What does billowing white foam on the aeration tank indicate about the sludge?

Billowing white foam on the aeration tank typically indicates that the sludge is young and has poor settling characteristics. This is characterized by a higher concentration of microorganisms that have not yet had sufficient time to mature and form a more stable floc structure. Young sludge tends to be less dense and can produce foam due to the presence of surfactants or excessive microbial activity. The formation of foam can hinder proper aeration and may affect the overall treatment process, indicating that adjustments may be necessary to ensure better settling and treatment efficiency in the tank.

In contrast, thicker and more stable sludge would not produce significant foam; instead, it would tend to settle adequately in the tank. Old sludge, being denser, might also not exhibit billowing foam as the flocs have had time to settle and mature. Properly aerated sludge typically remains well-mixed but does not produce an excessive amount of foam, indicating a healthy process and effective treatment conditions.