A Perspective of Solid-State Fermentation As Emergent Technology for Organic Waste Management in the Framework of Circular Bioeconomy

Abstract

Among the different technologies to treat and valorize organic waste, solid-state fermentation (SSF) is gaining relevance in recent years as it permits the recovery of valuable biomaterials from waste, changing the paradigm: “from waste to raw material source”. SSF is very similar to composting, as it implies the aerobic biodegradation of organic solid waste, but with the objective of obtaining bioproducts in some point of the process, although a compost-like end product may be also produced. Also, SSF can be coupled with anaerobic digestion, as solid digested materials can act as substrates for SSF, with a double benefit: renewable bioenergy and bioproducts. Among these bioproducts, SSF has moved from classical biotechnological compounds (enzymes or antibiotics) to more complex biomaterials, such as biopesticides, bioplastics, biosurfactants, or biostimulants, among others, which are now an emergent field of research and one of the main objectives of SSF. In summary, it is evident that SSF will have a predominant role in the framework of circular bioeconomy and in novel biorefineries for biowaste and wastewater sludge valorization, although some challenges still need further research (scale-up and down-stream).