Pyrolysis of oleaginous yeast biomass from wastewater treatment: Kinetics analysis and biocrude characterization

Pyrolysis of Trichosporon fermentans biomass, a type of oleaginous yeast from the fermentation of refined soybean oil wastewater, was studied in the present work. Based on the TG/DTG curves, the activation energy values for the thermal decomposition of Trichosporon fermentans biomass were evaluated by the KAS method (111.69 kJ/mol) and FWO method (116.93 kJ/mol), respectively. The pyrolysis behavior was represented by considering the parallel degradation of four components, namely carbohydrates, proteins, lipids, and others, and the fitting degree of the simulated curve was over 0.99. According to the FTIR spectra of the end-products, the increasing hydrocarbons at a temperature around 400 °C indicated the lipid degradation. Biocrude oil was collected from a fixed bed reactor and the chemical composition was characterized by GC-TOF/MS. The yield of hydrocarbons in the bio-oil was identified as being over 28% when the pyrolysis temperature was higher than 500 °C, whilst the content of nitrogen compounds was less than 18%. The fractional yield distributions of the end-products at different pyrolysis temperatures were compared and the maximum yield of bio-oil was achieved (around 42%) at 500 °C. This study proposed a cost-effective and environmentally friendly method for the preparation of biofuel from oleaginous yeast pyrolysis.