vor 5 Jahren

02 | 2010

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Report Fig 1– The bags

Report Fig 1– The bags are used to keep the tested material separate in a control pile Fig 2 – Several composts produced from food residues Composting Experience of the Mediterranean Agronomic Institute The Mediterranean Agronomic Institute of Bari (MAIB) is a centre for post-graduate training, applied scientific research and international cooperation projects among the Mediterranean countries. It includes a campus area, frequented daily by about 300 students and workers, and an experimental farm. The site, of about six hectares, includes an experimental composting plant for training, dissemination and research purposes. In 2009 MAIB started to evaluate whether the organic waste from the institute could be internally recycled by composting. All organic waste was collected separately, the food and coffee residues using polyethylene bags, the other green material in a container that was brought to a compost unit on a weekly basis. In a first series of six composting trials food scraps, crushed green materials, and a bulking ligno-cellulosic agent were mixed in proportion 5:4:1 on a fresh weight basis to achieve a balanced carbon/nitrogen ratio (C/N ~ 30). After an active phase in a biocontainer with forced aeration for about 3 weeks, and a subsequent composting phase in a trapezoidal pile with weekly turning, the final compost was sieved and evaluated. Even if, from a chemical point of view, the compost quality was good, because of clearly visible plastics and other pollutants the result was not satisfying. Thus, in addition to improved education of the restaurant staff, MAIB decided to replace the plastic materials by biodegradable plastics, starting first with the PE bags. In order to find the best solution, MAIB tested many biodegradable materials for their compostability in full scale processes. The tested materials were based on thermoplastic polymers or on cellulosic biocomposites. Some compost piles were prepared as incubators for bags containing the materials to be tested (fig.1). Several 40-litre bags made of a non-degradable plastic net (1 mm mesh) to allow water and air exchange, with the external pile were filled with 10 kg of composting mixture (see above) and 100 grams of biodegradable material. The compost processes were monitored for temperature daily and for moisture content weekly. The processes were controlled by turning and wetting according to the monitored data. During pile turning the bags were removed and opened for visual inspection and manual rotation. After 12 weeks of process the compost in the bags was sieved using a 2 mm net. The residual materials were cleaned, dried at 40°C and weighed to evaluate the degree of potential disintegration (target: >98%). One of the best tested materials was chosen to produce a biodegradable and compostable bag to be used for food residues and coffee grounds separated collection. A new compost production was prepared similar to the previous one, but the difference was the use of these compostable bags. The compost was produced by keeping the bags within the starting mixture. The final compost did not change its chemical and physical characteristics in a significant way. Moreover, the amount of non-degradable plastics inside the final products was clearly reduced (fig.2). In future, when compostable tableware is used instead of traditional plastic versions, the results are expected to be even better. Article contributed by F.G: Ceglie, Mediterranean Agronomic Institute of Bari (MAIB – CIHEAM), Italy Acknowledgment Thanks to Aspic and Novamont for providing some of the tested materials. Special thanks to Vincenzo Verrastro and Flora Erriquens for their helpful cooperation. 10 bioplastics MAGAZINE [02/10] Vol. 5

Polylactic Acid Uhde Inventa-Fischer extended its portfolio to technology and production plants for PLA, based on its long-term experience with PA and PET. The feedstock for our PLA process is lactic acid which can be produced from local agricultural products containing starch or sugar. The application range is similar to that of polymers based on fossil resources. Physical properties of PLA can be tailored to meet the requirements of packaging, textile and other applications. Think. Invest. Earn. Uhde Inventa-Fischer GmbH Holzhauser Strasse 157–159 13509 Berlin Germany Tel. +49 30 43 567 5 Fax +49 30 43 567 699 Uhde Inventa-Fischer AG Via Innovativa 31 7013 Domat/Ems Switzerland Tel. +41 81 632 63 11 Fax +41 81 632 74 03 Uhde Inventa-Fischer

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