Modelling of fixed bed biosorption columns in continuous metal ion removal processes. The case of single solute local equilibrium

摘要

A modelling approach for a fixed bed biosorption column is presented. The developed model includes the solute bulk movement through the void space of the bed, a solute dispersion term for simulating cases of non ideal flow, and sorption terms expressed by the appropriate sorption isotherm. The main assumption of the model is that biosorption equilibrium is rapid and no transfer resistances exist in the liquid and solid phase. The resulting second order non-linear partial differential equation describes the performance of a column fined with biosorbent material and used to remove single solute metal ions from dilute solutions. The model predicts the optimum expected operation of the bed by simulating breakthrough and concentration profile curves, under different operating conditions. Sensitivity analysis of the operating parameters, revealed that the most important of them are the sorption capacity and the sorption intensity of the biosorbent material as these terms are expressed through the Freundlich's isotherm coefficients.