Performance evaluation and bacterial characterization of membrane bioreactors

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment Technologies

Background:

• Membrane bioreactors (MBRs) are advanced wastewater treatment systems.
• Different MBR configurations (C-MBR, MB-MBR, A/O-MBR) offer varied performance characteristics.
• Understanding bacterial diversity and nutrient removal efficiency is crucial for optimizing MBRs.

Purpose of the Study:

• To compare the treatment performance and bacterial diversity of conventional (C-MBR), moving bed (MB-MBR), and anoxic/oxic (A/O-MBR) membrane bioreactors.
• To evaluate the removal of organics (COD) and nutrients (Nitrogen and Phosphorus).
• To identify key microbial populations involved in nutrient cycling within different MBR systems.

Main Methods:

• Bench-scale operation of C-MBR, MB-MBR, and A/O-MBR under similar conditions.
• Analysis of effluent for Chemical Oxygen Demand (COD) and nutrient (N, P) concentrations.
• Bacterial isolation using pure culture techniques and identification via API 20E kit.
• Detection of specific nitrifying and denitrifying bacteria using Polymerase Chain Reaction (PCR).

Main Results:

• The A/O-MBR achieved the highest Total Nitrogen (TN) removal, attributed to specific media addition and lower Dissolved Oxygen (DO).
• Pseudomonas aeruginosa, a denitrifying bacterium, was exclusively isolated from the A/O-MBR.
• The MB-MBR demonstrated superior nitrification compared to the C-MBR.
• Nitrosomonas europaea was detected only in the MB-MBR, while Nitrobacter winogradskyi was present in all reactors.

Conclusions:

• The A/O-MBR configuration is highly effective for enhanced nutrient removal, particularly Total Nitrogen.
• The MB-MBR configuration shows promise for efficient nitrification processes in wastewater treatment.
• Specific microbial communities, including key nitrifying and denitrifying bacteria, are differentially distributed across MBR types, influencing overall treatment performance.