超声破解对剩余污泥内含营养物及粒径的影响

Effect of ultrasonic cracking on nutrients and particle size of excess sludge

利用超声技术破解剩余污泥,不仅能有效降低污泥含水率,提高污泥稳定性,还能在上清液中释放C、N和P等有机物,为污泥资源化利用提供条件。通过考察超声时间、功率及频率等因素,分析超声空化对污泥稳定化程度和污泥内含营养物质释放的影响规律,形成超声破解污泥的最优实验方案。综合考虑超声效果与节能,选择超声频率22 k Hz,超声功率800 W,超声时间15 min为优化的工艺条件,其上清液中的COD浓度高达954.33 mg·L^(-1),总氮含量为153.16 mg·L^(-1),总磷含量为72.65 mg·L^(-1),污泥颗粒粒径显著减小,d50从原泥的34.82μm减小至2.99μm,并形成少量纳米级颗粒,探讨了纳米颗粒对污泥活性的影响,有利于后续污泥稳定化和减量化。

Ultrasonic cracking excess sludge can not only decrease the water content in sludge and improve its stability, but also can release some organic species such as C, N and P from the sludge, which is beneficial for resource recycling and utilization. By examining the time, power and frequency of ultrasonic treatment, the effects of ultrasonic cavitation on the sludge stability and the nutrients releasing were systematically analyzed, which achieved the optimized experimental program for ultrasonic cracking excess sludge. Comprehensively considering the ultrasonic effect and energy-saving, the ultrasonic time of 15 min and power of 800 W with the frequency of 22 k Hz were selected as the proper experimental parameters. In this condition, the concentrations of SCOD, total nitrogen and total phosphorus in the supernatant raised up to 954.33, 153.16 and 72.65 mg·L^（-1）, respectively. Furthermore,the particle size of sludge was significantly reduced. For example, the particle size of d_（50） in the initial sludge was reduced from 34.82 μm to 2.99 μm. In addition, a small amount of nanoparticles were also produced. The effect of nanoparticles on sludge activity was briefly discussed, which was proposed to be conducive to the stabilization and reduction of subsequent sludge.