Effects of alkaline and beating pretreatment on anaerobic digestion of distillery co-products

Whiskey distillery co-products are a high strength organic waste, typically consisting of pot ale (liquid waste) and draff (solid waste). Treatment and disposal of these waste streams is important from an environmental and economic point of view. Anaerobic digestion of pot ale and spent lees mixture (with 5:1 the ratio) has been performed after application of alkaline and beating pretreatments in order to improve the digestibility of the substrate. Using a Response Surface Methodology (RSM) approach, different digestion temperatures (32-35-38○C), beating times (0-7.5- 15 minutes) and sludge percentages (10-30-50 %) were assessed in batch mode, focusing on maximizing the yield of biogas. Alkaline pretreatment was applied first by using 1M NaOH solution up to pH 10, based on significant results have been obtained from the preliminary experiments. The optimum beating time was determined as 7.5 minutes, correspondingly the maximum biogas yields was achieved by 7.5 minutes beaten samples under the 50 % sludge and 38 ○C digestion temperatures with 5966.87 mL biogas per gram total solids.