Optimization of a biosorption column performance

The dynamics of copper and zinc biosorption by Sargassum fluitans was analyzed under variable column operating conditions including different column lengths (15 and 45 cm), metal-feed solution concentrations (1 and 6 meq L(-1)), metal-sorbent affinities (2.01 and 0.45), and interstitial velocities (12 and 4 cm min(-1)). The experimental breakthrough curves obtained under these varying conditions were also simulated using a mathematical model taking into account the mass transfer as well as the axial dispersion phenomena. The column performance was evaluated using two performance indicators: the service time (t(s)) and the unused portion of the column as reflected in the area under the breakthrough curve (A(c)). Sensitivity analysis results indicated that the feed stream concentration, mass transfer coefficient, column length, and interstitial velocity had the most important effect on the column performance. Applying chromatography theories, the optimization of the biosorption process for productivity and sorption performance, in terms of operating conditions (interstitial velocity) and design parameters (column length), was outlined. The corresponding optimum curve relating the interstitial velocity and the column length resulted with the pressure drop limitations recognized. As an example, a laboratory column 100 cm long will necessitate an interstitial velocity of 19 cm min(-1) to yield the best sorption results.