Enhancing anammox granular sludge for mainstream anammox process by adding iron-loaded diatomite: Performance and intrinsic mechanism

Fanghua Xing; Xuejie Ma; Binbin Sun; Tao Wang; Fei Lian; Luyao Wang; Ziyi Fu

doi:10.1016/j.envres.2025.120806

Enhancing anammox granular sludge for mainstream anammox process by adding iron-loaded diatomite: Performance and intrinsic mechanism

Environ Res. 2025 Jan 9:268:120806. doi: 10.1016/j.envres.2025.120806. Online ahead of print.

Authors

Fanghua Xing¹, Xuejie Ma¹, Binbin Sun², Tao Wang³, Fei Lian¹, Luyao Wang¹, Ziyi Fu¹

Affiliations

¹ School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China.
² School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China. Electronic address: sunbinnaruto@126.com.
³ School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China. Electronic address: wangtaotl1982@hotmail.com.

PMID: 39798656
DOI: 10.1016/j.envres.2025.120806

Abstract

Iron-loaded diatomite (Fe-DE) was developed as the innovative material to enhance anammox granular sludge (AnGS) and mainstream anammox performance. By adding Fe-DE with the Fe:DE ratio of 1:20 and the dosage of 3 g/L, the start-up period of mainstream anammox process was shortened from 29 d to 17 d and its nitrogen removal rate was increased from 0.234 kg N/(m³·d) to 0.437 kg N/(m³·d). AnGS generated more hydrophobic functional groups and redox substances, forming the robust particle structure and improving the electron transfer of anammox reaction. In addition, the key genes PleC, PleD and TrpE/G, related to quorum sensing, increased from 502.69, 91.18 and 18.25 CPM to 532.84, 103.66 and 19.96 CPM. The key genes hzs and hdh related to anammox process also increased by 30.76% and 24.26%. As a result, formation of AnGS was promoted and the enrichment level of Candidatus Brocadia was improved. This study provides a novel insight into the development of innovative material for enhancing mainstream anammox process.

Keywords: Anammox granular sludge; Extracellular electron transfer; Iron-loaded diatomite; Mainstream anammox; Metagenomic analysis.