Development of quality assurance and quality characteristics of composts and digestates in Germany
During the last 20 years numerous companies have undertaken considerable and successful efforts in order to open necessary markets for compost in Germany.
Contrary to other branches the compost industry is a branch which is not only profitable on account of their product sales but also on the treatment of biowaste. Compost and digestate products are produced from separately collected biodegradable waste materials. For the composting industry, which is preponderantly organised by the private and municipal waste industry in Germany, it was necessary to undertake a lot of efforts to provide consumer confidence for these secondary waste derived products.
In order to achieve this target the producers of compost and the marketing enterprises have founded in 1989 the Quality assurance organisation 'Bundesgütegemeinschaft Kompost e.V. (BGK)â€. BGK is recognised by RAL, the German Institute for Quality Assurance and Certification, as being the organisation to handle monitoring and controlling of all quality labels in Germany.
The ‘RAL Compost Quality Label’ (RAL GZ 251) was awarded in January 1992. It was also registered in the trade mark register at the Federal Patent Office. In the year 2000 an additional quality assurance system for digestion residuals (RAL GZ 256) was introduced. With the revision in 2007 the digestate products are divided into two product groups for digestion residuals according to the input materials: the RAL GZ 245 for digestion products and the RAL GZ 246 for digestion products produced from renewable energy crops.
The quality assurance system of BGK contains the definition of quality requirements, enables quality monitoring, and can enforce quality standards or discipline plants for failure to meet regulations and labelling of the quality standard. In order to guarantee an identical standard for the monitoring all over Germany, BGK established a central office where all results originated from external monitoring are evaluated and controlled.
Regarding and evaluating the analyses results of more than 37.000 compost samples of the last 15 years it can be shown, that compost from separate collected biowaste has a defined quality with a stable composition of nutrients, organic matter and further benefits for use. Today RAL-quality assured compost is the most analysed and documented soil improver and organic fertiliser in Germany which guarantee an environmental sound and successful use for soil improving and fertilising purposes.
The quality of the digestate products is much more different. First of all the quality is influenced strongly by the kind and composition of the input materials and secondly the product characteristics vary on the type (liquid or solid) of digestate.
