Which of the following are the three main stages of municipal wastewater treatment?

The three main stages of municipal wastewater treatment are classified as primary treatment, secondary treatment, and tertiary treatment.

Primary treatment focuses on the physical removal of solids from wastewater. This typically involves processes such as screening to remove large debris and sedimentation that allows heavier solids to settle out.

Secondary treatment, on the other hand, addresses the organic matter still present after primary treatment. This stage primarily involves biological processes, where microorganisms degrade organic pollutants. Methods like activated sludge systems or trickling filters are commonly used here to further reduce the biochemical oxygen demand (BOD) of the wastewater.

Tertiary treatment is the final stage, which aims to polish the effluent from the secondary treatment to make it suitable for discharge or reuse. This can involve advanced filtration, nutrient removal, or disinfection processes (like chlorination or UV treatment) depending on the desired quality of the treated water.

Understanding these stages is crucial as they represent the structured approach to achieving effective wastewater management, ensuring public health and environmental protection.