Pretreatment and Extraction of Anaerobic Digestion-Derived VFAs for Efficient Harnessing of Microbial Lipids and Their Subsequent Extraction

Anaerobic digestion-derived volatile fatty acids (VFAs) have emerged as key intermediates in sustainable biofuels and biochemicals production, offering a circular approach to organic waste valorization. This review explores recent advancements in enhancing VFA production through tailored pre-treatment strategies, optimized feedstock selection, and controlled process conditions. Furthermore, VFA extraction methodologies are discussed, with a focus on energy-efficient separation techniques. The integration of VFAs as feedstock for microbial lipid production is analyzed, highlighting substrate preferences, metabolic insights, and growth conditions for oleaginous yeast, which can thereby be cultivated in non-sterile conditions because of using VFAs as feedstock. Additionally, innovative lipid extraction technologies, including pulsed electric fields, hydrothermal liquefaction, and ionic liquids, are reviewed for their potential to enhance lipid recovery. By consolidating advancements across these domains, this review provides a comprehensive understanding of the technological landscape, identifying key challenges and future research directions to optimize VFA-driven biofuel production.