Tennessee Wastewater Operator Practice Exam

In terms of wastewater treatment, what does a strong BOD indicate?

1. High levels of alkalinity

2. Low levels of organic matter

3. Presence of easily biodegradable materials

4. Effective treatment processes

The correct answer is: Presence of easily biodegradable materials

A strong biochemical oxygen demand (BOD) indicates the presence of easily biodegradable materials in wastewater. This measurement reflects the amount of oxygen that microorganisms will consume while decomposing organic matter over a specified period, typically five days at a controlled temperature. When the BOD is high, it signifies a substantial amount of organic substances that can be broken down by bacteria, pointing to a significant presence of easily biodegradable materials. This information is crucial for wastewater treatment facilities because it helps them determine the necessary approaches for treating the wastewater effectively. For example, if the BOD is high, more aeration and biological treatment processes may be required to enhance the breakdown of organic material before discharge or further treatment. In contrast, high levels of alkalinity do not directly correlate with BOD since alkalinity measures the buffering capacity of water against pH changes rather than the organic content. Low levels of organic matter would indicate a low BOD, and effective treatment processes would generally lead to a reduction in BOD levels in the treated effluent. Therefore, identifying a strong BOD is essential for understanding the characteristics of wastewater and designing an appropriate treatment strategy.