Foaming in Aerated Stabilization Basins

Foaming in Aerated Stabilization BasinsFoaming occurs when air is trapped within a thin film of water. Foam is a natural process of mechanical mixing of aeration but can be aggravated by environmental factors. Foaming in aerated stabilization basins (ASBs) and in activated sludge systems have many of the same drivers. Two of the biggest problems, which are additive in nature, are Nocardioform filaments and surfactants. Nocardioform filaments are composed of a diverse group of bacteria that have a branched structure. This morphology along with a natural inclination towards hydrophobicity causes Nocardioforms to preferentially enter a foam phase. Air bubbles can become entrained in the branched structure of the filaments and hydrophobic floc can act as an entraining substrate, which leads to foaming. Surfactants are chemical additives, such as industrial detergents, that increase the strength of the water film over a bubble. This has the effect allowing foam to accumulate faster than bubbles can naturally dissipate. Surfactants alone or Norcardioforms alone can cause mild to moderate foaming issues. However, serious foaming issues can occur when the two are mixed. Foaming acts as a foam stabilizer, which compliments the exponential growth of Nocardioforms leading to overwhelming amounts of foam in a relatively short period of time. The foam from these two elements can become very thick and dense due to the high content of floc solids entrained in the foam. There are a variety of methods for dealing with this type of foam as well as the less common types. These methods include, selectors (either aerobic, anoxic, or anaerobic), cationic polymers, chlorinination followed by bioaugmentation, foam trapping, and foam collection/destruction. Each foaming situation has its own idiosyncrasies that mush be evaluated on a case-by-case basis. Implementing the wrong technique can be worse that doing nothing at all. Environmental Business Specialists has experience dealing with several different foaming scenarios. Our biological laboratory is equipped to identify the types of filaments present in an ASB or Activated Sludge sample, which can be useful in identifying engineering controls that can be used to deter filament growth. EBS also has a respirometry laboratory that is used to conduct bench tests for various foaming solutions to evaluate the best solution for each individual problem.

If you any questions about our capabilities or would like to know more about your foaming issues, please contact us at 985-674-0660.

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