Enhanced denitrification driven by a novel iron-carbon coupled primary cell: chemical and mixotrophic denitrification

Ruofan Wu, Paramsothy Jeyakumar, Nanthi Bolan, Xu Zhai, Hailong Wang, Minghui Pan, Jiapan Lian, Liping Cheng, Jiangzhou Li, Minghei Hou, Yonghe Cui, Xiaoe Yang, Kuai Dai

Research output: Contribution to journalArticlepeer-review

Abstract

Iron-carbon micro-electrolysis system is a promising method for promoting electron transfer in nitrate removal. However, many traditional approaches involving simple physical mixing inevitably suffered from the confined iron-carbon contact area and short validity period, leading to the overuse of iron. Here, a ceramsite-loaded microscale zero-valent iron (mZVI) and acidified carbon (AC) coupled-galvanic cell (CMC) was designed to support chemical, autotrophic and heterotrophic denitrification. Long-term experiments were conducted to monitor the nitrogen removal performance of denitrification reactors filled with CMC and thus optimized the denitrification performance by improving fabrication parameters and various operating conditions. The denitrification contributions test showed that the chemical denitrification pathway contributed most to nitrate removal (57.3%), followed by autotrophic (24.6%) and heterotrophic denitrification pathways (18.1%). The microbial analysis confirmed the significant aggregation of related denitrifying bacteria in the reactors, while AC promoted the expression of relevant nitrogen metabolism genes because of accelerated uptake and utilization of iron complexes. Meanwhile, the electrochemical analysis revealed a significantly improved electron transfer capacity of AC compared to pristine carbon. Overall, our study demonstrated the application of a novel mZVI-AC coupled material for effective nitrate removal and revealed the potential impact of CMC in the multipathway denitrification process. Graphical Abstract: [Figure not available: see fulltext.]

Original languageEnglish
Article number5
JournalBiochar
Volume6
Issue number1
Early online date10 Jan 2024
DOIs
Publication statusE-pub ahead of print - 10 Jan 2024

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