Mild Tuning of the Microbial Habitat via Titanium-Based Pre-coagulation Mitigates Reverse Osmosis Membrane Fouling

Membrane fouling remains a persistent challenge in reverse osmosis (RO) systems. Devising effective strategies to mitigate membrane fouling has become crucial for sustainable water treatment. Here, we propose a titanium-based pre-coagulation strategy for RO fouling mitigation through regulation of the microbial habitat in RO feed. The pre-coagulation performance of Ti(SO 4 ) 2 for desulfurization wastewater and the subsequent RO fouling mechanism were systematically investigated. Our findings revealed that the Ti pre-coagulation induced an acidized environment, maintained a balance between organic and inorganic depositions, and fostered a beneficial microbial community that resisted rapid fouling. The 20 day RO operations in different pre-coagulation scenarios (Ti, Al, and Ctrl) showed that the Ti group membranes maintained the highest normalized flux at 57.15%, outperforming the Ctrl and Al groups by 7.92% and 15.16%, respectively. Microbial community analyses, including taxonomic profiling and metagenomic analysis, demonstrated that Ti-based pre-coagulation reduced the dominance of extracellular polymeric substance (EPS)-secreting genera, such as Sphingopyxis, while promoting Terrimonas and Paenarthrobacter, with acid-tolerance traits and reduced EPS production. This shift mitigated biofouling by enhancing microbial balance and limiting biofilm formation. These results underscored the potential of the Ti pre-coagulation-based microbial habitat tuning strategy in enhancing RO system sustainability, offering a practical solution for improving industrial wastewater treatment.