Food waste valorisation for biohydrogen production: Technologies, kinetic modelling, techno-economic aspects and scale-up perspectives

Food waste (FW) is an abundant organic resource that is often underutilised in conventional treatment systems, which mainly focus on stabilisation or volume reduction and therefore lead to loss of recoverable energy. As a result, conventional disposal routes generate low-value outputs and limited recovery of biogenic energy. In this context, biohydrogen production provides an alternative pathway to recover part of this energy by converting FW into renewable hydrogen through acidogenic fermentation processes. This review examines the potential of FW as a feedstock for biohydrogen production and evaluates how different biological pathways can be integrated to improve energy recovery. The performance of dark fermentation, photo-fermentation, and microbial electrolysis cells is critically discussed, with emphasis on their roles in sequential hydrogen production, associated process losses, and operational limitations under heterogeneous waste conditions. The review also examines kinetic modelling approaches used to describe microbial growth, substrate conversion, and inhibition behaviour in complex fermentation systems. These models are assessed in terms of their ability to represent non-ideal behaviour in FW digestion systems and their usefulness for process interpretation. In addition, techno-economic aspects are discussed to identify the influence of feedstock variability, reactor configuration, and co-product recovery on process feasibility. The findings provide a structured understanding of key bottlenecks and integration opportunities for FW-to-biohydrogen systems. The insights from this review are intended for wide audiences including environmental engineers, researchers and waste management stakeholders involved in the development of bioenergy systems.