Which treatment variant is designed to remove nutrients and pathogens beyond secondary treatment?

• A. Septic Tanks
• B. Wetland-Based Treatment Systems
• C. Tertiary Sewage Treatment
• D. Secondary Sewage Treatment

Answer: (C)

The main idea is that after secondary treatment, the extra step aimed at cleaning up what secondary miss is called tertiary treatment. Secondary treatment reduces organic matter and solids but often leaves nutrients like nitrogen and phosphorus and some pathogens. Tertiary sewage treatment specifically targets these remaining issues, using processes to remove nutrients and to disinfect the water so it meets higher standards for discharge or reuse. That’s why this variant is described as designed to remove nutrients and pathogens beyond secondary treatment. Septic tanks are an early, primary step that mainly settles solids and begins digestion, not a polishing stage beyond secondary. Wetland-based systems can provide additional polishing and can remove some nutrients and pathogens, but the standard term for the beyond-secondary polishing focused on nutrients and pathogens is tertiary sewage treatment.