Organic Fouling Behavior and Mitigation Strategies in Pressure-Driven Distillation

Pressure-driven distillation (PD) is a membrane-based water treatment process that uses applied pressure to drive vapor transport through a porous hydrophobic membrane. PD offers potential advantages in selectivity and chemical resilience, but its performance with feedwaters containing foulants remains poorly understood. In this study, we examine the organic fouling behavior of PD, isolate the effect of pressure on flux decline, and explore potential fouling mitigation strategies. We find the severity of organic fouling is highly dependent on foulant properties, with more hydrophobic humic acid causing the most severe flux decline and bovine serum albumin proteins causing moderate fouling. Sodium alginate, a hydrophilic gel-forming polysaccharide, showed the least severe fouling despite higher surface coverage. Even after severe flux decline, PD membranes do not show signs of wetting or a loss of rejection. We find that the applied pressure in PD exacerbates fouling by comparing performance in PD to osmotic distillation, an unpressurized analogous process. Finally, we evaluate two fouling mitigation strategies: cleaning with sodium hydroxide, which restores nearly full flux, and continuous direct ozonation, which partially suppresses fouling. Overall, this work provides insights into organic fouling behavior in PD and demonstrates effective fouling mitigation strategies.