Tennessee Wastewater Operator Practice Exam

Which of the following factors can affect the performance of an anaerobic digester?

1. Temperature and pH levels

2. Only feedstock type

3. Pressure levels in tanks

4. Water quality only

The correct answer is: Temperature and pH levels

The performance of an anaerobic digester is significantly influenced by various environmental factors, among which temperature and pH levels are critical. Anaerobic digestion is a process that relies on a complex community of microorganisms that break down organic matter in the absence of oxygen. These microorganisms have optimal temperature ranges, and deviations from these can slow down metabolic rates, reduce biogas production, and affect overall digestion efficiency. Typically, mesophilic (around 30-40°C) and thermophilic (around 50-60°C) temperatures are preferred, depending on the specific microbial community being utilized. pH levels also play a crucial role in this process. Most anaerobic bacteria thrive in a neutral to slightly alkaline environment, with a pH range typically between 6.5 and 8.5. If the pH drops too low (becoming too acidic), it can inhibit methanogenic bacteria, which are responsible for producing methane from digested organic matter. This can lead to reduced biogas production and instability in the digestion process. While factors like feedstock type, pressure levels in tanks, and water quality can also impact digestion, they do not encompass the entire range of influential factors as comprehensively as temperature and pH do. Therefore