California Wastewater Treatment Operator Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The main stages of wastewater treatment are correctly identified as preliminary treatment, primary treatment, secondary treatment, and tertiary treatment. This structured process is essential for effectively removing contaminants from wastewater before it is released into the environment or reused.

Preliminary treatment involves the initial removal of large debris and solids that could interfere with subsequent treatment processes. This is typically done through screening and grit removal.

Primary treatment follows, where the wastewater is allowed to settle in large tanks, leading to the separation of solids from liquids. This stage focuses on removing a significant portion of suspended solids and biochemical oxygen demand (BOD).

Secondary treatment is where biological processes come into play, utilizing microorganisms to further degrade organic matter in the wastewater. This stage is critical for reducing contaminants that remain after primary treatment.

Lastly, tertiary treatment is the final stage, aimed at polishing the effluent through additional filtration, disinfection, or advanced treatment methods. This ensures that the treated water meets the necessary standards before it is discharged or reused.

Each of these stages builds on the previous one, contributing to the overall effectiveness of wastewater treatment and protecting public health and the environment.