Perhaps it is not really a Shakespearean dilemma, but the question about the difference between a biodegradable and a compostable material is one of those that we have all made at least once. The answer can be found in international standard EN 13432 of the European Standardization Committee.
This is more or less how it stands. Biodegradable is defined as a material that can degrade – due to the action of bacteria, sunlight and other natural physical agents – in simple chemical compounds such as water, carbon dioxide and methane. And at least 90% of this process must occur within 6 months.
On the other hand, a material is defined as compostable (can be transformed into compost, a natural fertilizer) if it is both biodegradable and disintegrable (90% of its weight in fragments smaller than 2 mm) within 3 months and it does not release more than a certain amount of hazardous substances capable of altering the quality of the compost itself.
IT’S EASY TO SAY BIOPLASTICS
Bioplastics is one of those words that has come into everyday use. But exactly what does it mean? The term refers to different types of plastic made from materials that are completely or partially of biological origin, usually vegetable and, therefore, renewable. These include corn, wheat, sweet potatoes, sugar cane, algae, vegetable oils and others. Bioplastics can be divided into two main groups: bioplastics of biological origin but with a molecular structure identical to traditional plastics, such as Bio-PE, (made from sugar cane); and brand new bioplastics, such as Mater-Bi® (derived from starch) or PLA (Polylactic Acid).
Bioplastics can also be divided into those that are biodegradable and those that are not, and it should not be taken for granted that a plastic of vegetable origin is necessarily biodegradable. Regarding their end of life, all materials should be disposed of according to existing recommendations for each specific type. Those of a composition identical to conventional plastic can be correctly disposed of with other plastics (plastic or multi-material collection). Others, such as Mater-Bi® or PLA, are also compostable, so where recycling and composting are in place these new materials can be disposed of together with wet waste.
In all cases, however, the amount of CO2 emitted during the life cycle (Carbon Footprint) is lower than conventional plastics. Encouraging their use, despite their higher production costs compared to those of petroleum-based plastics, is the growing demand for eco-compatible products by consumers. However, these new materials are sometimes criticized because large portions of agricultural land normally used for food crops are often taken away and converted to their production.