic, and does not contain heavy metals.
However, compostable plastics generally need to be biodegradable in an industrial composting environment, and there are specific requirements for the pH value, oxygen concentration, moisture, and temperature of the soil environment. Contrary to what most consumers crave, compostable plastics don't break down in regular composting facilities or in home composts, so if you potted compostable plastic at home and waited for it to degrade into plant fertilizer, you'd be disappointed too.
3. How to recycle biodegradable plastics? Is it as simple as we imagined?
Most compostable plastics cannot be recycled with conventional plastics mainly because of their different chemical composition. For biodegradable plastics to be successfully converted, there must be favorable environmental conditions for degradation. If degradable plastics are mixed with a batch of traditional plastic recyclable materials, it is likely to affect the quality of the entire batch of plastics.
