Importance of storage time in mesophilic anaerobic digestion of food waste

Storage was used as a pretreatment to enhance the methanization performance of mesophilic anaerobic digestion of food waste. Food wastes were separately stored for 0, 1, 2, 3, 4, 5, 7, and 12 days, and then fed into a methanogenic reactor for a biochemical methane potential (BMP) test lasting up to 60 days. Relative to the methane production of food waste stored for 0–1 day (285–308 mL/g-added volatile solids (VS_added)), that after 2–4 days and after 5–12 days of storage increased to 418–530 and 618–696 mL/g-VS_added, respectively. The efficiency of hydrolysis and acidification of pre-stored food waste in the methanization reactors increased with storage time. The characteristics of stored waste suggest that methane production was not correlated with the total hydrolysis efficiency of organics in pre-stored food waste but was positively correlated with the storage time and acidification level of the waste. From the results, we recommend 5–7 days of storage of food waste in anaerobic digestion treatment plants.