High water content in sludge has consistently posed a significant challenge in sludge treatment processes. As an effective

approach for sludge dewatering, ultrasound treatment induces cavitation effects, mechanical vibration, and thermal 

effects to rapidly disrupt sludge floc structures and release bound water, with sonication energy density and ultrasonic 

duration serving as key control parameters that ultimately determine dewatering efficiency. This study identified the optimal

sonication energy densities and ultrasonic durations for sludge volumes of 500 ml, 750 ml, 1000 ml, 1250 ml, and 

1500 ml as 0.161 W/ml, 0.165 W/ml, 0.171 W/ml, 0.177 W/ml, 0.180 W/ml and 31s, 33s, 34s, 37s, 41s, respectively. 

Comprehensive analyses including WC, SRF, viscosity, particle size distribution, SEM, FTIR, and NMR were conducted 

on sludge samples of different volumes under these optimal ultrasonic conditions. The results demonstrated that while 

ultrasound treatment significantly reduced WC compared to raw sludge across all volumes, the degree of reduction varied 

with sludge volume. As sludge volume increased, the required ultrasonic intensity and duration increased accordingly, with 

the improvement in water reduction showing an initial enhancement followed by a gradual decline. The study established 

optimal sonication energy densities and durations for different sludge volumes, investigated the variations in WC and 

specific resistance to filtration under optimal ultrasonic conditions, examined the relationship between sonication energy 

density, ultrasonic duration, and sludge volume, and provided mechanistic insights through microscopic and spectroscopic 

analyses. These findings offer valuable guidance for industrial-scale sludge treatment by identifying appropriate ultrasonic 

conditions to enhance sludge reduction efficiency for large-volume applications.