Simultaneous nitrogen removal and phosphorus recovery in granular sludge-based partial denitrification/anammox-hydroxyapatite precipitation (PD/A-HAP) process under low C/N ratio and dissolved oxygen limitation

Lijie Chen; Zhenjun Wu; Jiayu Niu; Yihan Wang; Ming Cai; Jiale Xi; Yanlei Cui; Lang Cheng; Xinyi Fan

doi:10.1016/j.biortech.2025.132045

Simultaneous nitrogen removal and phosphorus recovery in granular sludge-based partial denitrification/anammox-hydroxyapatite precipitation (PD/A-HAP) process under low C/N ratio and dissolved oxygen limitation

Bioresour Technol. 2025 Jan 10:132045. doi: 10.1016/j.biortech.2025.132045. Online ahead of print.

Authors

Lijie Chen¹, Zhenjun Wu², Jiayu Niu¹, Yihan Wang¹, Ming Cai³, Jiale Xi¹, Yanlei Cui¹, Lang Cheng¹, Xinyi Fan¹

Affiliations

¹ School of Environmental Engineering, Henan University of Technology, Zhengzhou 450001, China; Zhengzhou Key Laboratory of Water Safety and Water Ecology Technology, Zhengzhou 450001, China; Henan International Joint Laboratory of Environmental Pollution Remediation and Grain Quality Security, Zhengzhou 450001, China.
² School of Environmental Engineering, Henan University of Technology, Zhengzhou 450001, China; Zhengzhou Key Laboratory of Water Safety and Water Ecology Technology, Zhengzhou 450001, China; Henan International Joint Laboratory of Environmental Pollution Remediation and Grain Quality Security, Zhengzhou 450001, China. Electronic address: wuzhenjun@haut.edu.cn.
³ Yellow River Engineering Consulting Co., Ltd., Zhengzhou 450001, China.

PMID: 39799988
DOI: 10.1016/j.biortech.2025.132045

Abstract

This study integrates partial denitrification/Anammox (PD/A) with hydroxyapatite (HAP) crystallization in a single reactor, achieving simultaneous nitrogen and phosphorus removal along with phosphorus recovery. By adjusting pH, sludge concentration, low COD/TN ratio, and applying moderate dissolved oxygen stress, the system operated stably and promoted the synergistic growth of HAP and biomass. Results showed a nitrogen removal efficiency (NRE) of 94.13 % and a phosphorus removal efficiency (PRE) of 73.6 %. Metagenomic analysis revealed that under dissolved oxygen stress, The abundance of Candidatus Brocadia increased from 1 % to 26.1 %, significantly boosting anammox activity. indicating enhanced microbial activity. The upregulation of related genes (sdh, suc, hzs) further boosted AnAOB activity. HAP was identified as the main inorganic component of the granule. This process shows strong potential for nitrogen and phosphorus removal with resource recovery in wastewater treatment.

Keywords: Anammox; Hydroxyapatite; Nitrogen removal; Partial denitrification; Phosphorus removal.