Unlocking long-term hypersalinity stress in nitrite-dependent sulfide-based autotrophic denitrification process:
Kaiyu Zhang1, Xin Zhang1, Fangjian Xu1
1Zhejiang Key Laboratory of Solid Waste Pollution Control and Resource Utilization, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, China.
None:
Sulfur-based autotrophic denitrification offers a carbon-neutral solution for nitrogen removal, yet hypersalinity severely challenges its application. This study investigates the failure mechanisms of a nitrite-dependent sulfide autotrophic denitrification (NiSAD) process under 5.14 % salinity and evaluates glutamate-driven recovery. Under hypersaline stress, nitrite removal efficiency collapsed to 22.21 % ± 5.52 %, driven by synergistic osmotic stress (granular sludge disintegration, SVI increase to 13.57 mL/g) and ion toxicity (ROS surge to 524.99 %, ATP decline to 1.05 mg/g SS). Key functional genera Sulfurovum and Thiobacillus decreased by 27.77 % and 68.00 %, respectively, while stochastic assembly dominated community dynamics (normalized stochasticity ratio (NST) > 50 %). Glutamate supplementation (1 mmol/L) restored nitrite and sulfide removal to 47.30 % and 77.28 % respectively, via antioxidant-mediated ROS reduction (406.62 %) and ATP recovery (1.19 mg/g SS); Molecular ecological network analysis and community assembly mechanism studies demonstrated that glutamate supplementation promoted mutualistic interactions among key microorganisms and shifted the community assembly process from stochastic to deterministic.
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