Tehran University of Medical Sciences International Journal of Occupational Hygiene 2008-5109 5 3 2015 10 11 109 116 EN ALI KARIMI Occupational Health Department, School of Public Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Iran AND Occupational Health Eng. Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. FARIDEH GOLBABAEI Occupational Health Eng. Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. MOHAMMADREZA MEHRNIA Biotechnology Group, School of Chemical Engineering, University College of Engineering, University of Tehran, Tehran, Iran. KAZEM MOHAMMAD Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. MASOUD NEGHAB Occupational Health Department, School of Public Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Iran. AHMAD NIKPEY Occupational Health Department, School of Public Health, Qazvin University of Medical Sciences, Qazvin, Iran. MOHAMMADREZA POURMAND Pathobiology Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 10 2015 10 10 A laboratory stirred tank bioreactor with six single and dual-impeller configurations was tested to obtain the optimum operating conditions for future biological processes. Six impeller combinations consisting of three basic impeller types, namely Rushton turbine (RT), pitched 4blade (P4B) and pitched 2blade (P2B) downward flow were investigated in 1.77 L bioreactor working volume. Power consumption and gas hold-up measurements were taken over a range of 100-1000 rpm of stirring speed and 1-5 Lmin-1 of air flowrates, for all the six combinations consisting of any single and dual impellers. Using predicted data some empirical correlations were derived which present relations in estimation of power consumption in stirred tanks with various impeller configurations. Electrical measurement method was use to determine the power drown in the stirred bioreactor. Gas hold-up increased with an increase in stirring speed and superficial gas velocity for all the impellers employed. The number and type of impellers in stirred bioreactor had considerable influence on gas hold-up behavior of the stirred bioreactor. Besides, Rushton turbine-dual Impeller gave comparably maximum gas hold-up, but at significantly higher power consumption levels. The proposed correlations offered good agreement with theexperimental data. https://ijoh.tums.ac.ir/index.php/ijoh/article/view/76 https://ijoh.tums.ac.ir/index.php/ijoh/article/download/76/76