Embodied water consumption between typical desalination projects: Reverse osmosis versus low-temperature multi-effect distillation

Abstract

At present, there are more than 20 kinds of seawater desalination technologies utilized worldwide including Reverse Osmosis and Low-Temperature Multi-effect Distillation. To compare the embodied water consumption of the main seawater desalination technologies, this study assesses the water consumption of Reverse Osmosis and Low-Temperature Multi-effect Distillation desalination projects in China based on the system analysis method. Taking full account of the direct and indirect water consumption in the desalination projects, the embodied water consumption of the Reverse Osmosis desalination project is 3.96E+04 m3 in the construction stage, whereas that of the Low-Temperature Multi-effect Distillation project is 7.22E+05 m3 at the same daily water production capacity. In the operation stage, the Low-Temperature Multi-effect Distillation process has the potential to utilize waste heat generated by the thermal power plant for hydropower cogeneration, while the Reverse Osmosis process requires regular maintenance and replacement of reverse osmosis membranes. With respect to the embodied water consumption, the Reverse Osmosis desalination project presents more advantages than the Low-Temperature Multi-effect Distillation desalination project in terms of water savings and economic costs during the construction stage, but relevant departments should also take actual local requirements and water resources conditions into consideration. On the basis of providing comparisons between different projects, this study attempts to play a vital role in the rational allocation of desalination projects, the promotion of reasonable water-saving policies, and sustainable economic and social development from a macro perspective.