Enhanced denitrification performance of strain YSF15 by different molecular weight of humic acid: Mechanism based on the biological products and activity

• Published in: Bioresource technology Vol. 325; p. 124709
• Main Authors: Zhang, Shuai, Su, Junfeng, Ali, Amjad, Zheng, Zhijie, Sun, Yi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-04-2021
• Subjects: Biological Products; Bioreactors; Denitrification; Electron shuttle; Humic acid; Humic Substances; Low C/N ratio; Molecular Weight; Nitrates; Nitrogen - analysis; Denitrification; Humic acid; Low C/N ratio; Molecular weight; Electron shuttle
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2021.124709

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•MW < 3 kDa in HA had better denitrification facilitation in low C/N and nitrate load.•Endogenous HA and compact protein structure were facilitated by WM < 3 kDa.•Each HA fraction increased the bio-product and bioactivity of strain YSF15.•More nitrogen was utilized via assimilation affected by each HA fraction.
This study aimed to clarify the facilitation by humic acid (HA) fractions (>100, 100–50, 50–30, 30–10, 10–3 and < 3 kDa), as well as their variable effect on denitrification of strain YSF15 under low carbon–nitrogen ratio and nitrate conditions. All HA fractions with 7 mg L−1 were able to accelerate nitrate removal by strain YSF15 and the role of carbon source was inconspicuous. The molecular weight (MW) < 3 kDa was the best promoter for denitrification, with the efficiency (91.32%) far exceeding the control (43.27%), resulting in more stable oxidation–reduction potential, higher nutrients utilization and electron transport activity, more compact protein structure in extracellular polymeric substances and the production of endogenous HA. Each HA fraction could change the bio-products and denitrification activity of strain YSF15. This study sheds light on the facilitation of HA in denitrification from the perspective of MW, implying the potential effect of HA on denitrifying bacteria in community.