Influence of Storage Time of Food Waste on the Substrate Characteristics and Energetic Potential Through Anaerobic Digestion

摘要

The storage time (ST) of food waste (FW) influences the anaerobic digestion (AD) process. This study evaluated the effect of the ST (A 1:0 - fresh FW; A2:2, A3:3 and A4:4 days) on the substrate characteristics, the biochemical methane potential (BMP), the substrate hydrolysis (k_h) and the FW energy potential, considering two energy potential scenarios (A: energy use for electricity production and B: use of methane as biofuel) against C: final disposal in landfills, in terms of greenhouse gas (GHG) emissions and transportation costs. Although ST reduced the lignin content of the substrate (by 20) for A4, this favoured the subsequent formation of humic substances (HS) and increased acidogenic activity, inhibiting the methanogenesis, being the BMPs for A1 and A2 (103.3 and 110.40 NmLCH_4 gVS~(-1)) higher than for A3 and A4 (14 and 34 respectively, p＜0.05,); additionally, the k_h values for A3 and A4 were 39 and 73 lower than A2, with the highest k_h (0.101 day~(-1)). The scenarios A and B would avoid FW transport to the landfill and reduce annual diesel consumption costs by 639 and 1005, respectively, while C would increase GHG emissions by 258 and 812 over scenarios A and B, respectively, being the least desirable option.