PRODUCTION OF L(-LACTIC ACID USING IMMOBILIZED RHIZOPUS-ORYZAE - REACTOR PERFORMANCE-BASED ON KINETIC-MODEL AND SIMULATION())

The production of L(+)-lactic acid using alginate immobilized Rhizopus oryzae in tapered-column fluidized-bed batch reactor was tested and s imulated using the kinetic data taken independently in shake-flask cul tures. The data show saturation kinetics with substrate and product in hibitions in linear form. Analysis of the kinetic data gave kinetic co nstants: V-m, 11.04 g lactic acid/(L-bead. h); K-m, 20.9 g glucose/L; and K-i, 365 g glucose/L for lactic acid production. The product inhib ition constant, K-p, was found to be 316 g lactic acid/L. The simulati on results showed a good agreement with the experimental results when the initial lag phase was taken into account in the simulation model. Without the adjustment for the initial lag period, the kinetic model s howed higher conversion. Starting with a glucose concentration of 150 g/L, it was possible to produce 73 g/L of L(+)-lactic acid in 44.5 h. The lactic acid yield was 64.8% by weight based on the amount of gluco se consumed.