(514ag) Enhanced Recovery from Anaerobic Digestion of Molasses Distillery Stillage with Wet Air Pretreatment and Scoria Support

This study aims to evaluate the performance of coupled techniques in treating a cane molasses distillery stillage towards energy recovery, the biological oxygen demand removal, chemical oxygen demand and toxicity reduction. Initially, the biochemical methane potential of the raw stillage has been determined in order to compare it with the quantity of the recovered biogas during the latter anaerobic digestion process performed without and with wet air pretreatment. Iron oxide coated sand is applied during the wet-air oxidation of stillage at atmospheric pressure. Following that, the changes in the chemical oxygen demand, color and the biological oxygen demand as well as toxicity of the stillage are established. Due to the iron oxide coated sand based wet air pretreatment, the amount and quality of biogas has improved, the toxicity of the stillage has significantly reduced, the bio-amenability of stillage has improved, and the chemical oxygen demand removed is maximized. In effect, wet air pretreatment showed better energy recovery with an improved chemical oxygen demand reduction (92%) compared to the one without pretreatment (80%). Such pretreatments of molasses stillage support the anaerobic digestion over other treatment methods in terms of resource recovery and sustainability.