Modified conventional bioreactor for microalgae cultivation.

Microalgae, a renewable source for third generation biofuel production, have a great potential if cultivated in high concentration economically. Bottleneck lies with designing economical and efficient photobioreactor. In addition, proportional C and N inputs in the known media does not support high specific growth rate and high biomass build-up. Nitrates in fermentation media, f/2 for Nannochloropsis sp. and Zarrouk's for Arthrospira platensis, were modified. Aeration and agitation were altered in conventional bioreactor (BIOFLO 110) to reduce power consumption, increase mixing time and prevents settling. This was achieved by introducing four way flow regime supporting uniform nutrient and cell distribution in media. Volumetric cell productivity for Nannochloropsis sp. and A. platensis were achieved as 0.618 g/l/d and 0.774 g/l/d, respectively. This photobioreactor also supported the maximum specific CO sequestration rates to the level of 0.42 g/g/h and 0.39 g/g/h for Nannochloropsis sp. and A. platensis, respectively, confirming efficient and effective operation.