Economic, Energy, Exergo-Economic, and Environmental Analyses and Multiobjective Optimization of Seawater Reverse Osmosis Desalination Systems with Boron Removal

We presented economic, energy, exergo-economic, and environmental analyses and multiobjective optimization (MOO) of seawater reverse osmosis (RO) desalination systems with boron restrictions. Exergo-economic unit cost for flows and exergy destruction for components were included. Life cycle assessment (LCA) principles with the contributions of construction and operating were introduced. An improved augmented epsilon-constraint method was adopted for solving the MOO problems. Unnecessary iterations were avoided by bypass parameter. Results showed that the Pareto-solution with a weighting of 0.4 could provide good performances for all objective functions. The CO2 emissions reduction of 9.0% could be achieved, while the water cost is increased by 3.3%. Fixed cost dominates EUC. The environmental impact of construction is neglectable, while electricity consumption accounts for the largest share of CO2 emissions from 93.4% to 97.8%. The details of energy utilization for components, the irreversibility, and equipment cost assigned to the streams are analyzed by using exergy and exergo-economic analyses. The overall emergy-based exergo-environmental performances of the systems are range between 81.5% and 84.6%. Both the component and exergy destruction related ecological emergy rates need to be improved.