Ontario Operator-in-Training (OIT) Practice Exam

Which type of lagoon requires oxygen for bacterial breakdown of organic matter?

1. Aerobic lagoons

2. Anaerobic lagoons

3. Facultative lagoons

4. Aerated lagoons

The correct answer is: Aerobic lagoons

The type of lagoon that requires oxygen for the bacterial breakdown of organic matter is the aerobic lagoon. In aerobic lagoons, the presence of oxygen supports the growth of aerobic bacteria, which are essential for the decomposition of organic materials. These bacteria utilize oxygen to break down waste products efficiently, leading to effective treatment of wastewater. Aerobic lagoons are designed to maintain aerobic conditions, typically through surface agitation or mechanical aeration, promoting a healthy population of aerobic microorganisms. This process not only aids in reducing organic load but also helps in controlling odors and generating less sludge compared to other types of lagoons. Facultative lagoons, while they can support both aerobic and anaerobic processes because they can function with or without oxygen, do not primarily rely on oxygen like aerobic lagoons do. Anaerobic lagoons operate without oxygen and are dependent on anaerobic bacteria for decomposition, leading to different treatment outcomes. Aerated lagoons involve mechanical aeration but are distinct from purely aerobic lagoons as they can vary in design and operational dynamics.