Novel low cost hybrid extraction-distillation-reverse osmosis process for complete removal of N,N-dimethylformamide from industrial wastewater

Toxic N,N-dimethylformamide (DMF) is extensively used as a versatile solvent in various processes and thus released in large quantities in many industrial effluents. Low degradability requires effective treatment of DMF wastewater. A novel process combining extraction, distillation, and reverse osmosis (RO) was proposed. After screening, chloroform was selected as the solvent for DMF extraction. The extraction process conditions, namely phase ratio and the number of counter-current theoretical stages were determined by calculation and batch simulation. Kerosene was then used for the extraction of the dissolved chloroform in the wastewater after DMF extraction. The distillation columns for the separation and recovery of DMF and extractants were designed by Aspen Plus. The simulation results showed that more than 99.8% of DMF could be recovered with a purity of 99%. The salinity of the wastewater was reduced to a much lower level through RO process, and the quality of the wastewater improved greatly. Economic analysis showed that a significant reduction of 72.74% in the total annual cost (TAC) can be obtained by using the proposed process. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.