Ultrafiltration membrane fouling of microalgae-derived intracellular organic matter exposed to pharmaceuticals and personal care products (PPCPs)

The frequent algae bloom induces the release of intracellular organic matter (IOM), which plays a significant role in the ultrafiltration (UF) process. The growth of algae is greatly impacted by the surrounding aquatic environment, including the pharmaceuticals and personal care products (PPCPs) due to their extensive use in the past decades. Thus, the release of IOM and the associated UF membrane performance are also affected by the PPCPs exposure. However, such studies have seldomly been reported before. In this study, the effects of two typical PPCPs (e.g., carbamazepine, CMZ and diclofenac sodium, DFC) exposure on the release of IOM and membrane filtration performance during UF of microalgae-laden water were systematically investigated. The results showed that when the microalgae were exposed to CMZ (0.25–100 μg/L), their produced IOM led to more irreversible fouling resistance (R_b), while the reversible fouling resistances (R_c) were reduced under low CMZ exposure (0.25 μg/L) but elevated at a high dosage of CMZ (> 1 μg/L). On the contrary, the exposure of DFC (0.25–1000 μg/L) caused a reduced R_b and an increased R_c. Further analysis revealed that R_b was positively correlated with the micromolecules released by microalgae, while the change of R_c was ascribed to the promoted/suppressed synthesis of macromolecules forming a cake layer. Nevertheless, reversible fouling played a primary role on IOM fouling development regardless of the exposure to CMZ and DFC. Our findings have significant implications for further identifying suitable fouling control strategies during UF of microalgae-laden water coexisting with PPCPs.