Sludge – from waste to secondary fuel
The starting point
The agricultural use of sludge is not ensured in the long run: Apart from heavy metals, sludges can contain organic pollutants (residues of pharmaceuticals, fragrances, plasticisers, etc.) as well as pathogens, of which the effects due to bioaccumulation and combination effects are barely assessable.
In conventional procedures, a thermal removal of the sludge is often accompanied with high costs and pollution, due to the transport of sludge with a high water content (filter cake has a water content of approx. 70-80%) and the use of fossil fuels while drying, among other things.
On the other hand, sludge drying concepts based on the use of low-temperature heat and solar energy are gaining in importance.
Hybrid sludge drying – The process
Hybrid sludge drying – an advancement of the mere solar drying – can make a positive economical and ecological contribution for a sustainable sludge disposal concept.