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Films | Flexibles | Bags

Films | Flexibles | Bags Composting with aeration screw Different types of composting facilities From the above mentioned eight major types of composting facilities six types of process cover approximately 50 % of the total number of plants and the annual capacity of all composting and anaerobic digestion plants listed at BGK. Table 2 lists these plants and some of their specifications. Table 3 shows an overview of the number of plants and annual capacities of these types of process. From each of the types of process named above one plant operator was chosen for the field test. Fig. 1: Overview of the sample weights in % at the time of screening sample weights in % 30% 25% 20% 15% 10% 5% 0% Plant 1 Plant 2 Plant 3 Plant 4 Plant 5 Plant 6 Plant 6 + storage in biobin 12th week 12th week 4th week 12th week 8th week 12th week 12th week Mater-Bi ® NF Mater-Bi ® CF Bioplast ® Ecopond Flex ® Bio-Flex ® Results The field tests show that the majority of samples meet the degradation requirements according to DIN EN 13432 or 14995 in nearly all plant types (Fig. 1). The red line marks 10% of the original weight of the sample weight which, according to the standards, may still be found after a composting time of twelve weeks in the sieve fraction > 2 mm. The remnants of film which were still present were often knots. However, these were obviously heavily decayed, too, because they could be easily crushed between fingers. In plant 4 (type of process: Bühler-Wendelin), the products made of Bio-Flex and Mater-Bi CF did not meet the rates of degradation. Due to the remnants of film that were found, it can be assumed that the biowaste bags were unfilled when put into system – against the test protocol. So the empty biowaste bags were crumpled, thus multiplying the material strength. The rate of degradation directly depends on the sample thickness thus the degradation took considerably longer. Moreover, the low degradation rates in the plant are presumably a result of the special test form. In the course of test in plant 6 a group of test materials had been stored in a household-biobin for one week before the test with the following observations made: While no or just minor traces of degradation were optically detected on the products made of Ecopond Flex, Bio-Flex, and Bioplast, both products made of Mater-Bi were already visibly affected. The weight determination of the samples at the end of the test showed the following results: All samples that had been 24 bioplastics MAGAZINE [06/13] Vol. 8

Films | Flexibles | Bags stored in the biobin for one week were clearly more degraded than the samples that had been put directly into the windrow. Furthermore, the analysis showed that that the composting time is much shorter in many plants than the 12 weeks required in the standards. In nearly all cases the biowaste bags were also degraded within the shorter composting times. In plant 3 (type of process: Herhof boxes) the compost was already sifted after four weeks. Even after this short time, only insignificant remnants of the biowaste bags were found (a maximum of 8% of the original material, mostly even < 5%). In plant 5 (type of process: Horstmann WTT tunnel) only the samples made of Ecopond Flex and Mater-Bi CF just dipped below the 10% mark. Conclusion In summary, it can be said standard biowaste bags quickly achieved high degradation rates in the field test. So it can be assumed that they do not cause any technical problems in relevant plant types, do not contaminate the compost optically and are thus suitable for municipal biowaste collection. Against the background of a planned increase in biowaste col- lection and the aspired increase in the rates of food waste capture, the citizen, who is an important link in the chain, must be motivated to participate. Water-proof compostable bags can make an important contribution here. If the consumers fill the bags completely and do not fasten them with a knot, even better degradation rates could possibly be achieved. In spite of the compostability logo printed on the bags, the recognisability of all tested biobags is difficult amidst the mass of biowaste. The labelling for compostable biowaste bags could be improved. All five product types that were tested look very different. When sorted by hand, they do not clearly differ from conventional plastic bags. So there is room for improvement on the part of the bioplastics’ converters. For instance, C.A.R.M.E.N., the Bavarian Agency for Renewable Raw Resources, recommends a standardised, hexagonal design for compostable bio-waste bags. This design is accepted and supported by a growing number of local authorities using bio-waste bags. Referenzens [1] Letalik C.; Schmidt, B.; Ziermann, A.; C.A.R.M.E.N. e. V., How compatible are compostable bags with major industrial composting and digestion technologies?, ORRBIT 2012, Rennes, France [2] Bidlingmaier, W. (2000): Biologische Abfallverwertung, Eugen Ulmer, Stuttgart, p. 95. [3] Bundesgütegemeinschaft Kompost (BGK), Ed. (2010): Hygiene Baumuster-Prüfsystem (HBPS) – Kompostierungsan- lagen Vergärungsanlagen, Cologne. [4] Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (BMU), Ed. (2011): Kreislaufwirtschaftsgesetz – KrWG, Berlin. [5] Comité Européen de Normalisation (CEN), Ed. (2000): Anforderungen an die Verwertung von Verpackungen durch Kompostierung und biologischen Abbau - Prüfschema und Bewertungskriterien für die Einstufung von Verpackungen; Deutsche Fassung DIN EN 13432:2000, Brussels. [6] Comité Européen de Normalisation (CEN), Ed. (2006): Kunststoffe - Bewertung der Kompostierbarkeit – Prüfschema und Spezifikationen; Deutsche Fassung DIN EN 14995:2006, Brussels. [7] Kehres, B.: Mündliche Aussage vom 25.02.2010, Cologne. bioplastics MAGAZINE [06/13] Vol. 8 25

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