Techno-economic assessment of electrodialysis and reverse osmosis desalination plants

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 $/m3 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 $/m3 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 $/m3 for a salinity <100 ppt.

Automated summary

The study compares the economic costs of electrodialysis (ED) and reverse osmosis (RO) desalination methods, finding that under certain salinity conditions, ED has lower costs and is able to handle highly saline water. A sensitivity analysis is conducted to identify key parameters affecting cost variations.