*4.2. Characterization of FA Regarding the FLUWA Treatment*

To estimate implementation planning and effort for FA leaching, the properties of all FA samples were grouped with similar properties into four different clusters. Of all MSWI plants, 16 out of 29 produce FA that shows very high or high leaching potential, and 13 MSWI plants produce FA that shows moderate or low leaching potential. FA with moderate or poor leaching potential require higher effort and has smaller return through the recovery of Zn. Thus, mixing of different FA types could be an expedient means of diminishing the effects of poor leaching potential. For optimized processing, FA composition is suggested to be monitored regularly by simple tests of ANC, Zn (Pb, Cu), and Al0. The cluster, however, provides preliminary information for general planning and FLUWA design.
