Odorant production surges induced by exogenous oxidative stress: An overlooked risk in PAA-based moderate preoxidation for algal-laden water

Cheng Cen; Kejia Zhang; Tuqiao Zhang; Zhenxun Yu; Xinwei Mao; Sihan Wang

doi:10.1016/j.jhazmat.2025.137141

Odorant production surges induced by exogenous oxidative stress: An overlooked risk in PAA-based moderate preoxidation for algal-laden water

J Hazard Mater. 2025 Jan 6:487:137141. doi: 10.1016/j.jhazmat.2025.137141. Online ahead of print.

Authors

Cheng Cen¹, Kejia Zhang², Tuqiao Zhang³, Zhenxun Yu⁴, Xinwei Mao³, Sihan Wang⁴

Affiliations

¹ School of Civil & Environmental Engineering and Geography Science, Ningbo University, Ningbo 315211, China; College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China.
² Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing 314100, China; College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China. Electronic address: zhangkj@zju.edu.cn.
³ Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing 314100, China; College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China.
⁴ School of Civil & Environmental Engineering and Geography Science, Ningbo University, Ningbo 315211, China.

PMID: 39787931
DOI: 10.1016/j.jhazmat.2025.137141

Abstract

Moderate preoxidation is feasible for odor-producing algae treatments, usually requiring trade-offs in algal removal and integrity maintenance. However, dosing oxidants may cause internal oxidative homeostasis imbalances and secondary odorous metabolite responses, adding new trade-offs for moderate treatments. Peracetic acid (PAA)/Fe processes are promising strategies in moderate treatments and thus were applied to examine how to achieve the following three trade-offs: good algal removal, no odorant increases and no releases. For algal removal, the highest removal efficiency was 71.1 %, 87.0 % and 98.1 %, respectively, in PAA/Fe(Ⅲ) separate, PAA/Fe(Ⅱ) separate and PAA/Fe(Ⅱ) simultaneous process. Odorant responses always followed a pattern of "promotion-low dosages, inhibition-high dosages", with the highest production reaching 3.91-fold of the control without PAA addition, well above odorant threshold concentrations (500 ng/L). Instant releases did not occur, yet with delayed releases observed during sludge retention in sedimentation tanks (5, 16 h). It was verified that exogenous oxidative stress stimulated odorant generation with multiple reactive species. Among them, PAA oxidant was crucial in algal removal and odorant promotion; R-O· and ·OH caused odorant generation and degradation, respectively. Overall, PAA/Fe(Ⅱ) processes were more suitable for moderate treatments, simultaneously avoiding odorant increases and allowing sludge retention. This work provides a novel perspective for moderate preoxidation, highlighting instant odorant generation and delayed releases triggered by exogenous PAA stressors.

Keywords: Exogenous oxidative stress; Moderate preoxidation; Odor-producing algae; Peracetic acid (PAA); Responsive mechanisms.