The performance of a novel double-tube ultrasound (US) reactor for waste activated sludge (WAS) pretreatment was assessed at a full-scale wastewater treatment plant (WWTP). For high transferability of the results, a well-performing WWTP with rather typical operating conditions was selected. The effects of the treatment (conducted at a specific energy input of 200 kJ per kg of total solids) were monitored regarding improvements in sludge viscosity, methane production, biosolids removal, and digestate dewaterability. The pretreatment caused a significant reduction of WAS viscosity (−5.8% on average, at p < 0.01) and a maximum yet insignificant increase in methane yield (+6.2%, at p < 0.1). No effect was observed for solids content, viscosity, or dewaterability of the digestate. The economic benefit of the reduced WAS viscosity was negligible, as the reduced pumping costs were less than 1‰ of the US reactor’s electricity costs. Additional methane yields enabled for partial cost recovery (roughly equivalent to the energy costs), while investment costs of the US equipment could not be regained. Yet, the incorporation of improved methane production in the economic assessment remains somewhat speculative, given the only insignificant increase. Results suggest that an economical application of ultrasonic WAS pretreatment is challenging for typical, well-performing WWTPs.

中文翻译：

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使用新型双管反应器进行超声波污泥预处理的全面评估

在大规模污水处理厂（WWTP）上评估了用于废物活性污泥（WAS）预处理的新型双管超声（US）反应器的性能。为了使结果具有较高的可传递性，选择了具有相当典型操作条件的性能良好的污水处理厂。监测处理效果（在每公斤总固体200 kJ的比能量输入下进行），以评估污泥粘度，甲烷产量，生物固体去除和消化脱水性能的改善。预处理引起显著还原粘度（平均-5.8％，在p <0.01）和最大但不显着增加产率的甲烷（+ 6.2％，在p<0.1）。没有观察到消化物的固体含量，粘度或脱水性的影响。降低的WAS粘度带来的经济利益可忽略不计，因为降低的泵送成本不到美国反应堆电力成本的1‰。额外的甲烷产量可以部分回收成本（大致相当于能源成本），而美国设备的投资成本无法收回。然而，鉴于仅有的微不足道的增长，将改进的甲烷生产纳入经济评估仍然有些投机。结果表明，对于典型的性能良好的污水处理厂，超声波WAS预处理的经济应用具有挑战性。