Wastewater New York State Practice Exam

When the temperature of the influent to a trickling filter is warmer than ambient air, what happens to the air?

1. It circulates unchanged

2. It cools rapidly

3. It flows up through the media

4. It becomes stagnant

The correct answer is: It flows up through the media

When the temperature of the influent to a trickling filter is warmer than the surrounding ambient air, the warmer air created by the influent tends to rise. This phenomenon occurs because warmer air is less dense than cooler air, leading to an upward flow. As the warmer influent passes through the filter media, it heats the air in the vicinity, causing the lighter, heated air to move upward through the media. This process promotes aeration, facilitating the treatment of wastewater by enhancing the oxygen transfer necessary for the microbial processes that occur within the trickling filter. This upward movement also aids in moisture evaporation and helps maintain a balance of oxygen and carbon dioxide in the environment of the trickling filter. The natural convection created by this temperature differential enhances the overall efficiency of the wastewater treatment process.