Sustainability analysis of orange peel biorefineries

Biorefineries are constantly evolving since new technological advances in enzyme and microbial processes are boosting research for producing new bio-based products. Nevertheless, the step towards real process imple-mentation must overcome a series of stages based on process sustainability in the early design stages. Orange peel (OP) has been profiled as a potential raw material for producing different products. Few studies have estimated the sustainability of OP-based biorefineries considering the upstream influence on the final process performance. This research aims to perform the sustainability assessment of several OP valorization pathways based on experimental data applying the biorefinery concept. Steam distillation and polyphenolic compound extraction prior to saccharification and anaerobic digestion increase the process performance. A glucose concentration and biogas yield of 21.43 g/L (0.44 g/g OP, db) and 415 mL/g SV were obtained, respectively. An essential oil extraction yield of 1.17 g/100 g OP (db) with a D-limonene content of 91.62% was produced. Moreover, hes-peridin, apigenin, and naringenin yields of 7.88 mg/g, 0.475 mg/g, and 0.675 mg/g were obtained. An OP-based biorefinery addressed to produce essential oil, polyphenolic compounds, and biogas with a processing 25 tons/ day (wb) has a sustainability index of 66.88%, higher than the values obtained with lesser upstream stages. In conclusion, an integral OP upgrading leads to better enzymatic and anaerobic digestion performances, as well as, a high process sustainability.

Automated summary

This study evaluated the sustainability of biorefineries using orange peel as a raw material. By applying the concept of biorefineries and experimental data, it was found that steam distillation and polyphenolic compound extraction can improve the process performance, resulting in higher yields of different products. The integrated utilization of orange peel in biorefineries showed a high sustainability index.