Biomass-specific rates as key performance indicators

Biomass-specific rates as key performance indicators: A nitrogen balancing method for biofilm-based electrochemical conversion

Winkelhorst, O.M. (TU Delft BT/Bioprocess Engineering)
Cabau Peinado, O. (TU Delft BT/Bioprocess Engineering)
Straathof, Adrie J.J. (TU Delft BT/Bioprocess Engineering)
Jourdin, L. (TU Delft BT/Bioprocess Engineering)

2023

Microbial electrochemical technologies (METs) employ microorganisms utilizing solid-state electrodes as either electron sink or electron source, such as in microbial electrosynthesis (MES). METs reaction rate is traditionally normalized to the electrode dimensions or to the electrolyte volume, but should also be normalized to biomass amount present in the system at any given time. In biofilm-based systems, a major challenge is to determine the biomass amount in a non-destructive manner, especially in systems operated in continuous mode and using 3D electrodes. We developed a simple method using a nitrogen balance and optical density to determine the amount of microorganisms in biofilm and in suspension at any given time. For four MES reactors converting CO₂ to carboxylates, >99% of the biomass was present as biofilm after 69 days of reactor operation. After a lag phase, the biomass-specific growth rate had increased to 0.12–0.16 days⁻¹. After 100 days of operation, growth became insignificant. Biomass-specific production rates of carboxylates varied between 0.08–0.37 mol_C mol_X⁻¹d⁻¹. Using biomass-specific rates, one can more effectively assess the performance of MES, identify its limitations, and compare it to other fermentation technologies.

bioelectrochemistry
biofilm
biomass-specific rates
chain elongation
CO2 conversion
continuous bioreactors
electroactive bacteria
microbial electrosynthesis

http://resolver.tudelft.nl/uuid:cf7b686f-e4de-40c4-994e-b9b824e2ae31

https://doi.org/10.3389/fbioe.2023.1096086

2296-4185

Frontiers in Bioengineering and Biotechnology, 11

Institutional Repository

journal article

© 2023 O.M. Winkelhorst, O. Cabau Peinado, Adrie J.J. Straathof, L. Jourdin