Enhanced remediation of black-odorous water using microalgae synergized with titanate nanotubes

Research on microalgae for wastewater treatment is extensive, and numerous emerging nanomaterials demonstrate excellent pollutant removal capabilities. However, the synergistic effects of combining these approaches for remediating black-odorous water have not been extensively studied. This study integrated titanate nanotubes (TNTs) with Chlorella vulgaris andScenedesmus quadricauda to treat artificially simulated black-odorous water. The growth, physiological status of the microalgae, and pollutant removal efficiencies were analyzed. Results indicate that TNTs(tested at 5–50 mg/L) enhanced the growth of Chlorella vulgarisbut inhibited Scenedesmus quadricauda. The synergistic action of TNTs and microalgae significantly improved the removal efficiencies of NH₄⁺-N and TN. Specifically, the C. vulgaris + TNTs system increased the removal of NH₄⁺-N and TN by approximately 15.9%and 17.2%, respectively, at optimal concentrations, while the S. quadricauda + TNTs system achieved removal rates exceeding 98% for both pollutants, representing more pronounced enhancements. Raman spectroscopy analysis revealed that TNTs promoted theproduction of photosynthetic pigments and proteins in microalgae. The observed synergy primarily stems from the combined roles of TNTs in adsorbing pollutants and stimulating microalgal metabolic assimilation. Furthermore, microbial community analysis indicated distinct differences between the control and TNT-treated groups, with TNTs inhibiting Deinococcus and Pseudomonas while promoting Flavobacterium and Porphyrobacter. It should be noted that this study employed simulated wastewater, which may not fully replicate the complexity of actual black-odorous water bodies. This study provides novel insights and data supporting new strategies for black-odorous water remediation.