What is the main goal of tertiary municipal wastewater treatment?

The main goal of tertiary municipal wastewater treatment is to provide advanced treatment to remove remaining contaminants that were not fully addressed by primary and secondary treatments. This includes the reduction of biochemical oxygen demand (BOD) and nutrients such as nitrogen and phosphorus.

In tertiary treatment processes, various methods, including chemical, biological, or physical treatments, are employed to achieve very high-quality effluent. This is particularly important to prevent eutrophication in receiving water bodies and to ensure that the water is safe for reuse or discharge into the environment.

While other choices describe processes that occur in earlier stages of wastewater treatment, such as the removal of grit and sand, settling of solids, and disinfection, they do not encompass the comprehensive goal of tertiary treatment, which focuses on nutrient removal and enhancing the overall quality of the water to support environmental sustainability and public health.