Comparison of photobioreactors for cultivation of the red microalga Porphyridium sp

The growth of the red microalga it Porphyridium sp was studied in three ben ch-scale bioreactors of 13 dm(3) volume: a bubble column, an airlift reacto r and a modified airlift reactor with helical flow promoters in the top of the downcomer. Most of the experiments reported were run with a photon flux density of 250 muE m(-2) s(-1), but other illuminances were studied as wel l. Superficial gas velocities were in the range of 5.4 x 10(-4) to 82 x 10( -4)ms(-1) (0.033-0.5vvm). Algal growth in the airlift reactor with helical flow promoters had lower gas requirements than in the other reactor configu rations. This implies lower costs in air compression and in air and CO2 req uirements. It was concluded that the advantages found are related to the pa rticular fluid dynamic characteristics of the reactor. (C) 2000 Society of Chemical Industry.