Which of the following is part of the collections system?

• A. Digester
• B. Interceptor
• C. Lagoon
• D. Clarifier

Answer: (B)

The main idea here is recognizing which components belong to the wastewater collections system—the network that gathers and conveys sewage toward the treatment facility. An interceptor is a large-diameter sewer that collects flow from smaller sewers and moves it toward the treatment plant. This is exactly the type of conveyance equipment that defines the collections system, since its purpose is to transport wastewater rather than treat or store it.

A digester, lagoon, and clarifier, on the other hand, are associated with treatment: a digester breaks down organic matter anaerobically, a lagoon serves as a treatment or storage pond, and a clarifier removes solids as part of the treatment process. So they belong to the treatment side rather than the collection network.