What is the main characteristic of tertiary (advanced) treatment?

The main characteristic of tertiary treatment, also known as advanced treatment, is its goal to significantly enhance the quality of wastewater, often to the point where it can be reused or safely discharged into sensitive environments. This treatment phase focuses primarily on chemical processes that target remaining contaminants, including those that conventional treatment methods may not eliminate effectively.

Chemical refinement to drinking water standards involves the use of advanced oxidation, filtration systems, and sometimes additional disinfection processes. These methods are designed to remove dissolved inorganic and organic substances, pathogens, and other trace contaminants that may still be present after primary and secondary treatment stages. Achieving drinking water standards means that the water is treated to such a high degree of purity that it meets or exceeds the regulatory limits set for potable water.

In contrast, other options address different functionalities in wastewater treatment. The physical removal of solids primarily relates to primary treatment processes. The biological reduction of nutrients pertains to secondary treatment, focusing on the use of microbial processes to remove nitrogen and phosphorus. Grit and sand removal is a preliminary process that takes place before biological treatment. Each of these treatments plays a role in the overall wastewater treatment process, but they do not encapsulate the specialized nature of tertiary treatment as effectively as the refinement to drinking water standards does.