Secondary treatment of wastewater is accomplished by:

The secondary treatment of wastewater primarily involves the process where microorganisms are utilized to consume dissolved organic matter. This step is crucial in reducing the organic load of the wastewater, allowing for a more purified effluent. During secondary treatment, typically through biological processes, bacteria and other microorganisms break down organic pollutants, converting them into biomass and other byproducts. This not only helps in cleaning the water but also aids in nutrient removal, making it a fundamental stage in wastewater treatment.

The primary goal of secondary treatment is to enhance the quality of effluent by significantly lowering the concentration of organic matter and nutrients, completing or complementing the physical removal that typically occurs in the primary treatment phase, which focuses more on solids and large objects. Subsequent processes like disinfection may be performed afterward to eliminate pathogens, but the key function of secondary treatment revolves around the biological degradation of organic materials.