Which condition would likely result in sludge bulking?

Sludge bulking is a common issue in wastewater treatment that occurs when the activated sludge fails to settle properly, leading to a floating mass of microbes that cannot compact effectively. A low food-to-microorganism (F:M) ratio is significant in this context because it indicates that there is an insufficient amount of food available for the microorganisms.

When the F:M ratio is low, the microorganisms can become starved for food. In response, they can produce excess extracellular polymeric substances (EPS), which can cause the sludge particles to cling together more loosely, losing their ability to settle. This results in a less dense sludge that is prone to bulking. A more balanced F:M ratio helps maintain a healthy microbial population that can effectively flocculate and settle.

Understanding this condition is essential for operators and engineers to adjust operational parameters and mitigate bulking problems in wastewater treatment facilities. This emphasizes the importance of monitoring and maintaining appropriate nutrient levels in the system.