Excess sludge cell lysis by ultrasound combined with ozone

Abstract

• Ozone-ultrasonic process is an effective method for excess sludge cell lysis. • Ozone-ultrasonic process can improve the dewatering performance of excess sludge. • Ultrasound make up for the disadvantages of low utilization rate of ozone. Excess sludge is a by-product of sewage treatment. Due to its characteristics such as large volume, high moisture content, complex components and high processing cost, if not properly treated, it will cause extremely serious pollution to the surrounding soil, water and air, thus posing a threat to the ecological environment. Therefore, it is urgent to deal with it effectively. In this paper, excess sludge cell lysis by ultrasound combined with ozone was investigated. The optimal experimental conditions for excess sludge cell lysis with the ozone-ultrasonic process were explored. Results show that when the excess sludge concentration, ozone intake, ultrasonic power and frequency are 22,000 mg/L, 7 L/min, 600 W, and 40 kHz respectively, ozone-ultrasonic process has the best effect on excess sludge cell lysis. Besides, mixed liquid suspended solids (MLSS), total organic carbon (TOC), solluted chemical oxigen demand (SCOD), sedimentation properties, NH 3 -H, protein, polysaccharide, fulvic acid and humic acid. were determined at different time under the optimal experimental conditions. Finally, the mechanism of excess sludge cell lysis by ozone-ultrasonic process was analyzed. The experiments carried out in this paper prove that ozone-ultrasonic process is an efficient cell lysis technology for excess sludge.