Effect of Different Pretreatment Methods on Disruption Rate of Excess Sludge

To enhance the utilization rate of excess sludge resources, the effects of four pretreatment methods on sludge disruption rate were investigated by single factor test. Subsequently, the disruption effect of combined pretreatment was compared, and the best combined pretreatment method was determined. The morphological changes of excess sludge before and after disruption were observed by optical microscope. Finally, the change of sludge particle size was measured by laser particle size analyzer. Results show that ultrasonic pretreatment has the best effect on sludge disruption among ultrasonic, thermal hydrolysis, surfactant and complex enzyme pretreatment. The sludge disruption rate is 18.1% under 0.15 W/mL energy density and 10.0 min ultrasonic time. The surfactant pretreatment on sludge disruption has the least impact, and the sludge disruption rate is only 8.5% at 60 mg/g addition. Compared to the single pretreatment, the surfactant combined with ultrasonic pretreatment exhibits a synergistic effect. The sludge disruption rate increases by 9.0 %, and the sludge particle size decreases by 45.5%-67.9%.