Basic Wastewater Operator Practice Exam

What coats granular filter media with a biological slime used to filter wastewater?

1. Biological slime composed of soluble BOD and ammonia

2. Detritus

3. Grease

4. Clay

The correct answer is: Biological slime composed of soluble BOD and ammonia

The coating on granular filter media, referred to as biological slime, plays a crucial role in the wastewater treatment process. This biological slime is primarily composed of microorganisms that form a biofilm on the filter media. These microorganisms thrive on soluble biochemical oxygen demand (BOD) and ammonia present in the wastewater, utilizing these compounds as a food source. As wastewater passes through the granular filter media, the biological slime captures and breaks down organic pollutants, effectively removing contaminants from the water. This process is known as biological filtration and is essential in enhancing the efficiency of the filtration system by facilitating the degradation of organic compounds, thereby improving water quality. The other options, such as detritus, grease, and clay, do not represent a biological slime that specifically utilizes soluble BOD and ammonia for the filtration process. Detritus generally refers to decomposing organic matter and small particles, grease pertains to fatty substances that can impair treatment processes, and clay consists of fine soil particles that can clog filters rather than form the beneficial biofilm. Overall, the biological slime formed from the interaction of microorganisms with soluble BOD and ammonia is what makes this option the correct answer.