PYROLYSIS OF SEWAGE SLUDGE FROM THE WASTEWATER TREATMENT PLANT IN BOGOTA (COLOMBIA)

The aim of this work is to study the Sewage Sludge pyrolysis. For this purpose the raw material was characterized and pyrolysis experiments were done in two different devices. The characterization of sewage sludge included proximate and elemental analysis (determination of carbon, hydrogen, nitrogen and sulfur), and the determination of the high calorific value. An analysis of the sewage sludge composition by the determination of iron, calcium, magnesium, sodium, potassium, cadmium, arsenic, nickel and mercury by Atomic Absorption Spectroscopy is also done. In addition the sewage sludge and its ashes were analyzed by X-Ray Diffraction for the determination of crystalline compounds, and finally a study of elements and oxides was studied by X-Ray Fluorescence. First, pyrolysis is done according to the International Standard ISO 647 Brown coals and lignites determination of the yields of tar, water, gas and coke residue by low temperature distillation. The product fractions were determined and characterized. The solid product is characterized by the same methods as the raw material. The bio oil was characterized by elemental analysis and determination of the calorific value. The second part of this study was the pyrolysis in a thermobalance. Essays were performed with variation of the particle diameter, the material quantity and the heating rate. In all experiments nitrogen was used as inert gas. The principal fraction of pyrolysis products was liquid (56%). And the other fractions were solid (26%) and gas (18%).The distribution of the calorific value for liquid, solid, and gas products were 53%, 12%, 35% respectively (all values are free of water and ash). It was found that the pyrolysis products could be used as an energy source.