What is the purpose of the secondary treatment in wastewater management?

The purpose of secondary treatment in wastewater management is to break down organic matter using bacteria. This step is essential in the wastewater treatment process, as it focuses on reducing the biochemical oxygen demand (BOD) of the wastewater by utilizing microorganisms to decompose organic pollutants. During secondary treatment, bacteria feed on the organic material, converting it into biomass, carbon dioxide, and water. This process significantly improves the quality of the effluent being discharged into the environment.

In contrast to other options, secondary treatment is not interested in the initial removal of large objects or performing disinfection, which are typically parts of primary treatment and tertiary treatment, respectively. Additionally, filtering out residual contaminants does not characterize secondary treatment; that role is generally handled in later stages. Therefore, the primary function of secondary treatment is focused on the biological breakdown of organic matter, making it a crucial step in achieving cleaner and safer wastewater for discharge or further processing.