Experimental evaluation of decrease in the activities of polyphosphate/glycogen-accumulating organisms due to cell...

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering
• Biotechnology

Background:

• Bacterial activity decline in activated sludge stems from cell death and activity decay.
• Differentiating these causes is vital for effective wastewater treatment.
• Polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) are key players.

Purpose of the Study:

• To experimentally distinguish between cell death and activity decay as drivers of reduced bacterial activity.
• To quantify the contributions of cell death versus activity decay for PAOs and GAOs under famine conditions.

Main Methods:

• Maximal anaerobic phosphate release rates and volatile fatty acid uptake rates were measured.
• Membrane integrity was assessed using live/dead staining.
• Bacterial presence was confirmed with fluorescence in situ hybridization (FISH).

Main Results:

• Activity decay accounted for 58-80% of PAO activity decrease in BNR and PAO-SBR systems.
• Cell death contributed 20-42% to PAO activity decrease.
• In GAOs, activity decay represented 74% of the decrease, with cell death at 26%.

Conclusions:

• Activity decay is a more significant factor than cell death in reducing PAO and GAO activity.
• Findings highlight the importance of considering both mechanisms for optimizing biological nutrient removal.
• This research provides critical insights for managing bacterial populations in wastewater treatment.