Advances in Medium-Chain Fatty Acids Production from Biowastes: Process Engineering Strategies and Mechanism

Abstract

The rapid accumulation of biowastes has intensified the need for advanced biorefinery technologies to valorize organic residues into high-value recyclable carbon resources. Chain elongation (CE) offers a promising route for upgrading low-value biowaste-derived substrates into high-value medium-chain fatty acids (MCFAs). However, the broader implementation of CE is still constrained by several unresolved issues, including the interaction of the operating parameters in various technologies, the poorly quantified contribution of competing metabolic pathways and insufficient integration between production and product recovery. This review critically synthesizes recent advances in MCFA production from biowastes by linking biochemical mechanisms, microbial communities, process platforms, and operational regulation. The prevailing technologies, e.g., anaerobic fermentation, electro-fermentation and microbial electrosynthesis, as well as to the effects of substrates, electron donors, pH, temperature, hydraulic retention time, hydrogen partial pressure and inhibitor management. Ultimately, this review discusses the core challenges and prospective engineering directions, covering in-depth mechanism interpretation, low-cost efficiency promotion strategies, stable long-term operational maintenance, as well as integrated production and product recovery modes. This review establishes a process-oriented theoretical framework for optimizing circular economy-driven MCFA biosynthesis, and offers theoretical support for the future construction and industrial advancement of biowaste-oriented circular biorefinery systems.