[Changes of Microbial Community Structure in Activated Sludge Bulking at Low Temperature]

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Engineering
• Water Quality Management

Background:

• Activated sludge bulking is a common operational problem in wastewater treatment plants.
• Understanding the microbial dynamics during bulking events is crucial for effective treatment.
• Seasonal temperature variations can influence microbial community structure and function.

Purpose of the Study:

• To investigate the mechanisms of activated sludge bulking in the Zhengzhou wastewater treatment plant.
• To identify the microbial culprits responsible for sludge bulking.
• To correlate sludge bulking with environmental factors like temperature.

Main Methods:

• Measurement of key water quality parameters.
• High-throughput sequencing technology for microbial community analysis.
• Correlation analysis between sludge volume index (SVI) and seasonal temperature.

Main Results:

• Sludge bulking, indicated by increased SVI, occurred predominantly from December to April.
• SVI showed a significant negative correlation with seasonal temperature variations.
• High-throughput sequencing revealed distinct microbial community structures in bulking versus non-bulking sludge.
• Saprospiraceae and Flavobacterium were identified as the dominant filamentous bacteria during bulking events.
• Water quality parameters were not significantly affected despite the observed bulking.

Conclusions:

• Low temperatures are a primary driver for activated sludge bulking in this specific wastewater treatment plant.
• The proliferation of specific filamentous bacteria, namely Saprospiraceae and Flavobacterium, causes sludge bulking under cold conditions.
• Effective management strategies should consider temperature control or microbial interventions to mitigate bulking.