If there is excessive billowing white sudsy foam on the surface of an aerator, what is the likely cause?

Excessive billowing white sudsy foam on the surface of an aerator typically indicates a high Food to Microorganism (F/M) ratio. The F/M ratio is a critical parameter in wastewater treatment that reflects the balance between the amount of food available for microorganisms (usually measured in terms of Biological Oxygen Demand or BOD) and the mass of the microorganisms present in the system.

When the F/M ratio is too high, it means there is an abundance of organic matter (food) relative to the amount of microorganisms available to consume it. This situation can lead to the proliferation of certain bacteria that produce excess foam as a byproduct of their metabolic processes. The foam formation is often due to the presence of surfactants, which can be produced in higher amounts when microorganisms are stressed due to an overload of food.

In contrast, a low F/M ratio indicates that there is more biomass than food, which usually results in lower levels of foam since the microorganisms have enough time to fully digest the available organics without producing excessive foam.

Understanding the dynamics of the F/M ratio helps in troubleshooting and maintaining the efficiency of the aeration process in wastewater treatment, ensuring that the conditions remain favorable for effective microbial action.