What is the main goal of secondary treatment in wastewater management?

The main goal of secondary treatment in wastewater management is to convert organics to settleable solids. This stage primarily focuses on biologically breaking down organic matter that remains after primary treatment. During secondary treatment, microorganisms are used to metabolize organic pollutants, resulting in the formation of biomass (sludge) that can be easily removed from the wastewater. This process significantly reduces the concentration of organic material, helping to improve the overall quality of the treated water before it is discharged or further processed.

Secondary treatment often employs methods such as activated sludge processes, trickling filters, or biofilm reactors, which promote the growth of bacteria that consume the organic matter. The eventual formation of settleable solids enables easier separation from treated effluent, facilitating further purification and compliance with environmental discharge standards.

While other options address different aspects of wastewater treatment — such as removing floating materials, using aquatic plants, or aeration processes — they do not specifically capture the essence of what secondary treatment aims to achieve.