The experimental approach was designed for being able to
transfer the results of the lab-scale investigations to real application,
taking into account the common configuration of full-scale
plants. Due to known interactions of S(IV) compounds and Hg in
the liquid phase [12–15,17,18] the presence of S(IV) in realistic
concentrations in the FGD waste water is of major importance.
Consequently, the waste water was processed immediately after
removal from steady state FGD operation. Thus, the S(IV) concentrations
listed in this study represent the initial S(IV) content of
the waste water samples. As a result of the stripping of the samples
with air during the alkalization process, actual S(IV) concentration
is steadily decreasing due to the oxidation of S(IV) by O2.