Florida Wastewater Practice Test

If the pH in your plant is decreasing, effluent turbidity is increasing, and sludge is rising in the clarifier, what could be the problem?

1. Over aeration

2. Denitrification

3. Insufficient aeration

4. Chemical imbalance

The correct answer is: Denitrification

Denitrification refers to the process where nitrates are reduced and converted into nitrogen gas, which can occur in anaerobic or low-oxygen conditions. If the pH in a wastewater treatment plant is decreasing, it often indicates an acidic shift in the environment, which can inhibit beneficial microbial processes and lead to abnormal operational conditions. As denitrification may require specific oxygen levels and can generate by-products that contribute to inefficiencies, this could explain the increased effluent turbidity and the rising sludge in the clarifier. In this situation, the combination of a decreasing pH and increasing turbidity could suggest that the denitrifying bacteria are dominating at the expense of other necessary microbial populations, leading to an inadequate settlement and increased sludge. Therefore, the symptoms observed may indeed point to a denitrification issue that disrupts the overall treatment process and contributes to a rise in turbidity and sludge levels. Other potential problems, such as over aeration or chemical imbalances, typically manifest differently. For example, over aeration could lead to increased dissolved oxygen levels, which is contrary to what is seen here. Insufficient aeration might lead to ammonia accumulation rather than a significant decrease in pH linked to denitrification processes. Understanding the relationship between