The present study provides an overall view of the effect of the ultrasound treatment on waste activated sludge (WAS) rheological and dewatering properties as well as its impact on the economic balance of a theoretical wastewater treatment plant. The results showed that ultrasonication at 27,000 kJ/kg TS increased the soluble protein concentration (> 100%), bound water content (∼25%), and capillary suction time (> 100%) of WAS. The molecular weight distribution of the extracellular polymeric substances (EPS) revealed that the ultrasound treatment solubilised a portion of the peptides and low-molecular-weight proteins. The thixotropic behaviour of the WAS was analysed by means of a rheological structural model that defines the time evolution of a structural parameter as a function of kinetic coefficients for the breakdown and build-up processes. The ultrasound treatment reduced the kinetic coefficients for the breakdown process and changed the fast speed of alignment of flocs because of the reduction of WAS structures. Similarly, the creep tests revealed that the ultrasound treatment at 27,000 kJ/kg TS reduced the initial elasticity (∼80%) and the zero-shear rate viscosity (∼60%), which means that the internal structure of the WAS loosened and disrupted. Finally, a techno-economic analysis showed that ultrasonication was not yet economically favourable since its implementation increased 14% the net cost for WAS treatment and disposal. However, a sensitivity analysis illustrated that increasing electricity revenue and reducing biosolids disposal costs through improvement in WAS biodegradability is important to make ultrasound implementation economically attractive.

本研究提供了超声波处理对废弃活性污泥 (WAS) 流变学和脱水特性的影响及其对理论废水处理厂经济平衡的影响的总体看法。结果表明，27,000 kJ/kg TS 的超声处理增加了 WAS 的可溶性蛋白质浓度（> 100%）、结合水含量（~25%）和毛细管抽吸时间（> 100%）。胞外聚合物 (EPS) 的分子量分布表明，超声处理溶解了部分肽和低分子量蛋白质。WAS 的触变行为通过流变结构模型进行分析，该模型将结构参数的时间演变定义为分解和堆积过程的动力学系数的函数。由于WAS结构的减少，超声处理降低了分解过程的动力学系数，并改变了絮体快速排列的速度。类似地，蠕变试验表明，27,000 kJ/kg TS 的超声处理降低了初始弹性（~80%）和零剪切率粘度（~60%），这意味着 WAS 的内部结构松动和破坏. 最后，一项技术经济分析表明，超声波处理在经济上并不有利，因为它的实施使 WAS 处理和处置的净成本增加了 14%。然而，