title: Optimization of carbon dioxide supply in raceway reactors: Influence of carbon dioxide molar fraction and gas flow rate.
abstract: Influence of CO2 composition and gas flow rate to control pH in a pilot-scale raceway producing Scenedesmus sp. was studied. Light and temperature determined the biomass productivity whereas neither the CO2 molar fraction nor the gas flow rate used influenced it; because pH was always controlled and carbon limitation did not take place. The CO2 molar fraction and the gas flow rate influenced carbon loss in the system. At low CO2 molar fraction (2-6%) or gas flow rate (75-100l·min(-1)) the carbon efficiency in the sump was higher than 95%, 85% of the injected carbon being transformed into biomass. Conversely, at high CO2 molar fraction (14%) or gas flow rate (150l·min(-1)) the carbon efficiency in the sump was lower than 67%, 32% of the carbon being fixed as biomass. Analysis here reported allows the pH control to be optimized and production costs to be reduced by optimizing CO2 efficiency.
authors.affiliation: College of Chemistry and Food Engineering, Federal University of Rio Grande, Rio Grande, RS 96201-900, Brazil.
authors.forename: T
authors.initials: T
authors.lastname: Duarte-Santos
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Mendoza-Martín
authors.affiliation: Department of Chemical Engineering, University of Almería-CIESOL, 04120 Almería, Spain. Electronic address: facien@ual.es.
authors.forename: F G
authors.initials: FG
authors.lastname: Acién Fernández
authors.affiliation: Department of Chemical Engineering, University of Almería-CIESOL, 04120 Almería, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Molina
authors.affiliation: College of Chemistry and Food Engineering, Federal University of Rio Grande, Rio Grande, RS 96201-900, Brazil.
authors.forename: J A
authors.initials: JA
authors.lastname: Vieira-Costa
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Heaven
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D058086:Microalgae / Q000378:metabolism; D012212:Rheology; D044444:Scenedesmus / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide
keywords: CO(2) concentration; CO(2) efficiency; Gas flow; Microalgae; Raceway; pH