Optimal glycine betaine threshold for enhancing partial denitrification-anammox performance under carbon starvation:
Jing Chen1, Xinyu Long1, Lei Zhu2
1Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha 410114,China.
Abstract:
Partial denitrification-anammox (PD-A) systems under carbon-limited conditions (COD/NO3--N = 2.0) face severe nitrogen removal efficiency (TNRE) reduction. This study demonstrates that a critical glycine betaine (GB) concentration of 0.10 mM optimally enhances TNRE to 82.0% (±4.1%). This enhancement is achieved by simultaneously stimulating partial denitrifiers (OLB8 increased to 44.8%) and maintaining anaerobic ammonium-oxidizing bacteria (AnAOB) activity (Candidatus Kuenenia at 2.7%), further supported by favorable extracellular polymeric substances (EPS) shifts that improve nutrient transport. In contrast, excessive GB (0.20 mM) triggers competition from heterotrophic denitrifiers, reducing TNRE to 73.6% (±3.7%). Crucially, the system exhibits rapid resilience: upon GB withdrawal and COD/NO3--N adjustment to 2.5, TNRE recovers to 83% within 30 cycles (λ = 28 h), as quantified by Baranyi kinetics. These findings establish 0.10 mM as the optimal GB threshold for PD-A system optimization and prove its inhibitory effects are fully reversible, providing a novel and carbon-efficient strategy for wastewater treatment.
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