Biomethane is readily produced from waste bioresources - including food waste, sewage sludge, farm crop residues, and manures - via anaerobic digestion, and can be efficiently valorised through local heat and power recovery via a CHP system, or upgraded for injection into the gas grid. While the heat and energy generated are valuable renewable resources, burning biomethane inevitably results in carbon emissions.

An alternative approach involves anaerobic fermentation of these feedstocks to produce longer-chain molecules that can be recovered for direct use, integrated into existing refinery processes, or utilized in synthetic chemistry as high-value renewable feedstocks. The resulting products include liquid biofuels such as ethanol and renewable polymer precursors and food ingredients like acetic and lactic acid. Additionally, fermentation yields a range of volatile fatty acids (e.g., propionic, butyric, valeric) and longer-chain compounds such as caproic acid, which holds value as a perfume ingredient and as a precursor for nylon synthesis via caprolactam. Transitioning to anaerobic fermentation enables repurposing of existing anaerobic digestion reactors, facilitates the production of high-value compounds that replace crude-oil feedstocks, and retains carbon within the product / supply chain cycle rather than emitting it.

This paper presents early-stage findings from laboratory-scale, semi-continuous anaerobic fermentation experiments conducted under varying loading conditions, and identifies the corresponding product molecule profiles. We also identify key microbial species within the bioreactors using 16S rRNA gene amplicon sequencing and bioinformatics tools. Finally, we share preliminary modelling results, applying a modified version of ADM1 to predict product molecule profiles in response to different bioreactor operating conditions.