水平搅拌下低高径比SBR中好氧活性污泥的颗粒化

在设有水平机械搅拌、高径比（H/D）为1.2的圆柱形鼓风曝气SBR中，考察了活性污泥的颗粒化情况，对成熟颗粒污泥表面所受水力剪切速率进行了定量研究，分析了水平搅拌在颗粒化过程中的作用.结果表明：有水平搅拌存在下污泥逐渐颗粒化，形成了均值粒径为1.12mm的好氧颗粒污泥，污泥沉降速度为21.41m/h；计算结果表明污泥表面所受的平均剪切速率为27.25s^-1，剪切应力为3.38×10^-2N/m²；污泥表面所受平均剪切速率与机械搅拌速率和表观气速均呈正相关关系；实验条件下机械搅拌对剪切速率的贡献要远大于表观气速的贡献，前者指数约为后者的37.48倍.研究认为水平搅拌在反应器中形成的具有足够剪切强度的旋涡二次流是促使低高径比反应器好氧污泥颗粒化的关键水力条件.

Aerobic sludge granulation under horizontal mechanical agitation in a SBR with lower ratio of height to diameter

Aerobic sludge granulation was investigated in a horizontal mechanical stirred and aerated SBR with lower ratio of height to diameter (H/D) of 1.2. The average shear rate that granules suffered was calculated and the effect of horizontal agitation on the granulation process was discussed. The results show, the aerobic sludge was granulated in the reactor with a mean diameter of 1.12mm and settling velocity of 21.41m/h finally. The average shear rate of granules was calculated out as 27.25s^-1, and the shear force 3.38×10^-2N/m². The average shear rate acted on the surface of the granules positively related to mechanical agitation speed and superficial gas upflow velocity, of which the mechanical agitation speed contributed more to the shear rate, about 37.48times of that the superficial gas upflow velocity did. It was considered that the eddy secondary flow pattern with appropriate shear force caused by transverse rotation of stirrer was essential to aerobic sludge granulation in the reactor with lower ratio of height to diameter.