Techno-economic assessment of electrodialysis and reverse osmosis desalination plants

Abstract

• Economics of electrodialysis and reverse osmosis desalination plants are compared. • The specific water cost consists of all the elements of capital and operation aspects. • Sensitivity analysis identified the most influential parameters impacting the cost model. • ED is found economically feasible when salinity is less than 9 ppt compared to RO. • Highly saline water can be desalinated with ED at about 5 $/m 3 for a salinity <100 ppt. Assessment of desalination plants is essential to evaluate potable water production, energy consumption, and economic feasibility. A design model with a boundary layer effect, water transport effect, spacer effect, and Donnan potential was used for ED desalination. Similarly, a design model is also investigated for RO desalination with and without a pressure energy recovery device. Specific product water cost is evaluated based on annual expenses consisting of energy cost, fixed cost, labor cost, membrane replacement cost, maintenance cost, chemical cost, and insurance cost. Normalized sensitivity analysis is also conducted to identify the most influential parameters impacting the cost model. It is found that ED is economically feasible when salinity is less than 7 and 9 ppt compared to RO with and without PX, respectively. The product water cost is 0.384, 0.46, and 0.494 $/m 3 for ED, RO with PX, and RO without PX, respectively, at a salinity of 5 ppt (e.g., groundwater salinity). The product water cost increases to be 1.532, 0.559, and 0.857 $/m 3 for ED, RO with PX, and RO without PX, respectively, at a feed salinity of 35 ppt (e.g., seawater salinity). Also, highly saline water can be desalinated with ED at the cost of <5 $/m 3 for a salinity <100 ppt.