Membrane-Based Dehydration of N-Methyl-2-Pyrrolidone-Contaminated Wastewater: Experimental and Techno-Economic Analysis

Abstract

N-methyl-2-pyrrolidone (NMP), widely used in polymeric membrane production, generates over 50 billion liters of contaminated wastewater annually, posing major environmental and regulatory challenges. Because solvent substitution is often impractical, reducing wastewater volume through dehydration is an attractive option. This study compares three membrane-based technologies, nanofiltration/reverse osmosis (NF/RO), pervaporation (PV), and membrane distillation (MD), for dehydrating aqueous mixtures of NMP and glycerol representative of industrial effluents. Tight NF/RO membranes (AFC80 and AFC99) quickly lost flux and rejection at higher solvent contents, limiting use to initial concentration steps at high water fractions. Pervaporation with an S-3011 membrane achieved 20-30 kg m(-2) h(-1) flux and 90.4% water recovery, while membrane distillation with a PE membrane yielded 10-15 kg m(-2) h(-1) flux and up to 83.7% recovery. Technoeconomic analysis showed that membrane distillation and, to a lesser extent, pervaporation outperform conventional thermal treatment processes. Membrane distillation cut costs by up to 63% compared to distillation, driven by low-cost membranes and simple operation. Overall, pervaporation and membrane distillation offer efficient and cost-effective options for NMP wastewater dehydration.