Tunisian agro-food wastes recovery by pyrolysis: Thermogravimetric analysis and kinetic study

In keeping with the hierarchy of waste management methods, thermal treatment makes it possible to recover energy from wastes that could not be processed by recycling or material recovering. As far as agricultural wastes are concerned, this biomass has for a long time been covering the domestic energy needs of rural and urban areas, thus reducing the gas and oil import costs. In the context of climate change, biomass is neutral with respect to the carbon cycle, allowing it to be a reliable alternative to fossil fuels. In addition, bioenergy can be stored, which is a key advantage over other renewable energies and therefore allows on-demand energy production. However, the extreme diversity of resources, the wide variety of conversion technologies and the disparity of energy sectors give bioenergy a certain complexity unless technical and economic issues are overcome. In this perspective, the present study focused to identify, through the Tunisian territory, the biomass deposits, to map and evaluate their energy potential. This preliminary phase made it possible to conclude that although Tunisia is among the worldwide leading producers of dates and derivatives, olive oil, wine and concentrated tomatoes, the value chains for their by-products remain vulnerable. This paper is then devoted to the recovery of these wastes for the dual purpose of minimizing their increasing quantities on the one hand and to obtain the energy necessary to operate the process of pyrolysis at the lowest cost, while monitoring their gaseous and particulate emissions on the other hand. To carry out this work, the survey begins with proximate and elemental analyses (ash content, moisture content, calorific value, etc.). The thermal degradation of the different materials was carried out under an inert atmosphere in thermogravimetric analysis conditions. Kinetic models were tested to extract the kinetic parameters required for the development of industrial plants using these different materials as fuels.