A 2018 study by the Witzenhausen Institute for Waste, Environment and Energy from addresses the quality of compostable waste, especially compostable waste from households. The researchers found that in most households, bags - whether made of biodegradable materials or polythene (PE) - are used to collect compostable waste. Paper bags or newsprint are rarely used, however.
The ban on bin liners for compostable waste by some biogas and composting plants is a problem. Many people wish they could collect their compostable kitchen waste in bags. With this article, Naturabiomat would like to explain why concerns about bin liners for compostable waste leaving microplastics behind can be laid to rest.
For many people it is out of the question to throw compostable waste unwrapped into the organic waste bin. Especially because the bins then have to be laboriously rinsed out. Even paper bags are no answer: moist kitchen waste makes the paper soften and tear quickly - in the worst case scenario on the way from the kitchen to the collection point. No wonder then that many households resort to using bags that can be knotted instead. This is a big advantage in summer because it prevents a build-up of maggots in the compostable waste.
The above-mentioned study is one of many that prove that the use of biodegradable bags has no negative influence on the contamination level in compostable matter. On the contrary, one can even speak of a positive influence. Where biodegradable bags are banned, it is not unusual to resort to using bags made of polythene and oxo-biodegradable plastics. Oxo-biodegradable plastics are conventional plastics such as polythene, polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET), which are formulated with additives during processing that promote their decomposition into small fragments. These types of plastics do not meet the standard that biodegradable bags have to meet. While bags made of biodegradable materials are completely broken down, oxo-biodegradable plastics leave contaminants such as microplastics behind.
The standard we are talking about is DIN EN 13432, which not only specifies that the biodegradable bags must be degraded after 12 weeks of composting at the latest, but also what percentage of it must be degraded.
The standard we are talking about is DIN EN 13432, which not only specifies that the biodegradable bags must be broken down after 12 weeks of composting at the latest, but also what percentage of it must be broken down. It stipulates that 90% of the bag will break down into carbon dioxide. However, the remaining 10 % is not retained as contaminants. On the contrary. The 90 % stipulation is due to the measuring method. The conversion is measured by the carbon dioxide content, which is 90 %. The other 10 % is also broken down, but is not converted into carbon dioxide, serving as necessary building materials for the fungi and bacteria involved in the decomposition process to grow and multiply.
Hence, no contaminants are left behind – not even microplastics.