School of Civil & Environmental Engineering, University of Science & Technology Beijing, Xueyuan Road 30, 100083 Beijing, China.
Ultrason Sonochem. 2013 Nov;20(6):1384-9. doi: 10.1016/j.ultsonch.2013.03.010. Epub 2013 Apr 13.
The ultraviolet (UV) disinfection efficiency is often affected by suspended solids (SS). Given their high concentration or large particle size, SS can scatter UV light and provide shielding for bacteria. Thus, ultrasound is often employed as a pre-treatment process to improve UV disinfection. This work investigated the synergistic effect of ultrasound combined with UV for secondary effluent disinfection. Bench-scale experiments were conducted in using samples obtained from secondary sedimentation tanks. These tanks belonged to three wastewater treatment plants in Beijing that use different kinds of biological treatment methods. Several parameters may contribute to the changes in the efficiency of ultrasound and UV disinfection. Thus, the frequency and energy density of ultrasound, as well as the SS, were investigated. Results demonstrated that samples which have relatively higher SS concentrations or higher percentages of larger particles have less disinfection efficiency using UV disinfection alone. However, the presence of ultrasound could improve the disinfection efficiency because it has synergistic effect. Changes in the particle size distribution and SS concentration notably affected the efficiency of UV disinfection. The efficiency of Escherichia coli elimination can be decreased by 1.2 log units as the SS concentration increases from 16.9 mg/l to 25.4 mg/l at a UV energy density of 40 mJ/cm(2). UV disinfection alone reduced the E. coli population by 3.4 log units. However, the synergistic disinfection of ultrasound and UV could reach 5.4 log units during the reduction of E. coli at a 40 kHz frequency and an energy density of 2.64 kJ/l. The additional synergistic effect is 1.1 log units.
紫外线 (UV) 消毒效率通常会受到悬浮物 (SS) 的影响。由于 SS 浓度高或粒径大，其可以散射 UV 光并为细菌提供屏蔽。因此，超声通常被用作预处理过程以提高 UV 消毒效果。本工作研究了超声与 UV 联合用于二级出水消毒的协同作用。采用取自三个北京污水处理厂的二次沉淀池中的样品进行了台式实验。这些污水处理厂使用不同类型的生物处理方法。有几个参数可能会影响超声和 UV 消毒效率的变化。因此，研究了超声的频率和能量密度以及 SS。结果表明，单独使用 UV 消毒时，SS 浓度较高或较大粒径颗粒比例较高的样品的消毒效率较低。然而，超声的存在可以提高消毒效率，因为它具有协同作用。颗粒尺寸分布和 SS 浓度的变化显著影响 UV 消毒的效率。当 UV 能量密度为 40 mJ/cm(2) 时，SS 浓度从 16.9 mg/l 增加到 25.4 mg/l 时，大肠杆菌消除效率可降低 1.2 个对数单位。单独的 UV 消毒可使大肠杆菌减少 3.4 个对数单位。然而，在 40 kHz 频率和 2.64 kJ/l 的能量密度下，超声和 UV 的协同消毒可使大肠杆菌减少 5.4 个对数单位。协同作用的附加效果为 1.1 个对数单位。
