TG pyrolysis of a mixture of dried sludge from urban wastewater and wood pellets and identification of the composition of the resulting gases by infrared spectroscopy

The recent tendency of sewage sludge disposal is targeted towards the gasification for heat generation in small towns far from waste incineration plants. The scope of this article is to present the investigation into the mixture of dried sewage sludge and wood pellets during pyrolysis by thermogravimetry (TG) with evolved gas analysis by TG-coupled Fourier transformation infrared spectroscopy (FTIR) method. The maximum intensity of mass loss of sewage sludge material occurs at 300–310°C temperature and it differs from wood cellulose case of 360°C. The 50:50% mixture of these materials was investigated in more details. Pyrolysis reaction kinetics is described by a variation of three constituent parts from TG data. Prefactor A and activation energy E of the Arrhenius law were found, and reaction order n was determined by the Ozawa method employing Avrami phase change. The maximum of gas evolution is always related to the most intense mass loss, and gas composition correlates with the initial material.