Desulfurization behaviour of CaCO3 added during the calcination of wastewater sludge at 900º C: reuse of the ash after reactivation

Abstract

In the present work dry sewage sludge from a local municipal wastewater plant, has been incinerated at 900 º C with CaCO3 added at two sludge/CaCO3 ratios: 10 sludge /1 CaCO3 or 10 sludge /10 CaCO3 in weight. The ability of this salt to capture the SO2 produced during the incineration is studied. The SO2 captured is quantified as mole SO2 / mole of Ca. Results shows that the amount of SO2 captured /mole of CaCO3, is much higher at the 10 sludge /1 CaCO3 ratio. With the resulting ashes, reactivated at different ways, desulfurant sorbents were prepared and essayed in a desulfurization process at low temperature. Results of the process at low temperature showed that the highest value of SO2 captured was found with the sorbent coming from the ashes obtained from the mixture 10 sludge /1 CaCO3 and reactivated by hydration at room temperature.