Tennessee Wastewater Operator Practice Exam

What is one goal of anaerobic digestion?

1. To increase pH levels

2. To reduce the mass of VS

3. To speed up the decomposition process

4. To lower the temperature

The correct answer is: To reduce the mass of VS

One of the primary goals of anaerobic digestion is to reduce the mass of volatile solids (VS). This process occurs in environments where oxygen is absent, allowing microorganisms to break down organic matter. As these microorganisms metabolize the organic materials—like food waste, agricultural waste, and sewage—they convert it into biogas (which primarily contains methane and carbon dioxide) and digestate. Reducing the mass of volatile solids is significant for several reasons. First, it decreases the volume of waste that needs to be managed and disposed of, leading to lower costs associated with transportation and disposal. Second, anaerobic digestion stabilizes the organic material, making it less harmful and more environmentally friendly. The end products, biogas and digestate, can be repurposed; biogas can be used as a renewable energy source, while the digestate can be treated further and used as fertilizer. The other options, while they may relate to various aspects of the wastewater treatment process, do not encapsulate the main objectives of anaerobic digestion. Increasing pH levels, speeding up the decomposition process, or lowering temperature all pertain to different aspects of wastewater management and treatment but do not directly address the fundamental goal of reducing the mass of volatile solids through anaerobic digestion.