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bioplasticsMAGAZINE_0902

End of Life End-of-Life:

End of Life End-of-Life: Recovery Options Article based on the FAQ paper on bioplastics [1] by European Bioplastics e.V. Fig. 1: Compostable Logos Fig. 2: Industrial Composting (Photo: Vlaco vzw. Belgium) Common treatment options for plastic waste are the recovery routes of incineration (thermal recovery), mechanical (or physical [2]) recycling, chemical recycling [2], or the disposal on a landfill. Bioplastics offer in principle all the recovery options in place for conventional plastics - plus the additional option of organic recycling. However it must be kept in mind that bioplastic applications cover many different products with widely varying specific compositions and product design. The choice of the best, i.e. the most ecological and economically efficient recovery route for bioplastics is dependent on many factors such as the character of the product, market volume, existing infrastructure for collection and recovery, legislation, and last but not least, costs. These factors can differ greatly from region to region and from one application to another. A mix of recovery options will usually be provided by municipalities and/or private recycling companies, aiming at the most efficient use of the collected waste as a resource. Organic Recycling Organic recycling is for example defined by the EU Packaging and Packaging Waste Directive 94/62/EC, amended by 2004/12/EC, as the aerobic treatment 20 bioplastics MAGAZINE [02/09] Vol. 4

End of Life Fig. 3: Biogasification Plant (= composting) or anaerobic treatment (= biogasification) of packaging waste. The EU Directive is based on the European standard for the industrial compostability of plastic packaging, EN 13432. This standard is legally binding in all EU member states, so that claiming ‘compostability’ for a packaging material or a packaging will be based on proven compliance of the respective item with EN 13432. Equivalent standards have been approved for the testing of the compostability of plastics, these are ISO 17088, EN 14995 and ASTM D-6400. Whereas ‘aerobic biodegradation’ describes the microbial transformation of carbon containing material into CO 2 , H 2 O and biomass, ‘compostability’ is further defined by a time limitation in line with the requirements of industrial composting plants (usually 6-12 weeks). The biodegradation of compostable plastics is dependent on three main factors: elevated temperature, humidity and the abundance of microbes. Rapid biodegradation can only take place if all three criteria are fulfilled simultaneously. This occurs particularly in professional biowaste treatment plants. Composting of bioplastics (aerobic treatment) Most commercialized bioplastic products are certified ‘compostable’ according to the above mentioned international standards. Based on third party certification, logos like the European ‘seedling’ or the BPI ‘compostable’ logo in the U.S.A are awarded to compostable plastic or paper items (Fig. 1). When treated in composting plants (Fig. 2), certified products are converted completely to CO 2 , water and biomass (as part of the compost product). The resulting compost can be used as a soil improver and can also replace mineral fertilizers, at least in part. Compostable bioplastic products such as waste or shopping bags can be used to collect organic household waste in municipalities in many countries. By keeping the biowaste collection more hygienic and convenient, such bags contribute to the motivation of consumers for the separate collection of biowaste. These bags are highly breathable and allow the evaporation of water from the organic household waste, so that the weight of the collected waste decreases (advantage in case of weight related fees) and the oxygen content increases (better processability in the composting plant, higher quality of the compost product). Studies have shown that using compostable bags for the biowaste collection contributes to the diversion of organic waste from landfill. This results in the decrease of methane emissions from landfill. Separate collection and recovery of organic (household) waste should be installed wherever possible. Catering articles are another example of bioplastic products exhibiting advantages for waste management, for example at public events or in cafeterias. Compostable cups, plates or cutlery can be treated together with food residues. No separate handling of food waste and packaging waste is needed and no contamination of other waste streams (e.g. plastic recycling) occurs when these products are composted. The same benefit can be achieved for fruit or vegetables distributed in compostable packaging - if the food is damaged or expired, the complete packaging including the goods can be sent to organic recovery without unpacking. Biogasification (anaerobic treatment) In biogasification plants (Fig. 3), methane is produced from organic substrates. Biowaste is used as an input material for biogasification plants in an increasing number of municipalities and in private plants. The process is attractive because it yields both compost as a product and also renewable energy: the methane is captured to produce electricity and heat in power plants. In most cases the biowaste treatment in anaerobic plants combines an intial anaerobic phase of approx. 2 – 3 weeks and a second aerobic phase (‘aftertreatment’) of another 3 – 4 weeks to produce fertile compost. So also those bioplastics which show only slow biodegradation under anaerobic conditions, will subsequently be biodegraded in the second, aerobic phase. bioplastics MAGAZINE [02/09] Vol. 4 21

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