Evaluation of carbon dioxide mass transfer in raceway reactors for microalgae culture using flue gases

Mass transfer of CO2 from flue gas was quantified in a 100 m(2) raceway. The carbonation sump was operated with and without a baffle at different liquid/gas ratios, with the latter having the greatest influence on CO2 recovery from the flue gas. A rate of mass transfer sufficient to meet the demands of an actively growing algal culture was best achieved by maintaining pH at similar to 8. Full optimisation of the process required both pH control and selection of the best liquid/gas flow ratio. A carbon transfer rate of 10 gC min (1) supporting an algal productivity of 17 g m (2) day (1) was achieved with only 4% direct loss of CO2 in the sump. 66% of the carbon was incorporated into biomass, while 6% was lost by outgassing and the remainder as dissolved carbon in the liquid phase. Use of a sump baffle required additional power without significantly improving carbon mass transfer. (C) 2013 Elsevier Ltd. All rights reserved.