Addition of CaCO3 in the incineration of a wastewater sludge at 900° C preparation of desulfurant sorbents with the incinerated sludge

Abstract

With the aim of developing new uses of sewage sludge, a byproduct of municipal wastewater treatment plants, in the present work the calcination at 900° C of this waste with or without CaCO3 added was performed; the sludge was obtained from a local municipal wastewater treatment plant. The purpose was to study the ability of the CaCO3 to capture SO 2 during the incineration. The resulting ashes were reactivated at different experimental conditions to obtain desulfurant sorbents to be used in a further desulfurization process at low tempreature. The humidity, total solids and fixed and volatile solids were determined in the sludge with and without CaCO3 added. The elementary analysis of the dry sludge and of the calcinated was obtained. Results show that the C percentage highly decreases in the incineration due to the release of the volatile carbon compounds. The sulphur percentage increases principally due to the release of the volatile matter. The resulting ashes with or without CaCO3 added were studied by Thermogravimetry. T.G. curves show that not all the CaCO3 was calcinated mainly when the amout of CaCO3 added was high. The specific surface area of the dry sludge, of the ashes and of the sorbents prepared by reacitivation of the ashes was also determined