Consistent implementation of the EC standards for treatment of municipal wastewater (91/271/EWG) leads Europe-wide to increasing sewage sludge volumes, for which suitable utilisation routes and disposal capacities must be provided.
Landfilling of untreated sewage sludge contradicts the European efforts to reduce the biologically decomposable wastes to be landfilled (1999/31/EC standards of 26th April 1999 concerning waste sites) and is prohibited in Germany.
Agricultural utilisation of sewage sludge is considered increasingly critical for reasons of preventive environment and health protection.
The development of prices for disposal are presently uncalculable.
Sewage sludge is a regenerative energy source for municipalities. Organic pollutants are reliably destroyed in the thermal utilisation process. Heavy metals are bound in the inert, safely manageable incineration and flue gas cleaning residues.
Thermal sewage sludge treatment is increasingly gaining in importance. In Germany, more than 50% o the municipal sewage sludge is treated thermally already, usually in huge centralised incineration plants, or combined incineration in cement and coal-fired power stations.
The disadvantage of centralised thermal sewage sludge treatment: long transport ways. The sludge is either dewatered – i.e. 70 – 75% water are transported – or the sludge dried prior to transport – normally by using fossil energy sources.
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