Are paper coffee capsules biologically recyclable?
Coffee is an extremely popular drink. Around 42 % of Germans consume it. Their green coffee demand is around 17 kg /a. During roasting, the coffee mass reduces by around 20 % and when coffee is brewed, around 25 % of the roasted coffee dissolves.
Around 33 kg coffee residues per coffee consumer are produced each year. This number adds up to a total coffee consumption of around 1.1 mln Mg coffee residues. In 2017, 48.7 % of the coffee consumed in Germany was brewed in the form of filter coffee, 15 % from coffee machines, 10.4 % was made as instant coffee and 5.1 % using mocha pots. In addition to this are the individual portions in the form of coffee pads (12 %) and coffee capsules (8 %). The individual portions in particular are the subject of criticism, as waste coffee capsule are not to be classified as completely emptied packaging in waste management terms. These can generally only be disposed of as residual waste.
Coffee capsule waste consists of more than 90 % residual coffee. Coffee contains a very large fraction of readily biodegradable constituents, which can be easily converted into biogas. Like other biogenic waste, coffee residues contain comparatively large fractions of plant nutrients. Various manufacturers are therefore trying to produce the capsule part of the packaging from
biodegradable materials. In this way, use of waste coffee capsules in biowaste treatment plants could become interesting. For the degradation processes, it would be advantageous if the capsules opened relatively quickly so that the coffee remains are mixed with other biowaste. Otherwise, the intensive degradation processes could cause acidification of the coffee in the capsule, which obstructs biodegradation. Many of the coffee capsules on the market are made of bioplastics and take significantly longer to degrade under anaerobic conditions than the newly developed paper-based capsules. This was shown by tests performed as part of a current ZIM-funded cooperative project ("Ecologically advantageous coffee capsules made of paper and paper-textile composite materials – "ÖkoKap""). The paper-based coffee capsules developed by the project partners (Papiertechnische Stiftung PTS, Weyhmüller Verpackungstechnik GmbH, Dr. Günther Kast GmbH & Co. and bifa Umweltinstitut GmbH) are being tested by us for their biological recoverability in biogas and composting plants. In addition, an ecological life cycle assessment was carried out to examine which ecological advantages can be achieved in waste recycling if coffee capsules are made from paper.
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Dr. Klaus Hoffenheidt