低强度超声波改善污泥活性

采用城市污水处理厂的好氧活性污泥为试验材料,以好氧呼吸速率(OxygenUptakeRate,OUR)为指标,研究活性污泥在超声波强度0～1.2W/cm²、辐照时间0～40min处理后活性的变化.发现当采用超声波强度0.3W/cm²,辐照时间10min,对提高污泥活性的效果最为显著,不适当的处理时间与处理强度则不利于污泥活性的提高.因此,利用超声波激励污泥活性存在最佳的超声波强度和辐照持续时间.另外,研究了强度0.3W/cm²,辐照时间10min超声波辐射处理后0～48h中污泥活性的变化规律,发现超声辐照8h后污泥活性达到最大值,为辐射处理后初始活性的2倍,24h后超声波的强化作用基本消失.因此,可采用强度0.3W/cm²超声波每隔8h取反应器中的部分活性污泥辐照10min后再返回反应器,来提高生物反应器的处理效率.本文还对低强度的超声波改善污泥活性的可能机制进行了假说性解释.

Improvement of the Activity of Activated Sludge by Low Intensity Ultrasound

Aerobic activated sludge from domestic wastewater treatment plant was used as an experimental material. Oxygen Uptake Rate(OUR) was detected as the index to indicate the changes of sludge activity induced by ultrasound(US) at 35kHz in 0 - 40 min with the US intensities of 0 - 1 .2 W/cm2. The best results were achieved at a US intensity of 0.3 W/cm2 and irradiation time of 10 min. Improper US intensity and irradiation time lead to a decrease of sludge activity. Therefore, the stimulating effects of US on the sludge activity could be enhanced at an optimized US intensity and irradiation time. In addition, changes of sludge activities (within 48 hours) after US irradiation at 0.3 W/cm2 in 10 min were examined. The activity of sludge took 8 hours after irradiation to reach peak level, and the activity was as double as that of the initial level after irradiation. In 24 hours after irradiation, the enhancement effects induced by ultrasound disappeared. Therefore, to improve the treatment efficiency of biological reactor, ultrasound with intensity of 0.3W/cm2 could be employed to irradiate part of the sludge in the biological treatment system for 10 minutes every 8 hours. It also presented the hypothetical explanation of the mechanism of biological activity enhancement stimulated by ultrasound.