[Investigation of nitrogen removal performance with membrane sequencing batch reactor process]

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Context:

• Investigated nitrogen removal in an anaerobic/aerobic membrane sequencing batch reactor (MSBR) without sludge discharge over 300 days.
• Developed stable aerobic granular sludge with high MLSS (18 g/L) and large particle size (>100 µm).
• Observed significant populations of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) within the sludge.

Purpose:

• To evaluate the nitrogen removal performance of an MSBR system under specific operational conditions.
• To determine the optimal aeration strength and carbon-to-nitrogen (C/N) ratio for efficient nitrification and denitrification.
• To assess the impact of operational parameters on sludge characteristics and bacterial community composition.

Summary:

• Achieved complete nitrification, reducing influent NH4+-N (50 mg/L) to <1 mg/L within 180-210 minutes at an aeration strength of 100 m³/(m²·h).
• Identified optimal aeration (69 m³/(m²·h)) for denitrification, yielding a nitrate-N removal rate of 10.98 mg/(L·h) and low effluent NO3--N (4.4 mg/L).
• Found a C/N ratio of 2 to be optimal for denitrification, preventing nitrite accumulation.

Impact:

• Demonstrates the potential of MSBRs with aerobic granular sludge for high-efficiency nitrogen removal in wastewater treatment.
• Provides critical operational parameters (aeration, C/N ratio, volumetric exchange ratio) for optimizing MSBR performance.
• Highlights the importance of sludge granulation and bacterial community structure for effective nutrient removal.