What type of contaminants are targeted during tertiary treatment?

Tertiary treatment is the final stage in the wastewater treatment process that specifically aims to remove any remaining contaminants after the primary and secondary treatment phases. During these initial stages, larger solids and organic matter are eliminated, and biological processes reduce the concentration of biodegradable organic substances and some nutrients. However, tertiary treatment focuses on polishing the effluent by targeting residual contaminants such as remaining nutrients (phosphorus and nitrogen) and other pollutants that may still be present in the treated wastewater.

This stage often employs advanced treatment methods such as filtration, advanced oxidation, chemical coagulation, and nutrient removal techniques. By addressing these remaining contaminants, tertiary treatment helps ensure the water meets stringent regulatory standards for discharge or reuse, protecting environmental and public health.

This differentiates it from the other types of contaminants mentioned in the other options. For instance, while bacteria and viruses are typically targeted in secondary treatment, the goal of tertiary treatment is to achieve higher levels of purity that bacteria and viruses would not solely determine. Similarly, inorganic pollutants and heavy metals might be partially addressed in earlier stages, but tertiary treatment focuses on final polishing, addressing the full spectrum of remaining contaminants and nutrients in the effluent.