Intermediate pyrolysis of organic fraction of municipal solid waste and rheological study of the pyrolysis oil for potential use as bio-bitumen

This work presents a study on intermediate pyrolysis of the organic fraction of municipal solid waste (OFMSW) and characterisation of organic liquid product (pyrolysis oils) with particular focus on aging and rheological characteristics. The feedstock was a real municipal waste sample received from a local waste treatment plant. Shredded into small particles, it contained a high amount of moisture (51.2%) and ash (17.4%). A pilot-scale intermediate pyrolysis system was used to process the material. The process mass balance showed that the yield pyrolysis oil was 10.6%. GC-MS and FTIR experiments showed that the accelerated aging (80 °C for 24 h) did not cause an obvious change in the liquid chemical composition, but led to a significant reduction in the solids and moisture contents. The dynamic viscosity tests demonstrated that the intermediate pyrolysis oil derived from OFMSW is a non-Newtonian fluid. The dynamic viscosity of the pyrolysis oil reduced with the increase of temperature or shear rate, which can be modelled by WLF function and the Carreau model, respectively. A shear rate-temperature superposition method was proposed to construct the viscosity master curve at a wide range of shear rate, where WLF function was employed to model the shear rate-temperature shift factor. The accelerated aging caused an obvious reduction in dynamic viscosity, resulting from the decomposition of the semisolid organic agglomerates in the solids content during the aging of the OFMSW intermediate pyrolysis oil. The relatively high viscosity and reduced viscosity after aging of the OFMSW pyrolysis oil has indicated its potential for application as a substitute of the light fraction in the bitumen for road construction.