Which of the following describes tertiary treatment for wastewater?

Tertiary treatment for wastewater is an advanced treatment process that follows primary and secondary treatment stages. It is designed to further purify wastewater, making it suitable for discharge into the environment or for reuse. The process typically involves enhanced filtration, chemical treatment, and disinfection methods to remove remaining contaminants, including nutrients, pathogens, and suspended solids.

The correct answer encompasses the key components of tertiary treatment, which often include chemical coagulation, sedimentation, and filtration. Chemical coagulation helps to aggregate pollutants and particulate matter, making it easier to remove them during sedimentation. Filtration then further polishes the water, ensuring that very fine solids and other contaminants are captured prior to any disinfection processes. This comprehensive approach greatly improves the quality of treated wastewater, allowing for higher re-use potential and reduced environmental impact.

In contrast, the other options describe different stages or aspects of wastewater treatment. Initial filtration and screening are typically part of primary treatment. Aeration and nutrient removal are associated with secondary treatment, which primarily focuses on biological processes. Solids digestion and stabilization relate to the treatment of sludge rather than the wastewater itself. Understanding these distinctions is crucial for recognizing the role and process of tertiary treatment in the overall wastewater management system.