The study is focused on modeling of separation process and optimization. An adsorption separation process is simulated. The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory. The adsorption column achieves high surfactin recovery (94%) by up-flow methanol elution at 25 degrees C. The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium, based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed. The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428x10(-5) cm(2).S-1 by molecular dynamics simulation. The model developed can describe the complex interplay of adsorption kinetics, fluid dynamics, and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients, and is of adequate precision. The work involved in this paper is valuable for the optimization of the production process of surfactin.