What is a potential consequence of exceeding the typical range for VAs in a primary digester?

Exceeding the typical range for volatile acids (VAs) in a primary digester can lead to a decreased efficiency of methane formation. In anaerobic digestion, volatile acids are produced during the breakdown of organic materials, and they play a critical role in the overall digestion process. When the concentration of VAs becomes too high, it can inhibit the activity of methanogenic microorganisms, which are responsible for converting the acids into methane. This inhibition can disrupt the balance of the microbial community within the digester and negatively affect the overall stability and performance of the digestion process. As a result, the production of methane, which is a key goal of anaerobic digestion, diminishes, leading to inefficiencies in the process.

The other options either reflect outcomes not typically associated with high levels of VAs or involve situations that do not directly relate to the inhibition of methane production. For example, improved methane production and enhanced solids breakdown would generally not occur under conditions of excessive volatile acids, as these factors often indicate a well-balanced digestion process. Likewise, while increased pH levels can happen under certain conditions, they do not consistently correlate with the specific consequence of exceeding the VA range in terms of methane formation efficiency.