Leo S. Morf

Effect of operating conditions and input variations on the partitioning of metals in a municipal solid waste incinerator

The partitioning of copper, zinc, cadmium and lead between bottom ash and combustion flue gas was investigated in a municipal solid waste (MSW) incinerator. Material balances were established and transfer coefficients were determined for seven 2-h periods. Statistical analysis of the data allowed assessment of the uncertainty and investigation of the effect of waste input variations as well as process conditions. As a result, 6% of Cu, 54% of both Zn and Pb and 90% of Cd in the waste feed were transferred into the combustion flue gas, the rest was found in the bottom ash. The uncertainty of the partitioning in terms of relative width of 95% confidence intervals was estimated as 33% for Cu, 7% for Zn, 7% for Cd and 21% for Pb. Multiple linear regression indicates that, for the incinerator investigated, changes in combustion parameters have a negligible effect on the transfer coefficients of the selected metals; and the partitioning of Cd and Pb does not correlate significantly with changes in the waste composition. A significant positive regression between the transfer of Cu and the chlorine content of the waste feed was observed. The results of this study are instrumental to determine the waste composition by analysing a single combustion product only.

VI.3 - Thermal waste treatment – a necessary element for sustainable waste management

This chapter focuses on the role of thermal waste treatment in waste management. The amount of waste produced is a function of materials consumed. Recycling can divert an important fraction of the total waste stream back to consumption. But because of energetic and economic reasons, the total recycling of wastes is not feasible. Thus, the means to dispose large amounts of wastes in a safe and goal-oriented way are necessary. The goals of waste management comprise protection of man and the environment, the conservation of resources such as energy, materials and land and after-care-free landfills. Since wastes are important carriers of hazardous as well as valuable materials, waste management plays a major role in environmental protection and resource conservation. In service-oriented economies, non-hazardous wastes are larger carriers of hazardous substances than hazardous wastes. Hence, if risks from hazardous substances are to be minimized, the environmentally safe management of non-hazardous wastes, in particular municipal solid wastes (MSWs), is crucial. State-of-the-art thermal treatment is a feasible way to process many hazardous and non-hazardous wastes.