Tennessee Wastewater Operator Practice Exam

What substance can effectively diffuse through a biofilm?

1. Nitrogen

2. Dissolved oxygen

3. Phosphorus

4. Ammonia

The correct answer is: Dissolved oxygen

Dissolved oxygen is the correct answer because it plays a crucial role in the metabolic processes of microorganisms within a biofilm. Biofilms are complex communities of microorganisms that can adhere to surfaces in various environments, including wastewater treatment systems. The structure of a biofilm can create a gradient, affecting the availability of nutrients and gases. Dissolved oxygen diffuses more freely than many other substances due to its molecular size and the fact that it is a gas that dissolves in water. Microorganisms in the biofilm require oxygen for respiration, particularly in aerobic conditions. Their metabolic activity consumes oxygen, leading to a constant demand. While nitrogen, phosphorus, and ammonia are important nutrients as well, their diffusion through biofilms is often limited by various factors such as chemical composition, solubility, and biological uptake rates. Overall, the ability of dissolved oxygen to diffuse readily through biofilm structures is key for sustaining healthy microbial communities and ensuring effective wastewater treatment processes.