Tennessee Wastewater Operator Practice Exam

What happens to substances that are soluble and non-biodegradable during wastewater treatment?

1. They are completely removed from the system

2. They are oxidized into less harmful compounds

3. They are discharged into the final effluent

4. They are transformed into sludge

The correct answer is: They are discharged into the final effluent

When substances that are soluble and non-biodegradable enter a wastewater treatment system, they often resist degradation processes that are typically effective in breaking down organic materials. As a result, these substances do not undergo significant transformation during treatment. Instead, they remain in their original, dissolved form. In the context of the treatment process, soluble non-biodegradable substances can pass through the various stages of treatment, including primary and secondary treatment, without being effectively removed. Consequently, they end up in the final effluent—the treated water that is discharged from the treatment facility. This is concerning from an environmental perspective, as these substances may pose risks to aquatic life and ecosystems when released into waterways. This contrasts with other types of substances that are either biodegradable or insoluble, which may be removed, oxidized, or transformed into sludge. Therefore, recognizing the behavior of soluble non-biodegradable substances is crucial for understanding the effectiveness of a wastewater treatment process and the potential impacts of treated effluent.