Floating Membrane Bioreactors with High Gas Hold-Up for Syngas-to-Biomethane Conversion


Chandolias K., Pekgenç E., Taherzadeh M. J.

ENERGIES, vol.12, no.6, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 12 Issue: 6
  • Publication Date: 2019
  • Doi Number: 10.3390/en12061046
  • Journal Name: ENERGIES
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: floating MBR, syngas-to-biomethane conversion, high gas hold-up, inoculum-to-syngas ratio, ANAEROBIC GRANULAR SLUDGE, ETHANOL-PRODUCTION, METHANE PRODUCTION, CARBON-DIOXIDE, MASS-TRANSFER, FERMENTATION, SUBSTRATE, INOCULUM, HYDROGEN, BIOMASS
  • Istanbul Technical University Affiliated: Yes

Abstract

The low gas-to-liquid mass transfer rate is one of the main challenges in syngas biomethanation. In this work, a new concept of the floating membrane system with high gas hold-up was introduced in order to enhance the mass transfer rate of the process. In addition, the effect of the inoculum-to-syngas ratio was investigated. The experiments were conducted at 55 degrees C with an anaerobic mixed culture in both batch and continuous modes. According to the results from the continuous experiments, the H-2 and CO conversion rates in the floating membrane bioreactor were approximately 38% and 28% higher in comparison to the free (suspended) cell bioreactors. The doubling of the thickness of the membrane bed resulted in an increase of the conversion rates of H-2 and CO by approximately 6% and 12%, respectively. The highest H-2 and CO consumption rates and CH4 production rate recorded were approximately 22 mmol/(L center dot d), 50 mmol/(L center dot d), and 34.41 mmol/(L center dot d), respectively, obtained at the highest inoculum-to-syngas ratio of 0.2 g/mL. To conclude, the use of the floating membrane system enhanced the syngas biomethanation rates, while a thicker membrane bed resulted in even higher syngas conversion rates. Moreover, the increase of the inoculum-to-syngas ratio of up to 0.2 g/mL favored the syngas conversion.