What is one cause of foaming in an aeration basin?

Foaming in an aeration basin can be attributed to a high solids retention time (SRT). When the SRT is elevated, it leads to an increased concentration of microorganisms, which can produce excess extracellular polymeric substances (EPS). These EPS can trap air and create foam.

High SRT typically occurs when there is an extended period for microorganisms to proliferate in the system, allowing them to produce more biofilm and floc. The accumulation of these substances can facilitate the formation of foam, especially if factors like turbulence in the aeration process and the presence of certain organisms that are prone to foaming are also at play.

Other options, such as low temperature, insufficient oxygen, or low solids concentration, do not typically lead to foaming. Low temperatures can slow microbial activity, insufficient oxygen can limit the growth of microorganisms, and low solids concentration might not provide enough biomass to generate foam. These factors instead would more likely lead to other operational challenges in wastewater treatment rather than contributing to foaming in the aeration basin.