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Coupling seed sludge evolution with reactor spatial optimization: Simultaneous nitrogen and phosphorus removal from
Yunjing Wang1, Tianyuan Du2, Weikang Qi2
1National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China; Beijing Drainage Group Co., Ltd., Beijing 100044, China.
Bioresource Technology
|June 26, 2026
Summary
Simultaneous nitrogen and phosphorus removal in wastewater is difficult. Using anaerobic granular sludge in a fluidized bed reactor promoted larger microbial aggregates, enhancing nutrient removal efficiency.
Area of Science:
- Environmental Microbiology
- Water Treatment Engineering
Background:
- Simultaneous nitrogen and phosphorus removal in continuous-flow municipal wastewater treatment is a significant environmental challenge.
- The development and structure of microbial aggregates play a crucial role in biological nutrient removal processes.
Purpose of the Study:
- To evaluate the impact of different seed sludges (flocculent vs. anaerobic granular sludge) on microbial aggregate structure and function in a continuous self-circulating fluidized bed reactor.
- To investigate the relationship between microbial aggregate size, structure, and the efficiency of simultaneous nitrogen and phosphorus removal.
Main Methods:
- Treatment of real municipal wastewater using an aerated-volume-optimized continuous self-circulating fluidized bed (ACOAAP-Zier).
- Inoculation with either flocculent sludge (R_floc) or anaerobic granular sludge (R_AnGS).
- Analysis of microbial aggregate size distribution, structural characteristics, and microbial community composition.
Main Results:
- Anaerobic granular sludge (R_AnGS) promoted the formation of larger microbial aggregates compared to flocculent sludge (R_floc).
- Larger aggregates in R_AnGS (P3) favored the enrichment of denitrifying and phosphorus-removing microorganisms, including denitrifying polyphosphate-accumulating organisms (DPAOs).
- R_AnGS treatment resulted in enhanced phosphorus removal and coupled nitrogen removal pathways.
Conclusions:
- Microbial aggregate structure, influenced by seed sludge type, significantly impacts nutrient removal efficiency in continuous-flow systems.
- Optimizing aggregate size through seed sludge selection is a promising strategy for improving simultaneous nitrogen and phosphorus removal in wastewater treatment.
- Findings provide a basis for designing and operating fluidized bed reactors for enhanced biological nutrient removal.
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