Tennessee Wastewater Operator Practice Exam

What is the rate limiting step of anaerobic digestion?

1. Fermentation

2. Hydrolysis

3. Acidogenesis

4. Methanogenesis

The correct answer is: Hydrolysis

The rate limiting step of anaerobic digestion refers to the phase that most significantly limits the overall rate of the entire digestion process. Hydrolysis is identified as this step because it involves the breakdown of complex organic matter, such as fats, carbohydrates, and proteins, into simpler soluble compounds. During hydrolysis, larger organic molecules are converted into smaller, more manageable substances that can be further processed by other microbial populations in subsequent stages of anaerobic digestion. This step is crucial because if hydrolysis is slow or inefficient, it directly affects the availability of substrates for the following processes, such as acidogenesis and methanogenesis. The significance of hydrolysis becomes clear when considering the digestion pathway: it is the first step in the sequence of anaerobic digestion, and without adequate hydrolysis, the entire system would not function optimally. Therefore, improving the hydrolysis stage can enhance the overall efficiency of anaerobic digestion processes in wastewater treatment.