Tennessee Wastewater Operator Practice Exam

Which of the following best describes the initial conditions for the growth of PAO?

1. Aerobic conditions only

2. Anaerobic conditions with carbon source

3. High temperature and low pH

4. Presence of heavy metals

The correct answer is: Anaerobic conditions with carbon source

The growth of polyphosphate-accumulating organisms (PAO) is best described by anaerobic conditions with a carbon source. PAOs thrive in environments where they can utilize organic carbon sources anaerobically to store energy and accumulate polyphosphate. In anaerobic conditions, they take up volatile fatty acids, which serve as a carbon source and help them accumulate phosphate for later use when conditions change to aerobic. While aerobic conditions are necessary for the complete metabolic processes of PAOs, the initial growth phase requires the anaerobic environment to effectively uptake carbon and foster their development. High temperature and low pH, as well as the presence of heavy metals, can inhibit microbial growth and are not conducive to the optimal development of PAOs. Therefore, understanding the preferred anaerobic conditions with a carbon source is critical for promoting PAO growth in wastewater treatment applications.