Sustainable and low-cost drinking water production via electrodialysis by addressing membrane fouling mechanisms to optimize cleaning strategies

Abstract

Groundwater is a vital water source, providing drinking water to at least 50% of the world's population and accounting for 43% of water used in irrigation. In Sri Lanka, 39.6% of the population rely on groundwater for drinking purposes, with 72% of this group residing in rural areas. In several of these regions, groundwater quality is affected by geogenic contaminants such as excessive fluoride, hardness, and salinity, which are linked to chronic health issues. These ion-related problems highlight the need for selective separation technologies, with electrodialysis (ED) emerging as a promising and sustainable option. However, membrane fouling and scaling remain significant challenges. This study aims to investigate the mechanisms of membrane fouling and scaling in ED systems and develop effective cleaning strategies to restore membrane performance. The fouling process involves two stages: organic fouling dominant in the initial stages, followed by inorganic scaling. Pearson correlation analysis revealed a strong negative correlation of −0.94 for organic fouling and −0.63 for inorganic fouling. A similar two-stage fouling behavior was also observed in a one-year field experiment conducted in Sri Lanka, further supporting these findings. An integrated acid–base cleaning method was developed, with acidic cleaning effectively removing inorganic scales and alkaline cleaning addressing organic fouling. The acid–base cleaning approach stands out as a sustainable solution to tackle fouling in ED systems, making it suitable for decentralized groundwater treatment in Sri Lanka.