Overcoming salinity inhibition in biological wastewater treatment: AHLs synchronize aniline mineralization and nitrogen removal.
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75% confidenceThis MEC study investigates AHLs, Aniline, Biological nitrogen removal. The research focuses on system optimization and characterization.
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Abstract
High-salinity nitrogenous organic industrial wastewater poses a severe threat to microbial activity due to its extreme osmolarity and complex composition, often causing catastrophic failure of biological nitrogen removal systems. This study presents a novel strategy employing AHL-based quorum sensing to systematically mitigate salinity inhibition, achieving dual enhancement of complex organic nitrogen mineralization and inorganic nitrogen removal. The AHL 3-oxo-C6-HSL was identified as the most effective compound, promoting ammonia oxidation and minimizing nitrite accumulation under salinity stress. In SBR systems, 3-oxo-C6-HSL accelerated the completion of nitrification under 5 % salinity within 5 days, compared to 18 days in the control, and achieved a TN removal rate of 79.46 % under 8 % salinity, which was significantly higher than that of other AHLs. In the biological aerated filter, the addition of 3-oxo-C6-HSL enabled the system to maintain high stability and efficiency even at 8 % salinity. This enhancement was evidenced by a 37.87 % reduction in nitrite accumulation compared to the control, 99 % aniline degradation within 5 days, and the concurrent removal of 95 % COD and 80 % TN under saline conditions. Mechanistic analysis revealed that 3-oxo-C6-HSL activated microbial quorum sensing, thereby enhancing metabolic activity and salinity-tolerant defense mechanisms. Additionally, it facilitated the formation of a denser and more stable biofilm structure. Omics analysis further revealed that AHLs significantly enriched key aniline degraders, such as Azoarcus, systematically activating multiple rate-limiting enzymes within both the aniline degradation pathway and the inorganic nitrogen conversion cycle. This research presents an innovative and efficient microbial communication strategy for the biotreatment of high-salinity, nitrogenous organic wastewater, thereby expanding the understanding of biological nitrogen removal under extreme environmental stress.