Waste collection still generates a lot of confusion among people. After the directives on single-use products in bioplasticwe are still learning to live with some terms that we find written on plates, cutlery, glasses, food containers and more. Among all of them, the ones that cause the most confusion are biodegradable And compostable. Although the terms indicate two very similar things, the confusion between the two can lead us to fall into some errors in our waste sorting. In fact, we often ask ourselves: “But where do we throw away these biodegradable plastic cups?”. So let’s see what the difference is, which mainly lies in the time and in the way they use these materials to decompose.
What are biodegradable materials?
A material biodegradable It can degrade naturally thanks to the enzymatic action of microorganisms (such as bacteria for example) which break down the material into simple substances such as carbon dioxide, water and methane, without releasing pollutants during the process.
The definition of biodegradable given by the European Environment Agency is as follows:
Able to be rapidly decomposed by microorganisms under natural conditions (aerobic and/or anaerobic). Most organic materials, such as food waste and paper, are biodegradable.
Biodegradable materials undergo a process which can be imagined as what happens in our stomach: they are “digested”. In our stomach, the ones that transform the food are juices gastric; in the case of biodegradable materials they are bacteria And mushroomsin addition to the action of the sunlight or other natural physical agents. All these things together transform organic matter at a certain temperature and in certain conditions, until obtaining simple inorganic compounds such as carbon dioxide And waterfall, not further separable.
Just because this happens naturally doesn’t mean it’s easy. The process can take a long time – usually at least 6 months – and this depends a lot on the characteristics of the raw material and the environment in which the degradation occurs, so it is not easy to estimate precise times.
Precisely because it is a process complex which depends not only on the material but also on the conditions in which it is found, the biodegradability of a material is not a characteristic which actually comes certified. For this reason, when we read the words “biodegradable” (but not compostable) on a product, it is probably a marketing choice.
What are compostable materials?
A material compostableinstead, can be disposed of in the Organic waste because it is able to transform itself together with the latter into compostthrough the process of compostingComposting is a process of decomposition of an organic substance that occurs under controlled conditions. At the end of the process, compost is obtained, a substance composed mostly of humus and active microorganisms.
This product is used as fertilizer natural in the agricultural sector and has an appearance similar to soil. To become like this it goes through various processes such as shredding And fermentation in ventilated conditions forced and specific temperatures and humidity: composting, precisely.
The definition of ccomposting reported by the European Environment Agency is as follows:
The controlled biological decomposition of organic material in the presence of air to form a humus-like material. Controlled methods of composting include mechanical mixing and aeration, ventilating the materials by dropping them through a vertical series of aerated chambers, or placing the compost in open-air piles and periodically mixing or turning.
European legislation UNI EN 13432 of 2002 establishes what the requirements for which a packaging can be defined compostable:
- It must degrade at least by 90% in a period of 6 monthsif subjected to an environment rich in carbon dioxide;
- If in contact with organic materials for a period of 3 monthsthe mass of the material must consist of at least 90% from fragments of smaller size than 2mm;
- The material must have no effects negatives on the process of composting;
- The material must have a low concentration of the metals heavy additives;
- The values of pHcontent salineconcentration of solids volatile and of nitrogen, phosphorus, magnesium And potassium must return within the limits established.
An example of material compostable It is PLA plastic, a biopolymer often made from corn starch, or the Mater-Biplant biopolymer. Also the pulp Of cellulose It is a material of plant origin and is compostable, used alone or in combination with other bioplastics.
The difference between biodegradable and compostable
A compostable material is also biodegradable, but the opposite is not true! Consequently if a product is compostable It is usually disposed of in the waste collectionhumid (always follow the directions of one’s own common), if instead it is biodegradable we must read the instructions on the label to dispose of it correctly! In short, the only circumstance in which we can dispose of waste in the organic waste is if it says “compostable” and this is something that can happen not only with bioplastics but also with paper, cellulose or mixed packaging!
A classic mistake we can make also concerns the use of bags for the collection of organic waste: do not use biodegradable bags, but compostable ones! Don’t worry, since 2018 Supermarket and fruit and vegetable bags are both biodegradable and compostablealways according to the UNI EN 13432 law. For those we buy instead, it is important that the products (or their packaging) have the wording “compostable”, because this is the only property that can be certified.
