In most experiments, the TCLP value increased as the waste
loading ratio increased because the amount of insoluble material
decreased in the S/S sample. S/S samples fabricated with Na2S
(0.5 wt%) exhibited lower TCLP values than those fabricated without
Na2S; the difference in the TCLP values was much higher for
the high waste loading ratio (100 wt%) condition. As shown in
Table 1, the TCLP values of the fly ash from IWI #2, MDWI #1,
and LPF #1 were higher than those measured in the fly ash from
MWI #1 and the sludge from WTF #3. However, the TCLP values
of the S/S samples fabricated with fly ash from MWI #1, IWI #2,
MDWI #1, and LPF #1 exhibited similar trends, whereas the S/S
samples fabricated with sludge from WTF #3 had a relatively high
TCLP value.