Statistical analysis of heavy metal data from municipal waste incineration residues

Heavy Metal data from a measurement program at a municipal incinerator in Vienna, Austria are analysed. The experimental design had a nested structure, and analysis of variance is used to break down the total variability into several components; (1) variability between mean hourly concentrations, (2) variability between mean sample concentrations within intervals of an hour and (3) variability due to "measurement" errors. Results of a pre-experiment show, that if grab samples are taken, within hour variation is dominant. The results of analysis of variance were used to calculate an optimal number of samples, which ensure a predetermined accuracy for the mean concentrations. In two main measuring periods with different incinerated waste types, slag and fly ash (ESP dust and boiler ash) data are produced and analysed. For both slag and fly ash, significant differences in measures of location and dispersion between the data sets of the main experiment are found. This proves, that differences in the chemical set up of waste can be detected via incineration residues.