Valorization of volatile fatty acids from the dark fermentation waste Streams-A promising pathway for a biorefinery concept

In recent years, much attention has been directed towards the integration of dark fermentation process into a biorefinery concept to enhance the energetic gains, thereby improving the competitiveness of this process. The volatile fatty acids (VFAs) from dark fermentative H-2-producing processes serve as precursors for the microbial synthesis of a broad spectrum of biotechnologically-important products such as biofuels and biocommodities. These products are desirable substrates for secondary bioprocesses due to their biodegradable nature and affordability. This short review discusses the use of acidogenic-derived VFAs in the production of value-added compounds such as polyhydroxyalkanoates (PHAs) alongside the microbial-based fuels (hydrogen, biogas, and electricity), and other valuable compounds (succinic acid, citric acid, and butanol). The review also highlights the strategies that have been used to enhance the extraction of VFAs from acidogenic effluents and other related waste streams. The application of novel enhancement techniques such as nanoparticles during VFAs recovery is also discussed in this work. Furthermore, the work highlights some of the recent advances in dark fermentation-based biorefinery, particularly the development of pilot-scale processes. Finally, the review provides some suggestions on the advancement of dark fermentation-based biorefineries using VFAs that are derived from acidogenic processes.

Automated summary

The article explores the utilization of VFAs from dark fermentation for the production of valuable compounds such as PHAs, microbial-based fuels, and other important biotechnological products. It also discusses strategies for enhancing the extraction of VFAs from acidogenic effluents, as well as the application of nanoparticles in VFAs recovery processes. Furthermore, recent advancements in dark fermentation-based biorefineries, including pilot-scale processes, are highlighted, along with suggestions for the advancement of such biorefineries using VFAs derived from acidogenic processes.