ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbiotechnology
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1681450
This article is part of the Research TopicMicrobial Biotechnologies for Efficient Wastewater Treatment and Resource RecoveryView all 15 articles
Inhibition of ferric salts on phosphorus-accumulating organisms in simultaneous chemical precipitation for phosphorus removal
Provisionally accepted
- College of Environment and Ecology, Chongqing University, Chongqing, China
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To comply with the increasingly strict phosphorus (P) effluent standard, ferric salts are commonly used as a simultaneous precipitant to supplement the biological P removal process. However, ferric residue from the chemical process can be carried by the return sludge into the biological system, potentially affecting the biological P removal process. This study demonstrated that ferric salts had significant inhibitory effects on the biological P removal process. The activity and relative abundance of phosphate-accumulating organisms (PAOs) decreased after adding ferric salts. P uptake rate dropped from 10.31 to 2.39 mg/(g SS·h) and the relative abundance of PAOs decreased from 2.51% to 0.21% when ferric salts increased from 0 to 42 mg Fe3+/L. P release and uptake by PAOs were inhibited, and bioavailable P and poly-P in the sludge dropped after ferric addition. As a result, the chemical P removal with ferric precipitation contributed more to P removal, and the ortho-P in the sludge spiked. The inhibition of the biological P removal process may make it difficult to control simultaneous ferric dosing, where the biological P removal process is required to make a major contribution to P removal.
Keywords: Biological phosphorus removal, Chemical phosphorus removal, Ferric salts, Phosphorus fraction, Phosphate-accumulating organisms
Received: 07 Aug 2025; Accepted: 06 Oct 2025.
Copyright: © 2025 Xiao, Yu, Lin, Cao, Jian, Lin and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jian Zhou, zhoujiantt@cqu.edu.cn
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