The solar powered sewage sludge drying system developed by scientists of Stuttgart-Hohenheim University in Germany extracts a maximum amount of liquid from sludge with a minimum of energy input. The system produces a completely dry granulate which can be used as fuel due to its high caloric value. The Austrian municipalities are faced with increasing sludge amounts. Every kilo has to be treated, stored, transported and finally disposed. The environmental impact and the financial expenditure are considerable.
The running costs of solar energy use, on the other hand, are very low. In addition, the dry material does not smell any more and can rather easily be used for all permitted forms of recycling like recultivation and incineration. "If incineration is the choice, then several tons of coal can even be replaced," said Prof. Mühlbauer on the occasion of a seminar at the Umweltakademie.
The landfilling ordinance coming into force in 2004 and the provisions pertaining to the use of sewage sludge in agriculture will force wastewater utilities to develop plans for the further disposal of sewage sludge.
