Desalination Process Design Assisted by Osmotic Power for High Water Recovery and Low Energy Consumption

Membrane-based processes have been contributing greatly in tackling water scarcity issues. Besides, these processes are also being used in clean energy production, which makes membrane technology an important aspect in the water-energy nexus. The membrane-based reverse osmosis (RO) process is the most energy-efficient technology for seawater desalination. However, the energy consumption of RO desalination plants is still relatively high, and improvement in energy efficiency is needed. Pressure-retarded osmosis (PRO) has been investigated to reduce the energy consumption of seawater RO (SWRO) desalination. However, a simple integration of SWRO and PRO has not resulted in encouraging results. Hence, introducing a desalination process with high water recovery and low energy consumption seems to be a universal target. In this present work, we introduced a promising combined membrane-based process for producing both potable water and irrigation water, and energy utilizing seawater and treated wastewater effluents. Our integrated system provided high water productivity with low energy consumption. The energetic analysis of our combined process revealed that the specific energy consumption was around 1.4 kW h/m(3) with a total water recovery ratio of 88%. The results obtained using actual membrane performance, where the real dilution does not exceed 60% of the maximum theoretical dilution, showed promising economics. Finally, an economic analysis was carried out to evaluate the economic viability of the system. It was found that, with a water price of $0.6/m(3), the payback period is one year and the process shows a strong economic competitiveness in comparison with the conventional processes with a very short payback period and a strong competitiveness compared to other processes with equal production capacity. This result was confirmed with a high internal rate of return.