126-131An external loop airlift photobioreactor of 5 litre capacity was fabricated with glass as per the design. Blue green algae Anabaena ambigua was cultured in this external loop airlift photobioreactor using cross-shaped and circular sparger. For each type of sparger different sets of air velocities viz., 1 m/s, 1.5 m/s, 2 m/s, 2.5 m/s and 3 m/s were maintained and, once the culture reached stationary phase, the biomass was estimated by gravimetric method. For cross-shaped sparger maximum biomass was obtained at air velocity of 1.5 m/s and for circular sparger maximum biomass was obtained at air velocity of 2 m/s. Statistical analysis two-way analysis of variance (ANOVA) was performed using Microsoft Excel 2007. It was observed that there is a significant change in the biomass formed by changing the air velocity as well as changing the type of sparger. A maximum biomass of 0.809 g/L was obtained using cross-shaped sparger at air velocity of 1.5 m/s
