Mahsa Taghavi - Biotechnology Research Center, Sahand University of Technology, Tabriz, Iran
Sirous Ebrahim - Biotechnology Research Center, Sahand University of Technology, Tabriz, Iran
Jafarsadegh Moghaddas - Biotechnology Research Center, Sahand University of Technology, Tabriz, Iran
Shabnam Pouresmail - Biotechnology Research Center, Sahand University of Technology, Tabriz, Iran

Supension of solid particles in a liquid phase is one of the key processes in the chemical industries and compelete and homogeneous suspensions are of paramount importance in respect of the process type and may be the limiting factors in the success or failure of a process. In this work,homogeneity extent and minimum impeller speed for complete solid suspension (Njs) have been measured in stirred tank reactors. Three impeller types, ie propeller impeller, Rushton turbine andfour-pitched blade disk turbine with different combinations were used. The effects of impeller typeand its diameter, impeller spacing, multi impeller combination and impeller flow pattern were studied. Moreover, Njs speed was determined using three different methods with a good consistency

Solid suspension, Stirred tank reactor, Multi-impeller, Homogeneity, Njs speed