Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.

Due to the operation mode of traditional activated sludge systems, it is difficult for various functional bacteria to exert their respective advantages. In this study, immobilized fillers for hydrolytic acidification, nitrification, and denitrification were developed to allow independent operation a...

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Main Authors: Xuyan Liu, Hong Yang, Jiawei Wang
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0315864
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author Xuyan Liu
Hong Yang
Jiawei Wang
author_facet Xuyan Liu
Hong Yang
Jiawei Wang
author_sort Xuyan Liu
collection DOAJ
description Due to the operation mode of traditional activated sludge systems, it is difficult for various functional bacteria to exert their respective advantages. In this study, immobilized fillers for hydrolytic acidification, nitrification, and denitrification were developed to allow independent operation at each stage, enhancing nitrogen removal performance of overall process. The results showed that ammonia nitrogen and total nitrogen levels in the effluent stabilized at 0.75-0.83 and 1.5-2 mg/L, respectively, when the total hydraulic retention time (HRT) of the system was 6.4 h and the nitrification unit HRT was 3 h. These values represented significant improvements compared with the traditional activated sludge process. Unit performance tests revealed that reducing the hydrolytic-acidification time to 0 min increased nitrite nitrogen and nitrate nitrogen levels in the effluent of unit A2 to 6.11 ±  0.2 mg/L and 3.67 ±  0.1 mg/L, respectively. This demonstrates that an active hydrolysis - acidification stage is the prerequisite for A2 to fully utilize raw organic matter in the water for remove nitrogen. When raw organic matter in the water bypassed the A2 unit and entered the O1 unit directly, ammonia oxidation rate (AOR) significantly decreased (from 0.32-0.33 to 0.22-0.23 kg/m3 ⋅ d), with further reduction at a low temperature (down to 0.11-0.12 kg/m3 ⋅ d). At this time, the AOR, unaffected by organic matter, decreased only slightly. This indicates that directing organic matter into the nitrification stage is essential for maintaining stability and resisting low temperatures. This process has certain guiding significance for improving nitrogen removal efficiency in municipal wastewater processes.
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spelling doaj-art-49f32994069747aaaef1985ea503aab02025-08-20T03:52:46ZengPublic Library of Science (PLoS)PLoS ONE1932-62032025-01-01203e031586410.1371/journal.pone.0315864Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.Xuyan LiuHong YangJiawei WangDue to the operation mode of traditional activated sludge systems, it is difficult for various functional bacteria to exert their respective advantages. In this study, immobilized fillers for hydrolytic acidification, nitrification, and denitrification were developed to allow independent operation at each stage, enhancing nitrogen removal performance of overall process. The results showed that ammonia nitrogen and total nitrogen levels in the effluent stabilized at 0.75-0.83 and 1.5-2 mg/L, respectively, when the total hydraulic retention time (HRT) of the system was 6.4 h and the nitrification unit HRT was 3 h. These values represented significant improvements compared with the traditional activated sludge process. Unit performance tests revealed that reducing the hydrolytic-acidification time to 0 min increased nitrite nitrogen and nitrate nitrogen levels in the effluent of unit A2 to 6.11 ±  0.2 mg/L and 3.67 ±  0.1 mg/L, respectively. This demonstrates that an active hydrolysis - acidification stage is the prerequisite for A2 to fully utilize raw organic matter in the water for remove nitrogen. When raw organic matter in the water bypassed the A2 unit and entered the O1 unit directly, ammonia oxidation rate (AOR) significantly decreased (from 0.32-0.33 to 0.22-0.23 kg/m3 ⋅ d), with further reduction at a low temperature (down to 0.11-0.12 kg/m3 ⋅ d). At this time, the AOR, unaffected by organic matter, decreased only slightly. This indicates that directing organic matter into the nitrification stage is essential for maintaining stability and resisting low temperatures. This process has certain guiding significance for improving nitrogen removal efficiency in municipal wastewater processes.https://doi.org/10.1371/journal.pone.0315864
spellingShingle Xuyan Liu
Hong Yang
Jiawei Wang
Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
PLoS ONE
title Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
title_full Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
title_fullStr Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
title_full_unstemmed Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
title_short Optimizing nitrogen removal with an immobilized biological filler system: realizing stage-independent operational process.
title_sort optimizing nitrogen removal with an immobilized biological filler system realizing stage independent operational process
url https://doi.org/10.1371/journal.pone.0315864
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AT hongyang optimizingnitrogenremovalwithanimmobilizedbiologicalfillersystemrealizingstageindependentoperationalprocess
AT jiaweiwang optimizingnitrogenremovalwithanimmobilizedbiologicalfillersystemrealizingstageindependentoperationalprocess