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Sewage sludge – what happens to it? |
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 According to the Federal Statistical Office Germany (Statisches Bundesamt) in Series 19, Edition 2.1, the volume of sewage sludge in Germany in 2001 amounted to approximately 2.5 tonnes dry matter and thus was slightly lower than in 1998. In 2001, most of the residue continued to be channelled into agricultural use (approximately one third), the share treated by thermal treatment increased as oppose to 1998 from 16% to 23%. It is no longer permitted to deposit sewage sludge in landfills – the 7% dry matter that still went to landfills in 2001 has to be disposed of in a different manner today.
Using sewage sludge for fertilising purposes was highly criticized as far back as in 2000/2001, especially in light of the “Mad Cow's disease” case at the time. As a consequence, the effects of organic fertiliser in general were questioned. The article
 LCAs for the Utilisation of Organic Fertilisers (pdf 165KB, in German) was presented within the framework of a hearing of the BMU – BMVEL in October 2001.
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Projects |
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The question as to which option of disposal is most beneficial for sewage sludge from an environmental point of view was discussed and investigated in various projects at IFEU on behalf of both the public authorities and industrial enterprises.
Extensive ecological evaluations were done for the German states of North Rhine- Westphalia and Schleswig-Holstein, which serve as a basis for waste management planning. The work done by MUNLV NRW on the topic of sewage sludge was updated and published as a book (see below) and presented at the symposium Sewage Sludge Disposal on 27-28 April 2006. Results on the update of the ecological evaluation can be found in the script (in German) as well as on the presentation sheet. (pdf 141KB, in German).
From the industrial viewpoint, the question of co-incineration of sewage sludge in power plants is most interesting. In addition to corresponding studies, various projects have been initiated in the framework of environmental impacts assessments on thermal treatment of sewage sludge at IFEU.
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