T. Meinfelder, U. Richers
In Germany, thermal waste treatment is a major part of waste management and will gain even more importance due to the developments in the energy supply sector and the climate discussion. This report is focussed on summarizing the current status of bottom ash disposal. Bottom ash is a residue of waste incineration.
In a first stage, current legislation with respect to the disposal of bottom ashes was analyzed. In particular, the regulations of the Länderarbeitsgemeinschaft Abfall (LAGA, state association for waste treatment) were considered. Future modifications of the legislation were not dealt with, as no reliable information was available at the time this analysis was made. The project also covered the fundamentals of thermal waste treatment, potential impacts on quality, and the processing technologies required as a function of the bottom ash recycling path.
Various data sources were applied to make statements with respect to the bottom ash volume produced by waste incineration and the bottom ash quality. Data were obtained from questionnaires sent to operators of technical waste incineration plants. In addition, data from a literature search and a comprehensive research report were available.
Evaluation of these data yielded a bottom ash volume of 4.5 million tons for all 72 waste incineration plants in Germany in 2007. The average specific bottom ash volume arising was 250 kg per ton incinerated waste.
Based on all data sources, bottom ash quality was compared and assessed with the currently valid regulations. With few exceptions, pollutant concentrations of raw and deposited bottom ashes were below the limits specified in the regulations of LAGA. Other comparisons were made to study the relationship between furnace technology and waste input, on the one hand, and bottom ash properties, on the other.
Taking into account the varying ages of the data sets used, it was found that the pollutant contents of waste incineration bottom ashes and their eluates did not change significantly in recent years.