The performance modeling and optimization of integrated ultrasonic-persulfate advanced oxidation system to improve activated sludge dewaterability

Conventional sewage sludge dewatering methods demand excessive chemicals and energy due to the sludge’s complex nature, resulting in lower efficiency and environmental acceptance. This study investigated the use of ultrasonic (US) and persulfate (PS) together to improve dewatering and explored the key parameters. Sludge dewatering experiments were performed using an ultrasonic-equipped water bath at a constant 40 kHz ultrasonic frequency. The impacts of the parameters persulfate and ferrous sulfate (Fe) concentrations and reaction time on dewatering efficiency were studied. Utilizing the Design Expert software and CCD method, 20 experiments were designed and repeated, yielding optimal persulfate and ferrous sulfate concentrations of 2.3 g/L and 1.7 g/L, respectively, and an 85-min reaction time, resulting in a 50.73