To obtain reliable models despite the process' early design stage, conservative estimates were adopted when gaps in available experimental data were encountered. The developed Aspen Plus models predicted a 47.6 mol% paracetamol yield from β-pinene at 98 wt.% -99.9 wt.% product purity. Furthermore, a VLE-based CST separation model predicted that at least 38.5% of the β-pinene contained in CST can be recovered into a desulphurised β-pinene stream, with yield improvements expected upon experimental investigation of other CST separation techniques. Future work to eliminate model uncertainties should focus on the experimental identification of side and by-products. Proxy literature models had to be used to model waste treatment processes, as primary experimental data for waste treatment is generally not collected during early research. In this respect, the shortage of available tools to predict process flows associated with the treatment of non-recyclable process wastes was identified as a key challenge for rigorous LCI assembly at the early design stage.