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• A novel process for the treatment of N ,N- dimethylformamide (DMF) wastewater was proposed. • Chloroform was selected for the extraction of DMF in the wastewater. • Kerosene was used to extract the dissolved chloroform in the raffinate. • High purity DMF could be recovered and the water quality improved greatly after treatment. • Total annual cost of the novel process is significantly lower than conventional distillation. 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. [ABSTRACT FROM AUTHOR]

Hemodialysis consumes significant amounts of pure water and produces large amounts of spent dialysate. Recovering water from spent dialysate is a new attempt in medical industries to save water and costs. The recent proposal of using forward osmosis (FO) to concentrate the spent dialysate showed economic viability. However, there is still one key concern of potentially extended hemodialysis duration because commercial FO membranes have limited urea rejection, which would reduce the urea concentration gradient during hemodialysis. In this paper, a model was developed to quantify the effect of incomplete urea rejection in FO on subsequent hemodialysis duration. The impacts of average urea rejection, water recovery, and the number of hemodialysis sessions were systematically analyzed. Counter-intuitively, the results indicated that relatively low urea rejection of FO membranes actually has little impact on hemodialysis duration. Low urea concentration in the spent dialysate, partial urea rejection by the FO membrane, and further dilution of pre-diluted dialysis concentrate, largely reduces this impact. The result further supports the viability of FO in spent dialysate reuse. Although FO membrane with 100% rejection is expected, the present work indicates that commercial FO membranes with a low rejection of neutral matters are of practical utility in certain applications. • Osmotic dilution was used for recycling spent dialysate of hemodialysis. • A model was developed to evaluate the effect of several factors in the osmotic dilution on the hemodialysis duration. • A relatively low urea rejection of an FO membrane has a minor impact on the subsequent hemodialysis duration. • The reasons for the counter-intuitive result in recycling the spent dialysate by FO were revealed. [ABSTRACT FROM AUTHOR]