California Wastewater Treatment Operator Practice Exam 2025 - Free Wastewater Treatment Operator Practice Questions and Study Guide

The function of an aeration tank in wastewater treatment is primarily to promote the growth of bacteria that consume organic material. During the aeration process, air is introduced into the tank, which supplies the necessary oxygen for aerobic bacteria to thrive. These microorganisms play a crucial role in breaking down organic pollutants present in the wastewater, converting them into carbon dioxide, water, and new microbial biomass. This biological process is essential in reducing the biochemical oxygen demand (BOD) of the wastewater, ensuring that the treated effluent meets environmental standards before being discharged or further polished.

In contrast, other options do not accurately describe the role of the aeration tank. Heavy metal removal typically involves different treatment methods such as chemical precipitation or advanced filtration, which are not functions of the aeration tank. Filtering out larger debris is a task handled by preliminary treatment processes like screening and grit removal. Cooling wastewater before treatment is usually not a primary function of the aeration tank, as temperature management is typically addressed in separate treatment stages or systems, if needed.