Tennessee Wastewater Operator Practice Exam

What is the primary role of methanogens in anaerobic digestion?

1. Decomposing organic material

2. Utilizing ammonia as a nutrient source

3. Producing methane from organic substrates

4. Balancing nutrient levels

The correct answer is: Producing methane from organic substrates

Methanogens play a crucial role in anaerobic digestion by producing methane from organic substrates. This process is vital for the breakdown of organic matter in environments that lack oxygen. Methanogens are a specialized group of microorganisms that thrive in anaerobic conditions and are responsible for the final steps of anaerobic digestion, where they convert intermediate products formed by other bacteria—such as acetic acid, hydrogen, and carbon dioxide—into methane gas and water. This biological conversion not only helps in reducing the volume of organic waste but also plays a significant role in the production of biogas, which can be harnessed as a renewable energy source. The other roles mentioned, such as decomposing organic material or utilizing ammonia, are fulfilled by different types of microorganisms or processes within the broader anaerobic digestion system, but they are not the primary function of methanogens. The balancing of nutrient levels is also an important aspect of the overall ecosystem in anaerobic digestion but does not specifically pertain to the primary activity of methanogens.