[Start-up and Optimization of Denitrifying Phosphorus Removal in ABR-MBR Coupling Process]

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Conventional wastewater treatment struggles with simultaneous nitrogen and phosphorus removal.
• Membrane bioreactors (MBRs) offer advanced treatment but require efficient nutrient removal integration.
• Anaerobic baffled reactors (ABRs) can be adapted for biological nutrient removal processes.

Purpose of the Study:

• To investigate the feasibility of denitrifying phosphorus removal in an ABR-MBR system.
• To evaluate the microbial community characteristics associated with phosphorus removal.
• To optimize operational parameters for enhanced nutrient removal efficiency.

Main Methods:

• An ABR-MBR system was operated with high-concentration seeding activated sludge and gradually increased reflux ratios.
• System performance was monitored by measuring removal rates of COD, PO43--P, and TN.
• Microbial community analysis was performed using high-throughput sequencing.

Main Results:

• The ABR-MBR system achieved stable COD, PO43--P, and TN removal rates of 88.28%, 54.45%, and 61.93%, respectively.
• Optimal conditions yielded PO43--P and TN removal rates of 64.94% and 62.95% with specific VFA concentration and NO2--N/NO3--N ratios.
• Denitrifying phosphorus removal bacteria (DPAOs) were identified as key functional microorganisms, with significant anaerobic phosphorus release and anoxic uptake.

Conclusions:

• The ABR-MBR system effectively achieved short-cut nitrification and denitrifying phosphorus removal.
• Proteobacteria and Bacteroidetes were the dominant phyla, with specific genera identified as potential DPAOs.
• The study confirms the potential of ABR-MBR for efficient simultaneous nitrogen and phosphorus removal in wastewater treatment.