Which term describes wastewater not yet treated that enters a treatment facility?

The term that describes wastewater not yet treated that enters a treatment facility is "raw influent." This terminology is used because it specifies the state of the wastewater as it arrives at the treatment plant, indicating that it has not undergone any treatment processes and is in its original, unprocessed form. Using the term "raw" emphasizes the need for treatment to remove contaminants before the water can be safely released back into the environment or used for other purposes.

In contrast, "primary effluent," "final effluent," and "untreated influent" refer to different stages or types of wastewater within the treatment process. Primary effluent typically signifies wastewater that has gone through primary treatment, where some of the solids and organic matter have been removed. Final effluent indicates treated wastewater that has completed the entire treatment process and meets discharge standards. The term "untreated influent" could imply raw wastewater but is less commonly used and may lead to confusion, as "raw influent" is the more widely accepted terminology in the context of wastewater treatment processes.