Wastewater New York State Practice Exam 2025 - Free Wastewater Certification Practice Questions and Study Guide

When there's an upset in an anaerobic digester, the first measurable change is typically in the levels of volatile acids. This is due to the delicate balance of the microbial populations within the digester, which breaks down organic material.

In normal operating conditions, the bacteria that produce methane (methanogens) and those that produce volatile fatty acids (acidogenesis) are balanced. If there’s a disruption, such as a change in organic loading, temperature, or pH, the acid-producing bacteria can react more quickly than the methanogens, leading to an accumulation of volatile acids. This rise in volatile acids can be an early indicator of digester performance issues, as sustained high levels may inhibit the activity of methanogens and disrupt overall digestion.

In contrast, changes in volatile solids and methane production typically lag behind the initial increase in volatile acids. The temperature of the digester also stabilizes within certain ranges, so it is generally not the first indicator of an upset. Understanding the dynamics of these processes is essential in wastewater treatment operations to ensure the effective management of anaerobic digestion.