Thesis (M.Eng.)--Chulalongkorn University, 2006

In this research, the dynamic optimization of a fed-batch reactor with multiple feeds is studied. The production of lactic acid form the simultaneous saccharification and fermentation (SSF) process of starch is chosen as a case study. The optimization of a process involves the determination of the optimal feed rate of two substrates: starch and glucose. The simultaneous model solution and optimization approach is employed to solve the formulated dynamic optimization problem with an objective to maximize the production rate of lactic acid at the end of operation. Simulation results show that under the optimal operation and the fixed operating time of the fed-batch reactor, the lactic acid production through the SSF process with two feeds of starch and glucose is improved by comparison to that with single feed of starch. In addition, the effect of the operating time on the lactic acid production from the SSF process with two feeds of starch and glucose is analyzed. The result demonstrates that there is a minimum time for obtaining the maximum production of lactic acid.