Modeling and simulation of the adsorption of biogas hydrogen sulfide on treated sewage–sludge

•The dynamic behavior of a fixed bed with treated sewage–sludge for H2S removal is modeled.•The Bohart and Adams model does not predict suitably the complete breakthrough curves.•The Klinkenberg solution implies a linear isotherm, and the prediction is not good enough.•The LDF model with a non-linear isotherm provides a good approach of the adsorption process.•As an application, a scale-up of the lab scale to a larger one was performed and assessed.

For the design of a fixed-bed adsorber, it is essential to know the prediction of the column breakthrough. This paper compares two modeling approaches of the dynamic behavior of a fixed bed that contains treated sewage–sludge for biogas desulfurization. The first approach is based on the simple model by Bohart and Adams, which has been widely used to describe the adsorption dynamics when chemical reaction takes place, and the second one uses the linear driving force model (LDF), solving it analytically by Klinkenberg equation and numerically with the aid of Aspen Adsorption. While the Bohart–Adams model uses rectangular isotherm to describe the equilibrium, the LDF model is solved with a more realistic and suitable isotherm. The Klinkenberg solution implies a linear isotherm, and the prediction is not good enough, although better than that of the approach of Bohart–Adams. The trouble is that the linear isotherm used in the analytical solution is not realistic and a nonlinear isotherm is required. This paper presents a methodology to estimate the overall mass transfer coefficient dynamically as well as the isotherm that best fits. Thus, the LDF model with the Freundlich isotherm provide a breakthrough curve that match the experimental results much better than the Bohart–Adams approach. In order to apply the prediction obtained, a scaling up of the lab scale was performed, discussed and assessed.