What is the principal aim of the tertiary treatment process?

The principal aim of the tertiary treatment process is to achieve compliance with discharge standards. This stage follows primary and secondary treatment processes and focuses on removing remaining contaminants, including nutrients (such as phosphorus and nitrogen), dissolved solids, and pathogens, to ensure that the treated water meets the regulatory requirements for discharge into the environment or for reuse.

Tertiary treatment often employs advanced filtration methods, chemical treatment, or additional biological processes to enhance the quality of effluent to acceptable levels for specific uses, whether that be for safe discharge into water bodies or for reuse in irrigation or industrial processes. Thus, the emphasis on meeting stringent discharge standards aligns directly with the objectives of tertiary treatment.

The other options represent aspects of wastewater treatment that are more characteristic of earlier treatment stages or specific processes rather than the overarching goal of tertiary treatment, which is primarily regulatory compliance.