What type of contaminants may be removed during tertiary treatment?

During tertiary treatment, the primary goal is to further purify effluent that has already undergone primary and secondary treatment processes. This phase targets the removal of remaining contaminants that may pose risks to human health and the environment. One of the main focuses in tertiary treatment is the removal of pathogens, which are disease-causing microorganisms, and remaining solids, which can include those that were not fully settled or filtered out in previous stages.

In addition to removing pathogens, tertiary treatment can also improve the clarity and quality of the effluent, making it suitable for reuse or discharge into sensitive environments. This stage often employs advanced filtration methods, disinfection processes, and chemical treatments designed to ensure that any potential health risks are mitigated.

The other options do not fully encompass the broader scope of what occurs during tertiary treatment. While heavy metals and plastics may be addressed in certain advanced treatment processes, they are not the primary focus of tertiary treatment. Nutrients and chemical pollutants are important contaminants that may be removed at various stages, but they do not exclusively define the objectives during this advanced stage.