Factors determining the element behavior in municipal solid waste incinerators. 2. Laboratory experiments

Laboratory experiments with synthetic samples are conducted to obtain infor mation on the evaporation behavior of metals in incinerators. In combining the results obtained through field measurements presented in a companion pa per in this issue, hypotheses are postulated on the influence of physical a nd chemical conditions as well as of kinetics on the evaporation behavior o f the chosen elements in the furnace bed. These are validated by thermal tr eatment of bottom ash samples in the laboratory. A temperature increase of from 500 degrees C to 900 degrees C causes higher transfers of most metals into the gaseous phase. Mo and Sb are the exceptions. Chlorine availability generally favors evaporation. Increasing oxidative conditions cause lower Sn transfers. Transfer of the elements Cd, Mo, Sb, Sn, and Zn is negatively affected by their reaction with reaction partners other than oxygen and ch lorine occurring in municipal solid waste. Oxidation of organic carbon to C O and CO2 as well as HCl formation determine the distribution of temperatur e, redox conditions, and chlorine availability in the furnace bed. First in dications are obtained on the residence times of goods under these differen t local conditions. The knowledge acquired can be used to design new incine rators with "tailor-made" products that can either be recycled or landfille d without an adverse environmental impact for the long term. For this purpo se, mechanical processing techniques, thermal treatments at temperatures be tween 500 degrees C and 1100 degrees C, and high-temperature treatments (>1 100 degrees C) including melting processes will have to he combined.