Valorization of Fruit and Vegetable Waste by Anaerobic Digestion: Definition of Co-substrates and Inoculum

This study aimed to improve the efficiency in methane production of anaerobic digestion of fruit and vegetable waste. For this purpose, two strategies were evaluated: the first was the anaerobic co-digestion with coffee grounds and landfill leachate using different carbon-nitrogen ratios (C/N ratio 25:1 and 12.5:1); the second strategy was the use of two different inoculum sources (digested swine manure and a mixture composed of different inoculums-Mix). The samples were characterized before and after the biochemical methane potential (BMP) tests and methane production was monitored. The modified Gompertz kinetic model was used to predict the process of AD. The Mix inoculum and the co-digestion of FVW and SCG, with a C/N ratio of 25:1, resulted in the highest methane yield (198.1 Nml gVS(-1)). The results highlight that the choice of co-substrates with different properties than the FVW and the composition of an inoculum adapted to different types of substrates can contribute to the improvement in methane conversion from FVW. The kinetic analysis proved that the modified Gompertz model was adequate to describe the AD process, indicating that the studied conditions were favorable for methane production. [GRAPHICS] .