Gasification of char derived from sewage sludge was studied under different oxidizing atmospheres containing CO 2 , O 2 or H 2 O. The gasification tests were carried out in thermobalance at different temperatures and oxidizing reagent concentrations. The most efficient were the gaseous mixtures containing oxygen. The reaction took place at temperature 400-500°C, whilst in the case of CO 2 and steam much higher temperatures (700-900°C) were necessary to complete the conversion. Two rate models for gas-solid reaction were applied to describe the effect of char conversion on reaction rate. The shrinking core model for reaction-controlled regime was found to be the best for predicting the rate of char gasification in CO 2 and O 2 atmosphere. The experimental data for steam gasification of the char were fitted best by the first-order kinetics. The kinetic parameters estimated from the experimental data are in accordance with the literature for lignocellulosic char gasification and are the first published for sewage sludge char gasification.

A method of monitoring sewage sludge pyrolysis and gasification was proposed. Samples of sludge were pyrolysed in Ar and gasified in CO 2 in a thermobalance. The evolved gases were analysed on the calibrated MS, the samples of sludge and solid residues at different stages of the processes were subjected to elemental analysis. The identification and the quantitative characterisation of chemical reactions were performed, based on the DTG and MS profiles.

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