Carbon dioxide uptake efficiency by outdoor microalgal cultures in tubular airlift photobioreactors

Autor: T. Mazzuca Sobczuk, F.G. Acién Fernández, F. Camacho Rubio, F. García Camacho, E. Molina Grima
Rok vydání: 2000
Předmět:
Zdroj: Biotechnology and Bioengineering. 67:465-475
ISSN: 1097-0290
0006-3592
DOI: 10.1002/(sici)1097-0290(20000220)67:4<465::aid-bit10>3.0.co;2-9
Popis: The influence of solar irradiance and carbon dioxide molar fraction of injected CO2-air mixtures on the behavior of outdoor continuous cultures of the mi- croalga Phaeodactylum tricornutum in tubular airlift pho- tobioreactors was analyzed. Instantaneous solar irradi- ance, pH, dissolved oxygen, temperature, biomass con- centration, and the mass flow rates of both the inlet and outlet oxygen and carbon with both the liquid and gas phases were measured. In addition, elemental analysis of the biomass and the cell-free culture medium was per- formed. The oxygen production rate and carbon dioxide consumption rate increased hyperbolically with the inci- dent solar irradiance on the reactor surface. Carbon losses showed a negative correlation with the daily varia- tion of the carbon dioxide consumption rate. The maxi- mum CO2 uptake efficiency was 63% of the CO2 supplied when the CO2 concentration in the gas supplied was 60% v/v. Carbon losses were >100% during the night, due to CO2 production by respiration, and hyperbolically de- creased to values of 10% to 20% in the midday hours. An increase in the carbon fixed in the biomass with the solar cycle was observed. A slight daily decrease of carbon content of the cell-free culture medium indicated the ex- istence of carbon accumulation in the culture. A decrease in CO2 molar fraction in the injected gas had a double benefit: first, the biomass productivity of the system was enhanced from 2.05 to 2.47 g L ˛1 day ˛1 by reduction of CO2 inhibition and/or pH gradients; and second, the car- bon losses during the daylight period were reduced by 60%. The fluid dynamics in the reactor also influenced the carbon losses: the higher the liquid flow rate the higher the carbon losses. By using a previous mass transfer model the experimental results were simulated and the usefulness of this method in the evaluation and scale-up of tubular photobioreactors was estab- lished. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 67: 465-475, 2000.
Databáze: OpenAIRE
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