Combustion of Sewage Sludge: Kinetics and Speciation of the Combustible

Abstract

Combustion of sewage sludge has become a viable route for sewage sludge management especially as the agricultural use of sewage sludge has become increasingly difficult due to more stringent requirements regarding the quality of sewage sludge. Combustion of digested sewage sludge in dedicated monocombustion facilities is advantageous, as it substantially reduces the volume of the sludge and still allows for a recovery of phosphorus from the sewage sludge ash at a later stage. Despite increasing amounts of sewage sludge being combusted, knowledge on the respective combustion kinetics is still fragmentary. The goal of this study was, therefore, to identify the major combustion reactions of sewage sludge, assess their Arrhenius parameters (activation energy and pre-exponential factor), and assign suitable reference compounds to the individual reactions. For that purpose, experiments were conducted using a thermogravimetric analyzer (TGA). With matrix inversion, we identified 10 individual reactions. Despite ...