Environmental and economic impacts of the fertilizer drawn forward osmosis (FDFO) and nanofiltration (NF) hybrid system were conducted and compared with conventional reverse osmosis (RO) hybrid scenarios using microfiltration (MF) or ultrafiltration (UF) as a pre-treatment process. The results showed that the FDFO-NF hybrid system using thin film composite forward osmosis (TFC) FO membrane has less environmental impact than conventional RO hybrid systems due to lower consumption of energy and cleaning chemicals. The energy requirement for the treatment of mine impaired water by the FDFO-NF hybrid system was 1.08 kWh/m, which is 13.6% less energy than an MF-RO and 21% less than UF-RO under similar initial feed solution. In a closed-loop system, the FDFO-NF hybrid system using a TFC FO membrane with an optimum NF recovery rate of 84% had the lowest unit operating expenditure of AUD $0.41/m. Besides, given the current relatively high price and low flux performance of the cellulose triacetate and TFC FO membranes, the FDFO-NF hybrid system still holds opportunities to reduce operating expenditure further. Optimizing NF recovery rates and improving the water flux of the membrane would decrease the unit OPEX costs, although the TFC FO membrane would be less sensitive to this effect.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Funding for this research was also provided by Industrial Facilities & Infrastructure Research Program (grant number 17IFIP-B088091-04) by Ministry of Land, Infrastructure and Transport of Korean Government, King Abdullah University of Science and Technology (KAUST), Saudi Arabia, National Centre for Excellence in Desalination Australia (NCEDA), ARC Future Fellowship (grant number FT140101208) and University of Technology Sydney (UTS) Chancellor's postdoctoral research fellowship.