[Back]

G. Bauer, E. Schachermayer:
"Statistical Analysis of Heavy Metal Data from Municipal Waste Incineration Residues";
Environmental Science and Pollution Research, 3 (1996), 1; 10 - 16.

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 the analysis of variance were used to plan additional measurement programs, which ensured a predetermined accuracy of the mean concentrations. Additional stages of sampling preparations (compositing and mixing) are suggested to reduce uncertainty. 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. Comparison with the preexperiment proves the adequacy of a filter ash mixing process.
Key Words: Statistical analysis, experimental design, analysis of variance, waste incineration