A hybrid forward osmosis (FO) and reverse osmosis (RO)/nanofiltration (NF) system in a closed-loop operation with selected draw solutes was evaluated to treat coal mine impaired water. This study provides an insight of selecting the most suitable draw solution (DS) by conducting environmental and economic life cycle assessment (LCA). Baseline environmental LCA showed that the dominant components to energy use and global warming are the DS recovery processes (i.e. RO or NF processes) and FO membrane materials, respectively. When considering the DS replenishment in FO, the contribution of chemical use to the overall global warming impact was significant for all hybrid systems. Furthermore, from an environmental perspective, the FO-NF hybrid system with Na2SO4 shows the lowest energy consumption and global warming with additional considerations of final product water quality and FO brine disposal. From an economic perspective, the FO-NF with Na2SO4 showed the lowest total operating cost due to its lower DS loss and relatively low solute cost. In a closed-loop system, FO-NF with NaCl and Na2SO4 had the lowest total water cost at optimum NF recovery rates of 90 and 95%, respectively. FO-NF with Na2SO4 had the lowest environmental and economic impacts. Overall, draw solute performances and cost in FO and recovery rate in RO/NF play a crucial role in determining the total water cost and environmental impact of FO hybrid systems in a closed-loop operation.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors acknowledge the financial support of the National Centre of Excellence in Desalination Australia which is funded by the Australian Government through the National Urban Water and Desalination Plan. Funding for this research was also provided by Industrial Facilities & Infrastructure Research Program (code 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 (FT140101208) and University of Technology Sydney chancellor's postdoctoral research fellowship.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.