Pyrolysis of excavated waste from landfill mining: Characterisation of the process products

Abstract The current transition to a circular economy model laid the foundations for the development of the Enhanced Landfill Mining concept. Hitherto, a few studies have been performed on the thermochemical valorisation of excavated waste, of which a majority concern incineration or gasification. Nonetheless, no previous studies on excavated waste pyrolysis, including the characterisation of the process products, have been identified. Ergo, this study aims at filling this knowledge gap. The pyrolysis of refuse-derived fuel formed from excavated waste was performed in a lab-scale reactor in the temperature range of 400-700°C. The non-condensable products (non-condensables) were analysed using Micro GC, whereas the condensable products (condensables) were characterised using GC/MS. Additionally, the distribution of C, H, N, S, O, and Cl among the process products was analysed. The high content of C2-C3 hydrocarbons was detected in non-condensables, whereas the abundance of polycyclic aromatic hydrocarbons (PAHs) was detected among condensable products. However, due to feedstock complex thermal decomposition pattern, no overall tendency, covering the process product properties in relation to the process temperature, can be determined. These fluctuations of composition, therefore, have to be taken into account in the planning of the future utilisation of the excavated waste pyrolysis products. Moreover, two possible risks, connected with the further process products utilisation, were identified – namely, chlorine forming primarily organic compounds and sulphur forming mostly gaseous compounds (H2S).