In this study, we analyzed the characteristics of seawater raw water from the Pohang demonstration site and evaluated membrane fouling behavior to develop maintenance technologies for ultra-low energy SWRO processes. The seawater at the demonstration site exhibits high temporal variability due to seasonal and meteorological conditions. Comprehensive analysis including Dissolved Organic Matter (DOM), Excitation-Emission Matrix (EEM), and Particle Size Distribution (PSD) was conducted.EEM analysis revealed strong fluorescence peaks in areas corresponding to proteinaceous substances derived from microorganisms (Trp-like and Tyr-like), indicating that the DOM primarily originates from bacteria or microalgae rather than phytoplankton. These proteinaceous DOM components are known to be major precursors for biofilm formation on RO membrane surfaces. The average particle size of the raw water was 1.324 µm, and while 1 µm filtration can remove some particulate matter, PSD analysis confirmed a significant presence of sub-micron particles and bacteria-sized fractions (Table 1).

Table 1. Comparison of Pretreatment Efficiency and Membrane Fouling Indicators

To evaluate fouling potential, lab-scale SWRO experiments were conducted using four pretreatment conditions: Raw seawater, 1 µm filtered, 0.1 µm filtered (MF level), and 0.03 µm filtered (UF level) (Figure 1). The results showed a clear correlation [...]. Raw seawater exhibited the most [...] While 1 µm filtration mitigated fouling to some extent, it was insufficient to remove micro-colloids and proteinaceous DOM. The most effective fouling control was achieved with [...]