Analysis and optimization of continuous organic solvent nanofiltration by membrane cascade for pharmaceutical separation

The major part of the production costs of pharmaceuticals can be imputed to the downstream processing, where membrane technologies have to deal with some challenges as separations involving solutes with similar sizes or solvent recovery and recycling. This work contributes to the progress in the design of continuous organic solvent nanofiltration systems for this purpose and includes the configuration of dual membrane cascades, sensitivity analysis of the operation variables, and economic optimization as innovations. Analyzed configurations include multistage cascades up to three stages, and dual membrane cascades up to five stages. The total costs (TC) were chosen as the formulated objective function to minimize in the economic optimization strategy. The treatment of the residual stream leaving the system resulted the main cost of the process (more than 85% for dual cascades), but the solvent recovery units can significantly reduce the TC (64–77% depending on the required solvent quality). © 2014 American Institute of Chemical Engineers AIChE J, 60: 931–948, 2014