Interfering and foreign matter in biowaste
Abfallzweckverband Augsburg and AVA GmbH have biowaste examined
Increasingly stringent requirements are being set for the products from biowaste treatment. Among other things, the Biowaste and Fertiliser Regulations ("Bioabfall- und Düngemittelverordnung") provide for increasingly reduced levels of foreign constituents in compost fertiliser.
The foreign constituents include wastepaper, cardboard, glass, metal, thermoplastics and other plastics larger than 2 mm screenings. The other plastics prove to be particularly problematic, as their share of biowaste is increasing nationwide and ejecting them constitutes a challenge for the treatment technology. These plastics include, e.g. films and bags. To fulfil the legal requirements it is imperative to remove the foreign matter.
Biowaste is a valuable raw material, when it comes to the provision of organic fertiliser, the recovery of plant nutrients and the substitution of peat. At the same time, it is important that the compost from biowaste meets all the quality standards of the sales market. Increased foreign matter levels prevent use of biowaste compost as a soil improving product.
At its site within the city area of Augsburg, Abfallverwertung Augsburg GmbH (AVA) operates a biowaste fermentation plant in which the biowaste from the area of the Abfallzweckverband Augsburg (AZV) is recovered. The members of this waste association are the public waste disposal organisations, i.e. the city and district of Augsburg and the district of Aichach-Friedberg. Biogas, high-quality compost and liquid fertiliser are produced from the biowaste. The interfering and foreign matter sorted out during preparation of the biowaste are disposed of.
bifa Umweltinstitut is examining the biowaste for interfering and foreign matter levels on behalf of the AZV Augsburg and AVA GmbH in a broad-based sorting analysis. In total, more than 80 random samples from the whole AZV area will be taken in four seasonal campaigns at different vegetation and weather phases and analysed separately. A representative selection took place according to statistical aspects to enable reliable and meaningful extrapolation. Uniform distribution of individual samples during the course of the year ensures that seasonal effects are completely represented. Due to the size of the examined biowaste quantity and large number of individual samples, very good representativity will be achieved. The constituents of the biowaste are sorted into more than 22 categories in the sorting analysis. In addition to plastics and metals, here the focus is also on other foreign materials such as textile and hygiene products and nappies.
The analysis started in the autumn of 2017. Two campaigns have been implemented to date (autumn and winter). Two further campaigns (spring and summer) will take place by the autumn of 2018, before the evaluations are the performed by the end of 2018. The intention is for the results to be used to better characterise foreign and interfering matter in biowaste with regard to their type and origin, so that measures can be derived for reducing the interfering and foreign matter levels in biowaste.