Biparticle fluidized bed reactor

Recent examples of process improvement have been reported by Davison and Thomson [11] and Kaufman et al. [12]. They studied the simultaneous fermentation and recovery of lactic acid in a biparticle fluidized-bed reactor using L. delbreuckii as the biocatalyst. The immobilized bacterial cells (on calcium alginate beads of 0.7-0.8 mm diameter) were fluidized in the liquid media in a column reactor (see Fig. 1). During fermentation, solid particles of lactic acid adsorbent (polyvinylpyridine resin) are added batchwise to the top of the reactor, and fall countercurrently through the biocatalyst. After the adsorbents have fallen through the reactor, they are recovered and the adsorbed lactic acid is recovered. The adsorbents not only remove acid produced but also effectively maintain the broth pH at optimal levels. The increase in lactic acid production is significant. The reported volumetric productivity of 4.6 g/l/h was a 12-fold increase over the reactor without the adsorbents. 

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