Feasibility of microalgal cultivation in a pilot-scale airlift-driven raceway reactor.

A Scenedesmus sp. was cultivated in a 23-L airlift-driven raceway reactor under artificial lighting and laboratory conditions, in batch and continuous modes. In batch mode, a maximum volumetric biomass productivity of 0.085 dry g L(-1) day(-1) was achieved under sparging at a CO(2)-to-air ratio of 1%, and a maximum CO(2) utilization efficiency of 33% was achieved at a CO(2)-to-air ratio of 0.25%. In continuous mode, the maximum volumetric biomass productivity was 0.19 dry g L(-1) day(-1). Biomass productivities per unit power input achieved in this reactor configuration (0.60-0.69 dry g W(-1) day(-1)) were comparable to or better than those reported in the literature for different photobioreactor designs (0.10-0.51 dry g W(-1) day(-1)). Based on the energy-efficient productivity and the high CO(2) utilization efficiency demonstrated in this study, the proposed airlift-driven raceway design holds promise for cost-effective algal cultivation.