Cyanobacterial CO2 biofixation in batch and semi‐continuous cultivation, using hydrophobic and hydrophilic hollow fiber membrane photobioreactors

The performance of hollow fiber membrane photobioreactors (HFMPB) for the growth of Synechococcus elongatus at various CO2 concentrations (0.04% (ambient air), 10% and 15%) and medium re‐circulation flow rates (34.4, 60 and 86.6 mL/min) was studied. Cultivation was carried out at both batch and semi‐continuous modes in HFMPBs containing neat and hydrophilized in‐house fabricated poly propylene (PP) membranes at a fixed light intensity of 3000 lux and temperature of 27oC. Cyanobacterium showed better growth at 10% CO2 at an initial pH = 8.2 using BG11 medium in both cultivation modes and modules. Maximum biomass concentration, CO2 biofixation and specific growth rates equal with 2.1 g L–1, 2.08 g L–1d–1 and 1.76 d–1 were obtained for non‐wetted membranes, respectively. Comparing the performance of both modules showed that the impact of cultivation mode on the CO2 biofixation rate and CO2 removal is more influential than the impact of mass transfer resistance in membrane contactors.