微气泡曝气中微气泡收缩特性研究

微气泡曝气是一种新的气泡曝气方式,气泡特性对微气泡曝气性能具有显著影响。采用气-水旋流微气泡发生装置,考察了微气泡曝气中气泡尺寸和微气泡收缩特性及其影响因素。结果表明,微气泡发生装置在清水中产生的微气泡平均直径为55.85μm,标准偏差为30.03μm;40～50μm直径范围内的微气泡所占的体积分率最大,表面活性剂SDS会降低微气泡的平均直径。微气泡具有加速收缩消失的行为特性,微气泡初始直径与收缩时间之间存在显著的正相关关系,静态条件下相同初始直径的微气泡收缩过程存在明显差异。表面活性剂SDS存在时,微气泡的收缩时间显著延长。微气泡的收缩时间与传质区域面积具有负相关关系,表明微环境影响微气泡收缩过程。

Characteristics of microbubble's shrinkage in microbubble aeration

Microbubble aeration is a new type of bubble aeration and bubbles characteristics show great influence on the performance of microbubble aeration.The characteristics of microbubble size and its shrinkage in microbubble aeration were investigated using a gas-water circulation type microbubble generator.The average diameter of microbubbles produced by the microbubble generator in clean water was 55.85 μm and the standard deviation was 30.03 μm.The microbubbles with the diameter range from 40 μm to 50 μm had the maximum volumetric ratio.The existence of surfactant SDS decreased the average microbubble diameter.Microbubbles also showed the behaviors of accelerated shrinkage and disappearance.There was a significant positive correlation between microbubbles initial diameter and its shrinkage time.The microbubble shrinkage time was prolonged remarkably in the presence of surfactant SDS,compared to that in clean water.The shrinkage processes of different microbubbles with the same diameter showed diversity under the static condition.Furthermore,the negative correlation between microbubble shrinkage time and gas mass transfer area was observed,indicating that microbubble shrinkage was influenced by its micro-environment.