Basic Wastewater Operator Practice Exam

Which of the following is a purpose of anaerobic digestion in wastewater treatment?

1. Reduction of sludge volume

2. Increasing pH levels

3. Injecting oxygen into the system

4. Elimination of all pathogens

The correct answer is: Reduction of sludge volume

The purpose of anaerobic digestion in wastewater treatment is primarily focused on the reduction of sludge volume. This biological process occurs in the absence of oxygen, where microorganisms break down organic matter in the sludge, producing biogas (primarily methane and carbon dioxide) as a byproduct. This process not only reduces the overall volume of sludge that needs to be treated and disposed of but also stabilizes the sludge, making it less odorous and more manageable. While increasing pH levels, injecting oxygen, and eliminating all pathogens may occur in various wastewater treatment methods, they are not the main objectives of anaerobic digestion. The process is more about effective organic matter reduction and energy recovery through biogas production, which can be harnessed for various energy needs. Hence, the primary role of anaerobic digestion is to significantly decrease the volume of sludge produced in the treatment process.