Synergistic effects of sono-alkaline pretreatment on anaerobic biodegradability of waste activated sludge

The individual and combined effects of alkaline and ultrasonic pretreatment on both physical and chemical properties and anaerobic biodegradability of waste activated sludge (WAS) were investigated comprehensively in this study. The experimental results showed that both disintegration and anaerobic biodegradability of WAS were significantly improved by the combination of alkaline and ultrasonic (sono-alkaline) pretreatment. Besides, it was determined that the hydraulic retention time in anaerobic digester can be shortened by half using this combined pretreatment. However, it was also determined that sono-alkaline pretreatment was not feasible economically due to its high energy requirement.