Ontario Operator-in-Training (OIT) Practice Exam

What is typically true about organic materials in water with high BOD?

1. They promote fish growth

2. They are decomposable

3. They are beneficial for water quality

4. They indicate low levels of microorganisms

The correct answer is: They are decomposable

High Biological Oxygen Demand (BOD) indicates the amount of dissolved oxygen that aerobic microorganisms will consume while decomposing organic matter in water. This generally refers to the presence of organic materials that can be broken down by these microorganisms. When organic materials are present in high BOD conditions, it signifies that they can be decomposed by bacteria and other microorganisms in the water. The decomposition process consumes oxygen, which can lead to deficiencies in dissolved oxygen levels, negatively affecting aquatic life, particularly fish and other organisms that rely on oxygen-rich environments. Therefore, the fact that these materials are decomposable is a significant characteristic associated with high BOD levels. This aspect also explains why BOD is used as an important metric in assessing water quality.