Florida Wastewater Practice Test

Excessive billowing white sudsy foam on the surface of an aerator is most likely caused by?

1. Low temperature

2. Low BOD levels

3. F/M too high

4. High nutrient concentrations

The correct answer is: F/M too high

Excessive billowing white sudsy foam on the surface of an aerator is primarily indicative of a condition known as foaming. This phenomenon often occurs when the food to microorganism ratio (F/M ratio) is too high. In this context, a high F/M ratio suggests that there is an abundance of food available for the microorganisms in the treatment system relative to the number of microorganisms present. This imbalance can lead to the rapid growth of certain types of bacteria that produce foam, as their population increases significantly and results in the formation of foam stability. When the F/M ratio is elevated, it fosters not only the growth of desirable microorganisms but also promotes the proliferation of filamentous organisms. These filamentous bacteria are often responsible for the formation of foam because they create structures that trap air, leading to frothy conditions on the surface of aerators. Proper management of the F/M ratio is crucial in wastewater treatment facilities to ensure effective aeration and prevent excessive foaming, which can hinder the treatment process and operational efficiency. In contrast, other options such as low temperature or low BOD levels do not typically lead to foaming. Low nutrient concentrations may affect microbial growth, but they are less likely to cause excessive foam compared to an imbalance in the food