Economic and Environmental Assessment of a Novel Integrated Three-Column Extractive Distillation Process for Recycling Organics from Wastewater

Abstract

For diluted wastewater with azeotropes discharged from chemical plants, it is important to design a sustainable extractive distillation process to achieve efficient separation. By separating the dilute wastewater containing isopropanol and acetonitrile, it is proved that the four-column extractive distillation processes with a preconcentration column and a novel three-column process containing an integrated column with preconcentration and solvent recovery function can achieve energy conservation and cost reduction. At the same time, heat integration and heat pump-assisted technologies were further used to intensify the proposed processes. The proposed processes are evaluated in terms of economy, energy consumption, and CO2 emissions. The results display that the double heat pump-assisted extractive distillation process can obtain 75.10% energy saving and the heat integration of the extractive distillation process with a preheater can save 69.45% cost, compared with the conventional extractive distillation process.