Environmental Forum 2006

On the occasion of the Environmental Forum 2006 national and international leading experts discussed the actual risks of the sewage sludge output and the ecological and economical alternatives of sewage sludge disposal. On invitation of Mr. Hans Roth as well as the members of the provincial government Johann Seitinger and Ing. Manfred Wegscheider, the forward-looking event took place at Seggau castle. Following the scientific and technical discussions and the enthralling panel discussion with the attending experts the participants had the opportunity to visit the long-distance heating and power plant Mellach near Graz, where thermal treatment of sewage sludge is successfully practised within the scope of a pilot scheme.

Tenor of the event
Sewage sludge is not an economic good it is a waste product which should be expediently recycled or environmentally sound disposed.

Sewage sludge consists – among other substances – as well of nitrogen and phosphates therewith agriculturally usable fertiliser. After only a quarter of the sewage sludge quantity being agriculturally used, thermal treatment (e.g. in power plants or in the cement industry) seems to be a sensible and necessary endorsement. This procedure destroys the hazardous substances and is additionally conducive to reducing the usage of fossil fuels (and therefore reducing greenhouse gases) without generating harmful emissions.

Background information
The disposal of sewage sludge on sanitary landfills is prohibited according to the Landfill Directive. The deposition of sewage sludge on the land -  directly or after composting – is allowed furthermore in Styria according to the 18 year old Styrian Soil Protection Law. This is very problematic due to the accumulating contaminants in the soil. Therefore the deposition of sewage sludge on the land has been prohibited in e.g. Bavaria, Switzerland and some federal provinces of Austria (Tyrol, Salzburg, Vienna). In the Netherlands, Belgium and Sweden the strictly regulated exposure limit to hazardous substances makes it practically impossible for sewage sludge to be used in agriculture. Organic harmful substances are particularly dangerous. These are substances similar to hormones from medicines, pesticides or softeners where the smallest amount leads to changes in the organism. That way traces of the birth control pill can be found in sewage sludge.

Conclusion
Main goal of this event was the presentation of reasonable alternatives for the disposal of sewage sludge without polarisation. The sewage sludge incineration should be accounted as another possible method. This alternative is just another step to implement the Landfill Directive since the deposition of sewage sludge on the land is prohibited according to the Landfill Directive. At the same time sewage sludge incineration offers high use of energy and a solution to the emission problem.