Model-based evaluation of competition between polyphosphate- and glycogen-accumulating organisms

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering

Background:

• Glycogen-accumulating organisms (GAOs) compete with polyphosphate-accumulating organisms (PAOs) for organic substrates under anaerobic conditions.
• This competition can negatively impact enhanced biological phosphorus removal (EBPR) systems.

Purpose of the Study:

• To evaluate the competition between PAOs and GAOs in anaerobic/aerobic (A/O) systems under varying operational conditions.
• To identify strategies for controlling GAO dominance and ensuring stable EBPR.

Main Methods:

• Model-based evaluation of PAO and GAO competition.
• Analysis of system performance at different temperatures (20°C and 30°C) and sludge ages (3 and 10 days).

Main Results:

• At 30°C and 10-day sludge age, GAOs dominated due to a kinetic advantage in anaerobic acetate uptake.
• At 20°C and 10-day sludge age, PAOs were relatively dominant, leading to stable phosphorus removal.
• At 30°C and 3-day sludge age, aerobic PHA metabolism influenced dominance, with PAOs potentially outcompeting GAOs under specific conditions.

Conclusions:

• Temperature and sludge age are critical factors determining PAO/GAO competition and EBPR performance.
• Controlling operational parameters, particularly temperature and sludge age, is essential for managing GAO proliferation and maintaining effective EBPR.