Microbial population dynamics during sludge granulation in an A/O/A sequencing batch reactor.

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Engineering
• Biotechnology

Background:

• Granular sludge offers advantages in wastewater treatment due to its settling properties and microbial community.
• Understanding microbial dynamics is crucial for optimizing granulation and nutrient removal processes.

Purpose of the Study:

• To investigate the bacterial population evolution during the formation of denitrifying phosphorus removal granular sludge.
• To identify key microbial players involved in granulation and nutrient removal.

Main Methods:

• High-throughput pyrosequencing (MiSeq) was employed to analyze bacterial community composition.
• A sequencing batch reactor with an anaerobic/aerobic/anoxic (A/O/A) configuration was used.

Main Results:

• Mature, compact granular sludge was successfully formed under low organic loading (0.3 kg COD/(m³·d)).
• Simultaneous removal of chemical oxygen demand (COD), nitrogen, and phosphorus was achieved.
• Microbial diversity and richness increased significantly during granulation and stabilized post-formation.
• Specific rod-shaped microbes were observed on the granule surface, and functional groups were identified.

Conclusions:

• The study successfully elucidated the microbial succession during granular sludge formation.
• Identified functional bacteria are crucial for the efficient operation of biological reactors for nutrient removal.
• The findings support the development of advanced wastewater treatment systems for simultaneous nutrient removal.