What is the primary purpose of an aeration tank in wastewater treatment?

The primary purpose of an aeration tank in wastewater treatment is to provide oxygen for the growth of microorganisms. This aeration process is essential because these microorganisms play a crucial role in breaking down organic matter present in the wastewater. By supplying oxygen, the aeration tank creates an environment conducive to aerobic digestion, where these microorganisms metabolize the organic pollutants, converting them into simpler compounds, including carbon dioxide, water, and biomass. This biological treatment is fundamental for reducing the biochemical oxygen demand (BOD) and ensuring that the effluent released into the environment meets regulatory standards.

The other options focus on tasks that are not the primary function of an aeration tank, such as filtering solid waste, measuring sewage flow, or collecting sludge, which are typically associated with different stages or components of the wastewater treatment process.