Reducing ultrafiltration membrane fouling during potable water reuse using pre-ozonation

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Materials Science

Background:

• Wastewater reclamation is crucial for potable water supply.
• Low-pressure membrane processes like ultrafiltration (UF) are vital but susceptible to fouling by effluent organic matter (EfOM).
• Understanding fouling mechanisms is key to optimizing membrane performance.

Purpose of the Study:

• To investigate the impact of pre-ozonation on UF membrane fouling caused by EfOM.
• To compare the effectiveness of pre-ozonation on hydrophilic regenerated cellulose (RC) and hydrophobic polyethersulfone (PES) membranes.
• To elucidate the mechanisms behind fouling reduction through pre-ozonation.

Main Methods:

• Pre-ozonation of secondary wastewater effluent followed by ultrafiltration.
• Systematic investigation of physicochemical property changes in EfOM.
• Application of classical pore blocking and extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theories.

Main Results:

• Pre-ozonation significantly reduced membrane fouling, with greater efficacy on hydrophilic RC membranes compared to hydrophobic PES membranes.
• Ozone treatment degraded macromolecules in EfOM into smaller, more hydrophilic fractions.
• Interfacial properties between foulants and membranes were altered, increasing repulsion or decreasing attraction.

Conclusions:

• Pre-ozonation is an effective pre-treatment for mitigating UF membrane fouling by EfOM.
• The fouling alleviation mechanisms involve macromolecular degradation, enhanced foulant hydrophilicity, and modified interfacial interactions.
• Pre-ozonation prolongs the transition to cake filtration, reducing overall fouling in wastewater reclamation.