Multi-compartment denitrifying bioreactor for aquaculture tailwater treatment: Synergistic effects of temperature, HRT and nitrate loading on nitrogen removal and microbial community.

Authors

Yue Sun, Jie Tang, Lei Jia, Xueliang Sun, Zhitao Huang, Mingze Li, Xiaohan Yang

Published in

Water research. Volume 306. Pages 126588. Jul 28, 2026. Epub Jul 28, 2026.

Abstract

To address low nitrogen removal efficiency in aquaculture tailwater with a low carbon-to-nitrogen ratio, this study constructed a multi-compartment aerobic denitrification reactor (MPBR) integrating nitrification, slow-release carbon, anoxic denitrification, and simultaneous nitrification-denitrification zones. The synergistic effects of temperature (15 °C, 25 °C), hydraulic retention time (HRT; 4 h, 8 h, 10 h), and influent NO₃⁻-N load (20 mg/L, 50 mg/L) on nitrogen removal were investigated, along with microbial community dynamics via high-throughput sequencing. The partitioned structure ensured robust nitrification, with ammonia removal exceeding 90% under all conditions. Denitrification was highly sensitive to multi-parameter interactions: low temperature (15 °C) reduced NO₃⁻-N removal from 89.4% (25 °C) to 38.1%; high load (50 mg/L) increased absolute removal when HRT was sufficient (≥8 h) but caused inhibition when HRT was insufficient; HRT exhibited a threshold (∼8 h), with limited benefit at low temperatures. The simultaneous nitrification-denitrification zone maintained effluent NO₂⁻-N below 0.2 mg/L across all conditions. Pseudomonadota dominated the microbial community (75% average abundance), correlating positively with denitrification efficiency. At the genus level, Pseudomonas thrived at room temperature, whereas Simplicispira enriched significantly in the slow-release carbon zone under low temperature (up to 47.5%), exhibiting complementary succession and sustaining denitrification potential. Spatial niche differentiation across functional zones and functional compensation under stress supported system stability. This study elucidates the multi-factor regulation of aerobic denitrification and microbial compensation mechanisms, providing a theoretical basis for applying partitioned reactors in aquaculture tailwater treatment.

PMID:
42537278
Bibliographic data and abstract were imported from PubMed on 01 Aug 2026.

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