What are the three main processes in wastewater treatment?

The three main processes in wastewater treatment are primary treatment, secondary treatment, and tertiary treatment. Each of these stages plays a crucial role in removing contaminants from wastewater to protect public health and the environment.

Primary treatment involves the physical separation of solids from liquids through processes such as sedimentation. In this stage, larger particles settle to the bottom, while floating materials are removed from the surface. This step primarily focuses on eliminating solid waste and reducing the load on subsequent treatment processes.

Secondary treatment follows, which is primarily a biological process aimed at breaking down organic matter. In this stage, microorganisms are introduced to the wastewater to consume organic pollutants. This step is essential for significantly reducing the biochemical oxygen demand (BOD) of the effluent, making it safer for discharge into natural bodies of water or for further treatment.

Tertiary treatment is the final stage, which further polishes the wastewater, removing any remaining contaminants that were not addressed during the primary and secondary phases. This may include advanced filtration, nutrient removal, or disinfection processes such as chlorination or UV irradiation to eliminate pathogens, ensuring the treated water meets regulatory standards before it is released back into the environment or reused.

The other choices focus on specific methods or types of treatment that do not encompass the full