Environmental Evaluation of Emerging Bakery Waste Oil-Derived Sophorolipids Production by Applying Dynamic Life Cycle Assessment (dLCA)

Sophorolipids (SLs) are promising biosurfactants that have attracted the attention from both academia and industry due to its enhanced properties in comparison to their petroleum-derived surfactant counterparts. Increasingly, researchers are utilizing the waste streams as feedstocks to reduce the economic cost and meet the requirements of sustainability and green chemistry. Although such waste valorization minimizes the use of first-generation substrates, the systematic environmental impacts must be assessed by considering the different materials and processes to improve the sustainability of the process. For this reason, the dynamic Life Cycle Assessment (dLCA), due to its iterative nature, is applied to identify the tradeoffs between potential environmental impacts early on in the research and development phase. Our previous dLCA traversal has demonstrated that food waste hydrolysate (FWH) is a promising hydrophilic carbon source, while oleic acid as the 1st-generation hydrophobic carbon source, should be a significant pollution source. Hence, this work evaluates the environmental performance of using bakery waste oil (BWO) as a hydrophobic feedstock. The 4th and 5th traversal of the dLCA showed that although BWO brought more environmental pollution than the pure first-generation substrate, proper pH regulation could effectively reduce its environmental burden. In the 6th traversal, the further comparison showed that if SLs production is applied batch fermentation, using BWO as substrate was more environmentally friendly than using FWH. This paper suggests that multi-technique incorporation, such as feeding with FWH and BWO together equipped with fed-batch fermentation and in-situ separation, may further reduce environmental impacts, meanwhile providing a clear direction for the experimentalists.