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Hemodialysis is one of the therapies for patients with kidney failure. Hemodialysis requires large amounts of pure water, and is one of the most water-hungry medical procedures, and thus represents a clear opportunity where improvements should be made concerning the consumption and wastage of water. In this paper, we explored the potential of forward osmosis (FO) membrane for recycling the spent dialysate using the dialysis concentrate as the draw solution. Partially diluted dialysis concentrate could be further diluted with pure water to form dialysate for further dialysis process. Using commercial cellulose triacetate (CTA) FO membranes, the water recovery of approximately 64% was achieved and the final volume of the partially diluted dialysis concentrate was about four times the initial volume. Flux decline of the FO process was observed, mainly due to concentration of synthetic spent dialysate and dilution of dialysis concentrate, while membrane scaling had little impact on the flux decline. The urea rejection was found to be relatively low owing to the small size and electroneutral nature of the urea molecule. Obvious membrane scaling was observed after three FO cycles. The energy dispersive spectroscopy analysis of the scaling layer indicated that the scalants were phosphates and carbonates. The scaling was removed via osmotic backwash and almost completely recovery of FO flux was obtained. Economic analysis showed that the centralized treatment of spent dialysate in a dialysis center using the proposed osmotic dilution process could greatly save water resources and cost. Improving the urea rejection of FO membrane was identified as an important research focus for future research on the potential application of FO technology for recycling the spent dialysate in hemodialysis. Image 1 • Osmotic dilution was used for recycling spent dialysate of hemodialysis. • Decrease in osmotic pressure gradient mainly led to flux decline. • Membrane scaling occurred, but was cleaned by osmotic backwash. • Urea rejection of the FO membrane should be improved. • Centralized treatment of spent dialysate by FO could greatly save water resources and cost. [ABSTRACT FROM AUTHOR]

• 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]