Tennessee Wastewater Operator Practice Exam

What is the primary purpose of increasing the recirculation rate in a trickling filter?

1. To cool the effluent

2. To enhance nutrient removal

3. To increase biological treatment efficiency

4. To improve flow rates in the system

The correct answer is: To increase biological treatment efficiency

Increasing the recirculation rate in a trickling filter primarily enhances biological treatment efficiency. This process allows for a greater volume of wastewater to be distributed over the filter media multiple times, promoting improved contact between the wastewater and the biofilm of microorganisms that develop on the media. As wastewater is recirculated, it ensures that more organic material is exposed to these microbes, leading to higher rates of biodegradation of pollutants. This effectively enhances the overall treatment performance of the trickling filter, allowing for more effective removal of organic matter and improving the quality of the effluent produced. In contrast, while factors such as cooling the effluent, improving nutrient removal, or increasing flow rates may be considerations in a wastewater treatment process, they do not directly address the primary goal of recirculation in a trickling filter, which is to maximize the interaction between the wastewater and the biological treatment layer. The focus is on enhancing biological efficiency, making option C the correct choice.