Interfering and foreign substance content in the biowaste of the AZV Augsburg
Biowaste is the oldest waste fraction of the human race and yet we have still not solved all the problems it brings. In previous years, motivated by political impetus and requirements to increase the separate collection rates, efforts were made to significantly increase biowaste collection quantities on the municipal level. The efforts focussed on the waste stream from the biobin – so-called biomaterial – not only in the Augsburg region, but also throughout Germany.
However, with increasing quantities of waste, contamination was also found to increase. In other areas in Germany, for example, alarming foreign substance levels of over 10 % were discussed in some cases. Against the background of an increasingly stringent legal framework regarding foreign substance levels in compost, Augsburg’s special purpose association for waste (Abfallzweckverband - AZV) had the biowaste collected via the biobin and recovered by AVA GmbH examined for interfering and foreign substance levels.
In a large-scale sorting campaign over a period of a year, AVA GmbH took samples from different deliveries from the AZV area and these samples were analysed in the bifa Umweltinstitut’s technical centre. The examination of the foreign substance levels was based on the sorting catalogue of the Federal Compost Quality Association (Bundesgütegemeinschaft Kompost - BGK), to enable comparability with other investigations, some of which were undertaken at the same time in other areas of Germany. During the analysis period, a total of 40 collections from previously specifically determined collection areas of the special purpose waste association were sampled. Two samples were taken from each collection, so that the total number of samples was 80 and the sampled quantity of biowaste was 410 tonnes. From the results it can be stated that the actual level of foreign substance content is significantly better than initially expected. Assumptions that waste separation functions less well in a catchment area that is more urban than in a rural area were not confirmed. However, it was found that foreign substances such as hygiene products (especially nappies) and plastics (especially dustbin liners) as well as textiles, account for a significant fraction of the foreign substances for all members of the AZV Augsburg.