This work proposes a systems approach to model and characterize non-conventional streams, applied to the Hydrothermal Liquefaction (HTL) of sewage sludge towards biocrude. Biocrudes are complex mixtures involving a great many number of compounds, and this introduces challenges in their characterization and the HTL process modelling. For the development of suitable representations and property models for the HTL input/output streams, we create a mathematical model, and solve it using four different optimization algorithms. The optimization is based on experimental data found in the literature, mapping the quantitative and qualitative characteristics of different feedstocks and product streams (organic substrate, reactor inlet and biocrude) and byproducts. Results reveal the most efficient models in terms of their prediction accuracy and convergence speed.
