Florida Wastewater Practice Test

Which of the following conditions can indicate a problem in an anaerobic digester?

1. Stable pH and high gas production

2. High pH and decreased gas production

3. Decreased solids and improved effluent

4. Consistent temperature and nutrient levels

The correct answer is: High pH and decreased gas production

A high pH and decreased gas production in an anaerobic digester is a significant indication of potential problems. The pH level is crucial in anaerobic digestion, as it affects the metabolic processes of the microorganisms involved in breaking down organic matter. An elevated pH can create an environment that is unfavorable for specific groups of bacteria responsible for the digestion process, leading to inefficiencies. Decreased gas production signifies that the conversion of organic material into biogas is not occurring effectively, which is a critical function of anaerobic digestion. Biogas production is a measure of the digester’s health, and when it diminishes alongside a rise in pH, it suggests there may be issues such as the accumulation of inhibitory compounds or an imbalance in the microbial community. In contrast, stable pH and high gas production exemplify a properly functioning digester, while decreased solids and improved effluent typically indicate effective digestion and treatment. Consistent temperature and nutrient levels are also signs of system stability and health. Therefore, the combination of high pH and decreased gas production distinctly points to a problem within the anaerobic digestion process.