Disruption of granules by hydrodynamic force in internal circulation anaerobic reactor

A process of granule disruption by hydrodynamic force is discussed in this paper. Shear force and attrition among granules originated from hydrodynamic force are the main causes of the disruption. Since it is positively correlated to the attrition force, the shear force is utilized to describe the effect of hydrodynamic force on granule disruption. In the experiment, when increase rate of average shear rate (IR_γ) of the 1^st stage is about 0.2 s⁻¹·d⁻¹, the granules are disrupted; while re-granulation could develop when IR_γ is about 0.07 s⁻¹·d⁻¹; even when the shear rate is as high as about 30 s⁻¹, the granulation rate keeps stably at a relatively high level, which shows that granules could bear the high hydrodynamic force only if it increases by low increase rate. The experimental results would be valuable for the operation and controlling of the upflow reactors.