Membrane-sparger vs. membrane contactor as a photobioreactors for carbon dioxide biofixation of Synechococcus elongatus in batch and semi-continuous mode

• Published in: Journal of CO2 utilization 2016-12, Vol.16, p.23-31
• Main Authors: Mortezaeikia, V., Yegani, R., Tavakoli, O.
• Format: Article
• Language: English
• Subjects: Batch and semi-continuous cultivation; CO2 biofixation; Membrane contactor; Membrane sparger; Synechococcus elongates
• ISSN: 2212-9820; 2212-9839
• DOI: 10.1016/j.jcou.2016.05.009

[Display omitted] •Performance of membrane sparger was compared by the membrane contactor.•The impact of cultivation modes on the CO2 biofixation was investigated.•The impact of medium re-circulation flow rates on the mass transfer was studied.•The effect of CO2 content in inlet feed gas on the CO2 biofixation was investigated.•Finally, the impact of mass transfer vs. cultivation modes was investigated. In this work, performances of hollow fiber membrane-sparger (MS-PBR) and contactor (MC-PBR) photobioreactors on the growth and CO2 biofixation of Synechococcus elongatus for various CO2 contents, including 0.04% (ambient air), 5% and 10% in batch and semi-continuous cultivations, were investigated. The same numbers of hydrophobic poly propylene membranes via thermally induced phase separation method were incorporated in both MS-PBR and MC-PBR modules. BG11 medium with initial pH of 8.2 and continuous illumination of 3000lx at ambient temperature of 27°C were kept constant for both modules and cultivation modes. The impact of recirculation flow rates of liquid medium on the biomass growth and CO2 biofixation in semi-continuous cultivation mode for both modules were also investigated. The maximum CO2 biofixations of 2.43 and 2.08gLd−1 were obtained for MS-PBR and MC-PBR at CO2 content of 5 and 10%, respectively. It can be concluded that MS-PBR is suitable for high cell density cultivation at low CO2 content in equal gas flow rate due to the maximum growth rate under 5% CO2 condition. Cell growth was inhibited in the presence of 10% CO2 inlet feed gas. On the other hand, MC-PBR showed better growth at higher CO2 contents (10% CO2).