In 1994, the European directive on packaging and packaging waste introduced the principle that biodegradable packaging can be recovered together with bio-waste by organic recycling (e.g. composting). Recently, critical voices have been raised against this principle on the basis that packaging does not add nutrients to the compost and is also “lost”, i.e. mostly mineralized in CO and water. These opinions do not take into account the specificity of composting and are unfounded. The term compost comes from composite. In fact, it is necessary to mix together feedstocks with different biodegradation behaviour and different C/N ratios to start a composting process and obtain quality compost. For example, cellulose is a feedstock at medium biodegradation rate that brings energy and biomass. Energy is needed to heat the compost pile and ensure that the composting process, including pasteurization, takes place without any external energy source. On the other hand, lignin is quite recalcitrant, brings no energy to the process and forms the basic structure of compost. Cellulose does not contain nitrogen, but it is the most relevant feedstock in composting. Likewise, packaging is nitrogen-free and can be equated with cellulose in terms of biodegradation behaviour and role in the composting process. In fact, biodegradability of packaging is assessed by using cellulose as the reference material. A compostable packaging, whether based on cellulose-fibres (paper, cardboard) or based on biodegradable plastics behaves similarly to other composting feedstock and contributes to the composting process and to the production of good quality compost.
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