典型污染物对微气泡曝气中氧传质特性的影响

Effect of typical contaminants on oxygen transfer in microbubble aeration

微气泡曝气是一种新型的曝气方式,废水中的污染物对微气泡曝气中氧传质过程具有显著影响。采用气-水旋流微气泡发生装置进行空气微气泡曝气,考察了微气泡曝气中表面活性剂、油脂、苯酚、硝基苯、悬浮固体(高岭土)等典型污染物对氧传质的影响。结果表明,微气泡曝气和传统气泡曝气的表观状态具有明显差异,呈现乳浊状态。表面活性剂、豆油、苯酚、硝基苯等污染物均有助于微气泡的产生和稳定性,从而提高微气泡曝气的气含率和气泡平均停留时间。同时,这些污染物存在时,微气泡曝气氧传质系数为7.44～11.56h-1,α因子为0.77～1.20,显著高于传统气泡曝气。污染物对微气泡的形成和稳定性具有积极作用,可以克服其对氧传质过程的负面效应。气含率和污染物种类是影响微气泡曝气氧传质过程的重要因素。

Mierobubble aeration is a new type of bubble aeration, and contaminants in waste water has great influence on oxy gen transfer in microbubble aeration. The effects of different typical contaminants on oxygen transfer in rnierobubble aeration were investigated by using a gas-water circulation type microbubble generator, including surfaetants, soybean oil, phenol and nitrobenzene as well as suspended solid （kaolin）. The results indicate that different from traditional bubble aeration, rnicrobub ble aeration seems like milk-turbid due to very small bubble size. The soluble organic contaminants improve generation and sta bility of rnicrobubbles, resulting in higher gas holdup and gas retention time. The range of oxygen transfer coefficient KLa is 7. 44～11.56 h-1 , and the range of α-factors is 0. 77～1.20 in mierobubble aeration with the typical contaminants under all test conditions, larger than those in traditional bubble aeration. The improvement of microbubble generation and stability in pres ence of the contaminants should be responsible for the reduction of negative effect of contaminants on oxygen transfer. The gas hold-up and contaminant type are the irn!oortant influencing factors for oxygen transfer in microbubble aeration.