This study compares the performance of nanofiltration (NF) and reverse osmosis (RO) for the reclamation of ultrafiltered municipal wastewater for irrigation of food crops. RO and NF technologies were evaluated at different applied pressures; the performance of each technology was evaluated in terms of water flux, recovery rate, specific energy consumption and quality of permeate. It was found that the permeate from the reverse osmosis (RO) process complied with Food and Agriculture Organization (FAO) standards at pressures applied between 10 and 18 bar. At an applied pressure of 20 bar, the permeate quality did not comply with irrigation water standards in terms of chloride, sodium and calcium concentration. It was found that nanofiltration process was not suitable for the reclamation of wastewater as the concentration of chloride, sodium and calcium exceeded the allowable limits at all applied pressures. In the reverse osmosis process, the highest recovery rate was 36%, which was achieved at a pressure of 16 bar. The specific energy consumption at this applied pressure was 0.56 kWh/m3. The lowest specific energy of 0.46 kWh/m3 was achieved at an applied pressure of 12 bar with a water recovery rate of 32.7%.
Forward Osmosis (FO) is one of the promising technologies that can be used to combat growing water scarcity. However, FO membrane fouling hinders the widespread application of this technology by significantly reducing the water flux and membrane lifecycle. Although forward osmosis has shown lower membrane fouling when compared to other membrane technologies, forward osmosis membrane resistance to fouling must still be improved. In this study, Ti3C2Tx (MXene) was used to improve the fouling resistance of FO flat-thin film membranes. The mixed-matrix Ti3C2Tx (MXene)/ cellulose acetate (CA) membranes with different (wt%) loading of MXene were fabricated by covalent crosslinking followed by phase inversion method.The fabricated membranes were characterized by X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), contact angle measurement and scanning electron microscopy (SEM). The performance of the fabricated FO membranes was evaluated utilizing seawater as draw solution (DS) and two feed solutions (FS) namely; distilled water (DI) and treated sewage effluent (TSE). The water flux, reverse solute flux and the rejection of dissolved solids were evaluated in the FO process. It was observed that the cross-linked cellulose acetate membrane with 8 wt% MXene (CCAM-8%) showed higher resistance to fouling when compared with commercial thin-film iv composite (TFC) FO membrane, the water flux of CCAM-8% decreased by only 10.7% using TSE as FS compared to DI, where the water flux of the TFC commercial membrane decreased by 32.2% when using TSE as FS compared to DI.
v DEDICATIONThis work is dedicated to my parents. Also, to my friends who supported me.
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