Saving energy consumption and CO2 emission from sustainable efficient operating zones in inland electrodialysis reversal desalination

•System efficiency (SE) was validated in brackish water desalination.•SE was updated with water recovery rate through cell pairs (WRRTC) >0.5.•The safe efficient operation polarization degree (PD) was 600–1359 (A/m2) (L/eq).•The efficient demineralization (D) and WRRTC were 42.5–74.5% and 0.56–0.66.•8–15% of energy can be saved by operating EDR in this range of WRRTC, PD, and D.

A pre-design parameter, system efficiency (SE) was modeled for operations with water recovery rate through cell pairs (WRRTC)>0.5. The variables for equation were validated with data from a pilot scale study of electrodialysis reversal (EDR). The correlation between experimental and predicted SE are good at overall R2 0.924 with significant p 0.000. System efficiency-to-polarization degree ratio is inversely linear with demineralization, WRRTC, and polarization degree (PD). The most sensitive operational parameter was found to be PD. The sustainable efficient zones for PD, WRRTC, and demineralization were found to be 1040–1315 (A/m2) (L/eq), 0.57–0.67, and 62–90%. By operating EDR in this zone, 8–15% of energy consumption and CO2 emission were saved.