Just like a poorly poured pint of beer can wreak havoc on your coffee table, excessive foam formation in aeration tanks can create operational challenges for both municipal and industrial treatment plant operators. In municipal plants, foam formation is common during secondary treatment startup, as the young microbiology is unable to breakdown surfactants associated with soap, shampoo, etc. This phenomenon is typically short- term and goes away as the mean cell residence time increases. Filamentous organisms can cause foaming in aeration tanks and this viscous, brown biological foam can create issues with solids separation/inventory, and reactor volume decreasing effluent quality. In aerobic and anaerobic digestion processes the breakdown of microbial cells can create a significant, long-term foaming challenge.