Anaerobic Digestion of Corn Ethanol Thin Stillage for Biogas Production in Batch and By Downflow Fixed Film Reactor

Abstract

Anaerobic digestion (AD) of corn thin stillage (CTS) offers the potential to reduce corn grain ethanol production energy consumption. This thesis focuses on results collected from AD of CTS at mesophilic temperatures in batch and by down-flow fixed film reactor. Experiments conducted include a series of biochemical methane potential (BMP) assays that investigated the digestion of CTS as the sole carbon source at a variety of food-to- microorganism ratios with and without acclimated biomass, under co-digestion conditions and also with the addition of supplemental nutrients. Additional BMP assays were conducted which investigated the potential to reduce fresh water consumption by using of digested effluent for substrate dilution. Continuous studies employed two 28L down-flow stationary fixed film reactors to examine. Chemical oxygen demand and volatile solids removal efficiencies greater than 85% were achieved up to an organic loading rate of 7.4 g TCOD/L/d and hydraulic retention time of 5 days.