Liquid culture of microalgae in a photobioreactor (PBR) based on oscillatory baffled reactor (OBR) technology – A feasibility study

• A novel photobioreactor (PBR) was used to culture microalgae.
• The PBR was based on oscillatory baffled reactor (OBR) technology.
• Flotation effects were observed when sparged with small diameter bubbles.
• Linear growth (0.130 OD750/day) was achieved independent of the mixing intensity.
• Growth rates were 95% higher than those achieved in T-flasks (0.067 OD750/day).

Chlamydomonas reinhardtii (CCAP 11/32C) cells were grown in liquid culture under photoautotrophic conditions using a photobioreactor (PBR) based on oscillatory baffled reactor (OBR) technology. A flotation effect was observed when using a porous gas sparger which resulted in accumulation of microalgae at the top of the column. Linear growth was achieved with a different sparger, designed to produce larger, faster rising gas bubbles. Changes in the mixing intensity had no effect on the maximum growth rate of 0.130 OD750/day (±0.010) achieved which was 95% higher than that achieved in T-flasks of 0.067 OD750/day (±0.011) under comparable conditions. The increase in growth rate achieved in the OBR was probably a result of increased gas transfer, and exponential growth was not achieved probably due to the relatively low light intensity used of 78 μmol/m2 s (±20). The results demonstrate the feasibility of OBR technology for use as PBRs with the potential for the duel culture and harvest of microalgal biomass through manipulation of the bubble diameter. This could greatly improve bioprocess economics for microalgae culture.