Use of sponge iron as an indirect electron donor to provide ferrous iron for nitrate-dependent ferrous oxidation processes: Denitrification performance and mechanism

Peng Wang; Wenxuan Li; Shuang Ren; Yuzhuo Peng; Yaning Wang; Muyu Feng; Kehuan Guo; Huina Xie; Jie Li

doi:10.1016/j.biortech.2022.127318

Use of sponge iron as an indirect electron donor to provide ferrous iron for nitrate-dependent ferrous oxidation processes: Denitrification performance and mechanism

Bioresour Technol. 2022 Aug:357:127318. doi: 10.1016/j.biortech.2022.127318. Epub 2022 May 21.

Authors

Peng Wang¹, Wenxuan Li², Shuang Ren¹, Yuzhuo Peng¹, Yaning Wang¹, Muyu Feng¹, Kehuan Guo³, Huina Xie¹, Jie Li⁴

Affiliations

¹ College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
³ Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100123, PR China.
⁴ College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China; Gansu Membrane Science and Technology Research Institute Co., Ltd., Lanzhou 730020, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Lanzhou 730020, China. Electronic address: wye@mail.lzjtu.cn.

PMID: 35609754
DOI: 10.1016/j.biortech.2022.127318

Abstract

Sponge iron (SI) can serve as an indirect electron donor to provide Fe(II) for the nitrate-dependent ferrous oxidation (NDFO) process, producing OH^- and magnetite. The SI-NDFO system mainly uses Fe(OH)₂ as an electron donor, achieving a TN reduction rate of 0.42 mg-TN/(gVSS·h) for a period of at least 90 days. The enrichment of iron-oxidizing bacteria and the competition of iron-carbon micro-electrolysis for reaction sites on the surface of SI are the main reasons for the improvement of total nitrogen removal efficiency (TNRE). With an influent NO₃^--N concentration of 50 mg/L and a SI concentration of 50 g/L (at pH 5.0 and 30 °C), the TNRE reached a maximum level of 38.28%. In addition, reducing the pH environment was found to improve the denitrification efficiency of the SI-NDFO system, although denitrification stability was also reduced as a result. Overall, the SI-mediated NDFO process is a promising technique.

Keywords: Microbial community; NDFO; Nitrate removal; Sponge iron.

MeSH terms

Bioreactors
Denitrification*
Electrons
Ferrous Compounds
Iron
Nitrates*
Nitrogen
Nitrogen Oxides
Oxidation-Reduction

Substances

Ferrous Compounds
Nitrates
Nitrogen Oxides
Iron
Nitrogen