化学
反硝化
锌
亚硝酸盐
硝酸盐
无机化学
硝酸锌
亚硝酸盐还原酶
硫黄
硝酸还原酶
腐植酸
电子转移
胞外聚合物
核化学
氮气
有机化学
生物膜
生物
细菌
遗传学
肥料
作者
Wen-Jie Ma,Zi-Shang Ma,Hanmin Zhang
标识
DOI:10.1016/j.scitotenv.2024.174269
摘要
Sulfur-driven autotrophic denitrification (SAD) process is a cost-effective and sustainable method for nitrogen removal from wastewater. However, a higher concentration of zinc ions (Zn(II)) flowing into wastewater treatment plants poses a potential threat to the SAD process. This study examined that a half maximal inhibitory concentration (IC50) of Zn(II) was 7 mg·L−1 in the SAD process. Additionally, the addition of 20 mg·L−1 Zn(II) resulted in a severe accumulation of nitrite to 150.20 ± 6.00 mg·L−1 when the initial concentration of nitrate was 500 mg·L−1. Moreover, the activities of nitrate reductase, nitrite reductase, dehydrogenase and electron transport system were significantly inhibited under Zn(II) stress. The addition of Zn(II) inhibited EPS secretion and worsened electrochemical properties. The result was attributed to the spontaneous binding between EPS and Zn(II), with a ΔG of −17.50 KJ·mol−1 and a binding constant of 1.77 × 104 M−1, respectively. Meanwhile, the protein, fulvic acid, and humic-like substances occurred static quenching after Zn(II) addition, with -OH and -C=O groups providing binding sites. The binding sequence was fulvic acid→protein→humic acid and -OH → -C=O. Zn(II) also reduced the content of α-helix, which was unfavorable for electron transfer. Additionally, the Zn(II) loosened protein structure, resulting in a 50 % decrease in α-helix/(β-sheet+random coil). This study reveals the effect of Zn(II) on the SAD process and enhances our understanding of EPS behavior under metal ions stress.
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