Energetic and economic feasibility of a combined membrane-based process for sustainable water and energy systems

The water-energy nexus has received a surge of attention recently in the research community as the security of water and energy is becoming a focal concern amongst future uncertainties. Providing innovative technologies that assure water, energy, and food security is thus becoming crucial. In this study, a potential solution is introduced, a membrane-based process that combines seawater reverse osmosis (SWRO), nanofiltration (NF), and pressure retarded osmosis (PRO) to produce drinking water, energy, and water for irrigation. Firstly, an energetic study was performed to evaluate the performance of this process. The analysis of the total energy consumption showed a compelling amount of generated energy (similar to 0.38 kWh/m(3)). Secondly, a techno-economic study was realized to investigate the economic viability of the process. We found that, with membranes priced at $5/m(2), the system is economically feasible with the actual PRO membrane performance. An improvement of membrane performance is required when the membrane price is above $15/m(2). The effect of the plant capacity was also investigated. Results showed an improvement on the economics of the process with increased input flows. Finally, the effect of membrane fouling was investigated on the feasibility of the SWRO-PRO-NF process. It was shown that fouling has a drastic impact on the performance, and, thus, economic feasibility of the reported process. Recommendations are enumerated to improve the performance of SWRO-PRO-NF and to mitigate the impact of membrane fouling such optimization of pretreatment and introducing advanced antifouling membrane materials.