Oxygen transfer and evolution in microalgal culture in open raceways
2013
Mendoza, J.L. | Granados, M.R. | de Godos, I. | Acién, F.G. | Molina, E. | Heaven, S. | Banks, C.J.
The mass transfer characteristics of all sections of a 100m2 raceway were evaluated. The efficiency of different diffusers was determined dynamically and the most effective was used for steady state system characterisation at water depth 0.2m and velocity 0.22ms−1. Mass transfer coefficients at a gas flow rate of 6m3h−1 were 164.50, 63.66, 0.87 and 0.94h−1 for the paddlewheel, sump, straight and curved channel sections, with associated oxygen transfer rates of 106, 172, 27 and 39gh−1. Oxygen supersaturation during algal cultivation led to a reduction in biomass productivity, which was more severe with pure CO2 than flue gas. Simulations showed the energy required to increase mass transfer and reduce oxygen concentrations was more than compensated for by increased biomass and potential energy yields. Oxygen removal is likely to be a critical criterion, and maintenance of mass transfer by sparging may be necessary even when CO2 is not required.
显示更多 [+] 显示较少 [-]