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

The three main stages of wastewater treatment are indeed primary treatment, secondary treatment, and tertiary treatment.

In primary treatment, the focus is on the physical separation of solids from the liquid waste stream. This is typically achieved through processes like screening and sedimentation, allowing large solids and particulates to settle out.

Secondary treatment builds upon this foundation by employing biological processes to further reduce the organic matter in the wastewater. This stage usually involves the use of microorganisms that consume organic materials, thereby significantly improving the quality of the water.

Tertiary treatment is the final stage, which aims to remove remaining contaminants, including nutrients like nitrogen and phosphorus, as well as pathogens. This stage may involve advanced filtration, chemical treatment, or other methods to ensure that the treated water meets the required quality standards before it is released back into the environment or reused.

Understanding these three stages is fundamental to grasping how municipal wastewater treatment systems operate, as each stage serves a specific purpose in reducing pollution and safeguarding public health.